#include "cache.h"
#include "tag.h"
#include "commit.h"
#include "tree.h"
#include "blob.h"
#include "epoch.h"

#define SEEN            (1u << 0)
#define INTERESTING     (1u << 1)
#define COUNTED         (1u << 2)
#define SHOWN           (LAST_EPOCH_FLAG << 2)

static const char rev_list_usage[] =
        "usage: git-rev-list [OPTION] commit-id <commit-id>\n"
                      "  --max-count=nr\n"
                      "  --max-age=epoch\n"
                      "  --min-age=epoch\n"
                      "  --bisect\n"
                      "  --objects\n"
                      "  --unpacked\n"
                      "  --header\n"
                      "  --pretty\n"
                      "  --merge-order [ --show-breaks ]";

static int unpacked = 0;
static int bisect_list = 0;
static int tag_objects = 0;
static int tree_objects = 0;
static int blob_objects = 0;
static int verbose_header = 0;
static int show_parents = 0;
static int hdr_termination = 0;
static const char *prefix = "";
static unsigned long max_age = -1;
static unsigned long min_age = -1;
static int max_count = -1;
static enum cmit_fmt commit_format = CMIT_FMT_RAW;
static int merge_order = 0;
static int show_breaks = 0;
static int stop_traversal = 0;

static void show_commit(struct commit *commit)
{
        commit->object.flags |= SHOWN;
        if (show_breaks) {
                prefix = "| ";
                if (commit->object.flags & DISCONTINUITY) {
                        prefix = "^ ";     
                } else if (commit->object.flags & BOUNDARY) {
                        prefix = "= ";
                } 
        }                       
        printf("%s%s", prefix, sha1_to_hex(commit->object.sha1));
        if (show_parents) {
                struct commit_list *parents = commit->parents;
                while (parents) {
                        printf(" %s", sha1_to_hex(parents->item->object.sha1));
                        parents = parents->next;
                }
        }
        putchar('\n');
        if (verbose_header) {
                static char pretty_header[16384];
                pretty_print_commit(commit_format, commit->buffer, ~0, pretty_header, sizeof(pretty_header));
                printf("%s%c", pretty_header, hdr_termination);
        }       
}

static int filter_commit(struct commit * commit)
{
        if (merge_order && stop_traversal && commit->object.flags & BOUNDARY)
                return STOP;
        if (commit->object.flags & (UNINTERESTING|SHOWN))
                return CONTINUE;
        if (min_age != -1 && (commit->date > min_age))
                return CONTINUE;
        if (max_age != -1 && (commit->date < max_age)) {
                if (!merge_order)
                        return STOP;
                else {
                        stop_traversal = 1;
                        return CONTINUE;
                }
        }
        if (max_count != -1 && !max_count--)
                return STOP;
        return DO;
}

static int process_commit(struct commit * commit)
{
        int action=filter_commit(commit);

        if (action == STOP) {
                return STOP;
        }

        if (action == CONTINUE) {
                return CONTINUE;
        }

        show_commit(commit);

        return CONTINUE;
}

static struct object_list **add_object(struct object *obj, struct object_list **p, const char *name)
{
        struct object_list *entry = xmalloc(sizeof(*entry));
        entry->item = obj;
        entry->next = *p;
        entry->name = name;
        *p = entry;
        return &entry->next;
}

static struct object_list **process_blob(struct blob *blob, struct object_list **p, const char *name)
{
        struct object *obj = &blob->object;

        if (!blob_objects)
                return p;
        if (obj->flags & (UNINTERESTING | SEEN))
                return p;
        obj->flags |= SEEN;
        return add_object(obj, p, name);
}

static struct object_list **process_tree(struct tree *tree, struct object_list **p, const char *name)
{
        struct object *obj = &tree->object;
        struct tree_entry_list *entry;

        if (!tree_objects)
                return p;
        if (obj->flags & (UNINTERESTING | SEEN))
                return p;
        if (parse_tree(tree) < 0)
                die("bad tree object %s", sha1_to_hex(obj->sha1));
        obj->flags |= SEEN;
        p = add_object(obj, p, name);
        for (entry = tree->entries ; entry ; entry = entry->next) {
                if (entry->directory)
                        p = process_tree(entry->item.tree, p, entry->name);
                else
                        p = process_blob(entry->item.blob, p, entry->name);
        }
        return p;
}

static struct object_list *pending_objects = NULL;

static void show_commit_list(struct commit_list *list)
{
        struct object_list *objects = NULL, **p = &objects, *pending;
        while (list) {
                struct commit *commit = pop_most_recent_commit(&list, SEEN);

                p = process_tree(commit->tree, p, "");
                if (process_commit(commit) == STOP)
                        break;
        }
        for (pending = pending_objects; pending; pending = pending->next) {
                struct object *obj = pending->item;
                const char *name = pending->name;
                if (obj->flags & (UNINTERESTING | SEEN))
                        continue;
                if (obj->type == tag_type) {
                        obj->flags |= SEEN;
                        p = add_object(obj, p, name);
                        continue;
                }
                if (obj->type == tree_type) {
                        p = process_tree((struct tree *)obj, p, name);
                        continue;
                }
                if (obj->type == blob_type) {
                        p = process_blob((struct blob *)obj, p, name);
                        continue;
                }
                die("unknown pending object %s (%s)", sha1_to_hex(obj->sha1), name);
        }
        while (objects) {
                printf("%s %s\n", sha1_to_hex(objects->item->sha1), objects->name);
                objects = objects->next;
        }
}

static void mark_blob_uninteresting(struct blob *blob)
{
        if (!blob_objects)
                return;
        if (blob->object.flags & UNINTERESTING)
                return;
        blob->object.flags |= UNINTERESTING;
}

static void mark_tree_uninteresting(struct tree *tree)
{
        struct object *obj = &tree->object;
        struct tree_entry_list *entry;

        if (!tree_objects)
                return;
        if (obj->flags & UNINTERESTING)
                return;
        obj->flags |= UNINTERESTING;
        if (parse_tree(tree) < 0)
                die("bad tree %s", sha1_to_hex(obj->sha1));
        entry = tree->entries;
        while (entry) {
                if (entry->directory)
                        mark_tree_uninteresting(entry->item.tree);
                else
                        mark_blob_uninteresting(entry->item.blob);
                entry = entry->next;
        }
}

static void mark_parents_uninteresting(struct commit *commit)
{
        struct commit_list *parents = commit->parents;

        if (tree_objects)
                mark_tree_uninteresting(commit->tree);
        while (parents) {
                struct commit *commit = parents->item;
                commit->object.flags |= UNINTERESTING;
                parents = parents->next;
        }
}

static int everybody_uninteresting(struct commit_list *list)
{
        while (list) {
                struct commit *commit = list->item;
                list = list->next;
                if (commit->object.flags & UNINTERESTING)
                        continue;
                return 0;
        }
        return 1;
}

/*
 * This is a truly stupid algorithm, but it's only
 * used for bisection, and we just don't care enough.
 *
 * We care just barely enough to avoid recursing for
 * non-merge entries.
 */
static int count_distance(struct commit_list *entry)
{
        int nr = 0;

        while (entry) {
                struct commit *commit = entry->item;
                struct commit_list *p;

                if (commit->object.flags & (UNINTERESTING | COUNTED))
                        break;
                nr++;
                commit->object.flags |= COUNTED;
                p = commit->parents;
                entry = p;
                if (p) {
                        p = p->next;
                        while (p) {
                                nr += count_distance(p);
                                p = p->next;
                        }
                }
        }
        return nr;
}

static void clear_distance(struct commit_list *list)
{
        while (list) {
                struct commit *commit = list->item;
                commit->object.flags &= ~COUNTED;
                list = list->next;
        }
}

static struct commit_list *find_bisection(struct commit_list *list)
{
        int nr, closest;
        struct commit_list *p, *best;

        nr = 0;
        p = list;
        while (p) {
                nr++;
                p = p->next;
        }
        closest = 0;
        best = list;

        p = list;
        while (p) {
                int distance = count_distance(p);
                clear_distance(list);
                if (nr - distance < distance)
                        distance = nr - distance;
                if (distance > closest) {
                        best = p;
                        closest = distance;
                }
                p = p->next;
        }
        if (best)
                best->next = NULL;
        return best;
}

static struct commit_list *limit_list(struct commit_list *list)
{
        struct commit_list *newlist = NULL;
        struct commit_list **p = &newlist;
        while (list) {
                struct commit *commit = pop_most_recent_commit(&list, SEEN);
                struct object *obj = &commit->object;

                if (unpacked && has_sha1_pack(obj->sha1))
                        obj->flags |= UNINTERESTING;
                if (obj->flags & UNINTERESTING) {
                        mark_parents_uninteresting(commit);
                        if (everybody_uninteresting(list))
                                break;
                        continue;
                }
                p = &commit_list_insert(commit, p)->next;
        }
        if (bisect_list)
                newlist = find_bisection(newlist);
        return newlist;
}

static void add_pending_object(struct object *obj, const char *name)
{
        add_object(obj, &pending_objects, name);
}

static struct commit *get_commit_reference(const char *name, unsigned int flags)
{
        unsigned char sha1[20];
        struct object *object;

        if (get_sha1(name, sha1))
                usage(rev_list_usage);
        object = parse_object(sha1);
        if (!object)
                die("bad object %s", name);

        /*
         * Tag object? Look what it points to..
         */
        if (object->type == tag_type) {
                struct tag *tag = (struct tag *) object;
                object->flags |= flags;
                if (tag_objects && !(object->flags & UNINTERESTING))
                        add_pending_object(object, tag->tag);
                object = tag->tagged;
        }

        /*
         * Commit object? Just return it, we'll do all the complex
         * reachability crud.
         */
        if (object->type == commit_type) {
                struct commit *commit = (struct commit *)object;
                object->flags |= flags;
                if (parse_commit(commit) < 0)
                        die("unable to parse commit %s", name);
                return commit;
        }

        /*
         * Tree object? Either mark it uniniteresting, or add it
         * to the list of objects to look at later..
         */
        if (object->type == tree_type) {
                struct tree *tree = (struct tree *)object;
                if (!tree_objects)
                        return NULL;
                if (flags & UNINTERESTING) {
                        mark_tree_uninteresting(tree);
                        return NULL;
                }
                add_pending_object(object, "");
                return NULL;
        }

        /*
         * Blob object? You know the drill by now..
         */
        if (object->type == blob_type) {
                struct blob *blob = (struct blob *)object;
                if (!blob_objects)
                        return NULL;
                if (flags & UNINTERESTING) {
                        mark_blob_uninteresting(blob);
                        return NULL;
                }
                add_pending_object(object, "");
                return NULL;
        }
        die("%s is unknown object", name);
}

int main(int argc, char **argv)
{
        struct commit_list *list = NULL;
        int i, limited = 0;

        for (i = 1 ; i < argc; i++) {
                int flags;
                char *arg = argv[i];
                struct commit *commit;

                if (!strncmp(arg, "--max-count=", 12)) {
                        max_count = atoi(arg + 12);
                        continue;
                }
                if (!strncmp(arg, "--max-age=", 10)) {
                        max_age = atoi(arg + 10);
                        continue;
                }
                if (!strncmp(arg, "--min-age=", 10)) {
                        min_age = atoi(arg + 10);
                        continue;
                }
                if (!strcmp(arg, "--header")) {
                        verbose_header = 1;
                        continue;
                }
                if (!strncmp(arg, "--pretty", 8)) {
                        commit_format = get_commit_format(arg+8);
                        verbose_header = 1;
                        hdr_termination = '\n';
                        prefix = "commit ";
                        continue;
                }
                if (!strcmp(arg, "--parents")) {
                        show_parents = 1;
                        continue;
                }
                if (!strcmp(arg, "--bisect")) {
                        bisect_list = 1;
                        continue;
                }
                if (!strcmp(arg, "--objects")) {
                        tag_objects = 1;
                        tree_objects = 1;
                        blob_objects = 1;
                        continue;
                }
                if (!strcmp(arg, "--unpacked")) {
                        unpacked = 1;
                        limited = 1;
                        continue;
                }
                if (!strncmp(arg, "--merge-order", 13)) {
                        merge_order = 1;
                        continue;
                }
                if (!strncmp(arg, "--show-breaks", 13)) {
                        show_breaks = 1;
                        continue;
                }

                flags = 0;
                if (*arg == '^') {
                        flags = UNINTERESTING;
                        arg++;
                        limited = 1;
                }
                if (show_breaks && !merge_order)
                        usage(rev_list_usage);
                commit = get_commit_reference(arg, flags);
                if (!commit)
                        continue;
                commit_list_insert(commit, &list);
        }

        if (!merge_order) {             
                if (limited)
                        list = limit_list(list);
                show_commit_list(list);
        } else {
                if (sort_list_in_merge_order(list, &process_commit)) {
                          die("merge order sort failed\n");
                }
        }

        return 0;
}