#include "cache.h"
#include "refs.h"
#include "strbuf.h"
#include "worktree.h"
#include "dir.h"

void free_worktrees(struct worktree **worktrees)
{
        int i = 0;

        for (i = 0; worktrees[i]; i++) {
                free(worktrees[i]->path);
                free(worktrees[i]->id);
                free(worktrees[i]->head_ref);
                free(worktrees[i]);
        }
        free (worktrees);
}

/*
 * read 'path_to_ref' into 'ref'.  Also if is_detached is not NULL,
 * set is_detached to 1 (0) if the ref is detatched (is not detached).
 *
 * $GIT_COMMON_DIR/$symref (e.g. HEAD) is practically outside $GIT_DIR so
 * for linked worktrees, `resolve_ref_unsafe()` won't work (it uses
 * git_path). Parse the ref ourselves.
 *
 * return -1 if the ref is not a proper ref, 0 otherwise (success)
 */
static int parse_ref(char *path_to_ref, struct strbuf *ref, int *is_detached)
{
        if (is_detached)
                *is_detached = 0;
        if (!strbuf_readlink(ref, path_to_ref, 0)) {
                /* HEAD is symbolic link */
                if (!starts_with(ref->buf, "refs/") ||
                                check_refname_format(ref->buf, 0))
                        return -1;
        } else if (strbuf_read_file(ref, path_to_ref, 0) >= 0) {
                /* textual symref or detached */
                if (!starts_with(ref->buf, "ref:")) {
                        if (is_detached)
                                *is_detached = 1;
                } else {
                        strbuf_remove(ref, 0, strlen("ref:"));
                        strbuf_trim(ref);
                        if (check_refname_format(ref->buf, 0))
                                return -1;
                }
        } else
                return -1;
        return 0;
}

/**
 * Add the head_sha1 and head_ref (if not detached) to the given worktree
 */
static void add_head_info(struct strbuf *head_ref, struct worktree *worktree)
{
        if (head_ref->len) {
                if (worktree->is_detached) {
                        get_sha1_hex(head_ref->buf, worktree->head_sha1);
                } else {
                        resolve_ref_unsafe(head_ref->buf, 0, worktree->head_sha1, NULL);
                        worktree->head_ref = strbuf_detach(head_ref, NULL);
                }
        }
}

/**
 * get the main worktree
 */
static struct worktree *get_main_worktree(void)
{
        struct worktree *worktree = NULL;
        struct strbuf path = STRBUF_INIT;
        struct strbuf worktree_path = STRBUF_INIT;
        struct strbuf head_ref = STRBUF_INIT;
        int is_bare = 0;
        int is_detached = 0;

        strbuf_addstr(&worktree_path, absolute_path(get_git_common_dir()));
        is_bare = !strbuf_strip_suffix(&worktree_path, "/.git");
        if (is_bare)
                strbuf_strip_suffix(&worktree_path, "/.");

        strbuf_addf(&path, "%s/HEAD", get_git_common_dir());

        if (parse_ref(path.buf, &head_ref, &is_detached) < 0)
                goto done;

        worktree = xmalloc(sizeof(struct worktree));
        worktree->path = strbuf_detach(&worktree_path, NULL);
        worktree->id = NULL;
        worktree->is_bare = is_bare;
        worktree->head_ref = NULL;
        worktree->is_detached = is_detached;
        worktree->is_current = 0;
        add_head_info(&head_ref, worktree);

done:
        strbuf_release(&path);
        strbuf_release(&worktree_path);
        strbuf_release(&head_ref);
        return worktree;
}

static struct worktree *get_linked_worktree(const char *id)
{
        struct worktree *worktree = NULL;
        struct strbuf path = STRBUF_INIT;
        struct strbuf worktree_path = STRBUF_INIT;
        struct strbuf head_ref = STRBUF_INIT;
        int is_detached = 0;

        if (!id)
                die("Missing linked worktree name");

        strbuf_git_common_path(&path, "worktrees/%s/gitdir", id);
        if (strbuf_read_file(&worktree_path, path.buf, 0) <= 0)
                /* invalid gitdir file */
                goto done;

        strbuf_rtrim(&worktree_path);
        if (!strbuf_strip_suffix(&worktree_path, "/.git")) {
                strbuf_reset(&worktree_path);
                strbuf_addstr(&worktree_path, absolute_path("."));
                strbuf_strip_suffix(&worktree_path, "/.");
        }

        strbuf_reset(&path);
        strbuf_addf(&path, "%s/worktrees/%s/HEAD", get_git_common_dir(), id);

        if (parse_ref(path.buf, &head_ref, &is_detached) < 0)
                goto done;

        worktree = xmalloc(sizeof(struct worktree));
        worktree->path = strbuf_detach(&worktree_path, NULL);
        worktree->id = xstrdup(id);
        worktree->is_bare = 0;
        worktree->head_ref = NULL;
        worktree->is_detached = is_detached;
        worktree->is_current = 0;
        add_head_info(&head_ref, worktree);

done:
        strbuf_release(&path);
        strbuf_release(&worktree_path);
        strbuf_release(&head_ref);
        return worktree;
}

static void mark_current_worktree(struct worktree **worktrees)
{
        struct strbuf git_dir = STRBUF_INIT;
        struct strbuf path = STRBUF_INIT;
        int i;

        strbuf_addstr(&git_dir, absolute_path(get_git_dir()));
        for (i = 0; worktrees[i]; i++) {
                struct worktree *wt = worktrees[i];
                strbuf_addstr(&path, absolute_path(get_worktree_git_dir(wt)));
                wt->is_current = !fspathcmp(git_dir.buf, path.buf);
                strbuf_reset(&path);
                if (wt->is_current)
                        break;
        }
        strbuf_release(&git_dir);
        strbuf_release(&path);
}

struct worktree **get_worktrees(void)
{
        struct worktree **list = NULL;
        struct strbuf path = STRBUF_INIT;
        DIR *dir;
        struct dirent *d;
        int counter = 0, alloc = 2;

        list = xmalloc(alloc * sizeof(struct worktree *));

        if ((list[counter] = get_main_worktree()))
                counter++;

        strbuf_addf(&path, "%s/worktrees", get_git_common_dir());
        dir = opendir(path.buf);
        strbuf_release(&path);
        if (dir) {
                while ((d = readdir(dir)) != NULL) {
                        struct worktree *linked = NULL;
                        if (!strcmp(d->d_name, ".") || !strcmp(d->d_name, ".."))
                                continue;

                        if ((linked = get_linked_worktree(d->d_name))) {
                                ALLOC_GROW(list, counter + 1, alloc);
                                list[counter++] = linked;
                        }
                }
                closedir(dir);
        }
        ALLOC_GROW(list, counter + 1, alloc);
        list[counter] = NULL;

        mark_current_worktree(list);
        return list;
}

const char *get_worktree_git_dir(const struct worktree *wt)
{
        if (!wt)
                return get_git_dir();
        else if (!wt->id)
                return get_git_common_dir();
        else
                return git_common_path("worktrees/%s", wt->id);
}

const struct worktree *find_shared_symref(const char *symref,
                                          const char *target)
{
        const struct worktree *existing = NULL;
        struct strbuf path = STRBUF_INIT;
        struct strbuf sb = STRBUF_INIT;
        static struct worktree **worktrees;
        int i = 0;

        if (worktrees)
                free_worktrees(worktrees);
        worktrees = get_worktrees();

        for (i = 0; worktrees[i]; i++) {
                strbuf_reset(&path);
                strbuf_reset(&sb);
                strbuf_addf(&path, "%s/%s",
                            get_worktree_git_dir(worktrees[i]),
                            symref);

                if (parse_ref(path.buf, &sb, NULL)) {
                        continue;
                }

                if (!strcmp(sb.buf, target)) {
                        existing = worktrees[i];
                        break;
                }
        }

        strbuf_release(&path);
        strbuf_release(&sb);

        return existing;
}