/*
 * Builtin "git replace"
 *
 * Copyright (c) 2008 Christian Couder <chriscool@tuxfamily.org>
 *
 * Based on builtin/tag.c by Kristian Høgsberg <krh@redhat.com>
 * and Carlos Rica <jasampler@gmail.com> that was itself based on
 * git-tag.sh and mktag.c by Linus Torvalds.
 */

#include "cache.h"
#include "builtin.h"
#include "refs.h"
#include "parse-options.h"

static const char * const git_replace_usage[] = {
	N_("git replace [-f] <object> <replacement>"),
	N_("git replace -d <object>..."),
	N_("git replace [--format=<format>] [-l [<pattern>]]"),
	NULL
};

enum replace_format {
      REPLACE_FORMAT_SHORT,
      REPLACE_FORMAT_MEDIUM,
      REPLACE_FORMAT_LONG
};

struct show_data {
	const char *pattern;
	enum replace_format format;
};

static int show_reference(const char *refname, const unsigned char *sha1,
			  int flag, void *cb_data)
{
	struct show_data *data = cb_data;

	if (!wildmatch(data->pattern, refname, 0, NULL)) {
		if (data->format == REPLACE_FORMAT_SHORT)
			printf("%s\n", refname);
		else if (data->format == REPLACE_FORMAT_MEDIUM)
			printf("%s -> %s\n", refname, sha1_to_hex(sha1));
		else { /* data->format == REPLACE_FORMAT_LONG */
			unsigned char object[20];
			enum object_type obj_type, repl_type;

			if (get_sha1(refname, object))
				return error("Failed to resolve '%s' as a valid ref.", refname);

			obj_type = sha1_object_info(object, NULL);
			repl_type = sha1_object_info(sha1, NULL);

			printf("%s (%s) -> %s (%s)\n", refname, typename(obj_type),
			       sha1_to_hex(sha1), typename(repl_type));
		}
	}

	return 0;
}

static int list_replace_refs(const char *pattern, const char *format)
{
	struct show_data data;

	if (pattern == NULL)
		pattern = "*";
	data.pattern = pattern;

	if (format == NULL || *format == '\0' || !strcmp(format, "short"))
		data.format = REPLACE_FORMAT_SHORT;
	else if (!strcmp(format, "medium"))
		data.format = REPLACE_FORMAT_MEDIUM;
	else if (!strcmp(format, "long"))
		data.format = REPLACE_FORMAT_LONG;
	else
		die("invalid replace format '%s'\n"
		    "valid formats are 'short', 'medium' and 'long'\n",
		    format);

	for_each_replace_ref(show_reference, (void *) &data);

	return 0;
}

typedef int (*each_replace_name_fn)(const char *name, const char *ref,
				    const unsigned char *sha1);

static int for_each_replace_name(const char **argv, each_replace_name_fn fn)
{
	const char **p, *full_hex;
	char ref[PATH_MAX];
	int had_error = 0;
	unsigned char sha1[20];

	for (p = argv; *p; p++) {
		if (get_sha1(*p, sha1)) {
			error("Failed to resolve '%s' as a valid ref.", *p);
			had_error = 1;
			continue;
		}
		full_hex = sha1_to_hex(sha1);
		snprintf(ref, sizeof(ref), "refs/replace/%s", full_hex);
		/* read_ref() may reuse the buffer */
		full_hex = ref + strlen("refs/replace/");
		if (read_ref(ref, sha1)) {
			error("replace ref '%s' not found.", full_hex);
			had_error = 1;
			continue;
		}
		if (fn(full_hex, ref, sha1))
			had_error = 1;
	}
	return had_error;
}

static int delete_replace_ref(const char *name, const char *ref,
			      const unsigned char *sha1)
{
	if (delete_ref(ref, sha1, 0))
		return 1;
	printf("Deleted replace ref '%s'\n", name);
	return 0;
}

static int replace_object(const char *object_ref, const char *replace_ref,
			  int force)
{
	unsigned char object[20], prev[20], repl[20];
	enum object_type obj_type, repl_type;
	char ref[PATH_MAX];
	struct ref_transaction *transaction;
	struct strbuf err = STRBUF_INIT;

	if (get_sha1(object_ref, object))
		die("Failed to resolve '%s' as a valid ref.", object_ref);
	if (get_sha1(replace_ref, repl))
		die("Failed to resolve '%s' as a valid ref.", replace_ref);

	if (snprintf(ref, sizeof(ref),
		     "refs/replace/%s",
		     sha1_to_hex(object)) > sizeof(ref) - 1)
		die("replace ref name too long: %.*s...", 50, ref);
	if (check_refname_format(ref, 0))
		die("'%s' is not a valid ref name.", ref);

	obj_type = sha1_object_info(object, NULL);
	repl_type = sha1_object_info(repl, NULL);
	if (!force && obj_type != repl_type)
		die("Objects must be of the same type.\n"
		    "'%s' points to a replaced object of type '%s'\n"
		    "while '%s' points to a replacement object of type '%s'.",
		    object_ref, typename(obj_type),
		    replace_ref, typename(repl_type));

	if (read_ref(ref, prev))
		hashclr(prev);
	else if (!force)
		die("replace ref '%s' already exists", ref);

	transaction = ref_transaction_begin(&err);
	if (!transaction ||
	    ref_transaction_update(transaction, ref, repl, prev,
				   0, !is_null_sha1(prev), &err) ||
	    ref_transaction_commit(transaction, NULL, &err))
		die("%s", err.buf);

	ref_transaction_free(transaction);
	return 0;
}

int cmd_replace(int argc, const char **argv, const char *prefix)
{
	int list = 0, delete = 0, force = 0;
	const char *format = NULL;
	struct option options[] = {
		OPT_BOOL('l', "list", &list, N_("list replace refs")),
		OPT_BOOL('d', "delete", &delete, N_("delete replace refs")),
		OPT_BOOL('f', "force", &force, N_("replace the ref if it exists")),
		OPT_STRING(0, "format", &format, N_("format"), N_("use this format")),
		OPT_END()
	};

	check_replace_refs = 0;

	argc = parse_options(argc, argv, prefix, options, git_replace_usage, 0);

	if (list && delete)
		usage_msg_opt("-l and -d cannot be used together",
			      git_replace_usage, options);

	if (format && delete)
		usage_msg_opt("--format and -d cannot be used together",
			      git_replace_usage, options);

	if (force && (list || delete))
		usage_msg_opt("-f cannot be used with -d or -l",
			      git_replace_usage, options);

	/* Delete refs */
	if (delete) {
		if (argc < 1)
			usage_msg_opt("-d needs at least one argument",
				      git_replace_usage, options);
		return for_each_replace_name(argv, delete_replace_ref);
	}

	/* Replace object */
	if (!list && argc) {
		if (argc != 2)
			usage_msg_opt("bad number of arguments",
				      git_replace_usage, options);
		if (format)
			usage_msg_opt("--format cannot be used when not listing",
				      git_replace_usage, options);
		return replace_object(argv[0], argv[1], force);
	}

	/* List refs, even if "list" is not set */
	if (argc > 1)
		usage_msg_opt("only one pattern can be given with -l",
			      git_replace_usage, options);
	if (force)
		usage_msg_opt("-f needs some arguments",
			      git_replace_usage, options);

	return list_replace_refs(argv[0], format);
}