/*
 * "git fast-export" builtin command
 *
 * Copyright (C) 2007 Johannes E. Schindelin
 */
#include "builtin.h"
#include "cache.h"
#include "commit.h"
#include "object.h"
#include "tag.h"
#include "diff.h"
#include "diffcore.h"
#include "log-tree.h"
#include "revision.h"
#include "decorate.h"
#include "string-list.h"
#include "utf8.h"
#include "parse-options.h"

static const char *fast_export_usage[] = {
        "git fast-export [rev-list-opts]",
        NULL
};

static int progress;
static enum { VERBATIM, WARN, STRIP, ABORT } signed_tag_mode = ABORT;
static int fake_missing_tagger;

static int parse_opt_signed_tag_mode(const struct option *opt,
                                     const char *arg, int unset)
{
        if (unset || !strcmp(arg, "abort"))
                signed_tag_mode = ABORT;
        else if (!strcmp(arg, "verbatim") || !strcmp(arg, "ignore"))
                signed_tag_mode = VERBATIM;
        else if (!strcmp(arg, "warn"))
                signed_tag_mode = WARN;
        else if (!strcmp(arg, "strip"))
                signed_tag_mode = STRIP;
        else
                return error("Unknown signed-tag mode: %s", arg);
        return 0;
}

static struct decoration idnums;
static uint32_t last_idnum;

static int has_unshown_parent(struct commit *commit)
{
        struct commit_list *parent;

        for (parent = commit->parents; parent; parent = parent->next)
                if (!(parent->item->object.flags & SHOWN) &&
                    !(parent->item->object.flags & UNINTERESTING))
                        return 1;
        return 0;
}

/* Since intptr_t is C99, we do not use it here */
static inline uint32_t *mark_to_ptr(uint32_t mark)
{
        return ((uint32_t *)NULL) + mark;
}

static inline uint32_t ptr_to_mark(void * mark)
{
        return (uint32_t *)mark - (uint32_t *)NULL;
}

static inline void mark_object(struct object *object, uint32_t mark)
{
        add_decoration(&idnums, object, mark_to_ptr(mark));
}

static inline void mark_next_object(struct object *object)
{
        mark_object(object, ++last_idnum);
}

static int get_object_mark(struct object *object)
{
        void *decoration = lookup_decoration(&idnums, object);
        if (!decoration)
                return 0;
        return ptr_to_mark(decoration);
}

static void show_progress(void)
{
        static int counter = 0;
        if (!progress)
                return;
        if ((++counter % progress) == 0)
                printf("progress %d objects\n", counter);
}

static void handle_object(const unsigned char *sha1)
{
        unsigned long size;
        enum object_type type;
        char *buf;
        struct object *object;

        if (is_null_sha1(sha1))
                return;

        object = parse_object(sha1);
        if (!object)
                die ("Could not read blob %s", sha1_to_hex(sha1));

        if (object->flags & SHOWN)
                return;

        buf = read_sha1_file(sha1, &type, &size);
        if (!buf)
                die ("Could not read blob %s", sha1_to_hex(sha1));

        mark_next_object(object);

        printf("blob\nmark :%"PRIu32"\ndata %lu\n", last_idnum, size);
        if (size && fwrite(buf, size, 1, stdout) != 1)
                die ("Could not write blob %s", sha1_to_hex(sha1));
        printf("\n");

        show_progress();

        object->flags |= SHOWN;
        free(buf);
}

static void show_filemodify(struct diff_queue_struct *q,
                            struct diff_options *options, void *data)
{
        int i;
        for (i = 0; i < q->nr; i++) {
                struct diff_filespec *ospec = q->queue[i]->one;
                struct diff_filespec *spec = q->queue[i]->two;

                switch (q->queue[i]->status) {
                case DIFF_STATUS_DELETED:
                        printf("D %s\n", spec->path);
                        break;

                case DIFF_STATUS_COPIED:
                case DIFF_STATUS_RENAMED:
                        printf("%c \"%s\" \"%s\"\n", q->queue[i]->status,
                               ospec->path, spec->path);

                        if (!hashcmp(ospec->sha1, spec->sha1) &&
                            ospec->mode == spec->mode)
                                break;
                        /* fallthrough */

                case DIFF_STATUS_TYPE_CHANGED:
                case DIFF_STATUS_MODIFIED:
                case DIFF_STATUS_ADDED:
                        /*
                         * Links refer to objects in another repositories;
                         * output the SHA-1 verbatim.
                         */
                        if (S_ISGITLINK(spec->mode))
                                printf("M %06o %s %s\n", spec->mode,
                                       sha1_to_hex(spec->sha1), spec->path);
                        else {
                                struct object *object = lookup_object(spec->sha1);
                                printf("M %06o :%d %s\n", spec->mode,
                                       get_object_mark(object), spec->path);
                        }
                        break;

                default:
                        die("Unexpected comparison status '%c' for %s, %s",
                                q->queue[i]->status,
                                ospec->path ? ospec->path : "none",
                                spec->path ? spec->path : "none");
                }
        }
}

static const char *find_encoding(const char *begin, const char *end)
{
        const char *needle = "\nencoding ";
        char *bol, *eol;

        bol = memmem(begin, end ? end - begin : strlen(begin),
                     needle, strlen(needle));
        if (!bol)
                return git_commit_encoding;
        bol += strlen(needle);
        eol = strchrnul(bol, '\n');
        *eol = '\0';
        return bol;
}

static void handle_commit(struct commit *commit, struct rev_info *rev)
{
        int saved_output_format = rev->diffopt.output_format;
        const char *author, *author_end, *committer, *committer_end;
        const char *encoding, *message;
        char *reencoded = NULL;
        struct commit_list *p;
        int i;

        rev->diffopt.output_format = DIFF_FORMAT_CALLBACK;

        parse_commit(commit);
        author = strstr(commit->buffer, "\nauthor ");
        if (!author)
                die ("Could not find author in commit %s",
                     sha1_to_hex(commit->object.sha1));
        author++;
        author_end = strchrnul(author, '\n');
        committer = strstr(author_end, "\ncommitter ");
        if (!committer)
                die ("Could not find committer in commit %s",
                     sha1_to_hex(commit->object.sha1));
        committer++;
        committer_end = strchrnul(committer, '\n');
        message = strstr(committer_end, "\n\n");
        encoding = find_encoding(committer_end, message);
        if (message)
                message += 2;

        if (commit->parents &&
            get_object_mark(&commit->parents->item->object) != 0) {
                parse_commit(commit->parents->item);
                diff_tree_sha1(commit->parents->item->tree->object.sha1,
                               commit->tree->object.sha1, "", &rev->diffopt);
        }
        else
                diff_root_tree_sha1(commit->tree->object.sha1,
                                    "", &rev->diffopt);

        /* Export the referenced blobs, and remember the marks. */
        for (i = 0; i < diff_queued_diff.nr; i++)
                if (!S_ISGITLINK(diff_queued_diff.queue[i]->two->mode))
                        handle_object(diff_queued_diff.queue[i]->two->sha1);

        mark_next_object(&commit->object);
        if (!is_encoding_utf8(encoding))
                reencoded = reencode_string(message, "UTF-8", encoding);
        if (!commit->parents)
                printf("reset %s\n", (const char*)commit->util);
        printf("commit %s\nmark :%"PRIu32"\n%.*s\n%.*s\ndata %u\n%s",
               (const char *)commit->util, last_idnum,
               (int)(author_end - author), author,
               (int)(committer_end - committer), committer,
               (unsigned)(reencoded
                          ? strlen(reencoded) : message
                          ? strlen(message) : 0),
               reencoded ? reencoded : message ? message : "");
        free(reencoded);

        for (i = 0, p = commit->parents; p; p = p->next) {
                int mark = get_object_mark(&p->item->object);
                if (!mark)
                        continue;
                if (i == 0)
                        printf("from :%d\n", mark);
                else
                        printf("merge :%d\n", mark);
                i++;
        }

        log_tree_diff_flush(rev);
        rev->diffopt.output_format = saved_output_format;

        printf("\n");

        show_progress();
}

static void handle_tail(struct object_array *commits, struct rev_info *revs)
{
        struct commit *commit;
        while (commits->nr) {
                commit = (struct commit *)commits->objects[commits->nr - 1].item;
                if (has_unshown_parent(commit))
                        return;
                handle_commit(commit, revs);
                commits->nr--;
        }
}

static void handle_tag(const char *name, struct tag *tag)
{
        unsigned long size;
        enum object_type type;
        char *buf;
        const char *tagger, *tagger_end, *message;
        size_t message_size = 0;
        struct object *tagged;

        /* Trees have no identifer in fast-export output, thus we have no way
         * to output tags of trees, tags of tags of trees, etc.  Simply omit
         * such tags.
         */
        tagged = tag->tagged;
        while (tagged->type == OBJ_TAG) {
                tagged = ((struct tag *)tagged)->tagged;
        }
        if (tagged->type == OBJ_TREE) {
                warning("Omitting tag %s,\nsince tags of trees (or tags of tags of trees, etc.) are not supported.",
                        sha1_to_hex(tag->object.sha1));
                return;
        }

        buf = read_sha1_file(tag->object.sha1, &type, &size);
        if (!buf)
                die ("Could not read tag %s", sha1_to_hex(tag->object.sha1));
        message = memmem(buf, size, "\n\n", 2);
        if (message) {
                message += 2;
                message_size = strlen(message);
        }
        tagger = memmem(buf, message ? message - buf : size, "\ntagger ", 8);
        if (!tagger) {
                if (fake_missing_tagger)
                        tagger = "tagger Unspecified Tagger "
                                "<unspecified-tagger> 0 +0000";
                else
                        tagger = "";
                tagger_end = tagger + strlen(tagger);
        } else {
                tagger++;
                tagger_end = strchrnul(tagger, '\n');
        }

        /* handle signed tags */
        if (message) {
                const char *signature = strstr(message,
                                               "\n-----BEGIN PGP SIGNATURE-----\n");
                if (signature)
                        switch(signed_tag_mode) {
                        case ABORT:
                                die ("Encountered signed tag %s; use "
                                     "--signed-tag=<mode> to handle it.",
                                     sha1_to_hex(tag->object.sha1));
                        case WARN:
                                warning ("Exporting signed tag %s",
                                         sha1_to_hex(tag->object.sha1));
                                /* fallthru */
                        case VERBATIM:
                                break;
                        case STRIP:
                                message_size = signature + 1 - message;
                                break;
                        }
        }

        if (!prefixcmp(name, "refs/tags/"))
                name += 10;
        printf("tag %s\nfrom :%d\n%.*s%sdata %d\n%.*s\n",
               name, get_object_mark(tag->tagged),
               (int)(tagger_end - tagger), tagger,
               tagger == tagger_end ? "" : "\n",
               (int)message_size, (int)message_size, message ? message : "");
}

static void get_tags_and_duplicates(struct object_array *pending,
                                    struct string_list *extra_refs)
{
        struct tag *tag;
        int i;

        for (i = 0; i < pending->nr; i++) {
                struct object_array_entry *e = pending->objects + i;
                unsigned char sha1[20];
                struct commit *commit = commit;
                char *full_name;

                if (dwim_ref(e->name, strlen(e->name), sha1, &full_name) != 1)
                        continue;

                switch (e->item->type) {
                case OBJ_COMMIT:
                        commit = (struct commit *)e->item;
                        break;
                case OBJ_TAG:
                        tag = (struct tag *)e->item;

                        /* handle nested tags */
                        while (tag && tag->object.type == OBJ_TAG) {
                                parse_object(tag->object.sha1);
                                string_list_append(full_name, extra_refs)->util = tag;
                                tag = (struct tag *)tag->tagged;
                        }
                        if (!tag)
                                die ("Tag %s points nowhere?", e->name);
                        switch(tag->object.type) {
                        case OBJ_COMMIT:
                                commit = (struct commit *)tag;
                                break;
                        case OBJ_BLOB:
                                handle_object(tag->object.sha1);
                                continue;
                        default: /* OBJ_TAG (nested tags) is already handled */
                                warning("Tag points to object of unexpected type %s, skipping.",
                                        typename(tag->object.type));
                                continue;
                        }
                        break;
                default:
                        warning("%s: Unexpected object of type %s, skipping.",
                                e->name,
                                typename(e->item->type));
                        continue;
                }
                if (commit->util)
                        /* more than one name for the same object */
                        string_list_append(full_name, extra_refs)->util = commit;
                else
                        commit->util = full_name;
        }
}

static void handle_tags_and_duplicates(struct string_list *extra_refs)
{
        struct commit *commit;
        int i;

        for (i = extra_refs->nr - 1; i >= 0; i--) {
                const char *name = extra_refs->items[i].string;
                struct object *object = extra_refs->items[i].util;
                switch (object->type) {
                case OBJ_TAG:
                        handle_tag(name, (struct tag *)object);
                        break;
                case OBJ_COMMIT:
                        /* create refs pointing to already seen commits */
                        commit = (struct commit *)object;
                        printf("reset %s\nfrom :%d\n\n", name,
                               get_object_mark(&commit->object));
                        show_progress();
                        break;
                }
        }
}

static void export_marks(char *file)
{
        unsigned int i;
        uint32_t mark;
        struct object_decoration *deco = idnums.hash;
        FILE *f;

        f = fopen(file, "w");
        if (!f)
                error("Unable to open marks file %s for writing", file);

        for (i = 0; i < idnums.size; i++) {
                if (deco->base && deco->base->type == 1) {
                        mark = ptr_to_mark(deco->decoration);
                        fprintf(f, ":%"PRIu32" %s\n", mark,
                                sha1_to_hex(deco->base->sha1));
                }
                deco++;
        }

        if (ferror(f) || fclose(f))
                error("Unable to write marks file %s.", file);
}

static void import_marks(char *input_file)
{
        char line[512];
        FILE *f = fopen(input_file, "r");
        if (!f)
                die("cannot read %s: %s", input_file, strerror(errno));

        while (fgets(line, sizeof(line), f)) {
                uint32_t mark;
                char *line_end, *mark_end;
                unsigned char sha1[20];
                struct object *object;

                line_end = strchr(line, '\n');
                if (line[0] != ':' || !line_end)
                        die("corrupt mark line: %s", line);
                *line_end = '\0';

                mark = strtoumax(line + 1, &mark_end, 10);
                if (!mark || mark_end == line + 1
                        || *mark_end != ' ' || get_sha1(mark_end + 1, sha1))
                        die("corrupt mark line: %s", line);

                object = parse_object(sha1);
                if (!object)
                        die ("Could not read blob %s", sha1_to_hex(sha1));

                if (object->flags & SHOWN)
                        error("Object %s already has a mark", sha1);

                mark_object(object, mark);
                if (last_idnum < mark)
                        last_idnum = mark;

                object->flags |= SHOWN;
        }
        fclose(f);
}

int cmd_fast_export(int argc, const char **argv, const char *prefix)
{
        struct rev_info revs;
        struct object_array commits = { 0, 0, NULL };
        struct string_list extra_refs = { NULL, 0, 0, 0 };
        struct commit *commit;
        char *export_filename = NULL, *import_filename = NULL;
        struct option options[] = {
                OPT_INTEGER(0, "progress", &progress,
                            "show progress after <n> objects"),
                OPT_CALLBACK(0, "signed-tags", &signed_tag_mode, "mode",
                             "select handling of signed tags",
                             parse_opt_signed_tag_mode),
                OPT_STRING(0, "export-marks", &export_filename, "FILE",
                             "Dump marks to this file"),
                OPT_STRING(0, "import-marks", &import_filename, "FILE",
                             "Import marks from this file"),
                OPT_BOOLEAN(0, "fake-missing-tagger", &fake_missing_tagger,
                             "Fake a tagger when tags lack one"),
                OPT_END()
        };

        if (argc == 1)
                usage_with_options (fast_export_usage, options);

        /* we handle encodings */
        git_config(git_default_config, NULL);

        init_revisions(&revs, prefix);
        revs.topo_order = 1;
        revs.show_source = 1;
        argc = setup_revisions(argc, argv, &revs, NULL);
        argc = parse_options(argc, argv, prefix, options, fast_export_usage, 0);
        if (argc > 1)
                usage_with_options (fast_export_usage, options);

        if (import_filename)
                import_marks(import_filename);

        get_tags_and_duplicates(&revs.pending, &extra_refs);

        if (prepare_revision_walk(&revs))
                die("revision walk setup failed");
        revs.diffopt.format_callback = show_filemodify;
        DIFF_OPT_SET(&revs.diffopt, RECURSIVE);
        while ((commit = get_revision(&revs))) {
                if (has_unshown_parent(commit)) {
                        add_object_array(&commit->object, NULL, &commits);
                }
                else {
                        handle_commit(commit, &revs);
                        handle_tail(&commits, &revs);
                }
        }

        handle_tags_and_duplicates(&extra_refs);

        if (export_filename)
                export_marks(export_filename);

        return 0;
}