#include "builtin.h"
#include "cache.h"
#include "commit.h"
#include "diff.h"
#include "revision.h"
#include "tag.h"
#include "string-list.h"
#include "branch.h"
#include "fmt-merge-msg.h"
#include "gpg-interface.h"

static const char * const fmt_merge_msg_usage[] = {
        N_("git fmt-merge-msg [-m <message>] [--log[=<n>] | --no-log] [--file <file>]"),
        NULL
};

static int use_branch_desc;

int fmt_merge_msg_config(const char *key, const char *value, void *cb)
{
        if (!strcmp(key, "merge.log") || !strcmp(key, "merge.summary")) {
                int is_bool;
                merge_log_config = git_config_bool_or_int(key, value, &is_bool);
                if (!is_bool && merge_log_config < 0)
                        return error("%s: negative length %s", key, value);
                if (is_bool && merge_log_config)
                        merge_log_config = DEFAULT_MERGE_LOG_LEN;
        } else if (!strcmp(key, "merge.branchdesc")) {
                use_branch_desc = git_config_bool(key, value);
        } else {
                return git_default_config(key, value, cb);
        }
        return 0;
}

/* merge data per repository where the merged tips came from */
struct src_data {
        struct string_list branch, tag, r_branch, generic;
        int head_status;
};

struct origin_data {
        unsigned char sha1[20];
        unsigned is_local_branch:1;
};

static void init_src_data(struct src_data *data)
{
        data->branch.strdup_strings = 1;
        data->tag.strdup_strings = 1;
        data->r_branch.strdup_strings = 1;
        data->generic.strdup_strings = 1;
}

static struct string_list srcs = STRING_LIST_INIT_DUP;
static struct string_list origins = STRING_LIST_INIT_DUP;

struct merge_parents {
        int alloc, nr;
        struct merge_parent {
                unsigned char given[20];
                unsigned char commit[20];
                unsigned char used;
        } *item;
};

/*
 * I know, I know, this is inefficient, but you won't be pulling and merging
 * hundreds of heads at a time anyway.
 */
static struct merge_parent *find_merge_parent(struct merge_parents *table,
                                              unsigned char *given,
                                              unsigned char *commit)
{
        int i;
        for (i = 0; i < table->nr; i++) {
                if (given && hashcmp(table->item[i].given, given))
                        continue;
                if (commit && hashcmp(table->item[i].commit, commit))
                        continue;
                return &table->item[i];
        }
        return NULL;
}

static void add_merge_parent(struct merge_parents *table,
                             unsigned char *given,
                             unsigned char *commit)
{
        if (table->nr && find_merge_parent(table, given, commit))
                return;
        ALLOC_GROW(table->item, table->nr + 1, table->alloc);
        hashcpy(table->item[table->nr].given, given);
        hashcpy(table->item[table->nr].commit, commit);
        table->item[table->nr].used = 0;
        table->nr++;
}

static int handle_line(char *line, struct merge_parents *merge_parents)
{
        int i, len = strlen(line);
        struct origin_data *origin_data;
        char *src;
        const char *origin;
        struct src_data *src_data;
        struct string_list_item *item;
        int pulling_head = 0;
        unsigned char sha1[20];

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

        if (starts_with(line + 41, "not-for-merge"))
                return 0;

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

        i = get_sha1_hex(line, sha1);
        if (i)
                return 3;

        if (!find_merge_parent(merge_parents, sha1, NULL))
                return 0; /* subsumed by other parents */

        origin_data = xcalloc(1, sizeof(struct origin_data));
        hashcpy(origin_data->sha1, sha1);

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

        /*
         * At this point, line points at the beginning of comment e.g.
         * "branch 'frotz' of git://that/repository.git".
         * Find the repository name and point it with src.
         */
        src = strstr(line, " of ");
        if (src) {
                *src = 0;
                src += 4;
                pulling_head = 0;
        } else {
                src = line;
                pulling_head = 1;
        }

        item = unsorted_string_list_lookup(&srcs, src);
        if (!item) {
                item = string_list_append(&srcs, src);
                item->util = xcalloc(1, sizeof(struct src_data));
                init_src_data(item->util);
        }
        src_data = item->util;

        if (pulling_head) {
                origin = src;
                src_data->head_status |= 1;
        } else if (starts_with(line, "branch ")) {
                origin_data->is_local_branch = 1;
                origin = line + 7;
                string_list_append(&src_data->branch, origin);
                src_data->head_status |= 2;
        } else if (starts_with(line, "tag ")) {
                origin = line;
                string_list_append(&src_data->tag, origin + 4);
                src_data->head_status |= 2;
        } else if (skip_prefix(line, "remote-tracking branch ", &origin)) {
                string_list_append(&src_data->r_branch, origin);
                src_data->head_status |= 2;
        } else {
                origin = src;
                string_list_append(&src_data->generic, line);
                src_data->head_status |= 2;
        }

        if (!strcmp(".", src) || !strcmp(src, origin)) {
                int len = strlen(origin);
                if (origin[0] == '\'' && origin[len - 1] == '\'')
                        origin = xmemdupz(origin + 1, len - 2);
        } else
                origin = xstrfmt("%s of %s", origin, src);
        if (strcmp(".", src))
                origin_data->is_local_branch = 0;
        string_list_append(&origins, origin)->util = origin_data;
        return 0;
}

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

static void add_branch_desc(struct strbuf *out, const char *name)
{
        struct strbuf desc = STRBUF_INIT;

        if (!read_branch_desc(&desc, name)) {
                const char *bp = desc.buf;
                while (*bp) {
                        const char *ep = strchrnul(bp, '\n');
                        if (*ep)
                                ep++;
                        strbuf_addf(out, "  : %.*s", (int)(ep - bp), bp);
                        bp = ep;
                }
                strbuf_complete_line(out);
        }
        strbuf_release(&desc);
}

#define util_as_integral(elem) ((intptr_t)((elem)->util))

static void record_person(int which, struct string_list *people,
                          struct commit *commit)
{
        const char *buffer;
        char *name_buf, *name, *name_end;
        struct string_list_item *elem;
        const char *field;

        field = (which == 'a') ? "\nauthor " : "\ncommitter ";
        buffer = get_commit_buffer(commit, NULL);
        name = strstr(buffer, field);
        if (!name)
                return;
        name += strlen(field);
        name_end = strchrnul(name, '<');
        if (*name_end)
                name_end--;
        while (isspace(*name_end) && name <= name_end)
                name_end--;
        if (name_end < name)
                return;
        name_buf = xmemdupz(name, name_end - name + 1);
        unuse_commit_buffer(commit, buffer);

        elem = string_list_lookup(people, name_buf);
        if (!elem) {
                elem = string_list_insert(people, name_buf);
                elem->util = (void *)0;
        }
        elem->util = (void*)(util_as_integral(elem) + 1);
        free(name_buf);
}

static int cmp_string_list_util_as_integral(const void *a_, const void *b_)
{
        const struct string_list_item *a = a_, *b = b_;
        return util_as_integral(b) - util_as_integral(a);
}

static void add_people_count(struct strbuf *out, struct string_list *people)
{
        if (people->nr == 1)
                strbuf_addf(out, "%s", people->items[0].string);
        else if (people->nr == 2)
                strbuf_addf(out, "%s (%d) and %s (%d)",
                            people->items[0].string,
                            (int)util_as_integral(&people->items[0]),
                            people->items[1].string,
                            (int)util_as_integral(&people->items[1]));
        else if (people->nr)
                strbuf_addf(out, "%s (%d) and others",
                            people->items[0].string,
                            (int)util_as_integral(&people->items[0]));
}

static void credit_people(struct strbuf *out,
                          struct string_list *them,
                          int kind)
{
        const char *label;
        const char *me;

        if (kind == 'a') {
                label = "By";
                me = git_author_info(IDENT_NO_DATE);
        } else {
                label = "Via";
                me = git_committer_info(IDENT_NO_DATE);
        }

        if (!them->nr ||
            (them->nr == 1 &&
             me &&
             skip_prefix(me, them->items->string, &me) &&
             starts_with(me, " <")))
                return;
        strbuf_addf(out, "\n%c %s ", comment_line_char, label);
        add_people_count(out, them);
}

static void add_people_info(struct strbuf *out,
                            struct string_list *authors,
                            struct string_list *committers)
{
        if (authors->nr)
                qsort(authors->items,
                      authors->nr, sizeof(authors->items[0]),
                      cmp_string_list_util_as_integral);
        if (committers->nr)
                qsort(committers->items,
                      committers->nr, sizeof(committers->items[0]),
                      cmp_string_list_util_as_integral);

        credit_people(out, authors, 'a');
        credit_people(out, committers, 'c');
}

static void shortlog(const char *name,
                     struct origin_data *origin_data,
                     struct commit *head,
                     struct rev_info *rev,
                     struct fmt_merge_msg_opts *opts,
                     struct strbuf *out)
{
        int i, count = 0;
        struct commit *commit;
        struct object *branch;
        struct string_list subjects = STRING_LIST_INIT_DUP;
        struct string_list authors = STRING_LIST_INIT_DUP;
        struct string_list committers = STRING_LIST_INIT_DUP;
        int flags = UNINTERESTING | TREESAME | SEEN | SHOWN | ADDED;
        struct strbuf sb = STRBUF_INIT;
        const unsigned char *sha1 = origin_data->sha1;
        int limit = opts->shortlog_len;

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

        setup_revisions(0, NULL, rev, NULL);
        add_pending_object(rev, branch, name);
        add_pending_object(rev, &head->object, "^HEAD");
        head->object.flags |= UNINTERESTING;
        if (prepare_revision_walk(rev))
                die("revision walk setup failed");
        while ((commit = get_revision(rev)) != NULL) {
                struct pretty_print_context ctx = {0};

                if (commit->parents && commit->parents->next) {
                        /* do not list a merge but count committer */
                        if (opts->credit_people)
                                record_person('c', &committers, commit);
                        continue;
                }
                if (!count && opts->credit_people)
                        /* the 'tip' committer */
                        record_person('c', &committers, commit);
                if (opts->credit_people)
                        record_person('a', &authors, commit);
                count++;
                if (subjects.nr > limit)
                        continue;

                format_commit_message(commit, "%s", &sb, &ctx);
                strbuf_ltrim(&sb);

                if (!sb.len)
                        string_list_append(&subjects,
                                           sha1_to_hex(commit->object.sha1));
                else
                        string_list_append(&subjects, strbuf_detach(&sb, NULL));
        }

        if (opts->credit_people)
                add_people_info(out, &authors, &committers);
        if (count > limit)
                strbuf_addf(out, "\n* %s: (%d commits)\n", name, count);
        else
                strbuf_addf(out, "\n* %s:\n", name);

        if (origin_data->is_local_branch && use_branch_desc)
                add_branch_desc(out, name);

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

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

        string_list_clear(&authors, 0);
        string_list_clear(&committers, 0);
        string_list_clear(&subjects, 0);
}

static void fmt_merge_msg_title(struct strbuf *out,
        const char *current_branch) {
        int i = 0;
        char *sep = "";

        strbuf_addstr(out, "Merge ");
        for (i = 0; i < srcs.nr; i++) {
                struct src_data *src_data = srcs.items[i].util;
                const char *subsep = "";

                strbuf_addstr(out, sep);
                sep = "; ";

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

        if (!strcmp("master", current_branch))
                strbuf_addch(out, '\n');
        else
                strbuf_addf(out, " into %s\n", current_branch);
}

static void fmt_tag_signature(struct strbuf *tagbuf,
                              struct strbuf *sig,
                              const char *buf,
                              unsigned long len)
{
        const char *tag_body = strstr(buf, "\n\n");
        if (tag_body) {
                tag_body += 2;
                strbuf_add(tagbuf, tag_body, buf + len - tag_body);
        }
        strbuf_complete_line(tagbuf);
        if (sig->len) {
                strbuf_addch(tagbuf, '\n');
                strbuf_add_commented_lines(tagbuf, sig->buf, sig->len);
        }
}

static void fmt_merge_msg_sigs(struct strbuf *out)
{
        int i, tag_number = 0, first_tag = 0;
        struct strbuf tagbuf = STRBUF_INIT;

        for (i = 0; i < origins.nr; i++) {
                unsigned char *sha1 = origins.items[i].util;
                enum object_type type;
                unsigned long size, len;
                char *buf = read_sha1_file(sha1, &type, &size);
                struct strbuf sig = STRBUF_INIT;

                if (!buf || type != OBJ_TAG)
                        goto next;
                len = parse_signature(buf, size);

                if (size == len)
                        ; /* merely annotated */
                else if (verify_signed_buffer(buf, len, buf + len, size - len, &sig, NULL)) {
                        if (!sig.len)
                                strbuf_addstr(&sig, "gpg verification failed.\n");
                }

                if (!tag_number++) {
                        fmt_tag_signature(&tagbuf, &sig, buf, len);
                        first_tag = i;
                } else {
                        if (tag_number == 2) {
                                struct strbuf tagline = STRBUF_INIT;
                                strbuf_addch(&tagline, '\n');
                                strbuf_add_commented_lines(&tagline,
                                                origins.items[first_tag].string,
                                                strlen(origins.items[first_tag].string));
                                strbuf_insert(&tagbuf, 0, tagline.buf,
                                              tagline.len);
                                strbuf_release(&tagline);
                        }
                        strbuf_addch(&tagbuf, '\n');
                        strbuf_add_commented_lines(&tagbuf,
                                        origins.items[i].string,
                                        strlen(origins.items[i].string));
                        fmt_tag_signature(&tagbuf, &sig, buf, len);
                }
                strbuf_release(&sig);
        next:
                free(buf);
        }
        if (tagbuf.len) {
                strbuf_addch(out, '\n');
                strbuf_addbuf(out, &tagbuf);
        }
        strbuf_release(&tagbuf);
}

static void find_merge_parents(struct merge_parents *result,
                               struct strbuf *in, unsigned char *head)
{
        struct commit_list *parents, *next;
        struct commit *head_commit;
        int pos = 0, i, j;

        parents = NULL;
        while (pos < in->len) {
                int len;
                char *p = in->buf + pos;
                char *newline = strchr(p, '\n');
                unsigned char sha1[20];
                struct commit *parent;
                struct object *obj;

                len = newline ? newline - p : strlen(p);
                pos += len + !!newline;

                if (len < 43 ||
                    get_sha1_hex(p, sha1) ||
                    p[40] != '\t' ||
                    p[41] != '\t')
                        continue; /* skip not-for-merge */
                /*
                 * Do not use get_merge_parent() here; we do not have
                 * "name" here and we do not want to contaminate its
                 * util field yet.
                 */
                obj = parse_object(sha1);
                parent = (struct commit *)peel_to_type(NULL, 0, obj, OBJ_COMMIT);
                if (!parent)
                        continue;
                commit_list_insert(parent, &parents);
                add_merge_parent(result, obj->sha1, parent->object.sha1);
        }
        head_commit = lookup_commit(head);
        if (head_commit)
                commit_list_insert(head_commit, &parents);
        parents = reduce_heads(parents);

        while (parents) {
                for (i = 0; i < result->nr; i++)
                        if (!hashcmp(result->item[i].commit,
                                     parents->item->object.sha1))
                                result->item[i].used = 1;
                next = parents->next;
                free(parents);
                parents = next;
        }

        for (i = j = 0; i < result->nr; i++) {
                if (result->item[i].used) {
                        if (i != j)
                                result->item[j] = result->item[i];
                        j++;
                }
        }
        result->nr = j;
}

int fmt_merge_msg(struct strbuf *in, struct strbuf *out,
                  struct fmt_merge_msg_opts *opts)
{
        int i = 0, pos = 0;
        unsigned char head_sha1[20];
        const char *current_branch;
        void *current_branch_to_free;
        struct merge_parents merge_parents;

        memset(&merge_parents, 0, sizeof(merge_parents));

        /* get current branch */
        current_branch = current_branch_to_free =
                resolve_refdup("HEAD", RESOLVE_REF_READING, head_sha1, NULL);
        if (!current_branch)
                die("No current branch");
        if (starts_with(current_branch, "refs/heads/"))
                current_branch += 11;

        find_merge_parents(&merge_parents, in, head_sha1);

        /* get a line */
        while (pos < in->len) {
                int len;
                char *newline, *p = in->buf + pos;

                newline = strchr(p, '\n');
                len = newline ? newline - p : strlen(p);
                pos += len + !!newline;
                i++;
                p[len] = 0;
                if (handle_line(p, &merge_parents))
                        die ("Error in line %d: %.*s", i, len, p);
        }

        if (opts->add_title && srcs.nr)
                fmt_merge_msg_title(out, current_branch);

        if (origins.nr)
                fmt_merge_msg_sigs(out);

        if (opts->shortlog_len) {
                struct commit *head;
                struct rev_info rev;

                head = lookup_commit_or_die(head_sha1, "HEAD");
                init_revisions(&rev, NULL);
                rev.commit_format = CMIT_FMT_ONELINE;
                rev.ignore_merges = 1;
                rev.limited = 1;

                strbuf_complete_line(out);

                for (i = 0; i < origins.nr; i++)
                        shortlog(origins.items[i].string,
                                 origins.items[i].util,
                                 head, &rev, opts, out);
        }

        strbuf_complete_line(out);
        free(current_branch_to_free);
        free(merge_parents.item);
        return 0;
}

int cmd_fmt_merge_msg(int argc, const char **argv, const char *prefix)
{
        const char *inpath = NULL;
        const char *message = NULL;
        int shortlog_len = -1;
        struct option options[] = {
                { OPTION_INTEGER, 0, "log", &shortlog_len, N_("n"),
                  N_("populate log with at most <n> entries from shortlog"),
                  PARSE_OPT_OPTARG, NULL, DEFAULT_MERGE_LOG_LEN },
                { OPTION_INTEGER, 0, "summary", &shortlog_len, N_("n"),
                  N_("alias for --log (deprecated)"),
                  PARSE_OPT_OPTARG | PARSE_OPT_HIDDEN, NULL,
                  DEFAULT_MERGE_LOG_LEN },
                OPT_STRING('m', "message", &message, N_("text"),
                        N_("use <text> as start of message")),
                OPT_FILENAME('F', "file", &inpath, N_("file to read from")),
                OPT_END()
        };

        FILE *in = stdin;
        struct strbuf input = STRBUF_INIT, output = STRBUF_INIT;
        int ret;
        struct fmt_merge_msg_opts opts;

        git_config(fmt_merge_msg_config, NULL);
        argc = parse_options(argc, argv, prefix, options, fmt_merge_msg_usage,
                             0);
        if (argc > 0)
                usage_with_options(fmt_merge_msg_usage, options);
        if (shortlog_len < 0)
                shortlog_len = (merge_log_config > 0) ? merge_log_config : 0;

        if (inpath && strcmp(inpath, "-")) {
                in = fopen(inpath, "r");
                if (!in)
                        die_errno("cannot open '%s'", inpath);
        }

        if (strbuf_read(&input, fileno(in), 0) < 0)
                die_errno("could not read input file");

        if (message)
                strbuf_addstr(&output, message);

        memset(&opts, 0, sizeof(opts));
        opts.add_title = !message;
        opts.credit_people = 1;
        opts.shortlog_len = shortlog_len;

        ret = fmt_merge_msg(&input, &output, &opts);
        if (ret)
                return ret;
        write_in_full(STDOUT_FILENO, output.buf, output.len);
        return 0;
}