#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <flash.h>
#include <macros.h>

#include <fs/mufs.h>

#include "dir.h"
#include "tree.h"

struct mufs_dir {
	struct mufs *fs;
	struct mufs_tree *tree;
	uint32_t va;
};

char *mufs_abspath(const char *path)
{
	char *s, *p, *next, *prev;

	if (!(s = malloc(strlen(path) + 2)))
		return NULL;

	strcpy(s, path);

	for (p = s, next = p + strcspn(p, "/"); *p != '\0'; next = p + strcspn(p, "/")) {
		char c = *next;

		*next = '\0';

		if (*p == '\0' || strcmp(p, ".") == 0) {
			memmove(p, next + 1, strlen(next + 1) + 1);
			continue;
		}

		if (strcmp(p, "..") == 0) {
			if (!(prev = strrchr(s, '/'))) {
				memmove(p, next + 1, strlen(next + 1) + 1);
				continue;
			}

			*prev = '\0';

			if (!(prev = strrchr(s, '/'))) {
				memmove(s, next + 1, strlen(next + 1) + 1);
				p = s;
				continue;
			}

			memmove(prev + 1, next + 1, strlen(next + 1) + 1);
			p = prev + 1;
			continue;
		}

		*next = c;
		p = next + 1;
	}

	memmove(s + 1, s, strlen(s) + 1);
	*s = '/';

	return s;
}

static struct mufs_dir *mufs_opendirent(struct mufs *fs, struct mufs_dirent *entry)
{
	struct mufs_dir *dir;

	if (!(dir = malloc(sizeof *dir)))
		return NULL;

	dir->fs = fs;
	dir->va = 0;

	if (entry) {
		if (!(dir->tree = malloc(sizeof *dir->tree)))
			goto err_free_dir;

		memcpy(dir->tree, &entry->tree, sizeof *dir->tree);
	} else {
		dir->tree = &fs->root;
	}

	return dir;

err_free_dir:
	free(dir);
	return NULL;
}

struct mufs_tree *resolve_path(struct mufs *fs, const char *path)
{
	struct mufs_dir *dir;
	struct mufs_dirent entry;
	struct mufs_tree *tree;
	char *s, *p, *end;
	int ret;

	if (!path || *path == '\0')
		return NULL;

	if (!(s = mufs_abspath(path)))
		return NULL;

	if (strcmp(s, "/") == 0)
		return &fs->root;

	if (!(dir = mufs_opendirent(fs, NULL)))
		goto err_free_s;

	for (p = s + 1; *p != '\0'; p = end) {
		end = p + strcspn(p, "/");

		if (*end == '/')
			*end++ = '\0';

		while ((ret = mufs_readdir(dir, &entry)) == 0) {
			if (strcmp(entry.path, p) != 0)
				continue;

			mufs_closedir(dir);

			if (!(dir = mufs_opendirent(fs, &entry)))
				goto err_free_s;

			break;
		}

		if (ret < 0)
			goto err_close_dir;
	}

	tree = dir->tree;

	mufs_closedir(dir);

	return tree;

err_close_dir:
	mufs_closedir(dir);
err_free_s:
	free(s);
	return NULL;
}

struct mufs_dir *mufs_opendir(struct mufs *fs, const char *path)
{
	struct mufs_dir *dir;

	if (!(dir = malloc(sizeof(*dir))))
		return NULL;

	dir->fs = fs;

	if (!(dir->tree = resolve_path(fs, path)))
		goto err_free_dir;

	dir->va = 0;

	return dir;

err_free_dir:
	free(dir);
	return NULL;
}

void mufs_closedir(struct mufs_dir *dir)
{
	if (!dir)
		return;

	free(dir);
}

size_t read_dirent(struct mufs *fs, struct mufs_tree *tree,
	struct mufs_dirent *dirent, uint32_t va)
{
	struct flash_dev *dev = fs->dev;
	struct mufs_dentry entry;
	size_t ret = 0;
	size_t len;
	uint32_t base, offset;

	offset = va & ((UINT32_C(1) << dev->log2_block_size) - 1);
	base = align(va, dev->log2_block_size);

	if (va + sizeof(entry) > tree->file_size)
		return 0;

	if (mufs_tree_read(tree, &entry, va, sizeof entry) == 0)
		return 0;

	if (!entry.type)
		return 0;

	ret += sizeof entry;
	va += sizeof entry;
	len = min(entry.path_len, sizeof(dirent->path - 1));

	if (va + len > tree->file_size)
		return 0;

	if (mufs_tree_read(tree, dirent->path, va, len) == 0)
		return 0;

	dirent->path[len] = '\0';
	ret += len;

	dirent->type = entry.type;

	if (mufs_lookup_page(tree, &dirent->tree.va, base) < 0)
		return 0;

	dirent->tree.fs = fs;
	dirent->tree.va = (dirent->tree.va << dev->log2_block_size) + offset +
		offsetof(struct mufs_dentry, tree);
	dirent->tree.file_size = entry.tree.file_size;
	dirent->tree.root = entry.tree.root;
	dirent->tree.depth = entry.tree.depth;

	return ret;
}

size_t write_dirent(struct mufs_tree *tree,
	uint32_t va, struct mufs_dirent *dirent)
{
	struct mufs_dtree dtree;
	struct mufs_dentry entry;

	entry.type = dirent->type;
	entry.tree.file_size = dirent->tree.file_size;
	entry.tree.root = dirent->tree.root;
	entry.tree.depth = dirent->tree.depth;
	entry.path_len = strlen(dirent->path);

	if (mufs_tree_write(tree, dirent->path, va + sizeof entry,
		entry.path_len) == 0)
		return 0;

	if (mufs_tree_write(tree, &entry, va, sizeof entry) == 0)
		return 0;

	tree->file_size = max(tree->file_size, va + sizeof entry + entry.path_len);

	dtree.file_size = tree->file_size;
	dtree.root = tree->root;
	dtree.depth = tree->depth;

	if (flash_write(tree->fs->dev, tree->va, &dtree, sizeof dtree) == 0)
		return 0;

	return entry.path_len + sizeof entry;
}

int mufs_readdir(struct mufs_dir *dir, struct mufs_dirent *dirent)
{
	size_t ret;

	if (!dir || !dirent || dir->va >= dir->tree->file_size)
		return -1;

	if ((ret = read_dirent(dir->fs, dir->tree, dirent, dir->va)) > 0) {
		dir->va += ret;
		return 0;
	}

	dir->va = align_up(dir->va + 1, dir->fs->dev->log2_block_size);

	if ((ret = read_dirent(dir->fs, dir->tree, dirent, dir->va)) > 0) {
		dir->va += ret;
		return 0;
	}

	return -1;
}

int mufs_mkdir(struct mufs *fs, const char *path)
{
	struct mufs_dirent dirent;
	struct mufs_tree *tree;
	size_t len;
	char *s;
	char *name;

	if (!path || *path == '\0')
		return -1;

	if (!(s = mufs_abspath(path)))
		return -1;

	/* TODO: already exists. */
	if (resolve_path(fs, s)) {
		free(s);
		return 0;
	}

	if (!(name = strrchr(s, '/'))) {
		name = s;
		s = "/";
	} else {
		*name++ = '\0';
	}

	if (*name == '\0')
		return -1;

	if (!(tree = resolve_path(fs, s)))
		return -1;

	len = min(strlen(name), sizeof(dirent.path) - 1);
	memcpy(dirent.path, name, len);
	dirent.path[len] = '\0';
	dirent.type = MUFS_DIR;

	dirent.tree.fs = fs;
	dirent.tree.file_size = 0;
	dirent.tree.root = 0;
	dirent.tree.depth = 0;

	if (!is_aligned(tree->file_size, fs->dev->log2_block_size) &&
		write_dirent(tree, tree->file_size, &dirent) > 0)
		return 0;

	if (write_dirent(tree, align_up(tree->file_size,
		fs->dev->log2_block_size), &dirent) > 0)
		return 0;

	return -1;
}