#include "cache.h"
#include "submodule.h"
#include "dir.h"
#include "diff.h"
#include "commit.h"
#include "revision.h"
#include "run-command.h"
#include "diffcore.h"
#include "refs.h"

static int add_submodule_odb(const char *path)
{
        struct strbuf objects_directory = STRBUF_INIT;
        struct alternate_object_database *alt_odb;
        int ret = 0;
        const char *git_dir;

        strbuf_addf(&objects_directory, "%s/.git", path);
        git_dir = read_gitfile_gently(objects_directory.buf);
        if (git_dir) {
                strbuf_reset(&objects_directory);
                strbuf_addstr(&objects_directory, git_dir);
        }
        strbuf_addstr(&objects_directory, "/objects/");
        if (!is_directory(objects_directory.buf)) {
                ret = -1;
                goto done;
        }
        /* avoid adding it twice */
        for (alt_odb = alt_odb_list; alt_odb; alt_odb = alt_odb->next)
                if (alt_odb->name - alt_odb->base == objects_directory.len &&
                                !strncmp(alt_odb->base, objects_directory.buf,
                                        objects_directory.len))
                        goto done;

        alt_odb = xmalloc(objects_directory.len + 42 + sizeof(*alt_odb));
        alt_odb->next = alt_odb_list;
        strcpy(alt_odb->base, objects_directory.buf);
        alt_odb->name = alt_odb->base + objects_directory.len;
        alt_odb->name[2] = '/';
        alt_odb->name[40] = '\0';
        alt_odb->name[41] = '\0';
        alt_odb_list = alt_odb;
        prepare_alt_odb();
done:
        strbuf_release(&objects_directory);
        return ret;
}

void handle_ignore_submodules_arg(struct diff_options *diffopt,
                                  const char *arg)
{
        if (!strcmp(arg, "all"))
                DIFF_OPT_SET(diffopt, IGNORE_SUBMODULES);
        else if (!strcmp(arg, "untracked"))
                DIFF_OPT_SET(diffopt, IGNORE_UNTRACKED_IN_SUBMODULES);
        else if (!strcmp(arg, "dirty"))
                DIFF_OPT_SET(diffopt, IGNORE_DIRTY_SUBMODULES);
        else
                die("bad --ignore-submodules argument: %s", arg);
}

void show_submodule_summary(FILE *f, const char *path,
                unsigned char one[20], unsigned char two[20],
                unsigned dirty_submodule,
                const char *del, const char *add, const char *reset)
{
        struct rev_info rev;
        struct commit *commit, *left = left, *right = right;
        struct commit_list *merge_bases, *list;
        const char *message = NULL;
        struct strbuf sb = STRBUF_INIT;
        static const char *format = "  %m %s";
        int fast_forward = 0, fast_backward = 0;

        if (is_null_sha1(two))
                message = "(submodule deleted)";
        else if (add_submodule_odb(path))
                message = "(not checked out)";
        else if (is_null_sha1(one))
                message = "(new submodule)";
        else if (!(left = lookup_commit_reference(one)) ||
                 !(right = lookup_commit_reference(two)))
                message = "(commits not present)";

        if (!message) {
                init_revisions(&rev, NULL);
                setup_revisions(0, NULL, &rev, NULL);
                rev.left_right = 1;
                rev.first_parent_only = 1;
                left->object.flags |= SYMMETRIC_LEFT;
                add_pending_object(&rev, &left->object, path);
                add_pending_object(&rev, &right->object, path);
                merge_bases = get_merge_bases(left, right, 1);
                if (merge_bases) {
                        if (merge_bases->item == left)
                                fast_forward = 1;
                        else if (merge_bases->item == right)
                                fast_backward = 1;
                }
                for (list = merge_bases; list; list = list->next) {
                        list->item->object.flags |= UNINTERESTING;
                        add_pending_object(&rev, &list->item->object,
                                sha1_to_hex(list->item->object.sha1));
                }
                if (prepare_revision_walk(&rev))
                        message = "(revision walker failed)";
        }

        if (dirty_submodule & DIRTY_SUBMODULE_UNTRACKED)
                fprintf(f, "Submodule %s contains untracked content\n", path);
        if (dirty_submodule & DIRTY_SUBMODULE_MODIFIED)
                fprintf(f, "Submodule %s contains modified content\n", path);

        if (!hashcmp(one, two)) {
                strbuf_release(&sb);
                return;
        }

        strbuf_addf(&sb, "Submodule %s %s..", path,
                        find_unique_abbrev(one, DEFAULT_ABBREV));
        if (!fast_backward && !fast_forward)
                strbuf_addch(&sb, '.');
        strbuf_addf(&sb, "%s", find_unique_abbrev(two, DEFAULT_ABBREV));
        if (message)
                strbuf_addf(&sb, " %s\n", message);
        else
                strbuf_addf(&sb, "%s:\n", fast_backward ? " (rewind)" : "");
        fwrite(sb.buf, sb.len, 1, f);

        if (!message) {
                while ((commit = get_revision(&rev))) {
                        struct pretty_print_context ctx = {0};
                        ctx.date_mode = rev.date_mode;
                        strbuf_setlen(&sb, 0);
                        if (commit->object.flags & SYMMETRIC_LEFT) {
                                if (del)
                                        strbuf_addstr(&sb, del);
                        }
                        else if (add)
                                strbuf_addstr(&sb, add);
                        format_commit_message(commit, format, &sb, &ctx);
                        if (reset)
                                strbuf_addstr(&sb, reset);
                        strbuf_addch(&sb, '\n');
                        fprintf(f, "%s", sb.buf);
                }
                clear_commit_marks(left, ~0);
                clear_commit_marks(right, ~0);
        }
        strbuf_release(&sb);
}

unsigned is_submodule_modified(const char *path, int ignore_untracked)
{
        ssize_t len;
        struct child_process cp;
        const char *argv[] = {
                "status",
                "--porcelain",
                NULL,
                NULL,
        };
        struct strbuf buf = STRBUF_INIT;
        unsigned dirty_submodule = 0;
        const char *line, *next_line;
        const char *git_dir;

        strbuf_addf(&buf, "%s/.git", path);
        git_dir = read_gitfile_gently(buf.buf);
        if (!git_dir)
                git_dir = buf.buf;
        if (!is_directory(git_dir)) {
                strbuf_release(&buf);
                /* The submodule is not checked out, so it is not modified */
                return 0;

        }
        strbuf_reset(&buf);

        if (ignore_untracked)
                argv[2] = "-uno";

        memset(&cp, 0, sizeof(cp));
        cp.argv = argv;
        cp.env = local_repo_env;
        cp.git_cmd = 1;
        cp.no_stdin = 1;
        cp.out = -1;
        cp.dir = path;
        if (start_command(&cp))
                die("Could not run git status --porcelain");

        len = strbuf_read(&buf, cp.out, 1024);
        line = buf.buf;
        while (len > 2) {
                if ((line[0] == '?') && (line[1] == '?')) {
                        dirty_submodule |= DIRTY_SUBMODULE_UNTRACKED;
                        if (dirty_submodule & DIRTY_SUBMODULE_MODIFIED)
                                break;
                } else {
                        dirty_submodule |= DIRTY_SUBMODULE_MODIFIED;
                        if (ignore_untracked ||
                            (dirty_submodule & DIRTY_SUBMODULE_UNTRACKED))
                                break;
                }
                next_line = strchr(line, '\n');
                if (!next_line)
                        break;
                next_line++;
                len -= (next_line - line);
                line = next_line;
        }
        close(cp.out);

        if (finish_command(&cp))
                die("git status --porcelain failed");

        strbuf_release(&buf);
        return dirty_submodule;
}

static int find_first_merges(struct object_array *result, const char *path,
                struct commit *a, struct commit *b)
{
        int i, j;
        struct object_array merges;
        struct commit *commit;
        int contains_another;

        char merged_revision[42];
        const char *rev_args[] = { "rev-list", "--merges", "--ancestry-path",
                                   "--all", merged_revision, NULL };
        struct rev_info revs;
        struct setup_revision_opt rev_opts;

        memset(&merges, 0, sizeof(merges));
        memset(result, 0, sizeof(struct object_array));
        memset(&rev_opts, 0, sizeof(rev_opts));

        /* get all revisions that merge commit a */
        snprintf(merged_revision, sizeof(merged_revision), "^%s",
                        sha1_to_hex(a->object.sha1));
        init_revisions(&revs, NULL);
        rev_opts.submodule = path;
        setup_revisions(sizeof(rev_args)/sizeof(char *)-1, rev_args, &revs, &rev_opts);

        /* save all revisions from the above list that contain b */
        if (prepare_revision_walk(&revs))
                die("revision walk setup failed");
        while ((commit = get_revision(&revs)) != NULL) {
                struct object *o = &(commit->object);
                if (in_merge_bases(b, &commit, 1))
                        add_object_array(o, NULL, &merges);
        }

        /* Now we've got all merges that contain a and b. Prune all
         * merges that contain another found merge and save them in
         * result.
         */
        for (i = 0; i < merges.nr; i++) {
                struct commit *m1 = (struct commit *) merges.objects[i].item;

                contains_another = 0;
                for (j = 0; j < merges.nr; j++) {
                        struct commit *m2 = (struct commit *) merges.objects[j].item;
                        if (i != j && in_merge_bases(m2, &m1, 1)) {
                                contains_another = 1;
                                break;
                        }
                }

                if (!contains_another)
                        add_object_array(merges.objects[i].item,
                                         merges.objects[i].name, result);
        }

        free(merges.objects);
        return result->nr;
}

static void print_commit(struct commit *commit)
{
        struct strbuf sb = STRBUF_INIT;
        struct pretty_print_context ctx = {0};
        ctx.date_mode = DATE_NORMAL;
        format_commit_message(commit, " %h: %m %s", &sb, &ctx);
        fprintf(stderr, "%s\n", sb.buf);
        strbuf_release(&sb);
}

#define MERGE_WARNING(path, msg) \
        warning("Failed to merge submodule %s (%s)", path, msg);

int merge_submodule(unsigned char result[20], const char *path,
                    const unsigned char base[20], const unsigned char a[20],
                    const unsigned char b[20])
{
        struct commit *commit_base, *commit_a, *commit_b;
        int parent_count;
        struct object_array merges;

        int i;

        /* store a in result in case we fail */
        hashcpy(result, a);

        /* we can not handle deletion conflicts */
        if (is_null_sha1(base))
                return 0;
        if (is_null_sha1(a))
                return 0;
        if (is_null_sha1(b))
                return 0;

        if (add_submodule_odb(path)) {
                MERGE_WARNING(path, "not checked out");
                return 0;
        }

        if (!(commit_base = lookup_commit_reference(base)) ||
            !(commit_a = lookup_commit_reference(a)) ||
            !(commit_b = lookup_commit_reference(b))) {
                MERGE_WARNING(path, "commits not present");
                return 0;
        }

        /* check whether both changes are forward */
        if (!in_merge_bases(commit_base, &commit_a, 1) ||
            !in_merge_bases(commit_base, &commit_b, 1)) {
                MERGE_WARNING(path, "commits don't follow merge-base");
                return 0;
        }

        /* Case #1: a is contained in b or vice versa */
        if (in_merge_bases(commit_a, &commit_b, 1)) {
                hashcpy(result, b);
                return 1;
        }
        if (in_merge_bases(commit_b, &commit_a, 1)) {
                hashcpy(result, a);
                return 1;
        }

        /*
         * Case #2: There are one or more merges that contain a and b in
         * the submodule. If there is only one, then present it as a
         * suggestion to the user, but leave it marked unmerged so the
         * user needs to confirm the resolution.
         */

        /* find commit which merges them */
        parent_count = find_first_merges(&merges, path, commit_a, commit_b);
        switch (parent_count) {
        case 0:
                MERGE_WARNING(path, "merge following commits not found");
                break;

        case 1:
                MERGE_WARNING(path, "not fast-forward");
                fprintf(stderr, "Found a possible merge resolution "
                                "for the submodule:\n");
                print_commit((struct commit *) merges.objects[0].item);
                fprintf(stderr,
                        "If this is correct simply add it to the index "
                        "for example\n"
                        "by using:\n\n"
                        "  git update-index --cacheinfo 160000 %s \"%s\"\n\n"
                        "which will accept this suggestion.\n",
                        sha1_to_hex(merges.objects[0].item->sha1), path);
                break;

        default:
                MERGE_WARNING(path, "multiple merges found");
                for (i = 0; i < merges.nr; i++)
                        print_commit((struct commit *) merges.objects[i].item);
        }

        free(merges.objects);
        return 0;
}