/* This file is part of ToaruOS and is released under the terms
 * of the NCSA / University of Illinois License - see LICENSE.md
 * Copyright (C) 2014 Kevin Lange
 */
/* vim: tabstop=4 shiftwidth=4 noexpandtab
 *
 * Terminal Emulator - VGA
 */

#include <stdio.h>
#include <stdint.h>
#include <syscall.h>
#include <string.h>
#include <stdlib.h>
#include <signal.h>
#include <time.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <sys/wait.h>
#include <getopt.h>
#include <errno.h>

#include <wchar.h>

#include "lib/utf8decode.h"
#include "lib/pthread.h"
#include "lib/kbd.h"
#include "lib/graphics.h"

#include "gui/terminal/vga-palette.h"
#include "gui/terminal/lib/termemu.h"

#define USE_BELL 0

/* master and slave pty descriptors */
static int fd_master, fd_slave;
static FILE * terminal;

uint16_t term_width     = 80;    /* Width of the terminal (in cells) */
uint16_t term_height    = 25;    /* Height of the terminal (in cells) */
uint16_t csr_x          = 0;    /* Cursor X */
uint16_t csr_y          = 0;    /* Cursor Y */
term_cell_t * term_buffer    = NULL; /* The terminal cell buffer */
uint32_t current_fg     = 7;    /* Current foreground color */
uint32_t current_bg     = 0;    /* Current background color */
uint8_t  cursor_on      = 1;    /* Whether or not the cursor should be rendered */

uint8_t  _login_shell   = 0;    /* Whether we're going to display a login shell or not */
uint8_t  _hold_out      = 0;    /* state indicator on last cell ignore \n */

#define char_width 1
#define char_height 1

term_state_t * ansi_state = NULL;

void reinit(); /* Defined way further down */
void term_redraw_cursor();

/* Cursor bink timer */
static unsigned int timer_tick = 0;

void term_clear();

void dump_buffer();

wchar_t box_chars_in[] = L"▒␉␌␍␊°±␤␋┘┐┌└┼⎺⎻─⎼⎽├┤┴┬│≤≥";
wchar_t box_chars_out[] =  {176,0,0,0,0,248,241,0,0,217,191,218,192,197,196,196,196,196,196,195,180,193,194,179,243,242};

static int color_distance(uint32_t a, uint32_t b) {
	int a_r = (a & 0xFF0000) >> 16;
	int a_g = (a & 0xFF00) >> 8;
	int a_b = (a & 0xFF);

	int b_r = (b & 0xFF0000) >> 16;
	int b_g = (b & 0xFF00) >> 8;
	int b_b = (b & 0xFF);

	int distance = 0;
	distance += abs(a_r - b_r) * 3;
	distance += abs(a_g - b_g) * 6;
	distance += abs(a_b - b_b) * 10;

	return distance;
}

static uint32_t vga_base_colors[] = {
	0x000000,
	0xAA0000,
	0x00AA00,
	0xAA5500,
	0x0000AA,
	0xAA00AA,
	0x00AAAA,
	0xAAAAAA,
	0x555555,
	0xFF5555,
	0x55AA55,
	0xFFFF55,
	0x5555FF,
	0xFF55FF,
	0x55FFFF,
	0xFFFFFF,
};

static int is_gray(uint32_t a) {
	int a_r = (a & 0xFF0000) >> 16;
	int a_g = (a & 0xFF00) >> 8;
	int a_b = (a & 0xFF);

	return (a_r == a_g && a_g == a_b);
}

static int best_match(uint32_t a) {
	int best_distance = INT32_MAX;
	int best_index = 0;
	for (int j = 0; j < 16; ++j) {
		if (is_gray(a) && !is_gray(vga_base_colors[j]));
		int distance = color_distance(a, vga_base_colors[j]);
		if (distance < best_distance) {
			best_index = j;
			best_distance = distance;
		}
	}
	return best_index;
}


volatile int exit_application = 0;

static void set_term_font_size(float s) {
	/* do nothing */
}

/* Returns the lower of two shorts */
uint16_t min(uint16_t a, uint16_t b) {
	return (a < b) ? a : b;
}

/* Returns the higher of two shorts */
uint16_t max(uint16_t a, uint16_t b) {
	return (a > b) ? a : b;
}

void set_title(char * c) {
	/* Do nothing */
}

void input_buffer_stuff(char * str) {
	size_t s = strlen(str) + 1;
	write(fd_master, str, s);
}

unsigned short * textmemptr = (unsigned short *)0xB8000;
void placech(unsigned char c, int x, int y, int attr) {
	unsigned short *where;
	unsigned att = attr << 8;
	where = textmemptr + (y * 80 + x);
	*where = c | att;
}

/* ANSI-to-VGA */
char vga_to_ansi[] = {
	0, 4, 2, 6, 1, 5, 3, 7,
	8,12,10,14, 9,13,11,15
};

uint32_t ununicode(uint32_t c) {
	wchar_t * w = box_chars_in;
	while (*w) {
		if (*w == c) {
			return box_chars_out[w-box_chars_in];
		}
		w++;
	}
	return '?';
}

void
term_write_char(
		uint32_t val,
		uint16_t x,
		uint16_t y,
		uint32_t fg,
		uint32_t bg,
		uint8_t flags
		) {
	if (val > 128) val = ununicode(val);
	if (fg > 256) {
		fg = best_match(fg);
	}
	if (bg > 256) {
		bg = best_match(bg);
	}
	if (fg > 16) {
		fg = vga_colors[fg];
	}
	if (bg > 16) {
		bg = vga_colors[bg];
	}
	if (fg == 16) fg = 0;
	if (bg == 16) bg = 0;
	placech(val, x, y, (vga_to_ansi[fg] & 0xF) | (vga_to_ansi[bg] << 4));
}

static void cell_set(uint16_t x, uint16_t y, uint32_t c, uint32_t fg, uint32_t bg, uint8_t flags) {
	if (x >= term_width || y >= term_height) return;
	term_cell_t * cell = (term_cell_t *)((uintptr_t)term_buffer + (y * term_width + x) * sizeof(term_cell_t));
	cell->c     = c;
	cell->fg    = fg;
	cell->bg    = bg;
	cell->flags = flags;
}

static void cell_redraw(uint16_t x, uint16_t y) {
	if (x >= term_width || y >= term_height) return;
	term_cell_t * cell = (term_cell_t *)((uintptr_t)term_buffer + (y * term_width + x) * sizeof(term_cell_t));
	if (((uint32_t *)cell)[0] == 0x00000000) {
		term_write_char(' ', x * char_width, y * char_height, TERM_DEFAULT_FG, TERM_DEFAULT_BG, TERM_DEFAULT_FLAGS);
	} else {
		term_write_char(cell->c, x * char_width, y * char_height, cell->fg, cell->bg, cell->flags);
	}
}

static void cell_redraw_inverted(uint16_t x, uint16_t y) {
	if (x >= term_width || y >= term_height) return;
	term_cell_t * cell = (term_cell_t *)((uintptr_t)term_buffer + (y * term_width + x) * sizeof(term_cell_t));
	if (((uint32_t *)cell)[0] == 0x00000000) {
		term_write_char(' ', x * char_width, y * char_height, TERM_DEFAULT_BG, TERM_DEFAULT_FG, TERM_DEFAULT_FLAGS | ANSI_SPECBG);
	} else {
		term_write_char(cell->c, x * char_width, y * char_height, cell->bg, cell->fg, cell->flags | ANSI_SPECBG);
	}
}

static void cell_redraw_box(uint16_t x, uint16_t y) {
	if (x >= term_width || y >= term_height) return;
	term_cell_t * cell = (term_cell_t *)((uintptr_t)term_buffer + (y * term_width + x) * sizeof(term_cell_t));
	if (((uint32_t *)cell)[0] == 0x00000000) {
		term_write_char(' ', x * char_width, y * char_height, TERM_DEFAULT_FG, TERM_DEFAULT_BG, TERM_DEFAULT_FLAGS | ANSI_BORDER);
	} else {
		term_write_char(cell->c, x * char_width, y * char_height, cell->fg, cell->bg, cell->flags | ANSI_BORDER);
	}
}

void outb(unsigned char _data, unsigned short _port) {
	__asm__ __volatile__ ("outb %1, %0" : : "dN" (_port), "a" (_data));
}

void render_cursor() {
	unsigned int tmp = csr_y * 80 + csr_x;
	outb(14, 0x3D4);
	outb(tmp >> 8, 0x3D5);
	outb(15, 0x3D4);
	outb(tmp, 0x3D5);
}

void draw_cursor() {
	if (!cursor_on) return;
	timer_tick = 0;
	render_cursor();
}

void term_redraw_all() { 
	for (uint16_t y = 0; y < term_height; ++y) {
		for (uint16_t x = 0; x < term_width; ++x) {
			cell_redraw(x,y);
		}
	}
}

void term_scroll(int how_much) {
	if (how_much >= term_height || -how_much >= term_height) {
		term_clear();
		return;
	}
	if (how_much == 0) {
		return;
	}
	if (how_much > 0) {
		/* Shift terminal cells one row up */
		memmove(term_buffer, (void *)((uintptr_t)term_buffer + sizeof(term_cell_t) * term_width), sizeof(term_cell_t) * term_width * (term_height - how_much));
		/* Reset the "new" row to clean cells */
		memset((void *)((uintptr_t)term_buffer + sizeof(term_cell_t) * term_width * (term_height - how_much)), 0x0, sizeof(term_cell_t) * term_width * how_much);
		term_redraw_all();
	} else {
		how_much = -how_much;
		/* Shift terminal cells one row up */
		memmove((void *)((uintptr_t)term_buffer + sizeof(term_cell_t) * term_width), term_buffer, sizeof(term_cell_t) * term_width * (term_height - how_much));
		/* Reset the "new" row to clean cells */
		memset(term_buffer, 0x0, sizeof(term_cell_t) * term_width * how_much);
		term_redraw_all();
	}
}

int is_wide(uint32_t codepoint) {
	if (codepoint < 256) return 0;
	return wcwidth(codepoint) == 2;
}

void term_write(char c) {
	static uint32_t codepoint = 0;
	static uint32_t unicode_state = 0;

	cell_redraw(csr_x, csr_y);
	if (!decode(&unicode_state, &codepoint, (uint8_t)c)) {
		if (codepoint > 0xFFFF) {
			codepoint = '?';
			c = '?';
		}
		if (c == '\r') {
			csr_x = 0;
			return;
		}
		if (csr_x == term_width) {
			csr_x = 0;
			++csr_y;
		}
		if (csr_y == term_height) {
			term_scroll(1);
			csr_y = term_height - 1;
		}
		if (c == '\n') {
			if (csr_x == 0 && _hold_out) {
				_hold_out = 0;
				return;
			}
			++csr_y;
			if (csr_y == term_height) {
				term_scroll(1);
				csr_y = term_height - 1;
			}
			draw_cursor();
		} else if (c == '\007') {
			/* bell */
#if USE_BELL
			for (int i = 0; i < term_height; ++i) {
				for (int j = 0; j < term_width; ++j) {
					cell_redraw_inverted(j, i);
				}
			}
			syscall_nanosleep(0,10);
			term_redraw_all();
#endif
		} else if (c == '\b') {
			if (csr_x > 0) {
				--csr_x;
			}
			cell_redraw(csr_x, csr_y);
			draw_cursor();
		} else if (c == '\t') {
			csr_x += (8 - csr_x % 8);
			draw_cursor();
		} else {
			int wide = is_wide(codepoint);
			uint8_t flags = ansi_state->flags;
			if (wide && csr_x == term_width - 1) {
				csr_x = 0;
				++csr_y;
			}
			if (wide) {
				flags = flags | ANSI_WIDE;
			}
			cell_set(csr_x,csr_y, codepoint, current_fg, current_bg, flags);
			cell_redraw(csr_x,csr_y);
			csr_x++;
			if (wide && csr_x != term_width) {
				cell_set(csr_x, csr_y, 0xFFFF, current_fg, current_bg, ansi_state->flags);
				cell_redraw(csr_x,csr_y);
				cell_redraw(csr_x-1,csr_y);
				csr_x++;
			}
		}
	} else if (unicode_state == UTF8_REJECT) {
		unicode_state = 0;
	}
	draw_cursor();
}

void
term_set_csr(int x, int y) {
	cell_redraw(csr_x,csr_y);
	csr_x = x;
	csr_y = y;
	draw_cursor();
}

int
term_get_csr_x() {
	return csr_x;
}

int
term_get_csr_y() {
	return csr_y;
}

void
term_set_csr_show(uint8_t on) {
	cursor_on = on;
}

void term_set_colors(uint32_t fg, uint32_t bg) {
	current_fg = fg;
	current_bg = bg;
}

void term_redraw_cursor() {
	if (term_buffer) {
		draw_cursor();
	}
}

void flip_cursor() {
	static uint8_t cursor_flipped = 0;
	if (cursor_flipped) {
		cell_redraw(csr_x, csr_y);
	} else {
		render_cursor();
	}
	cursor_flipped = 1 - cursor_flipped;
}

void
term_set_cell(int x, int y, uint32_t c) {
	cell_set(x, y, c, current_fg, current_bg, ansi_state->flags);
	cell_redraw(x, y);
}

void term_redraw_cell(int x, int y) {
	if (x < 0 || y < 0 || x >= term_width || y >= term_height) return;
	cell_redraw(x,y);
}

void term_clear(int i) {
	if (i == 2) {
		/* Oh dear */
		csr_x = 0;
		csr_y = 0;
		memset((void *)term_buffer, 0x00, term_width * term_height * sizeof(term_cell_t));
		term_redraw_all();
	} else if (i == 0) {
		for (int x = csr_x; x < term_width; ++x) {
			term_set_cell(x, csr_y, ' ');
		}
		for (int y = csr_y + 1; y < term_height; ++y) {
			for (int x = 0; x < term_width; ++x) {
				term_set_cell(x, y, ' ');
			}
		}
	} else if (i == 1) {
		for (int y = 0; y < csr_y; ++y) {
			for (int x = 0; x < term_width; ++x) {
				term_set_cell(x, y, ' ');
			}
		}
		for (int x = 0; x < csr_x; ++x) {
			term_set_cell(x, csr_y, ' ');
		}
	}
}

#define INPUT_SIZE 1024
char input_buffer[INPUT_SIZE];
int  input_collected = 0;

void clear_input() {
	memset(input_buffer, 0x0, INPUT_SIZE);
	input_collected = 0;
}

uint32_t child_pid = 0;

void handle_input(char c) {
	write(fd_master, &c, 1);
}

void handle_input_s(char * c) {
	write(fd_master, c, strlen(c));
}

void key_event(int ret, key_event_t * event) {
	if (ret) {
		if (event->modifiers & KEY_MOD_LEFT_ALT || event->modifiers & KEY_MOD_RIGHT_ALT) {
			handle_input('\033');
		}
		handle_input(event->key);
	} else {
		if (event->action == KEY_ACTION_UP) return;
		switch (event->keycode) {
			case KEY_F1:
				handle_input_s("\033OP");
				break;
			case KEY_F2:
				handle_input_s("\033OQ");
				break;
			case KEY_F3:
				handle_input_s("\033OR");
				break;
			case KEY_F4:
				handle_input_s("\033OS");
				break;
			case KEY_F5:
				handle_input_s("\033[15~");
				break;
			case KEY_F6:
				handle_input_s("\033[17~");
				break;
			case KEY_F7:
				handle_input_s("\033[18~");
				break;
			case KEY_F8:
				handle_input_s("\033[19~");
				break;
			case KEY_F9:
				handle_input_s("\033[20~");
				break;
			case KEY_F10:
				handle_input_s("\033[21~");
				break;
			case KEY_F11:
				handle_input_s("\033[23~");
				break;
			case KEY_F12:
				/* XXX This is for testing only */
				handle_input_s("テスト");
				//handle_input_s("\033[24~");
				break;
			case KEY_ARROW_UP:
				handle_input_s("\033[A");
				break;
			case KEY_ARROW_DOWN:
				handle_input_s("\033[B");
				break;
			case KEY_ARROW_RIGHT:
				handle_input_s("\033[C");
				break;
			case KEY_ARROW_LEFT:
				handle_input_s("\033[D");
				break;
			case KEY_PAGE_UP:
				handle_input_s("\033[5~");
				break;
			case KEY_PAGE_DOWN:
				handle_input_s("\033[6~");
				break;
		}
	}
}

void * wait_for_exit(void * garbage) {
	int pid;
	do {
		pid = waitpid(-1, NULL, 0);
	} while (pid == -1 && errno == EINTR);
	/* Clean up */
	exit_application = 1;
	/* Exit */
	char exit_message[] = "[Process terminated]\n";
	write(fd_slave, exit_message, sizeof(exit_message));
}

void usage(char * argv[]) {
	printf(
			"VGA Terminal Emulator\n"
			"\n"
			"usage: %s [-b] [-F] [-h]\n"
			"\n"
			" -h --help       \033[3mShow this help message.\033[0m\n"
			"\n",
			argv[0]);
}

term_callbacks_t term_callbacks = {
	/* writer*/
	&term_write,
	/* set_color*/
	&term_set_colors,
	/* set_csr*/
	&term_set_csr,
	/* get_csr_x*/
	&term_get_csr_x,
	/* get_csr_y*/
	&term_get_csr_y,
	/* set_cell*/
	&term_set_cell,
	/* cls*/
	&term_clear,
	/* scroll*/
	&term_scroll,
	/* redraw_cursor*/
	&term_redraw_cursor,
	/* input_buffer_stuff*/
	&input_buffer_stuff,
	/* set_font_size*/
	&set_term_font_size,
	/* set_title*/
	&set_title,
};

void reinit(int send_sig) {
	if (term_buffer) {
		/* Do nothing */
	} else {
		term_buffer = malloc(sizeof(term_cell_t) * term_width * term_height);
		memset(term_buffer, 0x0, sizeof(term_cell_t) * term_width * term_height);
	}

	ansi_state = ansi_init(ansi_state, term_width, term_height, &term_callbacks);
	term_redraw_all();
}



void * handle_incoming(void * garbage) {
	int kfd = open("/dev/kbd", O_RDONLY);
	key_event_t event;
	char c;

	key_event_state_t kbd_state = {0};

	while (!exit_application) {
		int r = read(kfd, &c, 1);
		if (r > 0) {
			int ret = kbd_scancode(&kbd_state, c, &event);
			key_event(ret, &event);
		}
	}
	pthread_exit(0);
}

void * blink_cursor(void * garbage) {
	while (!exit_application) {
		timer_tick++;
		if (timer_tick == 3) {
			timer_tick = 0;
			flip_cursor();
		}
		usleep(90000);
	}
	pthread_exit(0);
}

int main(int argc, char ** argv) {

	_login_shell = 0;

	static struct option long_opts[] = {
		{"login",      no_argument,       0, 'l'},
		{"help",       no_argument,       0, 'h'},
		{0,0,0,0}
	};

	/* Read some arguments */
	int index, c;
	while ((c = getopt_long(argc, argv, "hl", long_opts, &index)) != -1) {
		if (!c) {
			if (long_opts[index].flag == 0) {
				c = long_opts[index].val;
			}
		}
		switch (c) {
			case 'l':
				_login_shell = 1;
				break;
			case 'h':
				usage(argv);
				return 0;
				break;
			case '?':
				break;
			default:
				break;
		}
	}

	putenv("TERM=toaru");

	syscall_openpty(&fd_master, &fd_slave, NULL, NULL, NULL);

	terminal = fdopen(fd_slave, "w");

	reinit(0);

	fflush(stdin);

	int pid = getpid();
	uint32_t f = fork();

	if (getpid() != pid) {
		dup2(fd_slave, 0);
		dup2(fd_slave, 1);
		dup2(fd_slave, 2);

		if (argv[optind] != NULL) {
			char * tokens[] = {argv[optind], NULL};
			int i = execvp(tokens[0], tokens);
			fprintf(stderr, "Failed to launch requested startup application.\n");
		} else {
			/*
			 * TODO: Check the public-readable passwd file to select which shell to run
			 */
			if (_login_shell) {
				char * tokens[] = {"/bin/login",NULL};
				int i = execvp(tokens[0], tokens);
			} else {
				char * tokens[] = {"/bin/sh",NULL};
				int i = execvp(tokens[0], tokens);
			}
		}

		exit_application = 1;

		return 1;
	} else {

		child_pid = f;

		pthread_t wait_for_exit_thread;
		pthread_create(&wait_for_exit_thread, NULL, wait_for_exit, NULL);

		pthread_t handle_incoming_thread;
		pthread_create(&handle_incoming_thread, NULL, handle_incoming, NULL);

		pthread_t cursor_blink_thread;
		pthread_create(&cursor_blink_thread, NULL, blink_cursor, NULL);

		unsigned char buf[1024];
		while (!exit_application) {
			int r = read(fd_master, buf, 1024);
			for (uint32_t i = 0; i < r; ++i) {
				ansi_put(ansi_state, buf[i]);
			}
		}

	}

	return 0;
}