--[[

DB Tables:

	Prosody - key-value, map

		| host | user | store | key | type | value |

	ProsodyArchive - list

		| host | user | store | key | time | stanzatype | jsonvalue |

Mapping:

	Roster - Prosody

		| host | user | "roster" | "contactjid" | type | value |

		| host | user | "roster" | NULL | "json" | roster[false] data |

	Account - Prosody

		| host | user | "accounts" | "username" | type | value |

	Offline - ProsodyArchive

		| host | user | "offline" | "contactjid" | time | "message" | json|XML |

]]

local type = type;

local tostring = tostring;

local tonumber = tonumber;

local pairs = pairs;

local next = next;

local setmetatable = setmetatable;

local xpcall = xpcall;

local json = require "util.json";

local build_url = require"socket.url".build;

local DBI;

local connection;

local host,user,store = module.host;

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

local dburi;

local connections = module:shared "/*/sql/connection-cache";

local function db2uri(params)

	return build_url{

		scheme = params.driver,

		user = params.username,

		password = params.password,

		host = params.host,

		port = params.port,

		path = params.database,

	};

end

local resolve_relative_path = require "util.paths".resolve_relative_path;

local function test_connection()

	if not connection then return nil; end

	if connection:ping() then

		return true;

	else

		module:log("debug", "Database connection closed");

		connection = nil;

		connections[dburi] = nil;

	end

end

local function connect()

	if not test_connection() then

		prosody.unlock_globals();

		local dbh, err = DBI.Connect(

			params.driver, params.database,

			params.username, params.password,

			params.host, params.port

		);

		prosody.lock_globals();

		if not dbh then

			module:log("debug", "Database connection failed: %s", tostring(err));

			return nil, err;

		end

		module:log("debug", "Successfully connected to database");

		dbh:autocommit(false); -- don't commit automatically

		connection = dbh;

		connections[dburi] = dbh;

	end

	return connection;

end

local function create_table()

	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");

	end

	local stmt, err = connection:prepare(create_sql);

	if stmt then

		local ok = stmt:execute();

		local commit_ok = connection:commit();

		if ok and commit_ok then

			module:log("info", "Initialized new %s database with prosody table", params.driver);

			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 stmt, err = connection:prepare(index_sql);

			local ok, commit_ok, commit_err;

			if stmt then

				ok, err = stmt:execute();

				commit_ok, commit_err = connection:commit();

			end

			if not(ok and commit_ok) then

				module:log("warn", "Failed to create index (%s), lookups may not be optimised", err or commit_err);

			end

		elseif params.driver == "MySQL" then  -- COMPAT: Upgrade tables from 0.8.0

			-- Failed to create, but check existing MySQL table here

			local stmt = connection:prepare("SHOW COLUMNS FROM prosody WHERE Field='value' and Type='text'");

			local ok = stmt:execute();

			local commit_ok = connection:commit();

			if ok and commit_ok then

				if stmt:rowcount() > 0 then

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

					local stmt = connection:prepare("ALTER TABLE prosody MODIFY COLUMN `value` MEDIUMTEXT");

					local ok, err = stmt:execute();

					local commit_ok = connection:commit();

					if ok and commit_ok then

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

					else

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

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

							err or "unknown error");

					end

				end

				repeat until not stmt:fetch();

			end

		end

	elseif params.driver ~= "SQLite3" then -- SQLite normally fails to prepare for existing table

		module:log("warn", "Prosody was not able to automatically check/create the database table (%s), "

			.."see https://prosody.im/doc/modules/mod_storage_sql#table_management for help.",

			err or "unknown error");

	end

end

do -- process options to get a db connection

	local ok;

	prosody.unlock_globals();

	ok, DBI = pcall(require, "DBI");

	if not ok then

		package.loaded["DBI"] = {};

		module:log("error", "Failed to load the LuaDBI library for accessing SQL databases: %s", DBI);

		module:log("error", "More information on installing LuaDBI can be found at https://prosody.im/doc/depends#luadbi");

	end

	prosody.lock_globals();

	if not ok or not DBI.Connect then

		return; -- Halt loading of this module

	end

	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");

	dburi = db2uri(params);

	connection = connections[dburi];

	assert(connect());

	-- 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 function dosql(sql, ...)

	if params.driver == "PostgreSQL" then

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

	end

	-- do prepared statement stuff

	local stmt, err = connection:prepare(sql);

	if not stmt and not test_connection() then error("connection failed"); end

	if not stmt then module:log("error", "QUERY FAILED: %s %s", err, debug.traceback()); return nil, err; end

	-- run query

	local ok, err = stmt:execute(...);

	if not ok and not test_connection() then error("connection failed"); end

	if not ok then return nil, err; end

	return stmt;

end

local function getsql(sql, ...)

	return dosql(sql, host or "", user or "", store or "", ...);

end

local function setsql(sql, ...)

	local stmt, err = getsql(sql, ...);

	if not stmt then return stmt, err; end

	return stmt:affected();

end

local function transact(...)

	-- ...

end

local function rollback(...)

	if connection then connection:rollback(); end -- FIXME check for rollback error?

	return ...;

end

local function commit(...)

	local success,err = connection:commit();

	if not success then return nil, "SQL commit failed: "..tostring(err); end

	return ...;

end

local function keyval_store_get()

	local stmt, err = getsql("SELECT * FROM `prosody` WHERE `host`=? AND `user`=? AND `store`=?");

	if not stmt then return rollback(nil, err); end

	local haveany;

	local result = {};

	for row in stmt:rows(true) do

		haveany = true;

		local k = row.key;

		local v = deserialize(row.type, row.value);

		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

	return commit(haveany and result or nil);

end

local function keyval_store_set(data)

	local affected, err = setsql("DELETE FROM `prosody` WHERE `host`=? AND `user`=? AND `store`=?");

	if not affected then return rollback(affected, err); end

	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);

				if not t then return rollback(t, value); end

				local ok, err = setsql("INSERT INTO `prosody` (`host`,`user`,`store`,`key`,`type`,`value`) VALUES (?,?,?,?,?,?)", key, t, value);

				if not ok then return rollback(ok, err); end

			else

				extradata[key] = value;

			end

		end

		if next(extradata) ~= nil then

			local t, extradata = serialize(extradata);

			if not t then return rollback(t, extradata); end

			local ok, err = setsql("INSERT INTO `prosody` (`host`,`user`,`store`,`key`,`type`,`value`) VALUES (?,?,?,?,?,?)", "", t, extradata);

			if not ok then return rollback(ok, err); end

		end

	end

	return commit(true);

end

local keyval_store = {};

keyval_store.__index = keyval_store;

function keyval_store:get(username)

	user,store = username,self.store;

	if not connection and not connect() then return nil, "Unable to connect to database"; end

	local success, ret, err = xpcall(keyval_store_get, debug.traceback);

	if not connection and connect() then

		success, ret, err = xpcall(keyval_store_get, debug.traceback);

	end

	if success then return ret, err; else return rollback(nil, ret); end

end

function keyval_store:set(username, data)

	user,store = username,self.store;

	if not connection and not connect() then return nil, "Unable to connect to database"; end

	local success, ret, err = xpcall(function() return keyval_store_set(data); end, debug.traceback);

	if not connection and connect() then

		success, ret, err = xpcall(function() return keyval_store_set(data); end, debug.traceback);

	end

	if success then return ret, err; else return rollback(nil, ret); end

end

function keyval_store:users()

	local stmt, err = dosql("SELECT DISTINCT `user` FROM `prosody` WHERE `host`=? AND `store`=?", host, self.store);

	if not stmt then

		return rollback(nil, err);

	end

	local next = stmt:rows();

	return commit(function()

		local row = next();

		return row and row[1];

	end);

end

local function map_store_get(key)

	local stmt, err = getsql("SELECT * FROM `prosody` WHERE `host`=? AND `user`=? AND `store`=? AND `key`=?", key or "");

	if not stmt then return rollback(nil, err); end

	local haveany;

	local result = {};

	for row in stmt:rows(true) do

		haveany = true;

		local k = row.key;

		local v = deserialize(row.type, row.value);

		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

	return commit(haveany and result[key] or nil);

end

local function map_store_set(key, data)

	local affected, err = setsql("DELETE FROM `prosody` WHERE `host`=? AND `user`=? AND `store`=? AND `key`=?", key or "");

	if not affected then return rollback(affected, err); end

	if data and next(data) ~= nil then

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

			local t, value = serialize(data);

			if not t then return rollback(t, value); end

			local ok, err = setsql("INSERT INTO `prosody` (`host`,`user`,`store`,`key`,`type`,`value`) VALUES (?,?,?,?,?,?)", key, t, value);

			if not ok then return rollback(ok, err); end

		else

			-- TODO non-string keys

		end

	end

	return commit(true);

end

local map_store = {};

map_store.__index = map_store;

function map_store:get(username, key)

	user,store = username,self.store;

	local success, ret, err = xpcall(function() return map_store_get(key); end, debug.traceback);

	if success then return ret, err; else return rollback(nil, ret); end

end

function map_store:set(username, key, data)

	user,store = username,self.store;

	local success, ret, err = xpcall(function() return map_store_set(key, data); end, debug.traceback);

	if success then return ret, err; else return rollback(nil, ret); end

end

local list_store = {};

list_store.__index = list_store;