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

#include <blue/core/random.h>
#include <blue/io/directory.h>
#include <blue/io/file.h>
#include <blue/io/path.h>
#include <blue/ds/string.h>
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <unistd.h>

struct b_file {
	struct b_dsref base;
	enum b_file_mode mode;
	int fd;
	struct b_path *path;
};

static void file_release(struct b_dsref *obj);

static struct b_dsref_type file_type = {
	.t_name = "corelib::file",
	.t_flags = B_DSREF_FUNDAMENTAL,
	.t_id = B_DSREF_TYPE_FILE,
	.t_instance_size = sizeof(struct b_file),
	.t_release = file_release,
};

#define CHECK_FLAG(v, f) (((v) & (f)) == (f))

static unsigned int b_mode_to_unix_mode(enum b_file_mode mode)
{
	unsigned int result = 0;

	if (CHECK_FLAG(mode, B_FILE_READ_WRITE)) {
		result |= O_RDWR;
	} else if (CHECK_FLAG(mode, B_FILE_READ_ONLY)) {
		result |= O_RDONLY;
	} else if (CHECK_FLAG(mode, B_FILE_WRITE_ONLY)) {
		result |= O_WRONLY;
	} else {
		return (unsigned int)-1;
	}

	if (CHECK_FLAG(mode, B_FILE_TRUNCATE)) {
		result |= O_TRUNC;
	}

	if (CHECK_FLAG(mode, B_FILE_CREATE)) {
		result |= O_CREAT;
	}

	if (CHECK_FLAG(mode, B_FILE_CREATE_ONLY)) {
		result |= O_EXCL;
	}

	return result;
}

b_result b_file_open(
	struct b_directory *root, const struct b_path *path,
	enum b_file_mode mode, struct b_file **out)
{
	struct b_path *file_path = b_path_retain((struct b_path *)path);
	unsigned int flags = b_mode_to_unix_mode(mode);

	if (flags == (unsigned int)-1) {
		b_path_release(file_path);
		return B_RESULT_ERR(INVALID_ARGUMENT);
	}

	struct b_path *root_path = NULL;
	if (root) {
		root_path = b_path_retain(
			(struct b_path *)b_directory_get_path(root));
	} else {
		root_path = b_path_create_cwd();
	}

	const struct b_path *parts[] = {
		root_path,
		file_path,
	};

	struct b_path *abs_path
		= b_path_join(parts, sizeof parts / sizeof parts[0]);
	b_path_release(root_path);
	b_path_release(file_path);

	if (!abs_path) {
		return B_RESULT_ERR(NO_MEMORY);
	}

	int fd = open(b_path_ptr(abs_path), flags, 0644);
	if (fd == -1) {
		b_path_release(abs_path);
		return B_RESULT_STATUS(
			b_status_from_errno(errno, B_ERR_IO_FAILURE));
	}

	struct b_file *file
		= (struct b_file *)b_dsref_type_instantiate(&file_type);
	if (!file) {
		close(fd);
		b_path_release(abs_path);
		return B_RESULT_ERR(NO_MEMORY);
	}

	file->fd = fd;
	file->path = abs_path;
	file->mode = mode;

	*out = file;
	return B_RESULT_SUCCESS;
}

b_result b_file_open_temp(enum b_file_mode mode, struct b_file **out)
{
	mode |= B_FILE_DELETE_ON_CLOSE;

	char name[16];
	char path[128];

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

		b_result status = b_file_open(
			B_DIRECTORY_ROOT, rpath, mode | B_FILE_CREATE_ONLY, out);

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

		b_path_unlink(rpath);
		b_path_release(rpath);

		return status;
	}
}

b_result b_file_open_shadow(
	struct b_file *original, enum b_file_mode mode, struct b_file **out)
{
	mode |= B_FILE_SHADOW | B_FILE_DELETE_ON_CLOSE | B_FILE_CREATE;

	struct b_path *dir;
	b_path_get_directory(original->path, &dir);

	struct b_string *filename = b_string_create();
	b_path_get_filename(original->path, filename);

	b_string_prepend_cstr(filename, ".~");

	struct b_path *shadow_filename
		= b_path_create_from_cstr(b_string_ptr(filename));
	b_string_release(filename);

	const struct b_path *parts[] = {
		dir,
		shadow_filename,
	};

	struct b_path *shadow_filepath
		= b_path_join(parts, sizeof parts / sizeof parts[0]);
	b_path_release(dir);
	b_path_release(shadow_filename);

	if (b_path_exists(shadow_filepath)) {
		b_path_unlink(shadow_filepath);
	}

	struct b_file *shadow_file;
	b_result status = b_file_open(
		B_DIRECTORY_ROOT, shadow_filepath, mode, &shadow_file);
	b_path_release(shadow_filepath);

	if (b_result_is_error(status)) {
		return status;
	}

	*out = shadow_file;
	return B_RESULT_SUCCESS;
}

static enum b_status stream_close(struct b_stream *stream)
{
	struct b_file *file = stream->s_ptr;
	b_file_release(file);

	return B_SUCCESS;
}

static enum b_status stream_getc(struct b_stream *stream, int *out)
{
	struct b_file *file = stream->s_ptr;
	char c;
	size_t nr_read = 0;

	enum b_status status
		= b_file_read(file, stream->s_cursor, sizeof c, &c, &nr_read);
	if (status != B_SUCCESS) {
		return status;
	}

	if (nr_read == 0) {
		return B_ERR_NO_DATA;
	}

	stream->s_cursor += nr_read;
	*out = c;
	return B_SUCCESS;
}

static enum b_status stream_read(
	struct b_stream *stream, unsigned char *buf, size_t max, size_t *nr_read)
{
	struct b_file *file = stream->s_ptr;

	enum b_status status
		= b_file_read(file, stream->s_cursor, max, buf, nr_read);

	stream->s_cursor += *nr_read;

	return status;
}

static enum b_status stream_write(
	struct b_stream *stream, const unsigned char *buf, size_t count,
	size_t *nr_written)
{
	struct b_file *file = stream->s_ptr;

	enum b_status status
		= b_file_write(file, stream->s_cursor, count, buf, nr_written);

	stream->s_cursor += *nr_written;

	return status;
}

static enum b_status stream_seek(
	struct b_stream *stream, long long offset, b_stream_seek_origin origin)
{
	b_seek_basis basis;
	switch (origin) {
	case B_STREAM_SEEK_START:
		basis = B_SEEK_BEGINNING;
		break;
	case B_STREAM_SEEK_CURRENT:
		basis = B_SEEK_CURRENT;
		break;
	case B_STREAM_SEEK_END:
		basis = B_SEEK_END;
		break;
	default:
		return B_ERR_INVALID_ARGUMENT;
	}

	struct b_file *file = stream->s_ptr;

	enum b_status status = b_file_seek(file, offset, basis);
	if (!B_OK(status)) {
		return status;
	}

	return b_file_cursor(file, &stream->s_cursor);
}

enum b_status b_file_open_stream(struct b_file *file, struct b_stream **out)
{
	struct b_stream *stream = malloc(sizeof *stream);
	if (!stream) {
		return B_ERR_NO_MEMORY;
	}

	memset(stream, 0x0, sizeof *stream);

	if (file->mode & B_FILE_READ_ONLY) {
		stream->s_mode |= B_STREAM_READ;
	}

	if (file->mode & B_FILE_WRITE_ONLY) {
		stream->s_mode |= B_STREAM_WRITE;
	}

	if (file->mode & B_FILE_BINARY) {
		stream->s_mode |= B_STREAM_BINARY;
	}

	stream->s_ptr = b_file_retain(file);
	stream->s_close = stream_close;
	stream->s_getc = stream_getc;
	stream->s_read = stream_read;
	stream->s_write = stream_write;
	stream->s_seek = stream_seek;

	*out = stream;

	return B_SUCCESS;
}

enum b_status b_file_stat(struct b_file *file, struct b_file_info *out)
{
	struct stat st;
	int err = fstat(file->fd, &st);

	if (err != 0) {
		return b_status_from_errno(errno, B_ERR_IO_FAILURE);
	}

	memset(out, 0x0, sizeof *out);

	return b_file_info_from_stat(&st, out);
}

enum b_status b_file_size(struct b_file *file, size_t *out_len)
{
	off_t cur = lseek(file->fd, 0, SEEK_CUR);
	if (cur == (off_t)-1) {
		return b_status_from_errno(errno, B_ERR_IO_FAILURE);
	}

	off_t len = lseek(file->fd, 0, SEEK_END);
	if (len == (off_t)-1) {
		return b_status_from_errno(errno, B_ERR_IO_FAILURE);
	}

	cur = lseek(file->fd, cur, SEEK_SET);
	if (cur == (off_t)-1) {
		return b_status_from_errno(errno, B_ERR_IO_FAILURE);
	}

	*out_len = (size_t)len;
	return B_SUCCESS;
}

enum b_status b_file_cursor(struct b_file *file, size_t *out_pos)
{
	off_t cur = lseek(file->fd, 0, SEEK_CUR);
	if (cur == (off_t)-1) {
		return b_status_from_errno(errno, B_ERR_IO_FAILURE);
	}

	*out_pos = (size_t)cur;
	return B_SUCCESS;
}

enum b_status b_file_resize(struct b_file *file, size_t len)
{
	int err = ftruncate(file->fd, len);
	if (err == 0) {
		return B_SUCCESS;
	}

	return b_status_from_errno(errno, B_ERR_IO_FAILURE);
}

enum b_status b_file_seek(
	struct b_file *file, long long offset, enum b_seek_basis basis)
{
	int whence;
	switch (basis) {
	case B_SEEK_BEGINNING:
		whence = SEEK_SET;
		break;
	case B_SEEK_CURRENT:
		whence = SEEK_CUR;
		break;
	case B_SEEK_END:
		whence = SEEK_END;
		break;
	default:
		return B_ERR_INVALID_ARGUMENT;
	}

	int err = lseek(file->fd, offset, whence);
	if (err == 0) {
		return B_SUCCESS;
	}

	return b_status_from_errno(errno, B_ERR_IO_FAILURE);
}

enum b_status b_file_swap_shadow(struct b_file *main_file, struct b_file *shadow_file)
{
	if (main_file->mode & B_FILE_SHADOW) {
		return B_ERR_NOT_SUPPORTED;
	}

	if (!(shadow_file->mode & B_FILE_SHADOW)) {
		return B_ERR_NOT_SUPPORTED;
	}

	struct b_path *dir_path;
	b_path_get_directory(main_file->path, &dir_path);

	struct b_path *tmp_path = NULL;

	while (1) {
		char tmp_name[16];
		z__b_io_generate_tmp_filename(tmp_name, sizeof tmp_name);
		struct b_path *tmp_name_p = b_path_create_from_cstr(tmp_name);

		const struct b_path *parts[] = {
			dir_path,
			tmp_name_p,
		};

		tmp_path = b_path_join(parts, sizeof parts / sizeof parts[0]);

		b_path_release(tmp_name_p);

		if (!b_path_exists(tmp_path)) {
			break;
		}

		b_path_release(tmp_path);
		tmp_path = NULL;
	}

	b_path_release(dir_path);

	int err;

	err = rename(b_path_ptr(main_file->path), b_path_ptr(tmp_path));
	err = rename(b_path_ptr(shadow_file->path), b_path_ptr(main_file->path));
	err = rename(b_path_ptr(tmp_path), b_path_ptr(shadow_file->path));

	b_path_release(tmp_path);

	int fd = main_file->fd;
	main_file->fd = shadow_file->fd;
	shadow_file->fd = fd;

	return B_SUCCESS;
}

enum b_status b_file_read(
	struct b_file *file, size_t offset, size_t len, void *buf, size_t *nr_read)
{
	if (offset != B_OFFSET_CURRENT) {
		lseek(file->fd, offset, SEEK_SET);
	}

	long r = read(file->fd, buf, len);

	enum b_status status = B_SUCCESS;

	if (r < 0) {
		status = b_status_from_errno(errno, B_ERR_IO_FAILURE);
	}

	*nr_read = r;
	return status;
}

enum b_status b_file_write(
	struct b_file *file, size_t offset, size_t len, const void *buf,
	size_t *nr_written)
{
	if (offset != B_OFFSET_CURRENT) {
		lseek(file->fd, offset, SEEK_SET);
	}

	long w = write(file->fd, buf, len);

	enum b_status status = B_SUCCESS;

	if (w < 0) {
		status = b_status_from_errno(errno, B_ERR_IO_FAILURE);
	}

	*nr_written = w;
	return status;
}

static void file_release(struct b_dsref *obj)
{
	struct b_file *file = (struct b_file *)obj;
	close(file->fd);

	if (file->mode & B_FILE_DELETE_ON_CLOSE) {
		b_path_unlink(file->path);
	}

	b_path_release(file->path);
}