netsurf/desktop/textarea.c

/*
 * Copyright 2006 John-Mark Bell <jmb@netsurf-browser.org>
 * Copyright 2009 Paul Blokus <paul_pl@users.sourceforge.net>
 *
 * This file is part of NetSurf, http://www.netsurf-browser.org/
 *
 * NetSurf is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; version 2 of the License.
 *
 * NetSurf is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

/** \file
 * Single/Multi-line UTF-8 text area (implementation)
 */

#include <stdint.h>
#include <string.h>
#include "css/utils.h"
#include "desktop/mouse.h"
#include "desktop/textarea.h"
#include "desktop/textinput.h"
#include "desktop/plotters.h"
#include "desktop/scrollbar.h"
#include "render/font.h"
#include "utils/log.h"
#include "utils/utf8.h"
#include "utils/utils.h"

#define CARET_COLOR 0x0000FF

static plot_style_t pstyle_stroke_caret = {
    .stroke_type = PLOT_OP_TYPE_SOLID,
    .stroke_colour = CARET_COLOR,
    .stroke_width = 1,
};

struct line_info {
	unsigned int b_start;		/**< Byte offset of line start */
	unsigned int b_length;		/**< Byte length of line */
};
struct textarea_drag {
	textarea_drag_type type;
	union {
		struct scrollbar* scrollbar;
	} data;
};

struct textarea_utf8 {
	char *data;		/**< UTF-8 text */
	unsigned int alloc;	/**< Size of allocated text */
	unsigned int len;	/**< Length of text, in bytes */
	unsigned int utf8_len;	/**< Length of text, in characters without
				 *   trailing NULL */
};

struct textarea {

	int scroll_x, scroll_y;		/**< scroll offsets for the textarea */

	struct scrollbar *bar_x;	/**< Horizontal scroll. */
	struct scrollbar *bar_y;	/**< Vertical scroll. */

	unsigned int flags;		/**< Textarea flags */
	int vis_width;			/**< Visible width, in pixels */
	int vis_height;			/**< Visible height, in pixels */

	int pad_top;		/**< Top padding, inside border, in pixels */
	int pad_right;		/**< Right padding, inside border, in pixels */
	int pad_bottom;		/**< Bottom padding, inside border, in pixels */
	int pad_left;		/**< Left padding, inside border, in pixels */

	int border_width;	/**< Border width, in pixels */
	colour border_col;	/**< Border colour */

	plot_font_style_t fstyle;	/**< Text style, inc. textarea bg col */
	plot_font_style_t sel_fstyle;	/**< Selected text style */

	struct textarea_utf8 text;	/**< Textarea text content */
#define PASSWORD_REPLACEMENT "\xe2\x80\xa2"
	struct textarea_utf8 password;	/**< Text for obscured display */

	struct textarea_utf8 *show;	/**< Points at .text or .password */

	struct {
		int line;		/**< Line caret is on */
		int char_off;		/**< Character index of caret on line */
	} caret_pos;

	int caret_x;			/**< cached X coordinate of the caret */
	int caret_y;			/**< cached Y coordinate of the caret */

	int sel_start;	/**< Character index of sel start (inclusive) */
	int sel_end;	/**< Character index of sel end (exclusive) */

	int h_extent;			/**< Width of content in px */
	int v_extent;			/**< Height of content in px */
	int line_count;			/**< Count of lines */
#define LINE_CHUNK_SIZE 16
	struct line_info *lines;	/**< Line info array */
	int line_height;		/**< Line height obtained from style */

	/** Callback function for messages to client */
	textarea_client_callback callback;

	void *data;			/**< Client data for callback */

	int drag_start_char;		/**< Character index of drag start */
	struct textarea_drag drag_info;	/**< Drag information */
};



/**
 * Normalises any line endings within the text, replacing CRLF or CR with
 * LF as necessary. If the textarea is single line, then all linebreaks are
 * converted into spaces.
 *
 * \param ta		Text area
 * \param b_start	Byte offset to start at
 * \param b_len		Byte length to check
 */
static void textarea_normalise_text(struct textarea *ta,
		unsigned int b_start, unsigned int b_len)
{
	bool multi = (ta->flags & TEXTAREA_MULTILINE) ? true : false;
	unsigned int index;

	/* Remove CR characters. If it's a CRLF pair delete the CR, or replace
	 * CR with LF otherwise.
	 */
	for (index = 0; index < b_len; index++) {
		if (ta->text.data[b_start + index] == '\r') {
			if (b_start + index + 1 <= ta->text.len &&
					ta->text.data[b_start + index + 1] ==
							'\n') {
				ta->text.len--;
				ta->text.utf8_len--;
				memmove(ta->text.data + b_start + index,
						ta->text.data + b_start +
								index + 1,
						ta->text.len - b_start - index);
			}
			else
				ta->text.data[b_start + index] = '\n';
		}
		/* Replace newlines with spaces if this is a single line
		 * textarea.
		 */
		if (!multi && (ta->text.data[b_start + index] == '\n'))
			ta->text.data[b_start + index] = ' ';
	}

}


/**
 * Selects a character range in the textarea and redraws it
 *
 * \param ta		Text area
 * \param c_start	First character (inclusive)
 * \param c_end		Last character (exclusive)
 * \return 		true on success false otherwise
 */
static bool textarea_select(struct textarea *ta, int c_start, int c_end)
{
	int swap;
	struct textarea_msg msg;

	/* Ensure start is the beginning of the selection */
	if (c_start > c_end) {
		swap = c_start;
		c_start = c_end;
		c_end = swap;
	}

	if (ta->sel_start == c_start && ta->sel_end == c_end)
		return true;

	ta->sel_start = c_start;
	ta->sel_end = c_end;

	msg.ta = ta;
	msg.type = TEXTAREA_MSG_REDRAW_REQUEST;
	msg.data.redraw.x0 = 0;
	msg.data.redraw.y0 = 0;
	msg.data.redraw.x1 = ta->vis_width;
	msg.data.redraw.y1 = ta->vis_height;

	ta->callback(ta->data, &msg);

	return true;
}


/**
 * Selects a text fragment, relative to current caret position.
 *
 * \param ta  Text area
 * \return True on success, false otherwise
 */
static bool textarea_select_fragment(struct textarea * ta)
{
	int caret_pos, sel_start = 0, sel_end = 0, index;
	size_t b_start, b_end;

	/* Fragment separators must be suitable for URLs and ordinary text */
	static const char *sep = " /:.\r\n";

	caret_pos = textarea_get_caret(ta);
	if (caret_pos < 0) {
		return false;
	}

	/* Compute byte offset of caret position */
	for (b_start = 0, index = 0; index < caret_pos;
			b_start = utf8_next(ta->show->data, ta->show->len,
					    b_start),
			index++) {
		/* Cache the character offset of the last separator */
		if (strchr(sep, ta->show->data[b_start]) != NULL) {
			/* Add one to start to skip over separator */
			sel_start = index + 1;
		}
	}

	/* Search for next separator, if any */
	for (b_end = b_start; b_end < ta->show->len;
			b_end = utf8_next(ta->show->data, ta->show->len,
					  b_end),
			index++) {
		if (strchr(sep, ta->show->data[b_end]) != NULL) {
			sel_end = index;
			break;
		}
	}

	if (sel_start < sel_end) {
		textarea_select(ta, sel_start, sel_end);
		return true;
	}

	return false;
}


/**
 * Scrolls a textarea to make the caret visible (doesn't perform a redraw)
 *
 * \param ta	The text area to be scrolled
 * \return 	true if textarea was scrolled false otherwise
 */
static bool textarea_scroll_visible(struct textarea *ta)
{
	int x0, x1, y0, y1; /* area we want caret inside */
	int x, y; /* caret pos */
	int xs = ta->scroll_x;
	int ys = ta->scroll_y;
	int vis;
	bool scrolled = false;

	if (ta->caret_pos.char_off == -1)
		return false;

	x0 = ta->border_width + ta->pad_left;
	x1 = ta->vis_width - (ta->border_width + ta->pad_right);

	/* Adjust scroll pos for reduced extents */
	vis = ta->vis_width - 2 * ta->border_width;
	if (ta->h_extent - xs < vis)
		xs -= vis - (ta->h_extent - xs);

	/* Get caret pos on screen */
	x = ta->caret_x - xs;

	/* scroll as required */
	if (x < x0)
		xs += (x - x0);
	else if (x > x1)
		xs += (x - x1);

	if (ta->bar_x == NULL && ta->scroll_x != 0 &&
			ta->flags & TEXTAREA_MULTILINE) {
		/* Scrollbar removed, set to zero */
		ta->scroll_x = 0;
		scrolled = true;

	} else if (xs != ta->scroll_x) {
		/* Scrolled, set new pos. */
		if (ta->bar_x != NULL) {
			scrollbar_set(ta->bar_x, xs, false);
			xs = scrollbar_get_offset(ta->bar_x);
			if (xs != ta->scroll_x) {
				ta->scroll_x = xs;
				scrolled = true;
			}

		} else if (!(ta->flags & TEXTAREA_MULTILINE)) {
			ta->scroll_x = xs;
			scrolled = true;

		}
	}

	/* check and change vertical scroll */
	if (ta->flags & TEXTAREA_MULTILINE) {
		y0 = 0;
		y1 = ta->vis_height - 2 * ta->border_width -
				ta->pad_top - ta->pad_bottom;

		/* Adjust scroll pos for reduced extents */
		vis = ta->vis_height - 2 * ta->border_width;
		if (ta->v_extent - xs < vis)
			xs -= vis - (ta->v_extent - xs);

		/* Get caret pos on screen */
		y = ta->caret_y - ys;

		/* scroll as required */
		if (y < y0)
			ys += (y - y0);
		else if (y > y1)
			ys += (y - y1);

		if (ys != ta->scroll_y && ta->bar_y != NULL) {
			/* Scrolled, set new pos. */
			scrollbar_set(ta->bar_y, ys, false);
			ys = scrollbar_get_offset(ta->bar_y);
			if (ys != ta->scroll_y) {
				ta->scroll_y = ys;
				scrolled = true;
			}

		} else if (ta->bar_y == NULL && ta->scroll_y != 0) {
			/* Scrollbar removed, set to zero */
			ta->scroll_y = 0;
			scrolled = true;
		}
	}

	return scrolled;
}


/**
 * Callback for scrollbar widget.
 */
static void textarea_scrollbar_callback(void *client_data,
		struct scrollbar_msg_data *scrollbar_data)
{
	struct textarea *ta = client_data;
	struct textarea_msg msg;

	switch(scrollbar_data->msg) {
	case SCROLLBAR_MSG_MOVED:
		/* Scrolled; redraw everything */
		ta->scroll_x = scrollbar_get_offset(ta->bar_x);
		ta->scroll_y = scrollbar_get_offset(ta->bar_y);

		msg.ta = ta;
		msg.type = TEXTAREA_MSG_REDRAW_REQUEST;
		msg.data.redraw.x0 = 0;
		msg.data.redraw.y0 = 0;
		msg.data.redraw.x1 = ta->vis_width;
		msg.data.redraw.y1 = ta->vis_height;

		ta->callback(ta->data, &msg);

		if (!(ta->flags & TEXTAREA_INTERNAL_CARET)) {
			/* Tell client where caret should be placed */
			msg.ta = ta;
			msg.type = TEXTAREA_MSG_MOVED_CARET;
			msg.data.caret.hidden = false;
			msg.data.caret.x = ta->caret_x - ta->scroll_x;
			msg.data.caret.y = ta->caret_y - ta->scroll_y;
			msg.data.caret.height = ta->line_height;

			ta->callback(ta->data, &msg);
		}
		break;

	case SCROLLBAR_MSG_SCROLL_START:
		ta->drag_info.type = TEXTAREA_DRAG_SCROLLBAR;
		ta->drag_info.data.scrollbar = scrollbar_data->scrollbar;

		msg.ta = ta;
		msg.type = TEXTAREA_MSG_DRAG_REPORT;
		msg.data.drag = ta->drag_info.type;

		/* Tell client we're handling a drag */
		ta->callback(ta->data, &msg);
		break;

	case SCROLLBAR_MSG_SCROLL_FINISHED:
		ta->drag_info.type = TEXTAREA_DRAG_NONE;

		msg.ta = ta;
		msg.type = TEXTAREA_MSG_DRAG_REPORT;
		msg.data.drag = ta->drag_info.type;

		/* Tell client we finished handling the drag */
		ta->callback(ta->data, &msg);
		break;

	default:
		break;
	}
}



/**
 * Reflow a text area from the given line onwards
 *
 * \param ta Text area to reflow
 * \param start Line number to begin reflow on
 * \return true on success false otherwise
 */
static bool textarea_reflow(struct textarea *ta, unsigned int start)
{
	char *text;
	unsigned int len;
	size_t b_off;
	int x;
	char *space, *para_end;
	unsigned int line; /* line count */
	unsigned int scroll_lines;
	int avail_width;
	int h_extent; /* horizontal extent */
	int v_extent; /* vertical extent */
	bool restart;

	if (ta->lines == NULL) {
		ta->lines =
			malloc(LINE_CHUNK_SIZE * sizeof(struct line_info));
		if (ta->lines == NULL) {
			LOG(("malloc failed"));
			return false;
		}
	}

	if (!(ta->flags & TEXTAREA_MULTILINE)) {
		/* Single line */
		int w = ta->vis_width - 2 * ta->border_width -
				ta->pad_left - ta->pad_right;

		if (ta->flags & TEXTAREA_PASSWORD &&
				ta->text.utf8_len != ta->password.utf8_len) {
			/* Make password-obscured text have same number of
			 * characters as underlying text */
			unsigned int c, b;
			int diff = ta->text.utf8_len - ta->password.utf8_len;
			unsigned int rep_len = sizeof(PASSWORD_REPLACEMENT) - 1;
			unsigned int b_len = ta->text.utf8_len * rep_len + 1;

			if (diff > 0 && b_len > ta->password.alloc) {
				/* Increase password alloaction */
				char *temp = realloc(ta->password.data,
						b_len + 64);
				if (temp == NULL) {
					LOG(("realloc failed"));
					return false;
				}

				ta->password.data = temp;
				ta->password.alloc = b_len + 64;
			}

			b_len--;
			for (c = 0; c < b_len; c += rep_len) {
				for (b = 0; b < rep_len; b++) {
					ta->password.data[c + b] =
							PASSWORD_REPLACEMENT[b];
				}
			}
			ta->password.data[b_len] = '\0';
			ta->password.len = b_len + 1;
			ta->password.utf8_len = ta->text.utf8_len;
		}

		ta->lines[0].b_start = 0;
		ta->lines[0].b_length = ta->show->len - 1;

		nsfont.font_width(&ta->fstyle, ta->show->data,
				ta->show->len, &x);

		if (x > w)
			w = x;

		ta->h_extent = w + ta->pad_left + ta->pad_right;
		ta->line_count = 1;

		return true;
	}

	/* Find max number of lines before vertical scrollbar is required */
	scroll_lines = (ta->vis_height - 2 * ta->border_width -
				ta->pad_top - ta->pad_bottom) /
				ta->line_height;

	if ((signed)start > ta->line_count)
		start = 0;
	/** \todo pay attention to start param, for now force start at zero */
	start = 0;

	do {
		/* Set line count to start point */
		line = start;

		/* Find available width */
		avail_width = ta->vis_width - 2 * ta->border_width -
				ta->pad_left - ta->pad_right;
		if (avail_width < 0)
			avail_width = 0;
		h_extent = avail_width;

		if (ta->text.len == 1) {
			/* Handle empty textarea */
			assert(ta->text.data[0] == '\0');
			ta->lines[line].b_start = 0;
			ta->lines[line++].b_length = 1;
		}

		restart = false;
		for (len = ta->text.len - 1, text = ta->text.data; len > 0;
				len -= b_off, text += b_off) {

			/* Find end of paragraph */
			for (para_end = text; para_end < text + len;
					para_end++) {
				if (*para_end == '\n')
					break;
			}

			/* Wrap current line in paragraph */
			nsfont.font_split(&ta->fstyle, text, para_end - text,
					avail_width, &b_off, &x);
			/* b_off now marks space, or end of paragraph */

			if (x > h_extent) {
				h_extent = x;
			}
			if (x > avail_width && ta->bar_x == NULL) {
				/* We need to insert a horizontal scrollbar */
				int w = ta->vis_width - 2 * ta->border_width;
				if (!scrollbar_create(true, w, w, w,
						ta, textarea_scrollbar_callback,
						&(ta->bar_x)))
					return false;
				if (ta->bar_y != NULL)
					scrollbar_make_pair(ta->bar_x,
							ta->bar_y);
				ta->pad_bottom += SCROLLBAR_WIDTH;

				/* Find new max visible lines */
				scroll_lines = (ta->vis_height -
						2 * ta->border_width -
						ta->pad_top - ta->pad_bottom) /
						ta->line_height;
			}

			if (line > 0 && line % LINE_CHUNK_SIZE == 0) {
				struct line_info *temp = realloc(ta->lines,
						(line + LINE_CHUNK_SIZE) *
						sizeof(struct line_info));
				if (temp == NULL) {
					LOG(("realloc failed"));
					return false;
				}

				ta->lines = temp;
			}

			if (para_end == text + b_off && *para_end == '\n') {
				/* Not found any spaces to wrap at, and we
				 * have a newline char */
				ta->lines[line].b_start = text - ta->text.data;
				ta->lines[line++].b_length = para_end - text;

				/* Jump newline */
				b_off++;

				if (len - b_off == 0) {
					/* reached end of input;
					 * add last line */
					ta->lines[line].b_start = text +
							b_off - ta->text.data;
					ta->lines[line++].b_length = 0;
				}

				if (line > scroll_lines && ta->bar_y == NULL)
					break;

				continue;

			} else if (len - b_off > 0) {
				/* soft wraped, find last space (if any) */
				for (space = text + b_off; space > text;
						space--) {
					if (*space == ' ')
						break;
				}

				if (space != text)
					b_off = space + 1 - text;
			}

			ta->lines[line].b_start = text - ta->text.data;
			ta->lines[line++].b_length = b_off;

			if (line > scroll_lines && ta->bar_y == NULL)
				break;
		}

		if (h_extent <= avail_width && ta->bar_x != NULL) {
			/* We need to remove a horizontal scrollbar */
			scrollbar_destroy(ta->bar_x);
			ta->bar_x = NULL;
			ta->pad_bottom -= SCROLLBAR_WIDTH;

			/* Find new max visible lines */
			scroll_lines = (ta->vis_height - 2 * ta->border_width -
					ta->pad_top - ta->pad_bottom) /
					ta->line_height;
		}

		if (line > scroll_lines && ta->bar_y == NULL) {
			/* Add vertical scrollbar */
			int h = ta->vis_height - 2 * ta->border_width;
			if (!scrollbar_create(false, h, h, h,
					ta, textarea_scrollbar_callback,
					&(ta->bar_y)))
				return false;
			if (ta->bar_x != NULL)
				scrollbar_make_pair(ta->bar_x,
						ta->bar_y);
			ta->pad_right += SCROLLBAR_WIDTH;
			restart = true;

		} else if (line <= scroll_lines && ta->bar_y != NULL) {
			/* Remove vertical scrollbar */
			scrollbar_destroy(ta->bar_y);
			ta->bar_y = NULL;
			ta->pad_right -= SCROLLBAR_WIDTH;
			restart = true;
		}
	} while (restart);

	h_extent += ta->pad_left + ta->pad_right -
			(ta->bar_y != NULL ? SCROLLBAR_WIDTH : 0);
	v_extent = line * ta->line_height + ta->pad_top +
				ta->pad_bottom -
				(ta->bar_x != NULL ? SCROLLBAR_WIDTH : 0);

	if (ta->bar_x != NULL) {
		/* Set horizontal scrollbar extents */
		int w = ta->vis_width - 2 * ta->border_width -
				(ta->bar_y != NULL ? SCROLLBAR_WIDTH : 0);
		scrollbar_set_extents(ta->bar_x, w, w, h_extent);
	}

	if (ta->bar_y != NULL) {
		/* Set vertical scrollbar extents */
		int h = ta->vis_height - 2 * ta->border_width;
		scrollbar_set_extents(ta->bar_y, h,
				h - (ta->bar_x != NULL ? SCROLLBAR_WIDTH : 0),
				v_extent);
	}

	ta->h_extent = h_extent;
	ta->v_extent = v_extent;
	ta->line_count = line;

	return true;
}


/**
 * get byte/character offset from the beginning of the text for some coordinates
 *
 * \param ta		Text area
 * \param x		X coordinate
 * \param y		Y coordinate
 * \param c_off		Updated to character offset
 */
static void textarea_get_xy_offset(struct textarea *ta, int x, int y,
		unsigned int *c_off)
{
	size_t bpos, temp; /* Byte positions in utf8 string */
	unsigned int cpos; /* Character positions in utf8 string */
	int line;

	if (!ta->line_count) {
		*c_off = 0;
		return;
	}

	x = x - ta->border_width - ta->pad_left + ta->scroll_x;
	y = y - ta->border_width - ta->pad_top + ta->scroll_y;

	if (x < 0)
		x = 0;

	line = y / ta->line_height;

	if (line < 0)
		line = 0;
	if (ta->line_count - 1 < line)
		line = ta->line_count - 1;

	/* Get byte position */
	nsfont.font_position_in_string(&ta->fstyle,
			ta->show->data + ta->lines[line].b_start,
			ta->lines[line].b_length, x, &bpos, &x);


	/* If the calculated byte offset corresponds with the number of bytes
	 * in the line, and the line has been soft-wrapped, then ensure the
	 * caret offset is before the trailing space character, rather than
	 * after it. Otherwise, the caret will be placed at the start of the
	 * following line, which is undesirable.
	 */
	if (ta->flags & TEXTAREA_MULTILINE &&
			bpos == (unsigned)ta->lines[line].b_length &&
			ta->show->data[ta->lines[line].b_start +
			ta->lines[line].b_length - 1] == ' ')
		bpos--;

	/* Get character position */
	for (temp = 0, cpos = 0; temp < bpos + ta->lines[line].b_start;
			temp = utf8_next(ta->show->data, ta->show->len, temp))
		cpos++;

	/* Set the return values */
	*c_off = cpos;
}


/**
 * Set the caret's position
 *
 * \param ta Text area
 * \param x X position of caret in a window relative to text area top left
 * \param y Y position of caret in a window relative to text area top left
 * \return true on success false otherwise
 */
static bool textarea_set_caret_xy(struct textarea *ta, int x, int y)
{
	unsigned int c_off;

	if (ta->flags & TEXTAREA_READONLY)
		return true;

	textarea_get_xy_offset(ta, x, y, &c_off);

	return textarea_set_caret(ta, c_off);
}


/**
 * Insert text into the text area
 *
 * \param ta		Text area
 * \param c_index	0-based character index to insert at
 * \param text		UTF-8 text to insert
 * \param b_len		Byte length of UTF-8 text
 * \return false on memory exhaustion, true otherwise
 */
static bool textarea_insert_text(struct textarea *ta, unsigned int c_index,
		const char *text, size_t b_len)
{
	size_t b_off;

	if (ta->flags & TEXTAREA_READONLY)
		return true;

	/* Find insertion point */
	if (c_index > ta->text.utf8_len)
		c_index = ta->text.utf8_len;

	/* find byte offset of insertion point */
	for (b_off = 0; c_index > 0;
			b_off = utf8_next(ta->text.data, ta->text.len, b_off))
		c_index--;

	if (b_len + ta->text.len >= ta->text.alloc) {
		char *temp = realloc(ta->text.data, b_len + ta->text.len + 64);
		if (temp == NULL) {
			LOG(("realloc failed"));
			return false;
		}

		ta->text.data = temp;
		ta->text.alloc = b_len + ta->text.len + 64;
	}

	/* Shift text following up */
	memmove(ta->text.data + b_off + b_len, ta->text.data + b_off,
			ta->text.len - b_off);
	/* Insert new text */
	memcpy(ta->text.data + b_off, text, b_len);
	ta->text.len += b_len;
	ta->text.utf8_len += utf8_bounded_length(text, b_len);

	textarea_normalise_text(ta, b_off, b_len);

	/** \todo calculate line to reflow from */
	return textarea_reflow(ta, 0);

}


static inline void textarea_char_to_byte_offset(struct textarea_utf8 *text,
		unsigned int start, unsigned int end,
		size_t *b_start, size_t *b_end)
{
	size_t diff = end - start;
	/* find byte offset of replace start */
	for (*b_start = 0; start-- > 0;
			*b_start = utf8_next(text->data, text->len, *b_start))
		; /* do nothing */

	/* find byte length of replaced text */
	for (*b_end = *b_start; diff-- > 0;
			*b_end = utf8_next(text->data, text->len, *b_end))
		; /* do nothing */
}


/**
 * Replace text in a text area
 *
 * \param ta		Text area
 * \param start		Start character index of replaced section (inclusive)
 * \param end		End character index of replaced section (exclusive)
 * \param rep		Replacement UTF-8 text to insert
 * \param rep_len	Byte length of replacement UTF-8 text
 * \param add_to_clipboard	True iff replaced text to be added to clipboard
 * \return false on memory exhaustion, true otherwise
 */
static bool textarea_replace_text(struct textarea *ta, unsigned int start,
		unsigned int end, const char *rep, size_t rep_len,
		bool add_to_clipboard)
{
	size_t b_start, b_end;

	if (ta->flags & TEXTAREA_READONLY)
		return true;

	if (start > ta->text.utf8_len)
		start = ta->text.utf8_len;
	if (end > ta->text.utf8_len)
		end = ta->text.utf8_len;

	if (start == end && rep != NULL)
		return textarea_insert_text(ta, start, rep, rep_len);

	if (start > end)
		return false;

	/* Place CUTs on clipboard */
	if (add_to_clipboard) {
		textarea_char_to_byte_offset(ta->show, start, end,
				&b_start, &b_end);
		gui_set_clipboard(ta->show->data + b_start, b_end - b_start,
				NULL, 0);
	}

	textarea_char_to_byte_offset(&ta->text, start, end, &b_start, &b_end);

	if (rep == NULL) {
		/* No replacement text */
		return true;
	}

	/* Ensure textarea's text buffer is large enough */
	if (rep_len + ta->text.len - (b_end - b_start) >= ta->text.alloc) {
		char *temp = realloc(ta->text.data,
			rep_len + ta->text.len - (b_end - b_start) + 64);
		if (temp == NULL) {
			LOG(("realloc failed"));
			return false;
		}

		ta->text.data = temp;
		ta->text.alloc =
			rep_len + ta->text.len - (b_end - b_start) + 64;
	}

	/* Shift text following to new position */
	memmove(ta->text.data + b_start + rep_len, ta->text.data + b_end,
			ta->text.len - b_end);

	/* Insert new text */
	memcpy(ta->text.data + b_start, rep, rep_len);

	ta->text.len += (int)rep_len - (b_end - b_start);
	ta->text.utf8_len = utf8_length(ta->text.data);
	textarea_normalise_text(ta, b_start, rep_len);

	/** \todo calculate line to reflow from */
	return textarea_reflow(ta, 0);
}


/**
 * Handles the end of a drag operation
 *
 * \param ta	Text area
 * \param mouse	the mouse state at drag end moment
 * \param x	X coordinate
 * \param y	Y coordinate
 * \return true if drag end was handled false otherwise
 */
static bool textarea_drag_end(struct textarea *ta, browser_mouse_state mouse,
		int x, int y)
{
	int c_end;
	unsigned int c_off;
	struct textarea_msg msg;

	assert(ta->drag_info.type != TEXTAREA_DRAG_NONE);

	switch (ta->drag_info.type) {
	case TEXTAREA_DRAG_SCROLLBAR:
		if (ta->drag_info.data.scrollbar == ta->bar_x) {
			x -= ta->border_width;
			y -= ta->vis_height - ta->border_width -
					SCROLLBAR_WIDTH;
		} else {
			x -= ta->vis_width - ta->border_width -
					SCROLLBAR_WIDTH;
			y -= ta->border_width;
		}
		scrollbar_mouse_drag_end(ta->drag_info.data.scrollbar,
				mouse, x, y);
		assert(ta->drag_info.type == TEXTAREA_DRAG_NONE);

		/* Return, since drag end already reported to textarea client */
		return true;

	case TEXTAREA_DRAG_SELECTION:
		ta->drag_info.type = TEXTAREA_DRAG_NONE;

		textarea_get_xy_offset(ta, x, y, &c_off);
		c_end = c_off;

		if (!textarea_select(ta, ta->drag_start_char, c_end))
			return false;

		break;

	default:
		return false;
	}

	/* Report drag end to client, if not already reported */
	assert(ta->drag_info.type == TEXTAREA_DRAG_NONE);

	msg.ta = ta;
	msg.type = TEXTAREA_MSG_DRAG_REPORT;
	msg.data.drag = ta->drag_info.type;

	ta->callback(ta->data, &msg);

	return true;
}




/* exported interface, documented in textarea.h */
struct textarea *textarea_create(const textarea_flags flags,
		const textarea_setup *setup,
		textarea_client_callback callback, void *data)
{
	struct textarea *ret;

	/* Sanity check flags */
	assert(!(flags & TEXTAREA_MULTILINE &&
			flags & TEXTAREA_PASSWORD));

	if (callback == NULL) {
		LOG(("no callback provided"));
		return NULL;
	}

	ret = malloc(sizeof(struct textarea));
	if (ret == NULL) {
		LOG(("malloc failed"));
		return NULL;
	}

	ret->callback = callback;
	ret->data = data;

	ret->flags = flags;
	ret->vis_width = setup->width;
	ret->vis_height = setup->height;

	ret->pad_top = setup->pad_top;
	ret->pad_right = setup->pad_right;
	ret->pad_bottom = setup->pad_bottom;
	ret->pad_left = setup->pad_left;

	ret->border_width = setup->border_width;
	ret->border_col = setup->border_col;

	ret->fstyle = setup->text;

	ret->sel_fstyle = setup->text;
	ret->sel_fstyle.foreground = setup->selected_text;
	ret->sel_fstyle.background = setup->selected_bg;

	ret->scroll_x = 0;
	ret->scroll_y = 0;
	ret->bar_x = NULL;
	ret->bar_y = NULL;
	ret->drag_start_char = 0;
	ret->drag_info.type = TEXTAREA_DRAG_NONE;


	ret->text.data = malloc(64);
	if (ret->text.data == NULL) {
		LOG(("malloc failed"));
		free(ret);
		return NULL;
	}
	ret->text.data[0] = '\0';
	ret->text.alloc = 64;
	ret->text.len = 1;
	ret->text.utf8_len = 0;

	if (flags & TEXTAREA_PASSWORD) {
		ret->password.data = malloc(64);
		if (ret->password.data == NULL) {
			LOG(("malloc failed"));
			free(ret->text.data);
			free(ret);
			return NULL;
		}
		ret->password.data[0] = '\0';
		ret->password.alloc = 64;
		ret->password.len = 1;
		ret->password.utf8_len = 0;

		ret->show = &ret->password;

	} else {
		ret->password.data = NULL;
		ret->password.alloc = 0;
		ret->password.len = 0;
		ret->password.utf8_len = 0;

		ret->show = &ret->text;
	}

	ret->line_height = FIXTOINT(FDIV((FMUL(FLTTOFIX(1.3),
			FMUL(nscss_screen_dpi, INTTOFIX((setup->text.size))))),
			FONT_SIZE_SCALE * F_72));

	ret->caret_pos.line = ret->caret_pos.char_off = -1;
	ret->caret_x = 0;
	ret->caret_y = 0;
	ret->sel_start = -1;
	ret->sel_end = -1;

	ret->line_count = 0;
	ret->lines = NULL;

	return ret;
}


/* exported interface, documented in textarea.h */
void textarea_destroy(struct textarea *ta)
{
	if (ta->bar_x)
		scrollbar_destroy(ta->bar_x);
	if (ta->bar_y)
		scrollbar_destroy(ta->bar_y);

	if (ta->flags & TEXTAREA_PASSWORD)
		free(ta->password.data);

	free(ta->text.data);
	free(ta->lines);
	free(ta);
}


/* exported interface, documented in textarea.h */
bool textarea_set_text(struct textarea *ta, const char *text)
{
	unsigned int len = strlen(text) + 1;

	if (len >= ta->text.alloc) {
		char *temp = realloc(ta->text.data, len + 64);
		if (temp == NULL) {
			LOG(("realloc failed"));
			return false;
		}
		ta->text.data = temp;
		ta->text.alloc = len + 64;
	}

	memcpy(ta->text.data, text, len);
	ta->text.len = len;
	ta->text.utf8_len = utf8_length(ta->text.data);

	textarea_normalise_text(ta, 0, len);

	return textarea_reflow(ta, 0);
}


/* exported interface, documented in textarea.h */
bool textarea_drop_text(struct textarea *ta, const char *text,
		size_t text_length)
{
	struct textarea_msg msg;
	unsigned int caret_pos;
	size_t text_chars;

	if (ta->flags & TEXTAREA_READONLY)
		return false;

	if (text == NULL)
		return false;

	text_chars = utf8_bounded_length(text, text_length);
	caret_pos = textarea_get_caret(ta);

	if (ta->sel_start != -1) {
		if (!textarea_replace_text(ta, ta->sel_start, ta->sel_end,
				text, text_length, false))
			return false;

		caret_pos = ta->sel_start + text_chars;
		ta->sel_start = ta->sel_end = -1;
	} else {
		if (!textarea_replace_text(ta, caret_pos, caret_pos,
				text, text_length, false))
			return false;
		caret_pos += text_chars;
	}

	textarea_set_caret(ta, caret_pos);

	msg.ta = ta;
	msg.type = TEXTAREA_MSG_REDRAW_REQUEST;
	msg.data.redraw.x0 = 0;
	msg.data.redraw.y0 = 0;
	msg.data.redraw.x1 = ta->vis_width;
	msg.data.redraw.y1 = ta->vis_height;

	ta->callback(ta->data, &msg);

	return true;
}


/* exported interface, documented in textarea.h */
int textarea_get_text(struct textarea *ta, char *buf, unsigned int len)
{
	if (buf == NULL && len == 0) {
		/* want length */
		return ta->text.len;

	} else if (buf == NULL) {
		/* Can't write to NULL */
		return -1;
	}

	if (len < ta->text.len) {
		LOG(("buffer too small"));
		return -1;
	}

	memcpy(buf, ta->text.data, ta->text.len);

	return ta->text.len;
}


/* exported interface, documented in textarea.h */
bool textarea_set_caret(struct textarea *ta, int caret)
{
	unsigned int c_len;
	unsigned int b_off;
	int i;
	int index;
	int x, y;
	int x0, y0, x1, y1;
	int text_y_offset;
	int width, height;
	struct textarea_msg msg;

	if (ta->flags & TEXTAREA_READONLY)
		return true;

	c_len = ta->show->utf8_len;

	if (caret != -1 && caret > (signed)c_len)
		caret = c_len;

	if (ta->flags & TEXTAREA_MULTILINE) {
		/* Multiline textarea */
		text_y_offset = ta->border_width + ta->pad_top;
	} else {
		/* Single line text area; text is vertically centered */
		text_y_offset = ta->border_width;
		text_y_offset += (ta->vis_height - ta->line_height + 1) / 2;
	}

	/* Delete the old caret */
	if (ta->caret_pos.char_off != -1) {
		x0 = ta->caret_x - ta->scroll_x;
		y0 = ta->caret_y + text_y_offset - ta->scroll_y;
		width = 2;
		height = ta->line_height;

		msg.ta = ta;
		msg.type = TEXTAREA_MSG_REDRAW_REQUEST;
		msg.data.redraw.x0 = x0;
		msg.data.redraw.y0 = y0;
		msg.data.redraw.x1 = x0 + width;
		msg.data.redraw.y1 = y0 + height;

		ta->callback(ta->data, &msg);
	}

	/* check if the caret has to be drawn at all */
	if (caret != -1) {
		/* Find byte offset of caret position */
		for (b_off = 0; caret > 0; caret--)
			b_off = utf8_next(ta->show->data, ta->show->len, b_off);

		/* Now find line in which byte offset appears */
		for (i = 0; i < ta->line_count - 1; i++)
			if (ta->lines[i + 1].b_start > b_off)
				break;

		ta->caret_pos.line = i;

		/* Now calculate the char. offset of the caret in this line */
		for (c_len = 0, ta->caret_pos.char_off = 0;
				c_len < b_off - ta->lines[i].b_start;
				c_len = utf8_next(ta->show->data +
						ta->lines[i].b_start,
						ta->lines[i].b_length, c_len))
			ta->caret_pos.char_off++;

		/* Finally, redraw the caret */
		index = textarea_get_caret(ta);
		if (index == -1)
			return false;

		/* find byte offset of caret position */
		for (b_off = 0; index-- > 0;
				b_off = utf8_next(ta->show->data,
						ta->show->len, b_off))
			; /* do nothing */

		nsfont.font_width(&ta->fstyle,
				ta->show->data +
				ta->lines[ta->caret_pos.line].b_start,
				b_off - ta->lines[ta->caret_pos.line].b_start,
				&x);

		x += ta->border_width + ta->pad_left;
		ta->caret_x = x;
		y = ta->line_height * ta->caret_pos.line + text_y_offset;
		ta->caret_y = y;

		if (!textarea_scroll_visible(ta) &&
				ta->flags & TEXTAREA_INTERNAL_CARET) {
			/* Didn't scroll, just moved caret.
			 * Caret is internal caret, redraw it */
			x -= ta->scroll_x;
			y -= ta->scroll_y;
			x0 = max(x - 1, ta->border_width);
			y0 = max(y, 0);
			x1 = min(x + 1, ta->vis_width - ta->border_width);
			y1 = min(y + ta->line_height,
					ta->vis_height);

			width = x1 - x0;
			height = y1 - y0;

			if (width > 0 && height > 0) {
				msg.ta = ta;
				msg.type = TEXTAREA_MSG_REDRAW_REQUEST;
				msg.data.redraw.x0 = x0;
				msg.data.redraw.y0 = y0;
				msg.data.redraw.x1 = x0 + width;
				msg.data.redraw.y1 = y0 + height;

				ta->callback(ta->data, &msg);
			}
		}

		if (!(ta->flags & TEXTAREA_INTERNAL_CARET)) {
			/* Tell client where caret should be placed */
			msg.ta = ta;
			msg.type = TEXTAREA_MSG_MOVED_CARET;
			msg.data.caret.hidden = false;
			msg.data.caret.x = x - ta->scroll_x;
			msg.data.caret.y = y - ta->scroll_y;
			msg.data.caret.height = ta->line_height;

			ta->callback(ta->data, &msg);
		}

	} else if (!(ta->flags & TEXTAREA_INTERNAL_CARET)) {
		/* Caret hidden, and client is responsible: tell client */
		msg.ta = ta;
		msg.type = TEXTAREA_MSG_MOVED_CARET;
		msg.data.caret.hidden = true;

		ta->callback(ta->data, &msg);
	}

	return true;
}


/* exported interface, documented in textarea.h */
int textarea_get_caret(struct textarea *ta)
{
	unsigned int c_off = 0, b_off;

	/* Ensure caret isn't hidden */
	if (ta->caret_pos.char_off < 0)
		textarea_set_caret(ta, 0);

	/* if the text is a trailing NUL only */
	if (ta->text.utf8_len == 0)
		return 0;

	/* Calculate character offset of this line's start */
	for (b_off = 0; b_off < ta->lines[ta->caret_pos.line].b_start;
			b_off = utf8_next(ta->text.data, ta->text.len, b_off))
		c_off++;

	return c_off + ta->caret_pos.char_off;
}


/* exported interface, documented in textarea.h */
void textarea_redraw(struct textarea *ta, int x, int y, colour bg, float scale,
		const struct rect *clip, const struct redraw_context *ctx)
{
	const struct plotter_table *plot = ctx->plot;
	int line0, line1, line, left, right, line_y;
	int chars, text_y_offset, text_y_offset_baseline;
	unsigned int c_pos, c_len, c_len_part, b_start, b_end, line_len;
	unsigned int sel_start, sel_end;
	char *line_text;
	struct rect r, s;
	bool selected = false;
	plot_font_style_t fstyle;
	int fsize = ta->fstyle.size;
	int line_height = ta->line_height;
	plot_style_t plot_style_fill_bg = {
		.stroke_type = PLOT_OP_TYPE_NONE,
		.stroke_width = 0,
		.stroke_colour = NS_TRANSPARENT,
		.fill_type = PLOT_OP_TYPE_SOLID,
		.fill_colour = ta->border_col
	};

	r = *clip;

	if (r.x1 < x || r.x0 > x + ta->vis_width || r.y1 < y ||
		   r.y0 > y + ta->vis_height)
		/* Textarea outside the clipping rectangle */
		return;

	if (ta->lines == NULL)
		/* Nothing to redraw */
		return;

	line0 = (r.y0 - y + ta->scroll_y) / ta->line_height - 1;
	line1 = (r.y1 - y + ta->scroll_y) / ta->line_height + 1;

	if (line0 < 0)
		line0 = 0;
	if (line1 < 0)
		line1 = 0;
	if (ta->line_count - 1 < line0)
		line0 = ta->line_count - 1;
	if (ta->line_count - 1 < line1)
		line1 = ta->line_count - 1;
	if (line1 < line0)
		line1 = line0;

	if (r.x0 < x)
		r.x0 = x;
	if (r.y0 < y)
		r.y0 = y;
	if (scale == 1.0) {
		if (r.x1 > x + ta->vis_width)
			r.x1 = x + ta->vis_width;
		if (r.y1 > y + ta->vis_height)
			r.y1 = y + ta->vis_height;
	} else {
		if (r.x1 > x + ta->vis_width * scale)
			r.x1 = x + ta->vis_width * scale;
		if (r.y1 > y + ta->vis_height * scale)
			r.y1 = y + ta->vis_height * scale;
	}

	plot->clip(&r);
	if (ta->border_col != NS_TRANSPARENT &&
			ta->border_width > 0) {
		/* Plot border */
		plot->rectangle(x, y, x + ta->vis_width, y + ta->vis_height,
				&plot_style_fill_bg);
	}
	if (ta->fstyle.background != NS_TRANSPARENT) {
		/* Plot background */
		plot_style_fill_bg.fill_colour = ta->fstyle.background;
		plot->rectangle(x + ta->border_width, y + ta->border_width,
				x + ta->vis_width - ta->border_width,
				y + ta->vis_height - ta->border_width,
				&plot_style_fill_bg);
	}

	if (scale == 1.0) {
		if (r.x0 < x + ta->border_width)
			r.x0 = x + ta->border_width;
		if (r.x1 > x + ta->vis_width - ta->border_width)
			r.x1 = x + ta->vis_width - ta->border_width;
		if (r.y0 < y + ta->border_width)
			r.y0 = y + ta->border_width;
		if (r.y1 > y + ta->vis_height - ta->border_width -
				(ta->bar_x != NULL ? SCROLLBAR_WIDTH : 0))
			r.y1 = y + ta->vis_height - ta->border_width -
					(ta->bar_x != NULL ? SCROLLBAR_WIDTH :
							0);
	} else {
		if (r.x0 < x + ta->border_width * scale)
			r.x0 = x + ta->border_width * scale;
		if (r.x1 > x + (ta->vis_width - ta->border_width) * scale)
			r.x1 = x + (ta->vis_width - ta->border_width) * scale;
		if (r.y0 < y + ta->border_width * scale)
			r.y0 = y + ta->border_width * scale;
		if (r.y1 > y + (ta->vis_height - ta->border_width -
				(ta->bar_x != NULL ? SCROLLBAR_WIDTH : 0)) *
				scale)
			r.y1 = y + (ta->vis_height - ta->border_width -
					(ta->bar_x != NULL ? SCROLLBAR_WIDTH :
							0) * scale);
	}

	if (line0 > 0)
		c_pos = utf8_bounded_length(ta->show->data,
				ta->lines[line0].b_start);
	else
		c_pos = 0;

	text_y_offset = text_y_offset_baseline = ta->border_width;
	if (ta->flags & TEXTAREA_MULTILINE) {
		/* Multiline textarea */
		text_y_offset += ta->pad_top;
		text_y_offset_baseline += (ta->line_height * 3 + 2) / 4 +
				ta->pad_top;
	} else {
		/* Single line text area; text is vertically centered */
		int vis_height = ta->vis_height - 2 * ta->border_width;
		text_y_offset += (vis_height - ta->line_height + 1) / 2;
		text_y_offset_baseline += (vis_height * 3 + 2) / 4;
	}

	if (scale != 1.0) {
		text_y_offset *= scale;
		text_y_offset_baseline *= scale;

		fsize *= scale;
		line_height *= scale;
	}

	plot_style_fill_bg.fill_colour = ta->sel_fstyle.background;

	for (line = line0; (line <= line1) &&
			(y + line * ta->line_height <= r.y1 + ta->scroll_y);
			line++) {
		if (ta->lines[line].b_length == 0) {
			c_pos++;
			continue;
		}

		/* reset clip rectangle */
		plot->clip(&r);

		c_len = utf8_bounded_length(
				&(ta->show->data[ta->lines[line].b_start]),
				ta->lines[line].b_length);

		b_end = 0;
		right = x + ta->border_width + ta->pad_left - ta->scroll_x;

		do {
			sel_start = ta->sel_start;
			sel_end = ta->sel_end;
			/* get length of part of line */
			if (ta->sel_end == -1 || ta->sel_end == ta->sel_start ||
					sel_end <= c_pos ||
					sel_start > c_pos + c_len) {
				/* rest of line unselected */
				selected = false;
				c_len_part = c_len;
				fstyle = ta->fstyle;

			} else if (sel_start <= c_pos &&
					sel_end > c_pos + c_len) {
				/* rest of line selected */
				selected = true;
				c_len_part = c_len;
				fstyle = ta->sel_fstyle;

			} else if (sel_start > c_pos) {
				/* next part of line unselected */
				selected = false;
				c_len_part = sel_start - c_pos;
				fstyle = ta->fstyle;

			} else if (sel_end > c_pos) {
				/* next part of line selected */
				selected = true;
				c_len_part = sel_end - c_pos;
				fstyle = ta->sel_fstyle;

			} else {
				assert(0);
			}
			fstyle.size = fsize;

			line_text = &(ta->show->data[ta->lines[line].b_start]);
			line_len = ta->lines[line].b_length;

			/* find b_start and b_end for this part of the line */
			b_start = b_end;

			chars = c_len_part;
			for (b_end = b_start; chars > 0; chars--)
				b_end = utf8_next(line_text, line_len, b_end);

			/* find clip left/right for this part of line */
			left = right;
			nsfont.font_width(&fstyle, line_text,
					b_end, &right);
			right += x + ta->border_width + ta->pad_left -
					ta->scroll_x;

			/* set clip rectangle for line part */
			s = r;
			if (s.x0 < left)
				s.x0 = left;
			if (s.x1 > right)
				s.x1 = right;

			plot->clip(&s);

			line_y = line * ta->line_height - ta->scroll_y;

			if (scale != 1.0) {
				line_y *= scale;
			}

			if (selected) {
				/* draw selection fill */
				plot->rectangle(s.x0, y + line_y +
					text_y_offset,
					s.x1, y + line_y + line_height +
							text_y_offset,
					&plot_style_fill_bg);
			}

			/* draw text */
			plot->text(x + ta->border_width + ta->pad_left -
					ta->scroll_x,
					y + line_y + text_y_offset_baseline,
					ta->show->data +
							ta->lines[line].b_start,
					ta->lines[line].b_length, &fstyle);

			c_pos += c_len_part;
			c_len -= c_len_part;

		} while (c_pos < c_pos + c_len);

		/* if there is a newline between the lines, skip it */
		if (line < ta->line_count - 1 &&
				ta->lines[line + 1].b_start !=
						ta->lines[line].b_start +
						ta->lines[line].b_length)
			c_pos++;
	}

	plot->clip(clip);

	if ((ta->sel_end == -1 || ta->sel_start == ta->sel_end) &&
			ta->caret_pos.char_off >= 0) {
		/* There is no selection, and caret visible: show caret */
		int caret_y = y - ta->scroll_y + ta->caret_y;

		if (ta->flags & TEXTAREA_INTERNAL_CARET) {
			/* Render our own caret */
			plot->line(x - ta->scroll_x + ta->caret_x, caret_y,
					x - ta->scroll_x + ta->caret_x,
					caret_y + ta->line_height,
					&pstyle_stroke_caret);
		}
	}

	if (ta->bar_x != NULL)
		scrollbar_redraw(ta->bar_x,
				x / scale + ta->border_width,
				y / scale + ta->vis_height - ta->border_width -
						SCROLLBAR_WIDTH,
				clip, scale, ctx);

	if (ta->bar_y != NULL)
		scrollbar_redraw(ta->bar_y,
				x / scale + ta->vis_width - ta->border_width -
						SCROLLBAR_WIDTH,
				y / scale + ta->border_width,
				clip, scale, ctx);
}


/* exported interface, documented in textarea.h */
bool textarea_keypress(struct textarea *ta, uint32_t key)
{
	struct textarea_msg msg;
	char utf8[6];
	unsigned int caret, caret_init, length, l_len, b_off, b_len;
	int c_line, c_chars, line;
	bool redraw = false;
	bool readonly;

	caret_init = caret = textarea_get_caret(ta);
	line = ta->caret_pos.line;
	readonly = (ta->flags & TEXTAREA_READONLY ? true : false);

	if (!(key <= 0x001F || (0x007F <= key && key <= 0x009F))) {
		/* normal character insertion */
		length = utf8_from_ucs4(key, utf8);
		utf8[length] = '\0';

		if (ta->sel_start != -1) {
			if (!textarea_replace_text(ta,
					ta->sel_start,
					ta->sel_end, utf8, length, false))
				return false;

			caret = ta->sel_start + 1;
			ta->sel_start = ta->sel_end = -1;
			redraw = true;
		} else {
			if (!textarea_replace_text(ta,
					caret, caret,
					utf8, length, false))
				return false;
			caret++;
			redraw = true;
		}

	} else switch (key) {
		case KEY_SELECT_ALL:
			caret = ta->text.utf8_len;

			ta->sel_start = 0;
			ta->sel_end = ta->text.utf8_len;
			redraw = true;
			break;
		case KEY_COPY_SELECTION:
			if (ta->sel_start != -1) {
				if (!textarea_replace_text(ta,
						ta->sel_start,
						ta->sel_end,
						NULL, 0, true))
					return false;
			}
			break;
		case KEY_DELETE_LEFT:
			if (readonly)
				break;
			if (ta->sel_start != -1) {
				if (!textarea_replace_text(ta,
				     		ta->sel_start,
						ta->sel_end, "", 0, false))
					return false;

				caret = ta->sel_start;
				ta->sel_start = ta->sel_end = -1;
				redraw = true;
			} else if (caret > 0) {
				if (!textarea_replace_text(ta,
						caret - 1,
						caret, "", 0, false))
					return false;
				caret--;
				redraw = true;
			}
			break;
		case KEY_NL:
			if (readonly)
				break;
			if(!textarea_insert_text(ta, caret, "\n", 1))
				return false;
			caret++;
			ta->sel_start = ta->sel_end = -1;
			redraw = true;
			break;
		case KEY_CUT_LINE:
			break;
		case KEY_PASTE:
		{
			char *clipboard;
			size_t clipboard_length;
			size_t clipboard_chars;

			if (readonly)
				break;

			gui_get_clipboard(&clipboard, &clipboard_length);
			if (clipboard == NULL)
				return false;
			clipboard_chars = utf8_bounded_length(clipboard,
					clipboard_length);

			if (ta->sel_start != -1) {
				if (!textarea_replace_text(ta,
						ta->sel_start, ta->sel_end,
						clipboard, clipboard_length,
						false))
					return false;

				caret = ta->sel_start + clipboard_chars;
				ta->sel_start = ta->sel_end = -1;
				redraw = true;
			} else {
				if (!textarea_replace_text(ta,
						caret, caret,
						clipboard, clipboard_length,
						false))
					return false;
				caret += clipboard_chars;
				redraw = true;
			}

			free(clipboard);
		}
			break;
		case KEY_CUT_SELECTION:
			if (readonly)
				break;
			if (ta->sel_start != -1) {
				if (!textarea_replace_text(ta,
						ta->sel_start,
						ta->sel_end, "", 0, true))
					return false;

				caret = ta->sel_start;
				ta->sel_start = ta->sel_end = -1;
				redraw = true;
			}
			break;
		case KEY_ESCAPE:
			/* Fall through to KEY_CLEAR_SELECTION */
		case KEY_CLEAR_SELECTION:
			ta->sel_start = -1;
			ta->sel_end = -1;
			redraw = true;
			break;
		case KEY_LEFT:
			if (readonly)
				break;
			if (caret > 0)
				caret--;
			if (ta->sel_start != -1) {
				ta->sel_start = ta->sel_end = -1;
				redraw = true;
			}
			break;
		case KEY_RIGHT:
			if (readonly)
				break;
			if (caret < ta->text.utf8_len)
				caret++;
			if (ta->sel_start != -1) {
				ta->sel_start = ta->sel_end = -1;
				redraw = true;
			}
			break;
		case KEY_PAGE_UP:
			if (readonly)
				break;
			if (ta->flags & TEXTAREA_MULTILINE) {
				/* +1 because one line is subtracted in
				   KEY_UP */
				line = ta->caret_pos.line - (ta->vis_height +
						ta->line_height - 1) /
						ta->line_height + 1;
			}
			/* fall through */
		case KEY_UP:
			if (readonly)
				break;
			if (ta->sel_start != -1) {
				ta->sel_start = ta->sel_end = -1;
				redraw = true;
			}
			if (ta->flags & TEXTAREA_MULTILINE) {
				line--;
				if (line < 0)
					line = 0;
				if (line == ta->caret_pos.line)
					break;

				b_off = ta->lines[line].b_start;
				b_len = ta->lines[line].b_length;

				c_line = ta->caret_pos.line;
				c_chars = ta->caret_pos.char_off;

				if (ta->text.data[b_off + b_len - 1] == ' '
						&& line < ta->line_count - 1)
					b_len--;

				l_len = utf8_bounded_length(
						&(ta->text.data[b_off]),
						b_len);


				ta->caret_pos.line = line;
				ta->caret_pos.char_off = min(l_len,
						(unsigned)
						ta->caret_pos.char_off);

				caret = textarea_get_caret(ta);

				ta->caret_pos.line = c_line;
				ta->caret_pos.char_off = c_chars;
			}
			break;
		case KEY_PAGE_DOWN:
			if (readonly)
				break;
			if (ta->flags & TEXTAREA_MULTILINE) {
				/* -1 because one line is added in KEY_DOWN */
				line = ta->caret_pos.line + (ta->vis_height +
						ta->line_height - 1) /
						ta->line_height
						- 1;
			}
			/* fall through */
		case KEY_DOWN:
			if (readonly)
				break;
			if (ta->sel_start != -1) {
				ta->sel_start = ta->sel_end = -1;
				redraw = true;
			}
			if (ta->flags & TEXTAREA_MULTILINE) {
				line++;
				if (line > ta->line_count - 1)
					line = ta->line_count - 1;
				if (line == ta->caret_pos.line)
					break;

				b_off = ta->lines[line].b_start;
				b_len = ta->lines[line].b_length;

				c_line = ta->caret_pos.line;
				c_chars = ta->caret_pos.char_off;

				if (ta->text.data[b_off + b_len - 1] == ' '
						&& line < ta->line_count - 1)
					b_len--;

				l_len = utf8_bounded_length(
						&(ta->text.data[b_off]),
						b_len);


				ta->caret_pos.line = line;
				ta->caret_pos.char_off = min(l_len,
						(unsigned)
						ta->caret_pos.char_off);

				caret = textarea_get_caret(ta);

				ta->caret_pos.line = c_line;
				ta->caret_pos.char_off = c_chars;
			}
			break;
		case KEY_DELETE_RIGHT:
			if (readonly)
				break;
			if (ta->sel_start != -1) {
				if (!textarea_replace_text(ta,
						ta->sel_start,
						ta->sel_end, "", 0, false))
					return false;

				caret = ta->sel_start;
				ta->sel_start = ta->sel_end = -1;
				redraw = true;
			} else {
				if (caret < ta->text.utf8_len) {
					if (!textarea_replace_text(ta,
							caret, caret + 1,
							"", 0, false))
						return false;
					redraw = true;
				}
			}
			break;
		case KEY_LINE_START:
			if (readonly)
				break;
			caret -= ta->caret_pos.char_off;
			if (ta->sel_start != -1) {
				ta->sel_start = ta->sel_end = -1;
				redraw = true;
			}
			break;
		case KEY_LINE_END:
			if (readonly)
				break;

			caret = utf8_bounded_length(ta->text.data,
					ta->lines[ta->caret_pos.line].b_start +
					ta->lines[ta->caret_pos.line].b_length);
			if (ta->text.data[ta->lines[ta->caret_pos.line].
					b_start +
					ta->lines[ta->caret_pos.line].b_length
					- 1] == ' ')
				caret--;
			if (ta->sel_start != -1) {
				ta->sel_start = ta->sel_end = -1;
				redraw = true;
			}
			break;
		case KEY_TEXT_START:
			if (readonly)
				break;
			caret = 0;
			if (ta->sel_start != -1) {
				ta->sel_start = ta->sel_end = -1;
				redraw = true;
			}
			break;
		case KEY_TEXT_END:
			if (readonly)
				break;
			caret = ta->text.utf8_len;
			if (ta->sel_start != -1) {
				ta->sel_start = ta->sel_end = -1;
				redraw = true;
			}
			break;
		case KEY_WORD_LEFT:
		case KEY_WORD_RIGHT:
			break;
		case KEY_DELETE_LINE_END:
			if (readonly)
				break;
			if (ta->sel_start != -1) {
				if (!textarea_replace_text(ta,
						ta->sel_start,
						ta->sel_end, "", 0, false))
					return false;
				ta->sel_start = ta->sel_end = -1;
			} else {
				b_off = ta->lines[ta->caret_pos.line].b_start;
				b_len = ta->lines[ta->caret_pos.line].b_length;
				l_len = utf8_bounded_length(
						&(ta->text.data[b_off]),
						b_len);
				if (!textarea_replace_text(ta, caret,
						caret + l_len, "", 0, false))
					return false;
			}
			redraw = true;
			break;
		case KEY_DELETE_LINE_START:
			if (readonly)
				break;
			if (ta->sel_start != -1) {
				if (!textarea_replace_text(ta,
						ta->sel_start,
						ta->sel_end, "", 0, false))
					return false;
				ta->sel_start = ta->sel_end = -1;
			} else {
				if (!textarea_replace_text(ta,
						caret - ta->caret_pos.char_off,
					caret, "", 0, false))
					return false;
				caret -= ta->caret_pos.char_off;
			}
			redraw = true;
			break;
		default:
			return false;
	}


	if (caret != caret_init)
		textarea_set_caret(ta, caret);
	//TODO:redraw only the important part
	if (redraw) {
		msg.ta = ta;
		msg.type = TEXTAREA_MSG_REDRAW_REQUEST;
		msg.data.redraw.x0 = 0;
		msg.data.redraw.y0 = 0;
		msg.data.redraw.x1 = ta->vis_width;
		msg.data.redraw.y1 = ta->vis_height;

		ta->callback(ta->data, &msg);
	}

	return true;
}


/* exported interface, documented in textarea.h */
bool textarea_mouse_action(struct textarea *ta, browser_mouse_state mouse,
		int x, int y)
{
	int c_start, c_end;
	int sx, sy; /* xy coord offset for scrollbar */
	int sl; /* scrollbar length */
	unsigned int c_off;
	struct textarea_msg msg;

	if (ta->drag_info.type != TEXTAREA_DRAG_NONE &&
			mouse == BROWSER_MOUSE_HOVER) {
		/* There is a drag that we must end */
		textarea_drag_end(ta, mouse, x, y);
	}

	if (ta->drag_info.type == TEXTAREA_DRAG_SCROLLBAR) {
		/* Scrollbar drag in progress; pass input to scrollbar */
		if (ta->drag_info.data.scrollbar == ta->bar_x) {
			x -= ta->border_width;
			y -= ta->vis_height - ta->border_width -
					SCROLLBAR_WIDTH;
		} else {
			x -= ta->vis_width - ta->border_width -
					SCROLLBAR_WIDTH;
			y -= ta->border_width;
		}
		scrollbar_mouse_action(ta->drag_info.data.scrollbar,
				mouse, x, y);
		return true;
	}

	/* Horizontal scrollbar */
	if (ta->bar_x != NULL && ta->drag_info.type == TEXTAREA_DRAG_NONE) {
		/* No drag happening, but mouse input is over scrollbar;
		 * pass input to scrollbar */
		sx = x - ta->border_width;
		sy = y - (ta->vis_height - ta->border_width - SCROLLBAR_WIDTH);
		sl = ta->vis_width - 2 * ta->border_width -
				(ta->bar_y != NULL ? SCROLLBAR_WIDTH : 0);

		if (sx >= 0 && sy >= 0 && sx < sl && sy < SCROLLBAR_WIDTH) {
			scrollbar_mouse_action(ta->bar_x, mouse, sx, sy);
			return true;
		}
	}

	/* Vertical scrollbar */
	if (ta->bar_y != NULL && ta->drag_info.type == TEXTAREA_DRAG_NONE) {
		/* No drag happening, but mouse input is over scrollbar;
		 * pass input to scrollbar */
		sx = x - (ta->vis_width - ta->border_width - SCROLLBAR_WIDTH);
		sy = y - ta->border_width;
		sl = ta->vis_height - 2 * ta->border_width;

		if (sx >= 0 && sy >= 0 && sx < SCROLLBAR_WIDTH && sy < sl) {
			scrollbar_mouse_action(ta->bar_y, mouse, sx, sy);
			return true;
		}
	}

	/* mouse button pressed above the text area, move caret */
	if (mouse & BROWSER_MOUSE_PRESS_1) {
		if (!(ta->flags & TEXTAREA_READONLY)) {
			textarea_get_xy_offset(ta, x, y, &c_off);
			ta->drag_start_char = c_off;

			textarea_set_caret(ta, c_off);
		}
		if (ta->sel_start != -1) {
			/* remove selection */
			ta->sel_start = ta->sel_end = -1;

			msg.ta = ta;
			msg.type = TEXTAREA_MSG_REDRAW_REQUEST;
			msg.data.redraw.x0 = 0;
			msg.data.redraw.y0 = 0;
			msg.data.redraw.x1 = ta->vis_width;
			msg.data.redraw.y1 = ta->vis_height;

			ta->callback(ta->data, &msg);
		}

	} else if (mouse & BROWSER_MOUSE_DOUBLE_CLICK) {
		if (!(ta->flags & TEXTAREA_READONLY)) {
			textarea_set_caret_xy(ta, x, y);
			return textarea_select_fragment(ta);
		}

	} else if (mouse & BROWSER_MOUSE_DRAG_1) {
		/* Selection start */
		textarea_get_xy_offset(ta, x, y, &c_off);
		c_start = ta->drag_start_char;
		c_end = c_off;
		ta->drag_info.type = TEXTAREA_DRAG_SELECTION;

		msg.ta = ta;
		msg.type = TEXTAREA_MSG_DRAG_REPORT;
		msg.data.drag = ta->drag_info.type;

		ta->callback(ta->data, &msg);

		return textarea_select(ta, c_start, c_end);
	} else if (mouse & BROWSER_MOUSE_HOLDING_1 &&
			ta->drag_info.type == TEXTAREA_DRAG_SELECTION) {
		/* Selection track */
		int scrx = 0;
		int scry = 0;

		textarea_get_xy_offset(ta, x, y, &c_off);
		c_start = ta->drag_start_char;
		c_end = c_off;

		/* selection auto-scroll */
		if (x < 0)
			scrx = x / 4;
		if (y < 0)
			scry = y / 4;
		if (x > ta->vis_width)
			scrx = (x - ta->vis_width) / 4;
		if (y > ta->vis_height)
			scry = (y - ta->vis_height) / 4;

		textarea_scroll(ta, scrx, scry);

		return textarea_select(ta, c_start, c_end);
	}

	return true;
}


/* exported interface, documented in textarea.h */
void textarea_get_dimensions(struct textarea *ta, int *width, int *height)
{
	if (width != NULL)
		*width = ta->vis_width;
	if (height != NULL)
		*height = ta->vis_height;
}


/* exported interface, documented in textarea.h */
void textarea_set_dimensions(struct textarea *ta, int width, int height)
{
	ta->vis_width = width;
	ta->vis_height = height;
	textarea_reflow(ta, 0);
}


/* exported interface, documented in textarea.h */
void textarea_set_layout(struct textarea *ta, int width, int height,
		int top, int right, int bottom, int left)
{
	ta->vis_width = width;
	ta->vis_height = height;
	ta->pad_top = top;
	ta->pad_right = right;
	ta->pad_bottom = bottom;
	ta->pad_left = left;
	textarea_reflow(ta, 0);
}


/* exported interface, documented in textarea.h */
bool textarea_scroll(struct textarea *ta, int scrx, int scry)
{
	bool handled_scroll = false;

	if (ta->bar_x != NULL && scrx != 0 &&
			scrollbar_scroll(ta->bar_x, scrx))
		handled_scroll = true;
	if (ta->bar_y != NULL && scry != 0 &&
			scrollbar_scroll(ta->bar_y, scry))
		handled_scroll = true;

	return handled_scroll;
}