#include "misc.h"
#include "posix.h"

#include <blue/core/error.h>
#include <blue/ds/string.h>
#include <blue/io/directory.h>
#include <errno.h>
#include <fcntl.h>
#include <fts.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <unistd.h>

/*** PRIVATE DATA *************************************************************/

enum directory_flags {
	DIRECTORY_DELETE_ON_CLOSE = 0x01u,
};

struct b_directory_p {
	enum directory_flags d_flags;
	int d_fd;
	b_path *d_path_rel;
	b_path *d_path_abs;
};

struct b_directory_iterator_p {
	struct b_directory_p *_p;

	FTS *fts;
	FTSENT *ent;

	b_directory_iterator_flags flags;
	b_directory *root;

	b_directory_entry entry;
};

/*** PRIVATE FUNCTIONS ********************************************************/
static const b_path *directory_get_path(const struct b_directory_p *dir)
{
	return dir->d_path_abs;
}

static const b_path *directory_get_rel_path(const struct b_directory_p *dir)
{
	return dir->d_path_rel;
}

static const char *directory_get_path_cstr(const struct b_directory_p *dir)
{
	return b_path_ptr(dir->d_path_abs);
}

static const char *directory_get_rel_path_cstr(const struct b_directory_p *dir)
{
	return b_path_ptr(dir->d_path_rel);
}

static b_result directory_delete(b_directory *dir, struct b_directory_p *dir_p)
{
	enum b_status status = B_SUCCESS;

	b_iterator *it = b_directory_begin(dir, B_DIRECTORY_ITERATE_PARENT_LAST);
	while (B_OK(b_iterator_get_status(it))) {
		b_iterator_erase(it);
	}

	status = b_iterator_get_status(it);
	if (!B_OK(status) && status != B_ERR_NO_DATA) {
		return B_RESULT_STATUS(status);
	}

	status = b_path_unlink(dir_p->d_path_abs);
	if (!B_OK(status)) {
		return B_RESULT_STATUS(status);
	}

	return B_RESULT_SUCCESS;
}

static bool directory_path_exists(
	const struct b_directory_p *root, const b_path *path)
{
	const b_path *parts[] = {
		root ? root->d_path_abs : NULL,
		path,
	};

	b_path *abs_path = b_path_join(parts, sizeof parts / sizeof parts[0]);
	if (!abs_path) {
		return false;
	}

	bool result = b_path_exists(abs_path);
	b_path_unref(abs_path);

	return result;
}

static bool directory_path_is_file(
	const struct b_directory_p *root, const b_path *path)
{
	const b_path *parts[] = {
		root ? root->d_path_abs : NULL,
		path,
	};

	b_path *abs_path = b_path_join(parts, sizeof parts / sizeof parts[0]);
	if (!abs_path) {
		return false;
	}

	bool result = b_path_is_file(abs_path);
	b_path_unref(abs_path);

	return result;
}

static bool directory_path_is_directory(
	const struct b_directory_p *root, const b_path *path)
{
	const b_path *parts[] = {
		root ? root->d_path_abs : NULL,
		path,
	};

	b_path *abs_path = b_path_join(parts, sizeof parts / sizeof parts[0]);
	if (!abs_path) {
		return false;
	}

	bool result = b_path_is_directory(abs_path);
	b_path_unref(abs_path);

	return result;
}

static b_result directory_path_stat(
	const struct b_directory_p *root, const b_path *path,
	struct b_file_info *out)
{
	const b_path *parts[] = {
		root ? root->d_path_abs : NULL,
		path,
	};

	b_path *abs_path = b_path_join(parts, sizeof parts / sizeof parts[0]);
	if (!abs_path) {
		return B_RESULT_ERR(NO_MEMORY);
	}

	enum b_status status = b_path_stat(abs_path, out);
	b_path_unref(abs_path);

	return B_RESULT_STATUS(status);
}

static b_result directory_path_unlink(
	const struct b_directory_p *root, const b_path *path)
{
	const b_path *parts[] = {
		root ? root->d_path_abs : NULL,
		path,
	};

	b_path *abs_path = b_path_join(parts, sizeof parts / sizeof parts[0]);
	if (!abs_path) {
		return B_RESULT_ERR(NO_MEMORY);
	}

	enum b_status status = b_path_unlink(abs_path);
	b_path_unref(abs_path);

	return B_RESULT_STATUS(status);
}

static b_result create_directory(struct b_directory_p *root, const char *path)
{
	int root_fd = root ? root->d_fd : -1;
	int err;

	if (root_fd == -1) {
		err = mkdir(path, 0755);
	} else {
		err = mkdirat(root_fd, path, 0755);
	}

	if (err == 0 || errno == EEXIST) {
		return B_RESULT_SUCCESS;
	}

	return b_result_from_errno_with_subfilepath(
		errno, path, directory_get_rel_path_cstr(root), B_ERR_IO_FAILURE);
}

static b_result create_directory_hierarchy(
	struct b_directory_p *root, const char *path)
{
	int root_fd = root ? root->d_fd : AT_FDCWD;

	char *path_buf = b_strdup(path);
	if (!path_buf) {
		return B_RESULT_ERR(NO_MEMORY);
	}

	b_result result = B_RESULT_SUCCESS;
	for (size_t i = 0; path_buf[i]; i++) {
		if (path_buf[i] != '/') {
			continue;
		}

		path_buf[i] = 0;

		int err = mkdirat(root_fd, path_buf, 0755);
		if (err != 0 && errno != EEXIST) {
			result = b_result_from_errno_with_subfilepath(
				errno, path_buf, directory_get_rel_path_cstr(root),
				B_ERR_IO_FAILURE);
			break;
		}

		path_buf[i] = '/';
	}

	int err = mkdirat(root_fd, path_buf, 0755);
	if (err != 0 && errno != EEXIST) {
		result = b_result_from_errno_with_subfilepath(
			errno, path_buf, directory_get_rel_path_cstr(root),
			B_ERR_IO_FAILURE);
	}

	free(path_buf);
	return result;
}

static b_result directory_open(
	struct b_directory_p *root, const b_path *path,
	b_directory_open_flags flags, b_directory **out)
{
	enum b_status status = B_SUCCESS;

	int root_fd = root ? root->d_fd : AT_FDCWD;

	const char *path_cstr = b_path_ptr(path);
	if (root) {
		while (*path_cstr == '/') {
			path_cstr++;
		}
	}

	b_result result = B_RESULT_SUCCESS;
	if ((flags & B_DIRECTORY_OPEN_CREATE_INTERMEDIATE)
	    == B_DIRECTORY_OPEN_CREATE_INTERMEDIATE) {
		result = create_directory_hierarchy(root, path_cstr);
	} else if ((flags & B_DIRECTORY_OPEN_CREATE) == B_DIRECTORY_OPEN_CREATE) {
		result = create_directory(root, path_cstr);
	}

	if (b_result_is_error(result)) {
		return b_result_propagate(result);
	}

	int fd = openat(root_fd, path_cstr, O_DIRECTORY);

	if (fd == -1) {
		status = b_status_from_errno(errno, B_ERR_IO_FAILURE);
		return B_RESULT_STATUS(status);
	}

	b_directory *dir = b_object_create(B_TYPE_DIRECTORY);
	b_path *cwd = NULL;
	struct b_directory_p *p = b_object_get_private(dir, B_TYPE_DIRECTORY);

	if (!root) {
		cwd = b_path_create_cwd();
	}

	const b_path *parts[] = {
		root ? root->d_path_abs : cwd,
		path,
	};

	b_path *new_path = b_path_join(parts, sizeof parts / sizeof parts[0]);
	if (!new_path) {
		return B_RESULT_ERR(NO_MEMORY);
	}

	if (cwd) {
		b_path_unref(cwd);
	}

	p->d_path_abs = new_path;
	p->d_path_rel = b_path_duplicate(path);
	p->d_fd = fd;

	if (flags & B_DIRECTORY_OPEN_DELETE_ON_CLOSE) {
		p->d_flags = DIRECTORY_DELETE_ON_CLOSE;
	}

	*out = dir;

	return B_RESULT_SUCCESS;
}

/*** PUBLIC FUNCTIONS *********************************************************/

b_result b_directory_open(
	b_directory *root, const b_path *path, b_directory_open_flags flags,
	b_directory **out)
{
	B_CLASS_DISPATCH_STATIC(
		B_TYPE_DIRECTORY, directory_open, root, path, flags, out);
}

b_result b_directory_open_temp(b_directory **out)
{
	char name[16];
	char path[128];

	while (1) {
		z__b_io_generate_tmp_filename(name, sizeof name);
		snprintf(path, sizeof path, "/tmp/%s", name);
		b_path *rpath = b_path_create_from_cstr(path);

		b_directory *dir = NULL;
		b_result status = b_directory_open(
			B_DIRECTORY_ROOT, rpath, B_DIRECTORY_OPEN_CREATE, &dir);
		struct b_directory_p *p
			= b_object_get_private(dir, B_TYPE_DIRECTORY);

		if (b_error_get_status_code(status) == B_ERR_NAME_EXISTS) {
			b_path_unref(rpath);
			continue;
		}

		if (dir) {
			p->d_flags |= DIRECTORY_DELETE_ON_CLOSE;
		}

		b_path_unlink(rpath);
		b_path_unref(rpath);

		return status;
	}
}

const b_path *b_directory_get_path(const b_directory *dir)
{
	B_CLASS_DISPATCH_STATIC_0(B_TYPE_DIRECTORY, directory_get_path, dir);
}

const b_path *b_directory_get_rel_path(const b_directory *dir)
{
	B_CLASS_DISPATCH_STATIC_0(B_TYPE_DIRECTORY, directory_get_rel_path, dir);
}

const char *b_directory_get_path_cstr(const b_directory *dir)
{
	B_CLASS_DISPATCH_STATIC_0(B_TYPE_DIRECTORY, directory_get_path_cstr, dir);
}

const char *b_directory_get_rel_path_cstr(const b_directory *dir)
{
	B_CLASS_DISPATCH_STATIC_0(
		B_TYPE_DIRECTORY, directory_get_rel_path_cstr, dir);
}

b_result b_directory_delete(b_directory *dir)
{
	struct b_directory_p *p = b_object_get_private(dir, B_TYPE_DIRECTORY);
	p->d_flags |= DIRECTORY_DELETE_ON_CLOSE;
	/* TODO allow object release functions to return a b_result value */
	b_directory_unref(dir);
	return B_RESULT_SUCCESS;
}

bool b_directory_path_exists(const b_directory *root, const b_path *path)
{
	B_CLASS_DISPATCH_STATIC(B_TYPE_DIRECTORY, directory_path_exists, root, path);
}

bool b_directory_path_is_file(const b_directory *root, const b_path *path)
{
	B_CLASS_DISPATCH_STATIC(
		B_TYPE_DIRECTORY, directory_path_is_file, root, path);
}

bool b_directory_path_is_directory(const b_directory *root, const b_path *path)
{
	B_CLASS_DISPATCH_STATIC(
		B_TYPE_DIRECTORY, directory_path_is_directory, root, path);
}

b_result b_directory_path_stat(
	const b_directory *root, const b_path *path, struct b_file_info *out)
{
	B_CLASS_DISPATCH_STATIC(
		B_TYPE_DIRECTORY, directory_path_stat, root, path, out);
}

b_result b_directory_path_unlink(const b_directory *root, const b_path *path)
{
	B_CLASS_DISPATCH_STATIC(B_TYPE_DIRECTORY, directory_path_unlink, root, path);
}

/*** VIRTUAL FUNCTIONS ********************************************************/

static void directory_init(b_object *obj, void *priv)
{
	struct b_directory_p *dir = priv;
}

static void directory_fini(b_object *obj, void *priv)
{
	struct b_directory_p *dir = priv;

	close(dir->d_fd);

	if (dir->d_flags & DIRECTORY_DELETE_ON_CLOSE) {
		directory_delete(obj, dir);
	}

	b_path_unref(dir->d_path_abs);
}

/*** ITERATOR FUNCTIONS *******************************************************/

static int ftsent_compare(const FTSENT **one, const FTSENT **two)
{
	return (strcmp((*one)->fts_name, (*two)->fts_name));
}

static void update_iterator_data(struct b_directory_iterator_p *it)
{
	if (it->entry.filepath) {
		b_path_unref((b_path *)it->entry.filepath);
		it->entry.filepath = NULL;
	}

	FTSENT *ent = it->ent;

	b_path *path = b_path_create_from_cstr(
		ent->fts_path + b_path_length(it->_p->d_path_abs) + 1);

	it->entry.filename = ent->fts_name;
	it->entry.filepath = path;

	memset(&it->entry.info, 0x0, sizeof it->entry.info);

	it->entry.info.length = ent->fts_statp->st_size;

	if (S_ISREG(ent->fts_statp->st_mode)) {
		it->entry.info.attrib |= B_FILE_ATTRIB_NORMAL;
	}

	if (S_ISDIR(ent->fts_statp->st_mode)) {
		it->entry.info.attrib |= B_FILE_ATTRIB_DIRECTORY;
	}

	if (S_ISBLK(ent->fts_statp->st_mode)) {
		it->entry.info.attrib |= B_FILE_ATTRIB_BLOCK_DEVICE;
	}

	if (S_ISCHR(ent->fts_statp->st_mode)) {
		it->entry.info.attrib |= B_FILE_ATTRIB_CHAR_DEVICE;
	}

	if (S_ISLNK(ent->fts_statp->st_mode)) {
		it->entry.info.attrib |= B_FILE_ATTRIB_SYMLINK;
	}
}

static void iterator_fini(b_object *obj, void *priv)
{
	struct b_directory_iterator_p *it = priv;

	if (it->entry.filepath) {
		b_path_unref((b_path *)it->entry.filepath);
		it->entry.filepath = NULL;
	}

	if (it->fts) {
		fts_close(it->fts);
	}
}

b_iterator *b_directory_begin(
	b_directory *directory, enum b_directory_iterator_flags flags)
{
	b_iterator *it_obj = b_object_create(B_TYPE_DIRECTORY_ITERATOR);
	struct b_directory_iterator_p *it
		= b_object_get_private(it_obj, B_TYPE_DIRECTORY_ITERATOR);

	it->flags = flags;
	it->root = directory;
	it->_p = b_object_get_private(directory, B_TYPE_DIRECTORY);

	int fts_flags = FTS_COMFOLLOW | FTS_NOCHDIR;

	const char *path_list[] = {
		b_path_ptr(it->_p->d_path_abs),
		NULL,
	};

	it->fts = fts_open((char *const *)path_list, fts_flags, ftsent_compare);

	bool done = false;

	while (!done) {
		it->ent = fts_read(it->fts);

		if (!it->ent) {
			b_iterator_set_status(it_obj, B_ERR_NO_DATA);
			return it_obj;
		}

		if (it->ent->fts_level == 0) {
			continue;
		}

		switch (it->ent->fts_info) {
		case FTS_DOT:
			continue;
		case FTS_F:
			done = true;
			break;
		case FTS_D:
			if (it->flags & B_DIRECTORY_ITERATE_PARENT_LAST) {
				continue;
			}

			done = true;
			break;
		case FTS_DP:
			if (it->flags & B_DIRECTORY_ITERATE_PARENT_FIRST) {
				continue;
			}
			done = true;
			break;
		default:
			done = true;
			break;
		}
	}

	update_iterator_data(it);
	return it_obj;
}

static b_iterator *iterator_begin(b_object *obj)
{
	return b_directory_begin(obj, B_DIRECTORY_ITERATE_PARENT_FIRST);
}

static const b_iterator *iterator_cbegin(const b_object *obj)
{
	return b_directory_begin((b_object *)obj, B_DIRECTORY_ITERATE_PARENT_FIRST);
}

static enum b_status iterator_move_next(const b_iterator *obj)
{
	struct b_directory_iterator_p *it
		= b_object_get_private(obj, B_TYPE_DIRECTORY_ITERATOR);
	if (!it || !it->fts) {
		return B_ERR_NO_DATA;
	}

	bool done = false;

	while (!done) {
		it->ent = fts_read(it->fts);

		if (!it->ent) {
			return B_ERR_NO_DATA;
		}

		if (it->ent->fts_level == 0) {
			continue;
		}

		switch (it->ent->fts_info) {
		case FTS_DOT:
			continue;
		case FTS_F:
			done = true;
			break;
		case FTS_D:
			if (it->flags & B_DIRECTORY_ITERATE_PARENT_LAST) {
				continue;
			}
			done = true;
			break;
		case FTS_DP:
			if (it->flags & B_DIRECTORY_ITERATE_PARENT_FIRST) {
				continue;
			}
			done = true;
			break;
		default:
			done = true;
			break;
		}
	}

	update_iterator_data(it);
	return B_SUCCESS;
}

static enum b_status iterator_erase(b_iterator *obj)
{
	struct b_directory_iterator_p *it
		= b_object_get_private(obj, B_TYPE_DIRECTORY_ITERATOR);
	b_result result = b_directory_path_unlink(it->root, it->entry.filepath);
	if (b_result_is_error(result)) {
		enum b_status status = b_error_get_status_code(result);
		b_error_release(result);
		return status;
	}

	return iterator_move_next(obj);
}

static b_iterator_value iterator_get_value(b_iterator *obj)
{
	struct b_directory_iterator_p *it
		= b_object_get_private(obj, B_TYPE_DIRECTORY_ITERATOR);

	return B_ITERATOR_VALUE_PTR(&it->entry);
}

static const b_iterator_value iterator_get_cvalue(const b_iterator *obj)
{
	struct b_directory_iterator_p *it
		= b_object_get_private(obj, B_TYPE_DIRECTORY_ITERATOR);

	return B_ITERATOR_VALUE_CPTR(&it->entry);
}

/*** CLASS DEFINITION *********************************************************/

// ---- b_directory DEFINITION
B_TYPE_CLASS_DEFINITION_BEGIN(b_directory)
	B_TYPE_CLASS_INTERFACE_BEGIN(b_object, B_TYPE_OBJECT)
		B_INTERFACE_ENTRY(to_string) = NULL;
	B_TYPE_CLASS_INTERFACE_END(b_object, B_TYPE_OBJECT)

	B_TYPE_CLASS_INTERFACE_BEGIN(b_iterable, B_TYPE_ITERABLE)
		B_INTERFACE_ENTRY(it_begin) = iterator_begin;
		B_INTERFACE_ENTRY(it_cbegin) = iterator_cbegin;
	B_TYPE_CLASS_INTERFACE_END(b_iterable, B_TYPE_ITERABLE)
B_TYPE_CLASS_DEFINITION_END(b_directory)

B_TYPE_DEFINITION_BEGIN(b_directory)
	B_TYPE_ID(0x10d36546, 0x7f96, 0x464b, 0xbc4d, 0xe504b283fa45);
	B_TYPE_CLASS(b_directory_class);
	B_TYPE_IMPLEMENTS(B_TYPE_ITERABLE);
	B_TYPE_INSTANCE_PRIVATE(struct b_directory_p);
	B_TYPE_INSTANCE_INIT(directory_init);
	B_TYPE_INSTANCE_FINI(directory_fini);
B_TYPE_DEFINITION_END(b_directory)

// ---- b_directory_iterator DEFINITION
B_TYPE_CLASS_DEFINITION_BEGIN(b_directory_iterator)
	B_TYPE_CLASS_INTERFACE_BEGIN(b_object, B_TYPE_OBJECT)
		B_INTERFACE_ENTRY(to_string) = NULL;
	B_TYPE_CLASS_INTERFACE_END(b_object, B_TYPE_OBJECT)

	B_TYPE_CLASS_INTERFACE_BEGIN(b_iterator, B_TYPE_ITERATOR)
		B_INTERFACE_ENTRY(it_move_next) = iterator_move_next;
		B_INTERFACE_ENTRY(it_erase) = iterator_erase;
		B_INTERFACE_ENTRY(it_get_value) = iterator_get_value;
		B_INTERFACE_ENTRY(it_get_cvalue) = iterator_get_cvalue;
	B_TYPE_CLASS_INTERFACE_END(b_iterator, B_TYPE_ITERATOR)
B_TYPE_CLASS_DEFINITION_END(b_directory_iterator)

B_TYPE_DEFINITION_BEGIN(b_directory_iterator)
	B_TYPE_ID(0xc707fce6, 0xc895, 0x4925, 0x8700, 0xa60641dee0cc);
	B_TYPE_EXTENDS(B_TYPE_ITERATOR);
	B_TYPE_CLASS(b_directory_iterator_class);
	B_TYPE_INSTANCE_PRIVATE(struct b_directory_iterator_p);
B_TYPE_DEFINITION_END(b_directory_iterator)