/*
 * 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_sha1(const char *object_ref,
                               unsigned char object[20],
                               const char *replace_ref,
                               unsigned char repl[20],
                               int force)
{
        unsigned char prev[20];
        enum object_type obj_type, repl_type;
        char ref[PATH_MAX];
        struct ref_lock *lock;

        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);

        lock = lock_any_ref_for_update(ref, prev, 0, NULL);
        if (!lock)
                die("%s: cannot lock the ref", ref);
        if (write_ref_sha1(lock, repl, NULL) < 0)
                die("%s: cannot update the ref", ref);

        return 0;
}

static int replace_object(const char *object_ref, const char *replace_ref, int force)
{
        unsigned char object[20], repl[20];

        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);

        return replace_object_sha1(object_ref, object, replace_ref, repl, force);
}

int cmd_replace(int argc, const char **argv, const char *prefix)
{
        int force = 0;
        const char *format = NULL;
        enum {
                MODE_UNSPECIFIED = 0,
                MODE_LIST,
                MODE_DELETE,
                MODE_REPLACE
        } cmdmode = MODE_UNSPECIFIED;
        struct option options[] = {
                OPT_CMDMODE('l', "list", &cmdmode, N_("list replace refs"), MODE_LIST),
                OPT_CMDMODE('d', "delete", &cmdmode, N_("delete replace refs"), MODE_DELETE),
                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 (!cmdmode)
                cmdmode = argc ? MODE_REPLACE : MODE_LIST;

        if (format && cmdmode != MODE_LIST)
                usage_msg_opt("--format cannot be used when not listing",
                              git_replace_usage, options);

        if (force && cmdmode != MODE_REPLACE)
                usage_msg_opt("-f only makes sense when writing a replacement",
                              git_replace_usage, options);

        switch (cmdmode) {
        case MODE_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);

        case MODE_REPLACE:
                if (argc != 2)
                        usage_msg_opt("bad number of arguments",
                                      git_replace_usage, options);
                return replace_object(argv[0], argv[1], force);

        case MODE_LIST:
                if (argc > 1)
                        usage_msg_opt("only one pattern can be given with -l",
                                      git_replace_usage, options);
                return list_replace_refs(argv[0], format);

        default:
                die("BUG: invalid cmdmode %d", (int)cmdmode);
        }
}