/*

 * libgit2 "describe" example - shows how to describe commits

 *

 * Written by the libgit2 contributors

 *

 * To the extent possible under law, the author(s) have dedicated all copyright

 * and related and neighboring rights to this software to the public domain

 * worldwide. This software is distributed without any warranty.

 *

 * You should have received a copy of the CC0 Public Domain Dedication along

 * with this software. If not, see

 * <http://creativecommons.org/publicdomain/zero/1.0/>.

 */

#include "common.h"

#include <assert.h>

/**

 * The following example partially reimplements the `git describe` command

 * and some of its options.

 *

 * These commands should work:

 * - Describe HEAD with default options (`describe`)

 * - Describe specified revision (`describe master~2`)

 * - Describe specified revisions (`describe master~2 HEAD~3`)

 * - Describe HEAD with dirty state suffix (`describe --dirty=*`)

 * - Describe consider all refs (`describe --all master`)

 * - Describe consider lightweight tags (`describe --tags temp-tag`)

 * - Describe show non-default abbreviated size (`describe --abbrev=10`)

 * - Describe always output the long format if matches a tag (`describe --long v1.0`)

 * - Describe consider only tags of specified pattern (`describe --match v*-release`)

 * - Describe show the fallback result (`describe --always`)

 * - Describe follow only the first parent commit (`describe --first-parent`)

 *

 * The command line parsing logic is simplified and doesn't handle

 * all of the use cases.

 */

/** describe_options represents the parsed command line options */

typedef struct {

	const char **commits;

	size_t commit_count;

	git_describe_options describe_options;

	git_describe_format_options format_options;

} describe_options;

typedef struct args_info args_info;

static void *xrealloc(void *oldp, size_t newsz)

{

	void *p = realloc(oldp, newsz);

	if (p == NULL) {

		fprintf(stderr, "Cannot allocate memory, exiting.\n");

		exit(1);

	}

	return p;

}

static void opts_add_commit(describe_options *opts, const char *commit)

{

	size_t sz;

	assert(opts != NULL);

	sz = ++opts->commit_count * sizeof(opts->commits[0]);

	opts->commits = xrealloc(opts->commits, sz);

	opts->commits[opts->commit_count - 1] = commit;

}

static void do_describe_single(git_repository *repo, describe_options *opts, const char *rev)

{

	git_object *commit;

	git_describe_result *describe_result;

	git_buf buf = { 0 };

	if (rev) {

		check_lg2(git_revparse_single(&commit, repo, rev),

			"Failed to lookup rev", rev);

		check_lg2(git_describe_commit(&describe_result, commit, &opts->describe_options),

			"Failed to describe rev", rev);

	}

	else

		check_lg2(git_describe_workdir(&describe_result, repo, &opts->describe_options),

			"Failed to describe workdir", NULL);

	check_lg2(git_describe_format(&buf, describe_result, &opts->format_options),

			"Failed to format describe rev", rev);

	printf("%s\n", buf.ptr);

}

static void do_describe(git_repository *repo, describe_options *opts)

{

	if (opts->commit_count == 0)

		do_describe_single(repo, opts, NULL);

	else

	{

		size_t i;

		for (i = 0; i < opts->commit_count; i++)

			do_describe_single(repo, opts, opts->commits[i]);

	}

}

static void print_usage(void)

{

	fprintf(stderr, "usage: see `git help describe`\n");

	exit(1);

}

/** Parse command line arguments */

static void parse_options(describe_options *opts, int argc, char **argv)

{

	args_info args = ARGS_INFO_INIT;

	for (args.pos = 1; args.pos < argc; ++args.pos) {

		const char *curr = argv[args.pos];

		if (curr[0] != '-') {

			opts_add_commit(opts, curr);

		} else if (!strcmp(curr, "--all")) {

			opts->describe_options.describe_strategy = GIT_DESCRIBE_ALL;

		} else if (!strcmp(curr, "--tags")) {

			opts->describe_options.describe_strategy = GIT_DESCRIBE_TAGS;

		} else if (!strcmp(curr, "--exact-match")) {

			opts->describe_options.max_candidates_tags = 0;

		} else if (!strcmp(curr, "--long")) {

			opts->format_options.always_use_long_format = 1;

		} else if (!strcmp(curr, "--always")) {

			opts->describe_options.show_commit_oid_as_fallback = 1;

		} else if (!strcmp(curr, "--first-parent")) {

			opts->describe_options.only_follow_first_parent = 1;

		} else if (optional_str_arg(&opts->format_options.dirty_suffix, &args, "--dirty", "-dirty")) {

		} else if (match_int_arg((int *)&opts->format_options.abbreviated_size, &args, "--abbrev", 0)) {

		} else if (match_int_arg((int *)&opts->describe_options.max_candidates_tags, &args, "--candidates", 0)) {

		} else if (match_str_arg(&opts->describe_options.pattern, &args, "--match")) {

		} else {

			print_usage();

		}

	}

	if (opts->commit_count > 0) {

		if (opts->format_options.dirty_suffix)

			fatal("--dirty is incompatible with commit-ishes", NULL);

	}

	else {

		if (!opts->format_options.dirty_suffix || !opts->format_options.dirty_suffix[0]) {

			opts_add_commit(opts, "HEAD");

		}

	}

}

/** Initialize describe_options struct */

static void describe_options_init(describe_options *opts)

{

	memset(opts, 0, sizeof(*opts));

	opts->commits = NULL;

	opts->commit_count = 0;

	git_describe_init_options(&opts->describe_options, GIT_DESCRIBE_OPTIONS_VERSION);

	git_describe_init_format_options(&opts->format_options, GIT_DESCRIBE_FORMAT_OPTIONS_VERSION);

}

int main(int argc, char **argv)

{

	git_repository *repo;

	describe_options opts;

	git_libgit2_init();

	check_lg2(git_repository_open_ext(&repo, ".", 0, NULL),

			"Could not open repository", NULL);

	describe_options_init(&opts);

	parse_options(&opts, argc, argv);

	do_describe(repo, &opts);

	git_repository_free(repo);

	git_libgit2_shutdown();

	return 0;

}