#include "builtin.h"
#include "cache.h"
#include "commit.h"
#include "diff.h"
#include "revision.h"
#include "tag.h"

static const char *fmt_merge_msg_usage =
        "git-fmt-merge-msg [--summary] [--no-summary] [--file <file>]";

static int merge_summary;

static int fmt_merge_msg_config(const char *key, const char *value)
{
        if (!strcmp("merge.summary", key))
                merge_summary = git_config_bool(key, value);
        return 0;
}

struct list {
        char **list;
        void **payload;
        unsigned nr, alloc;
};

static void append_to_list(struct list *list, char *value, void *payload)
{
        if (list->nr == list->alloc) {
                list->alloc += 32;
                list->list = xrealloc(list->list, sizeof(char *) * list->alloc);
                list->payload = xrealloc(list->payload,
                                sizeof(char *) * list->alloc);
        }
        list->payload[list->nr] = payload;
        list->list[list->nr++] = value;
}

static int find_in_list(struct list *list, char *value)
{
        int i;

        for (i = 0; i < list->nr; i++)
                if (!strcmp(list->list[i], value))
                        return i;

        return -1;
}

static void free_list(struct list *list)
{
        int i;

        if (list->alloc == 0)
                return;

        for (i = 0; i < list->nr; i++) {
                free(list->list[i]);
                free(list->payload[i]);
        }
        free(list->list);
        free(list->payload);
        list->nr = list->alloc = 0;
}

struct src_data {
        struct list branch, tag, r_branch, generic;
        int head_status;
};

static struct list srcs = { NULL, NULL, 0, 0};
static struct list origins = { NULL, NULL, 0, 0};

static int handle_line(char *line)
{
        int i, len = strlen(line);
        unsigned char *sha1;
        char *src, *origin;
        struct src_data *src_data;
        int pulling_head = 0;

        if (len < 43 || line[40] != '\t')
                return 1;

        if (!strncmp(line + 41, "not-for-merge", 13))
                return 0;

        if (line[41] != '\t')
                return 2;

        line[40] = 0;
        sha1 = xmalloc(20);
        i = get_sha1(line, sha1);
        line[40] = '\t';
        if (i)
                return 3;

        if (line[len - 1] == '\n')
                line[len - 1] = 0;
        line += 42;

        src = strstr(line, " of ");
        if (src) {
                *src = 0;
                src += 4;
                pulling_head = 0;
        } else {
                src = line;
                pulling_head = 1;
        }

        i = find_in_list(&srcs, src);
        if (i < 0) {
                i = srcs.nr;
                append_to_list(&srcs, strdup(src),
                                xcalloc(1, sizeof(struct src_data)));
        }
        src_data = srcs.payload[i];

        if (pulling_head) {
                origin = strdup(src);
                src_data->head_status |= 1;
        } else if (!strncmp(line, "branch ", 7)) {
                origin = strdup(line + 7);
                append_to_list(&src_data->branch, origin, NULL);
                src_data->head_status |= 2;
        } else if (!strncmp(line, "tag ", 4)) {
                origin = line;
                append_to_list(&src_data->tag, strdup(origin + 4), NULL);
                src_data->head_status |= 2;
        } else if (!strncmp(line, "remote branch ", 14)) {
                origin = strdup(line + 14);
                append_to_list(&src_data->r_branch, origin, NULL);
                src_data->head_status |= 2;
        } else {
                origin = strdup(src);
                append_to_list(&src_data->generic, strdup(line), NULL);
                src_data->head_status |= 2;
        }

        if (!strcmp(".", src) || !strcmp(src, origin)) {
                int len = strlen(origin);
                if (origin[0] == '\'' && origin[len - 1] == '\'') {
                        char *new_origin = xmalloc(len - 1);
                        memcpy(new_origin, origin + 1, len - 2);
                        new_origin[len - 2] = 0;
                        origin = new_origin;
                } else
                        origin = strdup(origin);
        } else {
                char *new_origin = xmalloc(strlen(origin) + strlen(src) + 5);
                sprintf(new_origin, "%s of %s", origin, src);
                origin = new_origin;
        }
        append_to_list(&origins, origin, sha1);
        return 0;
}

static void print_joined(const char *singular, const char *plural,
                struct list *list)
{
        if (list->nr == 0)
                return;
        if (list->nr == 1) {
                printf("%s%s", singular, list->list[0]);
        } else {
                int i;
                printf("%s", plural);
                for (i = 0; i < list->nr - 1; i++)
                        printf("%s%s", i > 0 ? ", " : "", list->list[i]);
                printf(" and %s", list->list[list->nr - 1]);
        }
}

static void shortlog(const char *name, unsigned char *sha1,
                struct commit *head, struct rev_info *rev, int limit)
{
        int i, count = 0;
        struct commit *commit;
        struct object *branch;
        struct list subjects = { NULL, NULL, 0, 0 };
        int flags = UNINTERESTING | TREECHANGE | SEEN | SHOWN | ADDED;

        branch = deref_tag(parse_object(sha1), sha1_to_hex(sha1), 40);
        if (!branch || branch->type != OBJ_COMMIT)
                return;

        setup_revisions(0, NULL, rev, NULL);
        rev->ignore_merges = 1;
        add_pending_object(rev, branch, name);
        add_pending_object(rev, &head->object, "^HEAD");
        head->object.flags |= UNINTERESTING;
        prepare_revision_walk(rev);
        while ((commit = get_revision(rev)) != NULL) {
                char *oneline, *bol, *eol;

                /* ignore merges */
                if (commit->parents && commit->parents->next)
                        continue;

                count++;
                if (subjects.nr > limit)
                        continue;

                bol = strstr(commit->buffer, "\n\n");
                if (!bol) {
                        append_to_list(&subjects, strdup(sha1_to_hex(
                                                        commit->object.sha1)),
                                        NULL);
                        continue;
                }

                bol += 2;
                eol = strchr(bol, '\n');

                if (eol) {
                        int len = eol - bol;
                        oneline = xmalloc(len + 1);
                        memcpy(oneline, bol, len);
                        oneline[len] = 0;
                } else
                        oneline = strdup(bol);
                append_to_list(&subjects, oneline, NULL);
        }

        if (count > limit)
                printf("\n* %s: (%d commits)\n", name, count);
        else
                printf("\n* %s:\n", name);

        for (i = 0; i < subjects.nr; i++)
                if (i >= limit)
                        printf("  ...\n");
                else
                        printf("  %s\n", subjects.list[i]);

        clear_commit_marks((struct commit *)branch, flags);
        clear_commit_marks(head, flags);
        free_commit_list(rev->commits);
        rev->commits = NULL;
        rev->pending.nr = 0;

        free_list(&subjects);
}

int cmd_fmt_merge_msg(int argc, const char **argv, const char *prefix)
{
        int limit = 20, i = 0;
        char line[1024];
        FILE *in = stdin;
        const char *sep = "";
        unsigned char head_sha1[20];
        const char *head, *current_branch;

        git_config(fmt_merge_msg_config);

        while (argc > 1) {
                if (!strcmp(argv[1], "--summary"))
                        merge_summary = 1;
                else if (!strcmp(argv[1], "--no-summary"))
                        merge_summary = 0;
                else if (!strcmp(argv[1], "-F") || !strcmp(argv[1], "--file")) {
                        if (argc < 2)
                                die ("Which file?");
                        if (!strcmp(argv[2], "-"))
                                in = stdin;
                        else {
                                fclose(in);
                                in = fopen(argv[2], "r");
                        }
                        argc--; argv++;
                } else
                        break;
                argc--; argv++;
        }

        if (argc > 1)
                usage(fmt_merge_msg_usage);

        /* get current branch */
        head = strdup(git_path("HEAD"));
        current_branch = resolve_ref(head, head_sha1, 1);
        current_branch += strlen(head) - 4;
        free((char *)head);
        if (!strncmp(current_branch, "refs/heads/", 11))
                current_branch += 11;

        while (fgets(line, sizeof(line), in)) {
                i++;
                if (line[0] == 0)
                        continue;
                if (handle_line(line))
                        die ("Error in line %d: %s", i, line);
        }

        printf("Merge ");
        for (i = 0; i < srcs.nr; i++) {
                struct src_data *src_data = srcs.payload[i];
                const char *subsep = "";

                printf(sep);
                sep = "; ";

                if (src_data->head_status == 1) {
                        printf(srcs.list[i]);
                        continue;
                }
                if (src_data->head_status == 3) {
                        subsep = ", ";
                        printf("HEAD");
                }
                if (src_data->branch.nr) {
                        printf(subsep);
                        subsep = ", ";
                        print_joined("branch ", "branches ", &src_data->branch);
                }
                if (src_data->r_branch.nr) {
                        printf(subsep);
                        subsep = ", ";
                        print_joined("remote branch ", "remote branches ",
                                        &src_data->r_branch);
                }
                if (src_data->tag.nr) {
                        printf(subsep);
                        subsep = ", ";
                        print_joined("tag ", "tags ", &src_data->tag);
                }
                if (src_data->generic.nr) {
                        printf(subsep);
                        print_joined("commit ", "commits ", &src_data->generic);
                }
                if (strcmp(".", srcs.list[i]))
                        printf(" of %s", srcs.list[i]);
        }

        if (!strcmp("master", current_branch))
                putchar('\n');
        else
                printf(" into %s\n", current_branch);

        if (merge_summary) {
                struct commit *head;
                struct rev_info rev;

                head = lookup_commit(head_sha1);
                init_revisions(&rev, prefix);
                rev.commit_format = CMIT_FMT_ONELINE;
                rev.ignore_merges = 1;
                rev.limited = 1;

                for (i = 0; i < origins.nr; i++)
                        shortlog(origins.list[i], origins.payload[i],
                                        head, &rev, limit);
        }

        /* No cleanup yet; is standalone anyway */

        return 0;
}