#include "tag.h"
#include "commit.h"
#include "cache.h"

const char *commit_type = "commit";

static struct commit *check_commit(struct object *obj, unsigned char *sha1)
{
        if (obj->type != commit_type) {
                error("Object %s is a %s, not a commit", 
                      sha1_to_hex(sha1), obj->type);
                return NULL;
        }
        return (struct commit *) obj;
}

struct commit *lookup_commit_reference(unsigned char *sha1)
{
        struct object *obj = parse_object(sha1);

        if (!obj)
                return NULL;
        if (obj->type == tag_type)
                obj = ((struct tag *)obj)->tagged;
        return check_commit(obj, sha1);
}

struct commit *lookup_commit(unsigned char *sha1)
{
        struct object *obj = lookup_object(sha1);
        if (!obj) {
                struct commit *ret = xmalloc(sizeof(struct commit));
                memset(ret, 0, sizeof(struct commit));
                created_object(sha1, &ret->object);
                ret->object.type = commit_type;
                return ret;
        }
        if (!obj->type)
                obj->type = commit_type;
        return check_commit(obj, sha1);
}

static unsigned long parse_commit_date(const char *buf)
{
        unsigned long date;

        if (memcmp(buf, "author", 6))
                return 0;
        while (*buf++ != '\n')
                /* nada */;
        if (memcmp(buf, "committer", 9))
                return 0;
        while (*buf++ != '>')
                /* nada */;
        date = strtoul(buf, NULL, 10);
        if (date == ULONG_MAX)
                date = 0;
        return date;
}

int parse_commit_buffer(struct commit *item, void *buffer, unsigned long size)
{
        void *bufptr = buffer;
        unsigned char parent[20];

        if (item->object.parsed)
                return 0;
        item->object.parsed = 1;
        get_sha1_hex(bufptr + 5, parent);
        item->tree = lookup_tree(parent);
        if (item->tree)
                add_ref(&item->object, &item->tree->object);
        bufptr += 46; /* "tree " + "hex sha1" + "\n" */
        while (!memcmp(bufptr, "parent ", 7) &&
               !get_sha1_hex(bufptr + 7, parent)) {
                struct commit *new_parent = lookup_commit(parent);
                if (new_parent) {
                        commit_list_insert(new_parent, &item->parents);
                        add_ref(&item->object, &new_parent->object);
                }
                bufptr += 48;
        }
        item->date = parse_commit_date(bufptr);
        return 0;
}

int parse_commit(struct commit *item)
{
        char type[20];
        void *buffer;
        unsigned long size;
        int ret;

        if (item->object.parsed)
                return 0;
        buffer = read_sha1_file(item->object.sha1, type, &size);
        if (!buffer)
                return error("Could not read %s",
                             sha1_to_hex(item->object.sha1));
        if (strcmp(type, commit_type)) {
                free(buffer);
                return error("Object %s not a commit",
                             sha1_to_hex(item->object.sha1));
        }
        ret = parse_commit_buffer(item, buffer, size);
        if (!ret) {
                item->buffer = buffer;
                return 0;
        }
        free(buffer);
        return ret;
}

struct commit_list *commit_list_insert(struct commit *item, struct commit_list **list_p)
{
        struct commit_list *new_list = xmalloc(sizeof(struct commit_list));
        new_list->item = item;
        new_list->next = *list_p;
        *list_p = new_list;
        return new_list;
}

void free_commit_list(struct commit_list *list)
{
        while (list) {
                struct commit_list *temp = list;
                list = temp->next;
                free(temp);
        }
}

static void insert_by_date(struct commit_list **list, struct commit *item)
{
        struct commit_list **pp = list;
        struct commit_list *p;
        while ((p = *pp) != NULL) {
                if (p->item->date < item->date) {
                        break;
                }
                pp = &p->next;
        }
        commit_list_insert(item, pp);
}

        
void sort_by_date(struct commit_list **list)
{
        struct commit_list *ret = NULL;
        while (*list) {
                insert_by_date(&ret, (*list)->item);
                *list = (*list)->next;
        }
        *list = ret;
}

struct commit *pop_most_recent_commit(struct commit_list **list,
                                      unsigned int mark)
{
        struct commit *ret = (*list)->item;
        struct commit_list *parents = ret->parents;
        struct commit_list *old = *list;

        *list = (*list)->next;
        free(old);

        while (parents) {
                struct commit *commit = parents->item;
                parse_commit(commit);
                if (!(commit->object.flags & mark)) {
                        commit->object.flags |= mark;
                        insert_by_date(list, commit);
                }
                parents = parents->next;
        }
        return ret;
}

/*
 * Generic support for pretty-printing the header
 */
static int get_one_line(const char *msg, unsigned long len)
{
        int ret = 0;

        while (len--) {
                char c = *msg++;
                ret++;
                if (c == '\n')
                        break;
                if (!c)
                        return 0;
        }
        return ret;
}

static int add_author_info(char *buf, const char *line, int len)
{
        char *date;
        unsigned int namelen;
        unsigned long time;
        int tz;

        line += strlen("author ");
        date = strchr(line, '>');
        if (!date)
                return 0;
        namelen = ++date - line;
        time = strtoul(date, &date, 10);
        tz = strtol(date, NULL, 10);

        return sprintf(buf, "Author: %.*s\nDate:   %s\n",
                namelen, line,
                show_date(time, tz));
}

unsigned long pretty_print_commit(const char *msg, unsigned long len, char *buf, unsigned long space)
{
        int hdr = 1;
        unsigned long offset = 0;

        for (;;) {
                const char *line = msg;
                int linelen = get_one_line(msg, len);

                if (!linelen)
                        break;

                /*
                 * We want some slop for indentation and a possible
                 * final "...". Thus the "+ 20".
                 */
                if (offset + linelen + 20 > space) {
                        memcpy(buf + offset, "    ...\n", 8);
                        offset += 8;
                        break;
                }

                msg += linelen;
                len -= linelen;
                if (linelen == 1)
                        hdr = 0;
                if (hdr) {
                        if (!memcmp(line, "author ", 7))
                                offset += add_author_info(buf + offset, line, linelen);
                        continue;
                }
                memset(buf + offset, ' ', 4);
                memcpy(buf + offset + 4, line, linelen);
                offset += linelen + 4;
        }
        /* Make sure there is an EOLN */
        if (buf[offset - 1] != '\n')
                buf[offset++] = '\n';
        buf[offset] = '\0';
        return offset;
}