const int Database::MAX_BUFFER_SIZE = (
	node::Buffer::kMaxLength > INT_MAX
		? INT_MAX
		: static_cast<int>(node::Buffer::kMaxLength)
);

const int Database::MAX_STRING_SIZE = (
	v8::String::kMaxLength > INT_MAX
		? INT_MAX
		: static_cast<int>(v8::String::kMaxLength)
);

Database::Database(
	v8::Isolate* isolate,
	Addon* addon,
	sqlite3* db_handle,
	v8::Local<v8::Value> logger
) :
	node::ObjectWrap(),
	db_handle(db_handle),
	open(true),
	busy(false),
	safe_ints(false),
	unsafe_mode(false),
	was_js_error(false),
	has_logger(logger->IsFunction()),
	iterators(0),
	addon(addon),
	logger(isolate, logger),
	stmts(),
	backups() {
	assert(db_handle != NULL);
	addon->dbs.insert(this);
}

Database::~Database() {
	if (open) addon->dbs.erase(this);
	CloseHandles();
}

// Whenever this is used, addon->dbs.erase() must be invoked beforehand.
void Database::CloseHandles() {
	if (open) {
		open = false;
		for (Statement* stmt : stmts) stmt->CloseHandles();
		for (Backup* backup : backups) backup->CloseHandles();
		stmts.clear();
		backups.clear();
		int status = sqlite3_close(db_handle);
		assert(status == SQLITE_OK); ((void)status);
	}
}

void Database::ThrowDatabaseError() {
	if (was_js_error) was_js_error = false;
	else ThrowSqliteError(addon, db_handle);
}

void Database::ThrowSqliteError(Addon* addon, sqlite3* db_handle) {
	assert(db_handle != NULL);
	ThrowSqliteError(addon, sqlite3_errmsg(db_handle), sqlite3_extended_errcode(db_handle));
}

void Database::ThrowSqliteError(Addon* addon, const char* message, int code) {
	assert(message != NULL);
	assert((code & 0xff) != SQLITE_OK);
	assert((code & 0xff) != SQLITE_ROW);
	assert((code & 0xff) != SQLITE_DONE);
	EasyIsolate;
	v8::Local<v8::Value> args[2] = {
		StringFromUtf8(isolate, message, -1),
		addon->cs.Code(isolate, code)
	};
	isolate->ThrowException(addon->SqliteError.Get(isolate)
		->NewInstance(OnlyContext, 2, args)
		.ToLocalChecked());
}

// Allows Statements to log their executed SQL.
bool Database::Log(v8::Isolate* isolate, sqlite3_stmt* handle) {
	assert(was_js_error == false);
	if (!has_logger) return false;
	char* expanded = sqlite3_expanded_sql(handle);
	v8::Local<v8::Value> arg = StringFromUtf8(isolate, expanded ? expanded : sqlite3_sql(handle), -1);
	was_js_error = logger.Get(isolate).As<v8::Function>()
		->Call(OnlyContext, v8::Undefined(isolate), 1, &arg)
		.IsEmpty();
	if (expanded) sqlite3_free(expanded);
	return was_js_error;
}

bool Database::Deserialize(
	v8::Local<v8::Object> buffer,
	Addon* addon,
	sqlite3* db_handle,
	bool readonly
) {
	size_t length = node::Buffer::Length(buffer);
	unsigned char* data = (unsigned char*)sqlite3_malloc64(length);
	unsigned int flags = SQLITE_DESERIALIZE_FREEONCLOSE | SQLITE_DESERIALIZE_RESIZEABLE;

	if (readonly) {
		flags |= SQLITE_DESERIALIZE_READONLY;
	}
	if (length) {
		if (!data) {
			ThrowError("Out of memory");
			return false;
		}
		memcpy(data, node::Buffer::Data(buffer), length);
	}

	int status = sqlite3_deserialize(db_handle, "main", data, length, length, flags);
	if (status != SQLITE_OK) {
		ThrowSqliteError(addon, status == SQLITE_ERROR ? "unable to deserialize database" : sqlite3_errstr(status), status);
		return false;
	}

	return true;
}

void Database::FreeSerialization(char* data, void* _) {
	sqlite3_free(data);
}

INIT(Database::Init) {
	v8::Local<v8::FunctionTemplate> t = NewConstructorTemplate(isolate, data, JS_new, "Database");
	SetPrototypeMethod(isolate, data, t, "prepare", JS_prepare);
	SetPrototypeMethod(isolate, data, t, "exec", JS_exec);
	SetPrototypeMethod(isolate, data, t, "backup", JS_backup);
	SetPrototypeMethod(isolate, data, t, "serialize", JS_serialize);
	SetPrototypeMethod(isolate, data, t, "function", JS_function);
	SetPrototypeMethod(isolate, data, t, "aggregate", JS_aggregate);
	SetPrototypeMethod(isolate, data, t, "table", JS_table);
	SetPrototypeMethod(isolate, data, t, "loadExtension", JS_loadExtension);
	SetPrototypeMethod(isolate, data, t, "close", JS_close);
	SetPrototypeMethod(isolate, data, t, "defaultSafeIntegers", JS_defaultSafeIntegers);
	SetPrototypeMethod(isolate, data, t, "unsafeMode", JS_unsafeMode);
	SetPrototypeGetter(isolate, data, t, "open", JS_open);
	SetPrototypeGetter(isolate, data, t, "inTransaction", JS_inTransaction);
	return t->GetFunction(OnlyContext).ToLocalChecked();
}

NODE_METHOD(Database::JS_new) {
	assert(info.IsConstructCall());
	REQUIRE_ARGUMENT_STRING(first, v8::Local<v8::String> filename);
	REQUIRE_ARGUMENT_STRING(second, v8::Local<v8::String> filenameGiven);
	REQUIRE_ARGUMENT_BOOLEAN(third, bool in_memory);
	REQUIRE_ARGUMENT_BOOLEAN(fourth, bool readonly);
	REQUIRE_ARGUMENT_BOOLEAN(fifth, bool must_exist);
	REQUIRE_ARGUMENT_INT32(sixth, int timeout);
	REQUIRE_ARGUMENT_ANY(seventh, v8::Local<v8::Value> logger);
	REQUIRE_ARGUMENT_ANY(eighth, v8::Local<v8::Value> buffer);

	UseAddon;
	UseIsolate;
	sqlite3* db_handle;
	v8::String::Utf8Value utf8(isolate, filename);
	int mask = readonly ? SQLITE_OPEN_READONLY
		: must_exist ? SQLITE_OPEN_READWRITE
		: (SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE);

	if (sqlite3_open_v2(*utf8, &db_handle, mask, NULL) != SQLITE_OK) {
		ThrowSqliteError(addon, db_handle);
		int status = sqlite3_close(db_handle);
		assert(status == SQLITE_OK); ((void)status);
		return;
	}

	assert(sqlite3_db_mutex(db_handle) == NULL);
	sqlite3_extended_result_codes(db_handle, 1);
	sqlite3_busy_timeout(db_handle, timeout);
	sqlite3_limit(db_handle, SQLITE_LIMIT_LENGTH, MAX_BUFFER_SIZE < MAX_STRING_SIZE ? MAX_BUFFER_SIZE : MAX_STRING_SIZE);
	sqlite3_limit(db_handle, SQLITE_LIMIT_SQL_LENGTH, MAX_STRING_SIZE);
	int status = sqlite3_db_config(db_handle, SQLITE_DBCONFIG_ENABLE_LOAD_EXTENSION, 1, NULL);
	assert(status == SQLITE_OK); ((void)status);
	status = sqlite3_db_config(db_handle, SQLITE_DBCONFIG_DEFENSIVE, 1, NULL);
	assert(status == SQLITE_OK); ((void)status);

	if (node::Buffer::HasInstance(buffer) && !Deserialize(buffer.As<v8::Object>(), addon, db_handle, readonly)) {
		int status = sqlite3_close(db_handle);
		assert(status == SQLITE_OK); ((void)status);
		return;
	}

	UseContext;
	Database* db = new Database(isolate, addon, db_handle, logger);
	db->Wrap(info.This());
	SetFrozen(isolate, ctx, info.This(), addon->cs.memory, v8::Boolean::New(isolate, in_memory));
	SetFrozen(isolate, ctx, info.This(), addon->cs.readonly, v8::Boolean::New(isolate, readonly));
	SetFrozen(isolate, ctx, info.This(), addon->cs.name, filenameGiven);

	info.GetReturnValue().Set(info.This());
}

NODE_METHOD(Database::JS_prepare) {
	REQUIRE_ARGUMENT_STRING(first, v8::Local<v8::String> source);
	REQUIRE_ARGUMENT_OBJECT(second, v8::Local<v8::Object> database);
	REQUIRE_ARGUMENT_BOOLEAN(third, bool pragmaMode);
	(void)source;
	(void)database;
	(void)pragmaMode;
	UseAddon;
	UseIsolate;
	v8::Local<v8::Function> c = addon->Statement.Get(isolate);
	addon->privileged_info = &info;
	v8::MaybeLocal<v8::Object> maybeStatement = c->NewInstance(OnlyContext, 0, NULL);
	addon->privileged_info = NULL;
	if (!maybeStatement.IsEmpty()) info.GetReturnValue().Set(maybeStatement.ToLocalChecked());
}

NODE_METHOD(Database::JS_exec) {
	Database* db = Unwrap<Database>(info.This());
	REQUIRE_ARGUMENT_STRING(first, v8::Local<v8::String> source);
	REQUIRE_DATABASE_OPEN(db);
	REQUIRE_DATABASE_NOT_BUSY(db);
	REQUIRE_DATABASE_NO_ITERATORS_UNLESS_UNSAFE(db);
	db->busy = true;

	UseIsolate;
	v8::String::Utf8Value utf8(isolate, source);
	const char* sql = *utf8;
	const char* tail;

	int status;
	const bool has_logger = db->has_logger;
	sqlite3* const db_handle = db->db_handle;
	sqlite3_stmt* handle;

	for (;;) {
		while (IS_SKIPPED(*sql)) ++sql;
		status = sqlite3_prepare_v2(db_handle, sql, -1, &handle, &tail);
		sql = tail;
		if (!handle) break;
		if (has_logger && db->Log(isolate, handle)) {
			sqlite3_finalize(handle);
			status = -1;
			break;
		}
		do status = sqlite3_step(handle);
		while (status == SQLITE_ROW);
		status = sqlite3_finalize(handle);
		if (status != SQLITE_OK) break;
	}

	db->busy = false;
	if (status != SQLITE_OK) {
		db->ThrowDatabaseError();
	}
}

NODE_METHOD(Database::JS_backup) {
	REQUIRE_ARGUMENT_OBJECT(first, v8::Local<v8::Object> database);
	REQUIRE_ARGUMENT_STRING(second, v8::Local<v8::String> attachedName);
	REQUIRE_ARGUMENT_STRING(third, v8::Local<v8::String> destFile);
	REQUIRE_ARGUMENT_BOOLEAN(fourth, bool unlink);
	(void)database;
	(void)attachedName;
	(void)destFile;
	(void)unlink;
	UseAddon;
	UseIsolate;
	v8::Local<v8::Function> c = addon->Backup.Get(isolate);
	addon->privileged_info = &info;
	v8::MaybeLocal<v8::Object> maybeBackup = c->NewInstance(OnlyContext, 0, NULL);
	addon->privileged_info = NULL;
	if (!maybeBackup.IsEmpty()) info.GetReturnValue().Set(maybeBackup.ToLocalChecked());
}

NODE_METHOD(Database::JS_serialize) {
	Database* db = Unwrap<Database>(info.This());
	REQUIRE_ARGUMENT_STRING(first, v8::Local<v8::String> attachedName);
	REQUIRE_DATABASE_OPEN(db);
	REQUIRE_DATABASE_NOT_BUSY(db);
	REQUIRE_DATABASE_NO_ITERATORS(db);

	UseIsolate;
	v8::String::Utf8Value attached_name(isolate, attachedName);
	sqlite3_int64 length = -1;
	unsigned char* data = sqlite3_serialize(db->db_handle, *attached_name, &length, 0);

	if (!data && length) {
		ThrowError("Out of memory");
		return;
	}

	info.GetReturnValue().Set(
		SAFE_NEW_BUFFER(isolate, reinterpret_cast<char*>(data), length, FreeSerialization, NULL).ToLocalChecked()
	);
}

NODE_METHOD(Database::JS_function) {
	Database* db = Unwrap<Database>(info.This());
	REQUIRE_ARGUMENT_FUNCTION(first, v8::Local<v8::Function> fn);
	REQUIRE_ARGUMENT_STRING(second, v8::Local<v8::String> nameString);
	REQUIRE_ARGUMENT_INT32(third, int argc);
	REQUIRE_ARGUMENT_INT32(fourth, int safe_ints);
	REQUIRE_ARGUMENT_BOOLEAN(fifth, bool deterministic);
	REQUIRE_ARGUMENT_BOOLEAN(sixth, bool direct_only);
	REQUIRE_DATABASE_OPEN(db);
	REQUIRE_DATABASE_NOT_BUSY(db);
	REQUIRE_DATABASE_NO_ITERATORS(db);

	UseIsolate;
	v8::String::Utf8Value name(isolate, nameString);
	int mask = SQLITE_UTF8;
	if (deterministic) mask |= SQLITE_DETERMINISTIC;
	if (direct_only) mask |= SQLITE_DIRECTONLY;
	safe_ints = safe_ints < 2 ? safe_ints : static_cast<int>(db->safe_ints);

	if (sqlite3_create_function_v2(db->db_handle, *name, argc, mask, new CustomFunction(isolate, db, *name, fn, safe_ints), CustomFunction::xFunc, NULL, NULL, CustomFunction::xDestroy) != SQLITE_OK) {
		db->ThrowDatabaseError();
	}
}

NODE_METHOD(Database::JS_aggregate) {
	Database* db = Unwrap<Database>(info.This());
	REQUIRE_ARGUMENT_ANY(first, v8::Local<v8::Value> start);
	REQUIRE_ARGUMENT_FUNCTION(second, v8::Local<v8::Function> step);
	REQUIRE_ARGUMENT_ANY(third, v8::Local<v8::Value> inverse);
	REQUIRE_ARGUMENT_ANY(fourth, v8::Local<v8::Value> result);
	REQUIRE_ARGUMENT_STRING(fifth, v8::Local<v8::String> nameString);
	REQUIRE_ARGUMENT_INT32(sixth, int argc);
	REQUIRE_ARGUMENT_INT32(seventh, int safe_ints);
	REQUIRE_ARGUMENT_BOOLEAN(eighth, bool deterministic);
	REQUIRE_ARGUMENT_BOOLEAN(ninth, bool direct_only);
	REQUIRE_DATABASE_OPEN(db);
	REQUIRE_DATABASE_NOT_BUSY(db);
	REQUIRE_DATABASE_NO_ITERATORS(db);

	UseIsolate;
	v8::String::Utf8Value name(isolate, nameString);
	auto xInverse = inverse->IsFunction() ? CustomAggregate::xInverse : NULL;
	auto xValue = xInverse ? CustomAggregate::xValue : NULL;
	int mask = SQLITE_UTF8;
	if (deterministic) mask |= SQLITE_DETERMINISTIC;
	if (direct_only) mask |= SQLITE_DIRECTONLY;
	safe_ints = safe_ints < 2 ? safe_ints : static_cast<int>(db->safe_ints);

	if (sqlite3_create_window_function(db->db_handle, *name, argc, mask, new CustomAggregate(isolate, db, *name, start, step, inverse, result, safe_ints), CustomAggregate::xStep, CustomAggregate::xFinal, xValue, xInverse, CustomAggregate::xDestroy) != SQLITE_OK) {
		db->ThrowDatabaseError();
	}
}

NODE_METHOD(Database::JS_table) {
	Database* db = Unwrap<Database>(info.This());
	REQUIRE_ARGUMENT_FUNCTION(first, v8::Local<v8::Function> factory);
	REQUIRE_ARGUMENT_STRING(second, v8::Local<v8::String> nameString);
	REQUIRE_ARGUMENT_BOOLEAN(third, bool eponymous);
	REQUIRE_DATABASE_OPEN(db);
	REQUIRE_DATABASE_NOT_BUSY(db);
	REQUIRE_DATABASE_NO_ITERATORS(db);

	UseIsolate;
	v8::String::Utf8Value name(isolate, nameString);
	sqlite3_module* module = eponymous ? &CustomTable::EPONYMOUS_MODULE : &CustomTable::MODULE;

	db->busy = true;
	if (sqlite3_create_module_v2(db->db_handle, *name, module, new CustomTable(isolate, db, *name, factory), CustomTable::Destructor) != SQLITE_OK) {
		db->ThrowDatabaseError();
	}
	db->busy = false;
}

NODE_METHOD(Database::JS_loadExtension) {
	Database* db = Unwrap<Database>(info.This());
	v8::Local<v8::String> entryPoint;
	REQUIRE_ARGUMENT_STRING(first, v8::Local<v8::String> filename);
	if (info.Length() > 1) { REQUIRE_ARGUMENT_STRING(second, entryPoint); }
	REQUIRE_DATABASE_OPEN(db);
	REQUIRE_DATABASE_NOT_BUSY(db);
	REQUIRE_DATABASE_NO_ITERATORS(db);
	UseIsolate;
	char* error;
	int status = sqlite3_load_extension(
		db->db_handle,
		*v8::String::Utf8Value(isolate, filename),
		entryPoint.IsEmpty() ? NULL : *v8::String::Utf8Value(isolate, entryPoint),
		&error
	);
	if (status != SQLITE_OK) {
		ThrowSqliteError(db->addon, error, status);
	}
	sqlite3_free(error);
}

NODE_METHOD(Database::JS_close) {
	Database* db = Unwrap<Database>(info.This());
	if (db->open) {
		REQUIRE_DATABASE_NOT_BUSY(db);
		REQUIRE_DATABASE_NO_ITERATORS(db);
		db->addon->dbs.erase(db);
		db->CloseHandles();
	}
}

NODE_METHOD(Database::JS_defaultSafeIntegers) {
	Database* db = Unwrap<Database>(info.This());
	if (info.Length() == 0) db->safe_ints = true;
	else { REQUIRE_ARGUMENT_BOOLEAN(first, db->safe_ints); }
}

NODE_METHOD(Database::JS_unsafeMode) {
	Database* db = Unwrap<Database>(info.This());
	if (info.Length() == 0) db->unsafe_mode = true;
	else { REQUIRE_ARGUMENT_BOOLEAN(first, db->unsafe_mode); }
	sqlite3_db_config(db->db_handle, SQLITE_DBCONFIG_DEFENSIVE, static_cast<int>(!db->unsafe_mode), NULL);
}

NODE_GETTER(Database::JS_open) {
	info.GetReturnValue().Set(Unwrap<Database>(info.This())->open);
}

NODE_GETTER(Database::JS_inTransaction) {
	Database* db = Unwrap<Database>(info.This());
	info.GetReturnValue().Set(db->open && !static_cast<bool>(sqlite3_get_autocommit(db->db_handle)));
}