#include <unistd.h>

#include "term.h"
#include "environment.h"


/**
 * Static handles.
 */
#define DEFAULT_CTX_LABEL "urn:lsup:default"


/** @brief Environment "singleton".
 */
LSUP_Env *LSUP_default_env = NULL;


/*
 * Hashmap callbacks.
 */

static uint64_t term_cache_hash_fn (
        const void *item, uint64_t seed0, uint64_t seed1)
{ return ((const LSUP_KeyedTerm *) item)->key; }


static int term_cache_cmp_fn (const void *a, const void *b, void *udata)
{
    return 
            ((const LSUP_KeyedTerm *) a)->key -
            ((const LSUP_KeyedTerm *) b)->key;
}


static void term_cache_free_fn (void *item)
{ LSUP_term_free (((LSUP_KeyedTerm *) item)->term); }


/*
 * API
 */

LSUP_Env *
LSUP_env_new (
        const char *default_ctx, const char *mdb_path,
        const LSUP_NSMap *nsmap)
{
    LSUP_Env *env;
    CALLOC_GUARD (env, NULL);

    // Default store context.
    LSUP_Term *default_ctx_uri = LSUP_iriref_new (default_ctx, NULL);
    env->default_ctx = LSUP_term_serialize (default_ctx_uri);
    LSUP_term_free (default_ctx_uri);
    log_info ("Set up default context.");

    // Set up store if not existing.
    if (LSUP_mdbstore_setup (mdb_path, false) != LSUP_OK) return NULL;
    env->mdb_store = LSUP_mdbstore_new (mdb_path, env->default_ctx);
    if (UNLIKELY (!env->mdb_store)) return NULL;
    log_info ("Initialized persistent back end at %s.", mdb_path);

    // Get default namespace from store.
    RCNL (LSUP_mdbstore_nsm_get (env->mdb_store, &env->nsm));

    return env;
}


LSUP_rc
LSUP_init (void)
{
    LSUP_rc rc = LSUP_NOACTION;

    if (LSUP_env_is_init) return rc;

#ifdef DEBUG
    // In debug mode, always use max logging.
    int loglevel = LOG_TRACE;
#else
    char *_loglevel = getenv ("LSUP_LOGLEVEL");
    int loglevel = (_loglevel == NULL) ? LOG_INFO : atoi (_loglevel);
#endif
    log_set_level (loglevel);

    // URI validation pattern.
    MALLOC_GUARD (LSUP_uri_ptn, LSUP_MEM_ERR);
    /* Uncomment in case a change in the URI regex results in an error.
    int regex_rc = regcomp (LSUP_uri_ptn, LSUP_URI_REGEX_STR, REG_EXTENDED);
    if (regex_rc != 0) {
        char err_msg[128];
        size_t err_msg_sz = regerror (regex_rc, LSUP_uri_ptn, err_msg, 128);
        log_error (
                "Error compiling regular expression pattern: %s.",
                err_msg);
        return LSUP_ERROR;
    }
    */
    if (regcomp (LSUP_uri_ptn, LSUP_URI_REGEX_STR, REG_EXTENDED) != 0) {
        log_error ("Error compiling regular expression pattern.");
        return LSUP_ERROR;
    }

    // Initialize term cache.
    LSUP_term_cache = hashmap_new (
            sizeof(LSUP_KeyedTerm), 0, LSUP_HASH_SEED, 0,
            term_cache_hash_fn, term_cache_cmp_fn, term_cache_free_fn, NULL);
    // Create and cache default literal datatype key.
    LSUP_default_datatype = LSUP_iriref_new (DEFAULT_DTYPE, NULL);
    uint32_t dtype_hash = LSUP_term_hash (LSUP_default_datatype );
    LSUP_tcache_add (dtype_hash, LSUP_default_datatype);

    // Default permanent store path.
    char *mdb_path = getenv ("LSUP_MDB_STORE_PATH");
    if (!mdb_path) {
        mdb_path = DEFAULT_ENV_PATH;
        log_warn (
            "`LSUP_MDB_STORE_PATH' environment variable is not "
            "set. The default location %s will be used as the graph "
            "store.", mdb_path
        );
    }

    // Default permanent store.
    LSUP_default_env = LSUP_env_new (
            DEFAULT_CTX_LABEL, mdb_path, NULL);
    if (UNLIKELY (!LSUP_default_env)) return LSUP_ERROR;

    // RAM disk store.
    if (LSUP_mdbstore_setup (LSUP_MDB_RAMDISK_PATH, true) != LSUP_OK) {
        log_error ("Error setting up RAM disk store files.");
        return LSUP_DB_ERR;
    }

    LSUP_default_env->mdb_store_ramdisk = LSUP_mdbstore_new (
            LSUP_MDB_RAMDISK_PATH, LSUP_default_env->default_ctx);
    if (UNLIKELY (!LSUP_default_env->mdb_store_ramdisk)) {
        log_error ("Error setting up RAM disk store.");
        return LSUP_DB_ERR;
    }

    log_info ("Initialized RAM disk back end at %s.", LSUP_MDB_RAMDISK_PATH);

    // Set automatic teardown TODO Is this a good idea?
    atexit (LSUP_done);

    LSUP_env_is_init = true;

    return LSUP_OK;
}


void
LSUP_env_free (LSUP_Env *env)
{
    LSUP_mdbstore_free (env->mdb_store);
    LSUP_mdbstore_free (env->mdb_store_ramdisk);
    LSUP_buffer_free (env->default_ctx);
    LSUP_nsmap_free (env->nsm);

    free (env);
}


void
LSUP_done (void)
{
    if (!LSUP_env_is_init) return;

    LSUP_env_free (LSUP_default_env);
    regfree (LSUP_uri_ptn);
    free (LSUP_uri_ptn);

    // Free ID cache, including default literal datatype.
    hashmap_free (LSUP_term_cache);

    LSUP_env_is_init = false;
}