#include <stdlib.h>
#include <fnmatch.h>
#include "cache.h"
#include "commit.h"
#include "refs.h"

static const char show_branch_usage[] =
"git-show-branch [--all] [--heads] [--tags] [--topo-order] [--more=count | --list | --independent | --merge-base ] [<refs>...]";

#define UNINTERESTING   01

#define REV_SHIFT        2
#define MAX_REVS        29 /* should not exceed bits_per_int - REV_SHIFT */

static struct commit *interesting(struct commit_list *list)
{
        while (list) {
                struct commit *commit = list->item;
                list = list->next;
                if (commit->object.flags & UNINTERESTING)
                        continue;
                return commit;
        }
        return NULL;
}

static struct commit *pop_one_commit(struct commit_list **list_p)
{
        struct commit *commit;
        struct commit_list *list;
        list = *list_p;
        commit = list->item;
        *list_p = list->next;
        free(list);
        return commit;
}

struct commit_name {
        const char *head_name; /* which head's ancestor? */
        int generation; /* how many parents away from head_name */
};

/* Name the commit as nth generation ancestor of head_name;
 * we count only the first-parent relationship for naming purposes.
 */
static void name_commit(struct commit *commit, const char *head_name, int nth)
{
        struct commit_name *name;
        if (!commit->object.util)
                commit->object.util = xmalloc(sizeof(struct commit_name));
        name = commit->object.util;
        name->head_name = head_name;
        name->generation = nth;
}

/* Parent is the first parent of the commit.  We may name it
 * as (n+1)th generation ancestor of the same head_name as
 * commit is nth generation ancestor of, if that generation
 * number is better than the name it already has.
 */
static void name_parent(struct commit *commit, struct commit *parent)
{
        struct commit_name *commit_name = commit->object.util;
        struct commit_name *parent_name = parent->object.util;
        if (!commit_name)
                return;
        if (!parent_name ||
            commit_name->generation + 1 < parent_name->generation)
                name_commit(parent, commit_name->head_name,
                            commit_name->generation + 1);
}

static int name_first_parent_chain(struct commit *c)
{
        int i = 0;
        while (c) {
                struct commit *p;
                if (!c->object.util)
                        break;
                if (!c->parents)
                        break;
                p = c->parents->item;
                if (!p->object.util) {
                        name_parent(c, p);
                        i++;
                }
                c = p;
        }
        return i;
}

static void name_commits(struct commit_list *list,
                         struct commit **rev,
                         char **ref_name,
                         int num_rev)
{
        struct commit_list *cl;
        struct commit *c;
        int i;

        /* First give names to the given heads */
        for (cl = list; cl; cl = cl->next) {
                c = cl->item;
                if (c->object.util)
                        continue;
                for (i = 0; i < num_rev; i++) {
                        if (rev[i] == c) {
                                name_commit(c, ref_name[i], 0);
                                break;
                        }
                }
        }

        /* Then commits on the first parent ancestry chain */
        do {
                i = 0;
                for (cl = list; cl; cl = cl->next) {
                        i += name_first_parent_chain(cl->item);
                }
        } while (i);

        /* Finally, any unnamed commits */
        do {
                i = 0;
                for (cl = list; cl; cl = cl->next) {
                        struct commit_list *parents;
                        struct commit_name *n;
                        int nth;
                        c = cl->item;
                        if (!c->object.util)
                                continue;
                        n = c->object.util;
                        parents = c->parents;
                        nth = 0;
                        while (parents) {
                                struct commit *p = parents->item;
                                char newname[1000], *en;
                                parents = parents->next;
                                nth++;
                                if (p->object.util)
                                        continue;
                                en = newname;
                                switch (n->generation) {
                                case 0:
                                        en += sprintf(en, "%s", n->head_name);
                                        break;
                                case 1:
                                        en += sprintf(en, "%s^", n->head_name);
                                        break;
                                default:
                                        en += sprintf(en, "%s~%d",
                                                n->head_name, n->generation);
                                        break;
                                }
                                if (nth == 1)
                                        en += sprintf(en, "^");
                                else
                                        en += sprintf(en, "^%d", nth);
                                name_commit(p, strdup(newname), 0);
                                i++;
                                name_first_parent_chain(p);
                        }
                }
        } while (i);
}

static int mark_seen(struct commit *commit, struct commit_list **seen_p)
{
        if (!commit->object.flags) {
                insert_by_date(commit, seen_p);
                return 1;
        }
        return 0;
}

static void join_revs(struct commit_list **list_p,
                      struct commit_list **seen_p,
                      int num_rev, int extra)
{
        int all_mask = ((1u << (REV_SHIFT + num_rev)) - 1);
        int all_revs = all_mask & ~((1u << REV_SHIFT) - 1);

        while (*list_p) {
                struct commit_list *parents;
                int still_interesting = !!interesting(*list_p);
                struct commit *commit = pop_one_commit(list_p);
                int flags = commit->object.flags & all_mask;

                if (!still_interesting && extra <= 0)
                        break;

                mark_seen(commit, seen_p);
                if ((flags & all_revs) == all_revs)
                        flags |= UNINTERESTING;
                parents = commit->parents;

                while (parents) {
                        struct commit *p = parents->item;
                        int this_flag = p->object.flags;
                        parents = parents->next;
                        if ((this_flag & flags) == flags)
                                continue;
                        if (!p->object.parsed)
                                parse_commit(p);
                        if (mark_seen(p, seen_p) && !still_interesting)
                                extra--;
                        p->object.flags |= flags;
                        insert_by_date(p, list_p);
                }
        }

        /*
         * Postprocess to complete well-poisoning.
         *
         * At this point we have all the commits we have seen in
         * seen_p list (which happens to be sorted chronologically but
         * it does not really matter).  Mark anything that can be
         * reached from uninteresting commits not interesting.
         */
        for (;;) {
                int changed = 0;
                struct commit_list *s;
                for (s = *seen_p; s; s = s->next) {
                        struct commit *c = s->item;
                        struct commit_list *parents;

                        if (((c->object.flags & all_revs) != all_revs) &&
                            !(c->object.flags & UNINTERESTING))
                                continue;

                        /* The current commit is either a merge base or
                         * already uninteresting one.  Mark its parents
                         * as uninteresting commits _only_ if they are
                         * already parsed.  No reason to find new ones
                         * here.
                         */
                        parents = c->parents;
                        while (parents) {
                                struct commit *p = parents->item;
                                parents = parents->next;
                                if (!(p->object.flags & UNINTERESTING)) {
                                        p->object.flags |= UNINTERESTING;
                                        changed = 1;
                                }
                        }
                }
                if (!changed)
                        break;
        }
}

static void show_one_commit(struct commit *commit, int no_name)
{
        char pretty[256], *cp;
        struct commit_name *name = commit->object.util;
        if (commit->object.parsed)
                pretty_print_commit(CMIT_FMT_ONELINE, commit->buffer, ~0,
                                    pretty, sizeof(pretty));
        else
                strcpy(pretty, "(unavailable)");
        if (!strncmp(pretty, "[PATCH] ", 8))
                cp = pretty + 8;
        else
                cp = pretty;

        if (!no_name) {
                if (name && name->head_name) {
                        printf("[%s", name->head_name);
                        if (name->generation) {
                                if (name->generation == 1)
                                        printf("^");
                                else
                                        printf("~%d", name->generation);
                        }
                        printf("] ");
                }
                else
                        printf("[%s] ",
                               find_unique_abbrev(commit->object.sha1, 7));
        }
        puts(cp);
}

static char *ref_name[MAX_REVS + 1];
static int ref_name_cnt;

static const char *find_digit_prefix(const char *s, int *v)
{
        const char *p;
        int ver;
        char ch;

        for (p = s, ver = 0;
             '0' <= (ch = *p) && ch <= '9';
             p++)
                ver = ver * 10 + ch - '0';
        *v = ver;
        return p;
}


static int version_cmp(const char *a, const char *b)
{
        while (1) {
                int va, vb;

                a = find_digit_prefix(a, &va);
                b = find_digit_prefix(b, &vb);
                if (va != vb)
                        return va - vb;

                while (1) {
                        int ca = *a;
                        int cb = *b;
                        if ('0' <= ca && ca <= '9')
                                ca = 0;
                        if ('0' <= cb && cb <= '9')
                                cb = 0;
                        if (ca != cb)
                                return ca - cb;
                        if (!ca)
                                break;
                        a++;
                        b++;
                }
                if (!*a && !*b)
                        return 0;
        }
}

static int compare_ref_name(const void *a_, const void *b_)
{
        const char * const*a = a_, * const*b = b_;
        return version_cmp(*a, *b);
}

static void sort_ref_range(int bottom, int top)
{
        qsort(ref_name + bottom, top - bottom, sizeof(ref_name[0]),
              compare_ref_name);
}

static int append_ref(const char *refname, const unsigned char *sha1)
{
        struct commit *commit = lookup_commit_reference_gently(sha1, 1);
        int i;

        if (!commit)
                return 0;
        /* Avoid adding the same thing twice */
        for (i = 0; i < ref_name_cnt; i++)
                if (!strcmp(refname, ref_name[i]))
                        return 0;

        if (MAX_REVS <= ref_name_cnt) {
                fprintf(stderr, "warning: ignoring %s; "
                        "cannot handle more than %d refs\n",
                        refname, MAX_REVS);
                return 0;
        }
        ref_name[ref_name_cnt++] = strdup(refname);
        ref_name[ref_name_cnt] = NULL;
        return 0;
}

static int append_head_ref(const char *refname, const unsigned char *sha1)
{
        unsigned char tmp[20];
        int ofs = 11;
        if (strncmp(refname, "refs/heads/", ofs))
                return 0;
        /* If both heads/foo and tags/foo exists, get_sha1 would
         * get confused.
         */
        if (get_sha1(refname + ofs, tmp) || memcmp(tmp, sha1, 20))
                ofs = 5;
        return append_ref(refname + ofs, sha1);
}

static int append_tag_ref(const char *refname, const unsigned char *sha1)
{
        if (strncmp(refname, "refs/tags/", 10))
                return 0;
        return append_ref(refname + 5, sha1);
}

static const char *match_ref_pattern = NULL;
static int match_ref_slash = 0;
static int count_slash(const char *s)
{
        int cnt = 0;
        while (*s)
                if (*s++ == '/')
                        cnt++;
        return cnt;
}

static int append_matching_ref(const char *refname, const unsigned char *sha1)
{
        /* we want to allow pattern hold/<asterisk> to show all
         * branches under refs/heads/hold/, and v0.99.9? to show
         * refs/tags/v0.99.9a and friends.
         */
        const char *tail;
        int slash = count_slash(refname);
        for (tail = refname; *tail && match_ref_slash < slash; )
                if (*tail++ == '/')
                        slash--;
        if (!*tail)
                return 0;
        if (fnmatch(match_ref_pattern, tail, 0))
                return 0;
        if (!strncmp("refs/heads/", refname, 11))
                return append_head_ref(refname, sha1);
        if (!strncmp("refs/tags/", refname, 10))
                return append_tag_ref(refname, sha1);
        return append_ref(refname, sha1);
}

static void snarf_refs(int head, int tag)
{
        if (head) {
                int orig_cnt = ref_name_cnt;
                for_each_ref(append_head_ref);
                sort_ref_range(orig_cnt, ref_name_cnt);
        }
        if (tag) {
                int orig_cnt = ref_name_cnt;
                for_each_ref(append_tag_ref);
                sort_ref_range(orig_cnt, ref_name_cnt);
        }
}

static int rev_is_head(char *head_path, int headlen,
                       char *name,
                       unsigned char *head_sha1, unsigned char *sha1)
{
        int namelen;
        if ((!head_path[0]) || memcmp(head_sha1, sha1, 20))
                return 0;
        namelen = strlen(name);
        if ((headlen < namelen) ||
            memcmp(head_path + headlen - namelen, name, namelen))
                return 0;
        if (headlen == namelen ||
            head_path[headlen - namelen - 1] == '/')
                return 1;
        return 0;
}

static int show_merge_base(struct commit_list *seen, int num_rev)
{
        int all_mask = ((1u << (REV_SHIFT + num_rev)) - 1);
        int all_revs = all_mask & ~((1u << REV_SHIFT) - 1);
        int exit_status = 1;

        while (seen) {
                struct commit *commit = pop_one_commit(&seen);
                int flags = commit->object.flags & all_mask;
                if (!(flags & UNINTERESTING) &&
                    ((flags & all_revs) == all_revs)) {
                        puts(sha1_to_hex(commit->object.sha1));
                        exit_status = 0;
                        commit->object.flags |= UNINTERESTING;
                }
        }
        return exit_status;
}

static int show_independent(struct commit **rev,
                            int num_rev,
                            char **ref_name,
                            unsigned int *rev_mask)
{
        int i;

        for (i = 0; i < num_rev; i++) {
                struct commit *commit = rev[i];
                unsigned int flag = rev_mask[i];

                if (commit->object.flags == flag)
                        puts(sha1_to_hex(commit->object.sha1));
                commit->object.flags |= UNINTERESTING;
        }
        return 0;
}

static void append_one_rev(const char *av)
{
        unsigned char revkey[20];
        if (!get_sha1(av, revkey)) {
                append_ref(av, revkey);
                return;
        }
        if (strchr(av, '*') || strchr(av, '?') || strchr(av, '[')) {
                /* glob style match */
                int saved_matches = ref_name_cnt;
                match_ref_pattern = av;
                match_ref_slash = count_slash(av);
                for_each_ref(append_matching_ref);
                if (saved_matches == ref_name_cnt &&
                    ref_name_cnt < MAX_REVS)
                        error("no matching refs with %s", av);
                if (saved_matches + 1 < ref_name_cnt)
                        sort_ref_range(saved_matches, ref_name_cnt);
                return;
        }
        die("bad sha1 reference %s", av);
}

int main(int ac, char **av)
{
        struct commit *rev[MAX_REVS], *commit;
        struct commit_list *list = NULL, *seen = NULL;
        unsigned int rev_mask[MAX_REVS];
        int num_rev, i, extra = 0;
        int all_heads = 0, all_tags = 0;
        int all_mask, all_revs;
        char head_path[128];
        const char *head_path_p;
        int head_path_len;
        unsigned char head_sha1[20];
        int merge_base = 0;
        int independent = 0;
        int no_name = 0;
        int sha1_name = 0;
        int shown_merge_point = 0;
        int topo_order = 0;

        setup_git_directory();

        while (1 < ac && av[1][0] == '-') {
                char *arg = av[1];
                if (!strcmp(arg, "--all"))
                        all_heads = all_tags = 1;
                else if (!strcmp(arg, "--heads"))
                        all_heads = 1;
                else if (!strcmp(arg, "--tags"))
                        all_tags = 1;
                else if (!strcmp(arg, "--more"))
                        extra = 1;
                else if (!strcmp(arg, "--list"))
                        extra = -1;
                else if (!strcmp(arg, "--no-name"))
                        no_name = 1;
                else if (!strcmp(arg, "--sha1-name"))
                        sha1_name = 1;
                else if (!strncmp(arg, "--more=", 7))
                        extra = atoi(arg + 7);
                else if (!strcmp(arg, "--merge-base"))
                        merge_base = 1;
                else if (!strcmp(arg, "--independent"))
                        independent = 1;
                else if (!strcmp(arg, "--topo-order"))
                        topo_order = 1;
                else
                        usage(show_branch_usage);
                ac--; av++;
        }
        ac--; av++;

        /* Only one of these is allowed */
        if (1 < independent + merge_base + (extra != 0))
                usage(show_branch_usage);

        /* If nothing is specified, show all branches by default */
        if (ac + all_heads + all_tags == 0)
                all_heads = 1;

        if (all_heads + all_tags)
                snarf_refs(all_heads, all_tags);
        while (0 < ac) {
                append_one_rev(*av);
                ac--; av++;
        }

        if (!ref_name_cnt) {
                fprintf(stderr, "No revs to be shown.\n");
                exit(0);
        }

        for (num_rev = 0; ref_name[num_rev]; num_rev++) {
                unsigned char revkey[20];
                unsigned int flag = 1u << (num_rev + REV_SHIFT);

                if (MAX_REVS <= num_rev)
                        die("cannot handle more than %d revs.", MAX_REVS);
                if (get_sha1(ref_name[num_rev], revkey))
                        die("'%s' is not a valid ref.", ref_name[num_rev]);
                commit = lookup_commit_reference(revkey);
                if (!commit)
                        die("cannot find commit %s (%s)",
                            ref_name[num_rev], revkey);
                parse_commit(commit);
                mark_seen(commit, &seen);

                /* rev#0 uses bit REV_SHIFT, rev#1 uses bit REV_SHIFT+1,
                 * and so on.  REV_SHIFT bits from bit 0 are used for
                 * internal bookkeeping.
                 */
                commit->object.flags |= flag;
                if (commit->object.flags == flag)
                        insert_by_date(commit, &list);
                rev[num_rev] = commit;
        }
        for (i = 0; i < num_rev; i++)
                rev_mask[i] = rev[i]->object.flags;

        if (0 <= extra)
                join_revs(&list, &seen, num_rev, extra);

        head_path_p = resolve_ref(git_path("HEAD"), head_sha1, 1);
        if (head_path_p) {
                head_path_len = strlen(head_path_p);
                memcpy(head_path, head_path_p, head_path_len + 1);
        }
        else {
                head_path_len = 0;
                head_path[0] = 0;
        }

        if (merge_base)
                return show_merge_base(seen, num_rev);

        if (independent)
                return show_independent(rev, num_rev, ref_name, rev_mask);

        /* Show list; --more=-1 means list-only */
        if (1 < num_rev || extra < 0) {
                for (i = 0; i < num_rev; i++) {
                        int j;
                        int is_head = rev_is_head(head_path,
                                                  head_path_len,
                                                  ref_name[i],
                                                  head_sha1,
                                                  rev[i]->object.sha1);
                        if (extra < 0)
                                printf("%c [%s] ",
                                       is_head ? '*' : ' ', ref_name[i]);
                        else {
                                for (j = 0; j < i; j++)
                                        putchar(' ');
                                printf("%c [%s] ",
                                       is_head ? '*' : '!', ref_name[i]);
                        }
                        /* header lines never need name */
                        show_one_commit(rev[i], 1);
                }
                if (0 <= extra) {
                        for (i = 0; i < num_rev; i++)
                                putchar('-');
                        putchar('\n');
                }
        }
        if (extra < 0)
                exit(0);

        /* Sort topologically */
        if (topo_order)
                sort_in_topological_order(&seen);

        /* Give names to commits */
        if (!sha1_name && !no_name)
                name_commits(seen, rev, ref_name, num_rev);

        all_mask = ((1u << (REV_SHIFT + num_rev)) - 1);
        all_revs = all_mask & ~((1u << REV_SHIFT) - 1);

        while (seen) {
                struct commit *commit = pop_one_commit(&seen);
                int this_flag = commit->object.flags;

                shown_merge_point |= ((this_flag & all_revs) == all_revs);

                if (1 < num_rev) {
                        for (i = 0; i < num_rev; i++)
                                putchar((this_flag & (1u << (i + REV_SHIFT)))
                                        ? '+' : ' ');
                        putchar(' ');
                }
                show_one_commit(commit, no_name);

                if (shown_merge_point && --extra < 0)
                        break;
        }
        return 0;
}