local json = require "util.json";

local resolve_relative_path = require "core.configmanager".resolve_relative_path;

local unpack = unpack

local function iterator(result)

	return function(result)

		local row = result();

		if row ~= nil then

			return unpack(row);

		end

	end, result, nil;

end

local mod_sql = module:require("sql");

local params = module:get_option("sql");

local engine; -- TODO create engine

local function create_table()

	--[[local Table,Column,Index = mod_sql.Table,mod_sql.Column,mod_sql.Index;

	local ProsodyTable = Table {

		name="prosody";

		Column { name="host", type="TEXT", nullable=false };

		Column { name="user", type="TEXT", nullable=false };

		Column { name="store", type="TEXT", nullable=false };

		Column { name="key", type="TEXT", nullable=false };

		Column { name="type", type="TEXT", nullable=false };

		Column { name="value", type="TEXT", nullable=false };

		Index { name="prosody_index", "host", "user", "store", "key" };

	};

	engine:transaction(function()

		ProsodyTable:create(engine);

	end);]]

	if not module:get_option("sql_manage_tables", true) then

		return;

	end

	local create_sql = "CREATE TABLE `prosody` (`host` TEXT, `user` TEXT, `store` TEXT, `key` TEXT, `type` TEXT, `value` TEXT);";

	if params.driver == "PostgreSQL" then

		create_sql = create_sql:gsub("`", "\"");

	elseif params.driver == "MySQL" then

		create_sql = create_sql:gsub("`value` TEXT", "`value` MEDIUMTEXT")

			:gsub(";$", " CHARACTER SET 'utf8' COLLATE 'utf8_bin';");

	end

	local index_sql = "CREATE INDEX `prosody_index` ON `prosody` (`host`, `user`, `store`, `key`)";

	if params.driver == "PostgreSQL" then

		index_sql = index_sql:gsub("`", "\"");

	elseif params.driver == "MySQL" then

		index_sql = index_sql:gsub("`([,)])", "`(20)%1");

	end

	local success,err = engine:transaction(function()

		engine:execute(create_sql);

		engine:execute(index_sql);

	end);

	if not success then -- so we failed to create

		if params.driver == "MySQL" then

			success,err = engine:transaction(function()

				local result = engine:execute("SHOW COLUMNS FROM prosody WHERE Field='value' and Type='text'");

				if result:rowcount() > 0 then

					module:log("info", "Upgrading database schema...");

					engine:execute("ALTER TABLE prosody MODIFY COLUMN `value` MEDIUMTEXT");

					module:log("info", "Database table automatically upgraded");

				end

				return true;

			end);

			if not success then

				module:log("error", "Failed to check/upgrade database schema (%s), please see "

					.."http://prosody.im/doc/mysql for help",

					err or "unknown error");

			end

		end

	end

end

local function set_encoding()

	if params.driver ~= "SQLite3" then

		local set_names_query = "SET NAMES 'utf8';";

		if params.driver == "MySQL" then

			set_names_query = set_names_query:gsub(";$", " COLLATE 'utf8_bin';");

		end

		local success,err = engine:transaction(function() return engine:execute(set_names_query); end);

		if not success then

			module:log("error", "Failed to set database connection encoding to UTF8: %s", err);

			return;

		end

		if params.driver == "MySQL" then

			-- COMPAT w/pre-0.9: Upgrade tables to UTF-8 if not already

			local check_encoding_query = "SELECT `COLUMN_NAME`,`COLUMN_TYPE` FROM `information_schema`.`columns` WHERE `TABLE_NAME`='prosody' AND ( `CHARACTER_SET_NAME`!='utf8' OR `COLLATION_NAME`!='utf8_bin' );";

			local success,err = engine:transaction(function()

				local result = engine:execute(check_encoding_query);

				local n_bad_columns = result:rowcount();

				if n_bad_columns > 0 then

					module:log("warn", "Found %d columns in prosody table requiring encoding change, updating now...", n_bad_columns);

					local fix_column_query1 = "ALTER TABLE `prosody` CHANGE `%s` `%s` BLOB;";

					local fix_column_query2 = "ALTER TABLE `prosody` CHANGE `%s` `%s` %s CHARACTER SET 'utf8' COLLATE 'utf8_bin';";

					for row in result:rows() do

						local column_name, column_type = unpack(row);

						engine:execute(fix_column_query1:format(column_name, column_name));

						engine:execute(fix_column_query2:format(column_name, column_name, column_type));

					end

					module:log("info", "Database encoding upgrade complete!");

				end

			end);

			local success,err = engine:transaction(function() return engine:execute(check_encoding_query); end);

			if not success then

				module:log("error", "Failed to check/upgrade database encoding: %s", err or "unknown error");

			end

		end

	end

end

do -- process options to get a db connection

	params = params or { driver = "SQLite3" };

	if params.driver == "SQLite3" then

		params.database = resolve_relative_path(prosody.paths.data or ".", params.database or "prosody.sqlite");

	end

	assert(params.driver and params.database, "Both the SQL driver and the database need to be specified");

	--local dburi = db2uri(params);

	engine = mod_sql:create_engine(params);

	-- Encoding mess

	set_encoding();

	-- Automatically create table, ignore failure (table probably already exists)

	create_table();

end

local function serialize(value)

	local t = type(value);

	if t == "string" or t == "boolean" or t == "number" then

		return t, tostring(value);

	elseif t == "table" then

		local value,err = json.encode(value);

		if value then return "json", value; end

		return nil, err;

	end

	return nil, "Unhandled value type: "..t;

end

local function deserialize(t, value)

	if t == "string" then return value;

	elseif t == "boolean" then

		if value == "true" then return true;

		elseif value == "false" then return false; end

	elseif t == "number" then return tonumber(value);

	elseif t == "json" then

		return json.decode(value);

	end

end

local host = module.host;

local user, store;

local function keyval_store_get()

	local haveany;

	local result = {};

	for row in engine:select("SELECT `key`,`type`,`value` FROM `prosody` WHERE `host`=? AND `user`=? AND `store`=?", host, user or "", store) do

		haveany = true;

		local k = row[1];

		local v = deserialize(row[2], row[3]);

		if k and v then

			if k ~= "" then result[k] = v; elseif type(v) == "table" then

				for a,b in pairs(v) do

					result[a] = b;

				end

			end

		end

	end

	if haveany then

		return result;

	end

end

local function keyval_store_set(data)

	engine:delete("DELETE FROM `prosody` WHERE `host`=? AND `user`=? AND `store`=?", host, user or "", store);

	if data and next(data) ~= nil then

		local extradata = {};

		for key, value in pairs(data) do

			if type(key) == "string" and key ~= "" then

				local t, value = serialize(value);

				assert(t, value);

				engine:insert("INSERT INTO `prosody` (`host`,`user`,`store`,`key`,`type`,`value`) VALUES (?,?,?,?,?,?)", host, user or "", store, key, t, value);

			else

				extradata[key] = value;

			end

		end

		if next(extradata) ~= nil then

			local t, extradata = serialize(extradata);

			assert(t, extradata);

			engine:insert("INSERT INTO `prosody` (`host`,`user`,`store`,`key`,`type`,`value`) VALUES (?,?,?,?,?,?)", host, user or "", store, "", t, extradata);

		end

	end

	return true;

end

local keyval_store = {};

keyval_store.__index = keyval_store;

function keyval_store:get(username)

	user,store = username,self.store;

	return select(2, engine:transaction(keyval_store_get));

end

function keyval_store:set(username, data)

	user,store = username,self.store;

	return engine:transaction(function()

		return keyval_store_set(data);

	end);

end

function keyval_store:users()

	local ok, result = engine:transaction(function()

		return engine:select("SELECT DISTINCT `user` FROM `prosody` WHERE `host`=? AND `store`=?", host, self.store);

	end);

	if not ok then return ok, result end

	return iterator(result);

end

local stores = {

	keyval = keyval_store;

};

local driver = {};

function driver:open(store, typ)

	local store_mt = stores[typ or "keyval"];

	if store_mt then

		return setmetatable({ store = store }, store_mt);

	end

	return nil, "unsupported-store";

end

function driver:stores(username)

	local sql = "SELECT DISTINCT `store` FROM `prosody` WHERE `host`=? AND `user`" ..

		(username == true and "!=?" or "=?");

	if username == true or not username then

		username = "";

	end

	local ok, result = engine:transaction(function()

		return engine:select(sql, host, username);

	end);

	if not ok then return ok, result end

	return iterator(result);

end

function driver:purge(username)

	return engine:transaction(function()

		local stmt,err = engine:delete("DELETE FROM `prosody` WHERE `host`=? AND `user`=?", host, username);

		return true,err;

	end);

end

module:provides("storage", driver);