#include "sortedcache.h"
GIT__USE_STRMAP
int git_sortedcache_new(
        git_sortedcache **out,
        size_t item_path_offset,
        git_sortedcache_free_item_fn free_item,
        void *free_item_payload,
        git_vector_cmp item_cmp,
        const char *path)
{
        git_sortedcache *sc;
        size_t pathlen, alloclen;
        pathlen = path ? strlen(path) : 0;
        GITERR_CHECK_ALLOC_ADD(&alloclen, sizeof(git_sortedcache), pathlen);
        GITERR_CHECK_ALLOC_ADD(&alloclen, alloclen, 1);
        sc = git__calloc(1, alloclen);
        GITERR_CHECK_ALLOC(sc);
        git_pool_init(&sc->pool, 1);
        if (git_vector_init(&sc->items, 4, item_cmp) < 0 ||
                git_strmap_alloc(&sc->map) < 0)
                goto fail;
        if (git_rwlock_init(&sc->lock)) {
                giterr_set(GITERR_OS, "Failed to initialize lock");
                goto fail;
        }
        sc->item_path_offset  = item_path_offset;
        sc->free_item         = free_item;
        sc->free_item_payload = free_item_payload;
        GIT_REFCOUNT_INC(sc);
        if (pathlen)
                memcpy(sc->path, path, pathlen);
        *out = sc;
        return 0;
fail:
        git_strmap_free(sc->map);
        git_vector_free(&sc->items);
        git_pool_clear(&sc->pool);
        git__free(sc);
        return -1;
}
void git_sortedcache_incref(git_sortedcache *sc)
{
        GIT_REFCOUNT_INC(sc);
}
const char *git_sortedcache_path(git_sortedcache *sc)
{
        return sc->path;
}
static void sortedcache_clear(git_sortedcache *sc)
{
        git_strmap_clear(sc->map);
        if (sc->free_item) {
                size_t i;
                void *item;
                git_vector_foreach(&sc->items, i, item) {
                        sc->free_item(sc->free_item_payload, item);
                }
        }
        git_vector_clear(&sc->items);
        git_pool_clear(&sc->pool);
}
static void sortedcache_free(git_sortedcache *sc)
{
        /* acquire write lock to make sure everyone else is done */
        if (git_sortedcache_wlock(sc) < 0)
                return;
        sortedcache_clear(sc);
        git_vector_free(&sc->items);
        git_strmap_free(sc->map);
        git_sortedcache_wunlock(sc);
        git_rwlock_free(&sc->lock);
        git__free(sc);
}
void git_sortedcache_free(git_sortedcache *sc)
{
        if (!sc)
                return;
        GIT_REFCOUNT_DEC(sc, sortedcache_free);
}
static int sortedcache_copy_item(void *payload, void *tgt_item, void *src_item)
{
        git_sortedcache *sc = payload;
        /* path will already have been copied by upsert */
        memcpy(tgt_item, src_item, sc->item_path_offset);
        return 0;
}
/* copy a sorted cache */
int git_sortedcache_copy(
        git_sortedcache **out,
        git_sortedcache *src,
        bool lock,
        int (*copy_item)(void *payload, void *tgt_item, void *src_item),
        void *payload)
{
        int error = 0;
        git_sortedcache *tgt;
        size_t i;
        void *src_item, *tgt_item;
        /* just use memcpy if no special copy fn is passed in */
        if (!copy_item) {
                copy_item = sortedcache_copy_item;
                payload   = src;
        }
        if ((error = git_sortedcache_new(
                        &tgt, src->item_path_offset,
                        src->free_item, src->free_item_payload,
                        src->items._cmp, src->path)) < 0)
                return error;
        if (lock && git_sortedcache_rlock(src) < 0) {
                git_sortedcache_free(tgt);
                return -1;
        }
        git_vector_foreach(&src->items, i, src_item) {
                char *path = ((char *)src_item) + src->item_path_offset;
                if ((error = git_sortedcache_upsert(&tgt_item, tgt, path)) < 0 ||
                        (error = copy_item(payload, tgt_item, src_item)) < 0)
                        break;
        }
        if (lock)
                git_sortedcache_runlock(src);
        if (error)
                git_sortedcache_free(tgt);
        *out = !error ? tgt : NULL;
        return error;
}
/* lock sortedcache while making modifications */
int git_sortedcache_wlock(git_sortedcache *sc)
{
        GIT_UNUSED(sc); /* prevent warning when compiled w/o threads */
        if (git_rwlock_wrlock(&sc->lock) < 0) {
                giterr_set(GITERR_OS, "Unable to acquire write lock on cache");
                return -1;
        }
        return 0;
}
/* unlock sorted cache when done with modifications */
void git_sortedcache_wunlock(git_sortedcache *sc)
{
        git_vector_sort(&sc->items);
        git_rwlock_wrunlock(&sc->lock);
}
/* lock sortedcache for read */
int git_sortedcache_rlock(git_sortedcache *sc)
{
        GIT_UNUSED(sc); /* prevent warning when compiled w/o threads */
        if (git_rwlock_rdlock(&sc->lock) < 0) {
                giterr_set(GITERR_OS, "Unable to acquire read lock on cache");
                return -1;
        }
        return 0;
}
/* unlock sorted cache when done reading */
void git_sortedcache_runlock(git_sortedcache *sc)
{
        GIT_UNUSED(sc); /* prevent warning when compiled w/o threads */
        git_rwlock_rdunlock(&sc->lock);
}
/* if the file has changed, lock cache and load file contents into buf;
 * returns <0 on error, >0 if file has not changed
 */
int git_sortedcache_lockandload(git_sortedcache *sc, git_buf *buf)
{
        int error, fd;
        if ((error = git_sortedcache_wlock(sc)) < 0)
                return error;
        if ((error = git_futils_filestamp_check(&sc->stamp, sc->path)) <= 0)
                goto unlock;
        if (!git__is_sizet(sc->stamp.size)) {
                giterr_set(GITERR_INVALID, "Unable to load file larger than size_t");
                error = -1;
                goto unlock;
        }
        if ((fd = git_futils_open_ro(sc->path)) < 0) {
                error = fd;
                goto unlock;
        }
        if (buf)
                error = git_futils_readbuffer_fd(buf, fd, (size_t)sc->stamp.size);
        (void)p_close(fd);
        if (error < 0)
                goto unlock;
        return 1; /* return 1 -> file needs reload and was successfully loaded */
unlock:
        git_sortedcache_wunlock(sc);
        return error;
}
void git_sortedcache_updated(git_sortedcache *sc)
{
        /* update filestamp to latest value */
        git_futils_filestamp_check(&sc->stamp, sc->path);
}
/* release all items in sorted cache */
int git_sortedcache_clear(git_sortedcache *sc, bool wlock)
{
        if (wlock && git_sortedcache_wlock(sc) < 0)
                return -1;
        sortedcache_clear(sc);
        if (wlock)
                git_sortedcache_wunlock(sc);
        return 0;
}
/* find and/or insert item, returning pointer to item data */
int git_sortedcache_upsert(void **out, git_sortedcache *sc, const char *key)
{
        int error = 0;
        khiter_t pos;
        void *item;
        size_t keylen, itemlen;
        char *item_key;
        pos = git_strmap_lookup_index(sc->map, key);
        if (git_strmap_valid_index(sc->map, pos)) {
                item = git_strmap_value_at(sc->map, pos);
                goto done;
        }
        keylen  = strlen(key);
        itemlen = sc->item_path_offset + keylen + 1;
        itemlen = (itemlen + 7) & ~7;
        if ((item = git_pool_mallocz(&sc->pool, (uint32_t)itemlen)) == NULL) {
                /* don't use GITERR_CHECK_ALLOC b/c of lock */
                error = -1;
                goto done;
        }
        /* one strange thing is that even if the vector or hash table insert
         * fail, there is no way to free the pool item so we just abandon it
         */
        item_key = ((char *)item) + sc->item_path_offset;
        memcpy(item_key, key, keylen);
        pos = kh_put(str, sc->map, item_key, &error);
        if (error < 0)
                goto done;
        if (!error)
                kh_key(sc->map, pos) = item_key;
        kh_val(sc->map, pos) = item;
        error = git_vector_insert(&sc->items, item);
        if (error < 0)
                git_strmap_delete_at(sc->map, pos);
done:
        if (out)
                *out = !error ? item : NULL;
        return error;
}
/* lookup item by key */
void *git_sortedcache_lookup(const git_sortedcache *sc, const char *key)
{
        khiter_t pos = git_strmap_lookup_index(sc->map, key);
        if (git_strmap_valid_index(sc->map, pos))
                return git_strmap_value_at(sc->map, pos);
        return NULL;
}
/* find out how many items are in the cache */
size_t git_sortedcache_entrycount(const git_sortedcache *sc)
{
        return git_vector_length(&sc->items);
}
/* lookup item by index */
void *git_sortedcache_entry(git_sortedcache *sc, size_t pos)
{
        /* make sure the items are sorted so this gets the correct item */
        if (!git_vector_is_sorted(&sc->items))
                git_vector_sort(&sc->items);
        return git_vector_get(&sc->items, pos);
}
/* helper struct so bsearch callback can know offset + key value for cmp */
struct sortedcache_magic_key {
        size_t offset;
        const char *key;
};
static int sortedcache_magic_cmp(const void *key, const void *value)
{
        const struct sortedcache_magic_key *magic = key;
        const char *value_key = ((const char *)value) + magic->offset;
        return strcmp(magic->key, value_key);
}
/* lookup index of item by key */
int git_sortedcache_lookup_index(
        size_t *out, git_sortedcache *sc, const char *key)
{
        struct sortedcache_magic_key magic;
        magic.offset = sc->item_path_offset;
        magic.key    = key;
        return git_vector_bsearch2(out, &sc->items, sortedcache_magic_cmp, &magic);
}
/* remove entry from cache */
int git_sortedcache_remove(git_sortedcache *sc, size_t pos)
{
        char *item;
        khiter_t mappos;
        /* because of pool allocation, this can't actually remove the item,
         * but we can remove it from the items vector and the hash table.
         */
        if ((item = git_vector_get(&sc->items, pos)) == NULL) {
                giterr_set(GITERR_INVALID, "Removing item out of range");
                return GIT_ENOTFOUND;
        }
        (void)git_vector_remove(&sc->items, pos);
        mappos = git_strmap_lookup_index(sc->map, item + sc->item_path_offset);
        git_strmap_delete_at(sc->map, mappos);
        if (sc->free_item)
                sc->free_item(sc->free_item_payload, item);
        return 0;
}