/*
 * Copyright (C) 2023  Patrick McDermott
 *
 * This file is part of opkg-opk.
 *
 * opkg-opk is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * opkg-opk is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with opkg-opk.  If not, see <https://www.gnu.org/licenses/>.
 */

#include <dirent.h>
#include <grp.h>
#include <pwd.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/sysmacros.h>
#include <unistd.h>
#include "../defs.h"
#include "../dirent.h"
#include "../gzip.h"
#include "../i18n.h"
#include "../opk.h"
#include "../specials.h"
#include "../ustar.h"
#include "opk.h"

enum _opkg_opk_opk_archive_type {
	OPKG_OPK_OPK_ARCHIVE_TYPE_CONTROL_ = 0,
	OPKG_OPK_OPK_ARCHIVE_TYPE_DATA_ = 1,
};
static const char *OPKG_OPK_OPK_ARCHIVE_NAMES_[]  = {
	"control.tar.gz",
	"data.tar.gz",
};

static int
_opkg_opk_opk_source_date_epoch(uint64_t *mtime)
{
	char *env;
	char *end;

	env = getenv("SOURCE_DATE_EPOCH");
	if (env == NULL) {
		return OPKG_OPK_ERROR;
	}
	*mtime = strtol(env, &end, 10);
	if (*end != '\0') {
		return OPKG_OPK_ERROR;
	}
	return OPKG_OPK_OK;
}

static int
_opkg_opk_opk_write_filter(const struct dirent *de)
{
	if (de->d_name[0] == '.') {
		if (de->d_name[1] == '\0') {
			return 0;
		}
		if (de->d_name[1] == '.' && de->d_name[2] == '\0') {
			return 0;
		}
	}
	return 1;
}

static int
_opkg_opk_opk_write_compar(const struct dirent **a, const struct dirent **b)
{
	return strcmp((*a)->d_name, (*b)->d_name);
}

static int
_opkg_opk_opk_write_dir_read(struct opkg_opk_opk *opk,
		struct opkg_opk_dirent *dir, size_t path_off)
{
	char                    *child_path;
	int                      children_n;
	struct dirent          **children;
	int                      children_i;
	struct opkg_opk_dirent   child;
	size_t                   name_i;
	struct stat              st;
	uid_t                    uid;
	char                    *uname;
	gid_t                    gid;
	char                    *gname;
	                         /* Extra byte (in macro definition) to detect
	                          * overflow, not for NUL */
	char                     link[OPKG_OPK_USTAR_LINKNAME_SIZE];
	ssize_t                  link_len;
	char                     type;
	uint32_t                 devmajor;
	uint32_t                 devminor;
	FILE                    *fp;
	char                    *buffer;
	size_t                   size;
	size_t                   num_read;
	size_t                   tot_read;
	int                      ret;

	child_path = opk->path_virt + path_off;
	children_n = scandir(opk->path_real, &children, _opkg_opk_opk_write_filter,
			_opkg_opk_opk_write_compar);
	for (children_i = 0; children_i < children_n; ++children_i) {
		child.name = children[children_i]->d_name;
		child.parent = dir;
		for (name_i = 0; children[children_i]->d_name[name_i] != '\0';
				++name_i) {
			if (path_off + name_i + 1 == OPKG_OPK_USTAR_NAME_SIZE) {
				fprintf(stderr, "Error: File name \"%s\" too "
						"long",
						children[children_i]->d_name);
				goto err;
			}
			child_path[name_i] =
				children[children_i]->d_name[name_i];
		}
		child_path[name_i] = '\0';
		if (lstat(opk->path_real, &st) != 0) {
			fprintf(stderr, _("Error: Failed to stat \"%s\"\n"),
					opk->path_real);
			goto err;
		}
		/* TODO: Ownership override */
		uid = st.st_uid;
		uname = getpwuid(uid)->pw_name;
		gid = st.st_gid;
		gname = getgrgid(gid)->gr_name;
		if (S_ISDIR(st.st_mode)) {
			if (path_off + name_i + 2 == OPKG_OPK_USTAR_NAME_SIZE) {
				fprintf(stderr, "Error: File name \"%s\" too "
						"long", child_path);
				goto err;
			}
			child_path[name_i] = '/';
			child_path[++name_i] = '\0';
			if (opkg_opk_ustar_write_header(opk->inner_ustar,
						&child, st.st_mode & 0777,
						uid, uname, gid, gname, 0, 0, 0,
						opk->mtime, 'd', NULL) !=
					OPKG_OPK_OK) {
				fputs(_("Error: Failed to write header\n"),
						stderr);
				goto err;
			}
			if (_opkg_opk_opk_write_dir_read(opk, &child,
						path_off + name_i) !=
					OPKG_OPK_OK) {
				goto err;
			}
		} else if (S_ISLNK(st.st_mode)) {
			link_len = readlink(opk->path_real, link,
					OPKG_OPK_USTAR_LINKNAME_SIZE);
			if (link_len < 0) {
				goto err;
			}
			if (link_len == OPKG_OPK_USTAR_LINKNAME_SIZE) {
				goto err;
			}
			link[link_len] = '\0';
			if (opkg_opk_ustar_write_header(opk->inner_ustar,
						&child, 0777,
						uid, uname, gid, gname, 0, 0, 0,
						opk->mtime, 'l', link) !=
					OPKG_OPK_OK) {
				fputs(_("Error: Failed to write header\n"),
						stderr);
				goto err;
			}
		} else if (S_ISCHR(st.st_mode)) {
			if (opkg_opk_ustar_write_header(opk->inner_ustar,
						&child, st.st_mode & 0777,
						uid, uname, gid, gname,
						major(st.st_rdev),
						minor(st.st_rdev),
						0, opk->mtime, 'c', NULL) !=
					OPKG_OPK_OK) {
				fputs(_("Error: Failed to write header\n"),
						stderr);
				goto err;
			}
		} else if (S_ISBLK(st.st_mode)) {
			if (opkg_opk_ustar_write_header(opk->inner_ustar,
						&child, st.st_mode & 0777,
						uid, uname, gid, gname,
						major(st.st_rdev),
						minor(st.st_rdev),
						0, opk->mtime, 'b', NULL) !=
					OPKG_OPK_OK) {
				fputs(_("Error: Failed to write header\n"),
						stderr);
				goto err;
			}
		} else if (S_ISFIFO(st.st_mode)) {
			if (opkg_opk_ustar_write_header(opk->inner_ustar,
						&child, st.st_mode & 0777,
						uid, uname, gid, gname, 0, 0, 0,
						opk->mtime, 'p', NULL) !=
					OPKG_OPK_OK) {
				fputs(_("Error: Failed to write header\n"),
						stderr);
				goto err;
			}
		} else if (S_ISREG(st.st_mode)) {
			if (opkg_opk_specials_find(opk->specials,
						opk->path_virt, &type,
						&devmajor, &devminor) ==
					OPKG_OPK_OK) {
				if (opkg_opk_ustar_write_header(
							opk->inner_ustar,
							&child,
							st.st_mode & 0777,
							uid, uname, gid, gname,
							devmajor, devminor, 0,
							opk->mtime, type, NULL)
						!= OPKG_OPK_OK) {
					fputs(_("Error: Failed to write header"
								"\n"), stderr);
					goto err;
				}
				continue;
			}
			if (opkg_opk_ustar_write_header(opk->inner_ustar,
						&child, st.st_mode & 0777,
						uid, uname, gid, gname, 0, 0,
						st.st_size, opk->mtime, '-',
						NULL) != OPKG_OPK_OK) {
				fputs(_("Error: Failed to write header\n"),
						stderr);
				goto err;
			}
			fp = fopen(opk->path_real, "rb");
			if (fp == NULL) {
				fprintf(stderr, _("Error: Failed to open file "
							"\"%s\"\n"),
						opk->path_real);
				goto err;
			}
			opkg_opk_ustar_get_buffer(opk->inner_ustar,
					&buffer, &size);
			tot_read = 0;
			while ((num_read = fread(buffer, 1, size, fp)) > 0) {
				opkg_opk_ustar_write_data(opk->inner_ustar,
						num_read);
				tot_read += num_read;
			}
			if (ferror(fp) != 0) {
				fputs(_("Error: Error reading file\n"), stderr);
				fclose(fp);
				goto err;
			}
			if (fclose(fp) != 0) {
				fputs(_("Error: Failed to close file\n"),
						stderr);
				goto err;
			}
			if ((uintmax_t) tot_read != (uintmax_t) st.st_size) {
				fprintf(stderr, _("Error: Expected %jd bytes "
							"but read %zu\n"),
							(intmax_t) st.st_size,
							num_read);
				goto err;
			}
		} else {
			fprintf(stderr, _("Error: Unknown type of file \"%s\"\n"
						), opk->path_real);
			goto err;
		}
	}

	ret = OPKG_OPK_OK;
	goto out;
 err:
	ret = OPKG_OPK_ERROR;
 out:
	for (children_i = 0; children_i < children_n; ++children_i) {
		free(children[children_i]);
	}
	free(children);
	return ret;
}

static int
_opkg_opk_opk_build_inner_archive(struct opkg_opk_opk *opk,
		enum _opkg_opk_opk_archive_type archive_type)
{
	FILE                   *fp;
	struct opkg_opk_dirent  dirent;
	struct stat             st;
	uid_t                   uid;
	char                   *uname;
	gid_t                   gid;
	char                    *gname;
	size_t                  written;
	char                   *buffer;
	size_t                  size;
	size_t                  num_read;
	size_t                  tot_read;

	/* Initialize inner gzip compressor. */
	if (sprintf(opk->temp_file_name, "%s~%s", opk->file_name,
				OPKG_OPK_OPK_ARCHIVE_NAMES_[archive_type]) <= 0)
	{
		goto err0;
	}
	fp = fopen(opk->temp_file_name, "w+b");
	if (fp == NULL) {
		fprintf(stderr, _("Error: Failed to open file \"%s\"\n"),
				opk->temp_file_name);
		goto err0;
	}
	opk->inner_gzip = opkg_opk_gzip_init_write(fp);
	if (opk->inner_gzip == NULL) {
		fputs(_("Error: Failed to initialize compressor\n"), stderr);
		goto err1;
	}

	/* Initialize inner ustar archiver. */
	opk->inner_ustar = opkg_opk_ustar_init(opk->inner_gzip);
	if (opk->inner_ustar == NULL) {
		fputs(_("Error: Failed to initialize archiver\n"), stderr);
		goto err2;
	}

	/* Write inner archive to temporary file. */
	dirent.name   = ".";
	dirent.parent = NULL;
	if (archive_type == OPKG_OPK_OPK_ARCHIVE_TYPE_CONTROL_) {
		sprintf(opk->path_real, "%s/", opk->control_dir);
		opk->path_virt = opk->path_real + opk->control_dir_len;
	} else {
		sprintf(opk->path_real, "%s/", opk->data_dir);
		opk->path_virt = opk->path_real + opk->data_dir_len;
	}
	if (stat(opk->path_real, &st) != 0) {
		fprintf(stderr, _("Error: Failed to stat \"%s\"\n"),
				opk->path_real);
		goto err3;
	}
	uid = st.st_uid;
	uname = getpwuid(uid)->pw_name;
	gid = st.st_gid;
	gname = getgrgid(gid)->gr_name;
	if (opkg_opk_ustar_write_header(opk->inner_ustar, &dirent,
				st.st_mode & 0777, uid, uname, gid, gname, 0,
				0, 0, opk->mtime, 'd', NULL) != OPKG_OPK_OK) {
		fputs(_("Error: Failed to write header\n"),
				stderr);
		goto err3;
	}
	if (_opkg_opk_opk_write_dir_read(opk, &dirent, 1 /* Skip '/' */) !=
			OPKG_OPK_OK) {
		goto err3;
	}

	/* Write trailer. */
	if (opkg_opk_ustar_write_trailer(opk->inner_ustar) != OPKG_OPK_OK) {
		fputs(_("Error: Failed to write trailer\n"), stderr);
		goto err3;
	}

	/* Finish inner archive. */
	opkg_opk_ustar_free(opk->inner_ustar);
	opkg_opk_gzip_finish_write(opk->inner_gzip);
	written = opkg_opk_gzip_written(opk->inner_gzip);
	opkg_opk_gzip_free(opk->inner_gzip);

	/* Write header in outer archive. */
	dirent.name   = OPKG_OPK_OPK_ARCHIVE_NAMES_[archive_type];
	dirent.parent = NULL;
	if (opkg_opk_ustar_write_header(opk->outer_ustar, &dirent, 0644,
				0, opk->outer_uname, 0, opk->outer_gname, 0, 0,
				written, opk->mtime, '-', NULL) !=
			OPKG_OPK_OK) {
		fputs(_("Error: Failed to write header\n"), stderr);
		goto err1;
	}

	/* Read temporary file into outer archive. */
	if (fseek(fp, 0L, SEEK_SET) != 0) {
		fputs(_("Error: Failed to seek in file\n"), stderr);
		goto err1;
	}
	opkg_opk_ustar_get_buffer(opk->outer_ustar, &buffer, &size);
	tot_read = 0;
	while ((num_read = fread(buffer, 1, size, fp)) > 0) {
		opkg_opk_ustar_write_data(opk->outer_ustar, num_read);
		tot_read += num_read;
	}
	if (ferror(fp) != 0) {
		fputs(_("Error: Error reading file\n"), stderr);
		fclose(fp);
		goto err1;
	}
	if (fclose(fp) != 0) {
		fputs(_("Error: Failed to close file\n"), stderr);
		goto err1;
	}
	unlink(opk->temp_file_name);
	if (tot_read != written) {
		fprintf(stderr, _("Error: Wrote %lu bytes but read %lu\n"),
					written, num_read);
		goto err1;
	}

	return OPKG_OPK_OK;

 err3:
	opkg_opk_ustar_free(opk->inner_ustar);
 err2:
	opkg_opk_gzip_free(opk->inner_gzip);
 err1:
	fclose(fp);
 err0:
	return OPKG_OPK_ERROR;
}

int
opkg_opk_opk_write(struct opkg_opk_opk *opk, const char *file_name)
{
	int                     ret;
	struct opkg_opk_dirent  dirent;
	char                   *buffer;
	size_t                  size;
	size_t                  path_len;

	ret = OPKG_OPK_OK;

	if (_opkg_opk_opk_source_date_epoch(&opk->mtime) == OPKG_OPK_ERROR) {
		fputs(_("Error: Missing or invalid SOURCE_DATE_EPOCH\n"),
				stderr);
		ret = OPKG_OPK_ERROR;
		goto out0;
	}

	opk->file_name = file_name;

	/* Open outer archive. */
	opk->file = fopen(file_name, "wb");
	if (opk->file == NULL) {
		fprintf(stderr, _("Error: Failed to open file \"%s\"\n"),
				file_name);
		ret = OPKG_OPK_ERROR;
		goto out0;
	}

	/* Initialize outer gzip compressor. */
	opk->outer_gzip = opkg_opk_gzip_init_write(opk->file);
	if (opk->outer_gzip == NULL) {
		fputs(_("Error: Failed to initialize\n"), stderr);
		ret = OPKG_OPK_ERROR;
		goto out1;
	}

	/* Initialize outer ustar archiver. */
	opk->outer_ustar = opkg_opk_ustar_init(opk->outer_gzip);
	if (opk->outer_ustar == NULL) {
		fputs(_("Error: Failed to initialize\n"), stderr);
		ret = OPKG_OPK_ERROR;
		goto out2;
	}

	opk->outer_uname = getpwuid(0)->pw_name;
	opk->outer_gname = getgrgid(0)->gr_name;

	/* Write version file. */
	dirent.name   = "debian-binary";
	dirent.parent = NULL;
	if (opkg_opk_ustar_write_header(opk->outer_ustar, &dirent, 0644,
				0, opk->outer_uname, 0, opk->outer_gname, 0, 0,
				4, opk->mtime, '-', NULL) != OPKG_OPK_OK) {
		fputs(_("Error: Failed to write header\n"), stderr);
		ret = OPKG_OPK_ERROR;
		goto out3;
	}
	opkg_opk_ustar_get_buffer(opk->outer_ustar, &buffer, &size);
	memcpy(buffer, "2.0\n", 4);
	if (opkg_opk_ustar_write_data(opk->outer_ustar, 4) != OPKG_OPK_OK) {
		fputs(_("Error: Failed to write data\n"), stderr);
		ret = OPKG_OPK_ERROR;
		goto out3;
	}

	/* Allocate control and data file path buffer. */
	if (opk->control_dir_len >= opk->data_dir_len) {
		path_len = opk->control_dir_len;
	} else {
		path_len = opk->data_dir_len;
	}
	path_len += 1 /* '/' */ + OPKG_OPK_USTAR_NAME_SIZE;
	opk->path_real = malloc(path_len);
	if (opk->path_real == NULL) {
		ret = OPKG_OPK_ERROR;
		goto out3;
	}

	/* Allocate temporary archive file name buffer. */
	opk->temp_file_name =
		malloc(strlen(file_name) + strlen("~control.tar.gz") + 1);
	if (opk->temp_file_name == NULL) {
		ret = OPKG_OPK_ERROR;
		goto out4;
	}

	if (_opkg_opk_opk_build_inner_archive(opk,
				OPKG_OPK_OPK_ARCHIVE_TYPE_CONTROL_) !=
			OPKG_OPK_OK) {
		ret = OPKG_OPK_ERROR;
		goto out4;
	}
	if (_opkg_opk_opk_build_inner_archive(opk,
				OPKG_OPK_OPK_ARCHIVE_TYPE_DATA_) !=
			OPKG_OPK_OK) {
		ret = OPKG_OPK_ERROR;
		goto out4;
	}

	/* Write trailer. */
	if (opkg_opk_ustar_write_trailer(opk->outer_ustar) != OPKG_OPK_OK) {
		fputs(_("Error: Failed to write trailer\n"), stderr);
		ret = OPKG_OPK_ERROR;
		goto out5;
	}

 out5:
	free(opk->temp_file_name);
 out4:
	free(opk->path_real);
 out3:
	opkg_opk_ustar_free(opk->outer_ustar);
 out2:
	opkg_opk_gzip_finish_write(opk->outer_gzip);
	opkg_opk_gzip_free(opk->outer_gzip);
 out1:
	fclose(opk->file);
 out0:
	return ret;
}