#include <stdlib.h>
#include <string.h>
#include <assert.h>

#include <sqlite3.h>

#include "common.h"
#include "notify.h"
#include "db.h"

static const char db_engine_[] = "sqlite3";

struct prepared_statement {
	const char *statement_name;
	const char *arguments;
	const char *query;
	sqlite3_stmt *statement;
} prepared_statements[] = {
	{ "begin_transaction", "", "BEGIN TRANSACTION", NULL },
	{ "end_transaction", "", "END TRANSACTION", NULL },
	{ "vacuum", "", "VACUUM", NULL },
	{ "uid_from_name", "s", "SELECT uid FROM uid_name WHERE name = ?", NULL },
	{ NULL, NULL, NULL, NULL }
};

enum prepared_statement_enums {
	PS_BEGIN,
	PS_END,
	PS_VACUUM,
	PS_UID_FROM_NAME,
	_NUM_PS_ENUMS
};

/**
 *  pre-prepare all queries used
 */
static int
db_init_all_statements_(sqlite3 *db)
{
	struct prepared_statement *s;
	int r;

	for (s = prepared_statements; s->statement_name; s++) {
		r = sqlite3_prepare_v2(db, s->query, -1, &s->statement, NULL);
		if (r != SQLITE_OK) {
			NOTIFY_ERROR("%s('%s'):%d:%s", "sqlite3_prepare_v2", s->statement_name, r, sqlite3_errmsg(db));
			return -1;
		}
	}

	return 0;
}

/**
 *  finalize all queries used
 */
static void
db_finalize_all_statements_(sqlite3 *db)
{
	struct prepared_statement *s;
	int r;

	for (s = prepared_statements; s->statement_name; s++) {
		if (s->statement) {
			r = sqlite3_finalize(s->statement);
			if (r != SQLITE_OK) {
				NOTIFY_ERROR("%s('%s'):%d:%s", "sqlite3_finalize", s->statement_name, r, sqlite3_errmsg(db));
			}
			s->statement = NULL;
		}
	}
}

const char *
db_engine()
{
	return db_engine_;
}

const char *
db_version()
{
	return sqlite3_libversion();
}


/**
 * 
 */
int
db_init(struct database *db, struct database_options *db_opts)
{
	int r;

	/* Ensure sqlite header matches library. */
	assert(sqlite3_libversion_number() == SQLITE_VERSION_NUMBER);
	assert(strncmp(sqlite3_sourceid(), SQLITE_SOURCE_ID, 80) == 0);
	assert(strcmp(sqlite3_libversion(), SQLITE_VERSION) == 0);

	r = sqlite3_open_v2(db_opts->db_file, &db->db, SQLITE_OPEN_READWRITE, NULL);
	if (r != SQLITE_OK) {
		NOTIFY_ERROR("error opening %s '%s': %s", "db_file", db_opts->db_file, sqlite3_errmsg(db->db));
		return -1;
	}

	if (db_init_all_statements_(db->db)) {
		NOTIFY_ERROR("%s:%s", "db_init_all_statements", "failed");
		return -1;
	}

	return 0;
}

/**
 * 
 */
void
db_fini(struct database *db)
{
	int r;

	db_finalize_all_statements_(db->db);
	r = sqlite3_close(db->db);
	if (r != SQLITE_OK) {
		NOTIFY_ERROR("%s:%s", "sqlite3_close", sqlite3_errmsg(db->db));
	}
	db->db = NULL;
}

/** 
 *  given a string, returns the uid which matches
 */
int
db_uid_from_name(struct database *db, unsigned char *name, int *uid)
{
	struct prepared_statement *ps = &prepared_statements[PS_UID_FROM_NAME];
	int retval = -1;
	int r;

	r = sqlite3_bind_text(ps->statement, 1, (char *)name, -1, SQLITE_TRANSIENT);
	if (r != SQLITE_OK) {
		NOTIFY_ERROR("%s('%s'):%d:%s", "sqlite3_bind_text", name, r, sqlite3_errmsg(db->db));
		return -2;
	}

	do {
		r = sqlite3_step(ps->statement);
		if (r == SQLITE_ROW) {
			if (retval == 0) {
				NOTIFY_ERROR("%s:%s", "internal db error", "multiple uids for name");
			}
			*uid = sqlite3_column_int(ps->statement, 0);
			retval = 0;

			if (*uid == 0) {
				if (SQLITE_INTEGER != sqlite3_column_type(ps->statement, 0)) {
					NOTIFY_ERROR("%s:%s", "internal db error", "uid is not an integer");
					retval = -3;
				}
			}
		}
	} while (r == SQLITE_ROW || r == SQLITE_BUSY);

	if (r != SQLITE_DONE) {
		NOTIFY_ERROR("%s('%s'):%d:%s", "sqlite3_step", name, r, sqlite3_errmsg(db->db));
		retval = -3;
	}

	r = sqlite3_reset(ps->statement);
	if (r != SQLITE_OK) {
		NOTIFY_ERROR("%s('%s'):%d:%s", "sqlite3_reset", name, r, sqlite3_errmsg(db->db));
	}
	r = sqlite3_clear_bindings(ps->statement);
	if (r != SQLITE_OK) {
		NOTIFY_ERROR("%s('%s'):%d:%s", "sqlite3_clear_bindings", name, r, sqlite3_errmsg(db->db));
	}

	return retval;
}