/* vim: tabstop=4 shiftwidth=4 noexpandtab
 */
#include <system.h>
#include <ext2.h>
#include <fs.h>
#include <logging.h>

ext2_superblock_t * initrd_superblock;
ext2_inodetable_t * initrd_root_node;
ext2_bgdescriptor_t * initrd_root_block;
ext2_inodetable_t * initrd_inode_table;
void * initrd_start;

fs_node_t *         initrd_root;
fs_node_t *         initrd_dev;

uint32_t initrd_node_from_file(ext2_inodetable_t *inode, ext2_dir_t *direntry, fs_node_t *fnode);
uint32_t read_initrd(fs_node_t *node, uint32_t offset, uint32_t size, uint8_t *buffer);
uint32_t write_initrd(fs_node_t *node, uint32_t offset, uint32_t size, uint8_t *buffer);
void open_initrd(fs_node_t *node, uint8_t read, uint8_t write);
void close_initrd(fs_node_t *node);
struct dirent *readdir_initrd(fs_node_t *node, uint32_t index);
fs_node_t *finddir_initrd(fs_node_t *node, char *name);
ext2_dir_t * ext2_get_direntry(ext2_inodetable_t * inode, uint32_t index);
ext2_inodetable_t * ext2_get_inode(uint32_t inode);
void * ext2_get_block(uint32_t block);
void * ext2_get_inode_block(ext2_inodetable_t * inode, uint32_t block);

uint32_t
read_initrd(
		fs_node_t *node,
		uint32_t offset,
		uint32_t size,
		uint8_t *buffer
		) {
	ext2_inodetable_t * inode = ext2_get_inode(node->inode);
	uint32_t end;
	if (offset + size > inode->size) {
		end = inode->size;
	} else {
		end = offset + size;
	}
	uint32_t block_size  = 1024 << initrd_superblock->log_block_size;
	uint32_t start_block = offset / block_size;
	uint32_t end_block   = end / block_size;
	uint32_t end_size    = end % block_size;
	uint32_t size_to_read = end - offset;
	if (start_block == end_block) {
		memcpy(buffer, (void *)((uintptr_t)ext2_get_inode_block(inode, start_block) + offset % block_size), size_to_read);
		return size_to_read;
	} else {
		uint32_t block_offset = start_block;
		uint32_t blocks_read = 0;
		for (block_offset = start_block; block_offset < end_block; ++block_offset) {
			if (block_offset == start_block) {
				memcpy(buffer, (void *)((uintptr_t)ext2_get_inode_block(inode, block_offset) + (offset % block_size)), (block_size - (offset % block_size)));
			} else {
				memcpy(buffer + block_size * blocks_read - (offset % block_size), ext2_get_inode_block(inode, block_offset), block_size);
			}
			blocks_read++;
		}
		memcpy(buffer + block_size * blocks_read - (offset % block_size), ext2_get_inode_block(inode, end_block), end_size);
	}
	return size_to_read;
}

uint32_t
write_initrd(
		fs_node_t *node,
		uint32_t offset,
		uint32_t size,
		uint8_t *buffer
		) {
	/*
	 * Not implemented
	 */
	return 0;
}

void
open_initrd(
		fs_node_t *node,
		uint8_t read,
		uint8_t write
		) {
	// woosh
}

void
close_initrd(
		fs_node_t *node
		) {
	free(node);
	/*
	 * Nothing to do here
	 */
}

struct dirent *
readdir_initrd(
		fs_node_t *node,
		uint32_t index
		) {
	ext2_inodetable_t * inode = ext2_get_inode(node->inode);
	assert(inode->mode & EXT2_S_IFDIR);
	ext2_dir_t * direntry = ext2_get_direntry(inode, index);
	if (!direntry) {
		return NULL;
	}
	struct dirent * dirent = malloc(sizeof(struct dirent));
	memcpy(&dirent->name, &direntry->name, direntry->name_len);
	dirent->name[direntry->name_len] = '\0';
	dirent->ino = direntry->inode;
	return dirent;
}

/*
 * find the child entry named `name` within the directory
 * node `node`. The VFS has already checked that `node` is
 * a valid directory, but we'll do that again just to be safe,
 * and just in case someone didn't use the VFS layer to call us.
 * Basically, run through the directory entries until we find
 * the one requested and build an fs_node_t for it. The requester
 * will have to free it when they are done with it.
 */
fs_node_t *
finddir_initrd(
		fs_node_t *node,
		char *name
		) {
	/*
	 * Find the actual inode in the ramdisk image for the requested file
	 */
	ext2_inodetable_t * inode = ext2_get_inode(node->inode);
	assert(inode->mode & EXT2_S_IFDIR);
	void * block;
	ext2_dir_t * direntry = NULL;
	block = (void *)ext2_get_inode_block(inode, 0);
	uint32_t dir_offset;
	dir_offset = 0;
	/*
	 * Look through the requested entries until we find what we're looking for
	 */
	while (dir_offset < inode->size) {
		ext2_dir_t * d_ent = (ext2_dir_t *)((uintptr_t)block + dir_offset);
#if 0
		if (strlen(name) != d_ent->name_len) {
			dir_offset += d_ent->rec_len;
			continue;
		}
#endif
		char * dname = malloc(sizeof(char) * (d_ent->name_len + 1));
		memcpy(dname, &d_ent->name, d_ent->name_len);
		dname[d_ent->name_len] = '\0';
		if (!strcmp(dname, name)) {
			free(dname);
			direntry = d_ent;
			break;
		}
		free(dname);
		dir_offset += d_ent->rec_len;
	}
	if (!direntry) {
		/*
		 * We could not find the requested entry in this directory.
		 */
		return NULL;
	}
	fs_node_t * outnode = malloc(sizeof(fs_node_t));
	initrd_node_from_file(ext2_get_inode(direntry->inode), direntry, outnode);
	return outnode;
}

uint32_t
initrd_node_from_file(
		ext2_inodetable_t * inode,
		ext2_dir_t * direntry,
		fs_node_t * fnode
		) {
	if (!fnode) {
		/* You didn't give me a node to write into, go *** yourself */
		return 0;
	}
	/* Information from the direntry */
	fnode->inode = direntry->inode;
	memcpy(&fnode->name, &direntry->name, direntry->name_len);
	fnode->name[direntry->name_len] = '\0';
	/* Information from the inode */
	fnode->uid = inode->uid;
	fnode->gid = inode->gid;
	fnode->length = inode->size;
	fnode->mask = inode->mode & 0xFFF;
	/* File Flags */
	fnode->flags = 0;
	if ((inode->mode & EXT2_S_IFREG) == EXT2_S_IFREG) {
		fnode->flags |= FS_FILE;
	}
	if ((inode->mode & EXT2_S_IFDIR) == EXT2_S_IFDIR) {
		fnode->flags |= FS_DIRECTORY;
	}
	if ((inode->mode & EXT2_S_IFBLK) == EXT2_S_IFBLK) {
		fnode->flags |= FS_BLOCKDEVICE;
	}
	if ((inode->mode & EXT2_S_IFCHR) == EXT2_S_IFCHR) {
		fnode->flags |= FS_CHARDEVICE;
	}
	if ((inode->mode & EXT2_S_IFIFO) == EXT2_S_IFIFO) {
		fnode->flags |= FS_PIPE;
	}
	if ((inode->mode & EXT2_S_IFLNK) == EXT2_S_IFLNK) {
		fnode->flags |= FS_SYMLINK;
	}
	fnode->read    = read_initrd;
	fnode->write   = write_initrd;
	fnode->open    = open_initrd;
	fnode->close   = close_initrd;
	fnode->readdir = readdir_initrd;
	fnode->finddir = finddir_initrd;
	return 1;
}

uint32_t
initrd_node_root(
		ext2_inodetable_t * inode,
		fs_node_t * fnode
		) {
	if (!fnode) {
		return 0;
	}
	/* Information from the direntry */
	fnode->inode = 2;
	fnode->name[0] = '/';
	fnode->name[1] = '\0';
	/* Information from the inode */
	fnode->uid = inode->uid;
	fnode->gid = inode->gid;
	fnode->length = inode->size;
	fnode->mask = inode->mode & 0xFFF;
	/* File Flags */
	fnode->flags = 0;
	if ((inode->mode & EXT2_S_IFREG) == EXT2_S_IFREG) {
		fnode->flags |= FS_FILE;
	}
	if ((inode->mode & EXT2_S_IFDIR) == EXT2_S_IFDIR) {
		fnode->flags |= FS_DIRECTORY;
	}
	if ((inode->mode & EXT2_S_IFBLK) == EXT2_S_IFBLK) {
		fnode->flags |= FS_BLOCKDEVICE;
	}
	if ((inode->mode & EXT2_S_IFCHR) == EXT2_S_IFCHR) {
		fnode->flags |= FS_CHARDEVICE;
	}
	if ((inode->mode & EXT2_S_IFIFO) == EXT2_S_IFIFO) {
		fnode->flags |= FS_PIPE;
	}
	if ((inode->mode & EXT2_S_IFLNK) == EXT2_S_IFLNK) {
		fnode->flags |= FS_SYMLINK;
	}
	fnode->read    = read_initrd;
	fnode->write   = write_initrd;
	fnode->open    = open_initrd;
	fnode->close   = close_initrd;
	fnode->readdir = readdir_initrd;
	fnode->finddir = finddir_initrd;
	return 1;
}

uint32_t
initrd_node_from_dirent(
		ext2_inodetable_t * inode,
		struct dirent * direntry,
		fs_node_t * fnode
		) {
	if (!fnode) {
		/* You didn't give me a node to write into, go *** yourself */
		return 0;
	}
	/* Information from the direntry */
	fnode->inode = direntry->ino;
	memcpy(&fnode->name, &direntry->name, strlen(direntry->name));
	fnode->name[strlen(direntry->name)] = '\0';
	/* Information from the inode */
	fnode->uid = inode->uid;
	fnode->gid = inode->gid;
	fnode->length = inode->size;
	fnode->mask = inode->mode & 0xFFF;
	/* File Flags */
	fnode->flags = 0;
	if ((inode->mode & EXT2_S_IFREG) == EXT2_S_IFREG) {
		fnode->flags |= FS_FILE;
	}
	if ((inode->mode & EXT2_S_IFDIR) == EXT2_S_IFDIR) {
		fnode->flags |= FS_DIRECTORY;
	}
	if ((inode->mode & EXT2_S_IFBLK) == EXT2_S_IFBLK) {
		fnode->flags |= FS_BLOCKDEVICE;
	}
	if ((inode->mode & EXT2_S_IFCHR) == EXT2_S_IFCHR) {
		fnode->flags |= FS_CHARDEVICE;
	}
	if ((inode->mode & EXT2_S_IFIFO) == EXT2_S_IFIFO) {
		fnode->flags |= FS_PIPE;
	}
	if ((inode->mode & EXT2_S_IFLNK) == EXT2_S_IFLNK) {
		fnode->flags |= FS_SYMLINK;
	}
	fnode->read    = read_initrd;
	fnode->write   = write_initrd;
	fnode->open    = open_initrd;
	fnode->close   = close_initrd;
	fnode->readdir = readdir_initrd;
	fnode->finddir = finddir_initrd;
	return 1;
}

ext2_inodetable_t *
ext2_get_inode(
		uint32_t inode
		) {
	return (ext2_inodetable_t *)((uintptr_t)initrd_inode_table + initrd_superblock->inode_size * (inode - 1));
}

void *
ext2_get_inode_block(
		ext2_inodetable_t * inode,
		uint32_t block
		) {
	if (block < 12) {
		return ext2_get_block(inode->block[block]);
	} else if (block < 12 + (1024 << initrd_superblock->log_block_size) / sizeof(uint32_t)) {
		return ext2_get_block(*(uint32_t*)((uintptr_t)ext2_get_block(inode->block[12]) + (block - 12) * sizeof(uint32_t)));
	} else if (block < 12 + 256 + 256 * 256) {
		uint32_t a = block - 12;
		uint32_t b = a - 256;
		uint32_t c = b / 256;
		uint32_t d = b - c * 256;
		void * c_block = ext2_get_block(*(uint32_t *)((uintptr_t)ext2_get_block(inode->block[13]) + (c) * sizeof(uint32_t)));
		return ext2_get_block(*(uint32_t *)((uintptr_t)c_block + (d) * sizeof(uint32_t)));
	}
	return NULL;
}

void *
ext2_get_block(
		uint32_t block
		) {
	return (void *)((uintptr_t)initrd_start + (1024 << initrd_superblock->log_block_size) * block);
}

ext2_dir_t *
ext2_get_direntry(
		ext2_inodetable_t * inode,
		uint32_t index
		) {
	void * block;
	block = (void *)ext2_get_inode_block(inode,0);
	uint32_t dir_offset;
	dir_offset = 0;
	uint32_t dir_index;
	dir_index = 0;
	while (dir_offset < inode->size) {
		ext2_dir_t * d_ent = (ext2_dir_t *)((uintptr_t)block + dir_offset);
		if (dir_index == index) {
			return d_ent;
		}
		dir_offset += d_ent->rec_len;
		dir_index++;
	}
	return NULL;
}

void
initrd_mount(
		uint32_t mem_head,
		uint32_t mem_top
		) {
	blog("Mounting EXT2 ramdisk...");
	initrd_start = (void *)mem_head;
	initrd_superblock = (ext2_superblock_t *)((uintptr_t)initrd_start + 1024);
	assert(initrd_superblock->magic == EXT2_SUPER_MAGIC);
	if (initrd_superblock->inode_size == 0) {
		/**
		 * Broken EXT2 instances may not give us a proper size for this.
		 * We will assume it is 128.
		 */
		initrd_superblock->inode_size = 128;
	}
	initrd_root_block = (ext2_bgdescriptor_t *)((uintptr_t)initrd_start + 1024 + 1024);
	initrd_inode_table = (ext2_inodetable_t *)((uintptr_t)initrd_start + (1024 << initrd_superblock->log_block_size) * initrd_root_block->inode_table);
	ext2_inodetable_t * root_inode = ext2_get_inode(2);
	initrd_root = (fs_node_t *)malloc(sizeof(fs_node_t));
	assert(initrd_node_root(root_inode, initrd_root));
	fs_root = initrd_root;
	LOG(INFO, "Mounted EXT2 ramdisk at 0x%x-0x%x, root VFS node is 0x%x", mem_head, mem_top, initrd_root);
	bfinish(0);
}