-- luacheck: ignore 113/unpack 211 212 411 213

local setmetatable, getmetatable = setmetatable, getmetatable;

local ipairs, unpack, select = ipairs, table.unpack or unpack, select;

local tonumber, tostring = tonumber, tostring;

local assert, xpcall, debug_traceback = assert, xpcall, debug.traceback;

local error = error

local type = type

local t_concat = table.concat;

local t_insert = table.insert;

local s_char = string.char;

local log = require "util.logger".init("sql");

local lsqlite3 = require "lsqlite3";

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

local ROW, DONE = lsqlite3.ROW, lsqlite3.DONE;

local err2str = {

	[0] = "OK";

	"ERROR";

	"INTERNAL";

	"PERM";

	"ABORT";

	"BUSY";

	"LOCKED";

	"NOMEM";

	"READONLY";

	"INTERRUPT";

	"IOERR";

	"CORRUPT";

	"NOTFOUND";

	"FULL";

	"CANTOPEN";

	"PROTOCOL";

	"EMPTY";

	"SCHEMA";

	"TOOBIG";

	"CONSTRAINT";

	"MISMATCH";

	"MISUSE";

	"NOLFS";

	[24] = "FORMAT";

	[25] = "RANGE";

	[26] = "NOTADB";

	[100] = "ROW";

	[101] = "DONE";

};

local assert = function(cond, errno, err)

	return assert(cond, err or err2str[errno]);

end

local _ENV = nil;

-- luacheck: std none

local column_mt = {};

local table_mt = {};

local query_mt = {};

--local op_mt = {};

local index_mt = {};

local function is_column(x) return getmetatable(x)==column_mt; end

local function is_index(x) return getmetatable(x)==index_mt; end

local function is_table(x) return getmetatable(x)==table_mt; end

local function is_query(x) return getmetatable(x)==query_mt; end

local function Integer(n) return "Integer()" end

local function String(n) return "String()" end

local function Column(definition)

	return setmetatable(definition, column_mt);

end

local function Table(definition)

	local c = {}

	for i,col in ipairs(definition) do

		if is_column(col) then

			c[i], c[col.name] = col, col;

		elseif is_index(col) then

			col.table = definition.name;

		end

	end

	return setmetatable({ __table__ = definition, c = c, name = definition.name }, table_mt);

end

local function Index(definition)

	return setmetatable(definition, index_mt);

end

function table_mt:__tostring()

	local s = { 'name="'..self.__table__.name..'"' }

	for i,col in ipairs(self.__table__) do

		s[#s+1] = tostring(col);

	end

	return 'Table{ '..t_concat(s, ", ")..' }'

end

table_mt.__index = {};

function table_mt.__index:create(engine)

	return engine:_create_table(self);

end

function table_mt:__call(...)

	-- TODO

end

function column_mt:__tostring()

	return 'Column{ name="'..self.name..'", type="'..self.type..'" }'

end

function index_mt:__tostring()

	local s = 'Index{ name="'..self.name..'"';

	for i=1,#self do s = s..', "'..self[i]:gsub("[\\\"]", "\\%1")..'"'; end

	return s..' }';

--	return 'Index{ name="'..self.name..'", type="'..self.type..'" }'

end

local function urldecode(s) return s and (s:gsub("%%(%x%x)", function (c) return s_char(tonumber(c,16)); end)); end

local function parse_url(url)

	local scheme, secondpart, database = url:match("^([%w%+]+)://([^/]*)/?(.*)");

	assert(scheme, "Invalid URL format");

	local username, password, host, port;

	local authpart, hostpart = secondpart:match("([^@]+)@([^@+])");

	if not authpart then hostpart = secondpart; end

	if authpart then

		username, password = authpart:match("([^:]*):(.*)");

		username = username or authpart;

		password = password and urldecode(password);

	end

	if hostpart then

		host, port = hostpart:match("([^:]*):(.*)");

		host = host or hostpart;

		port = port and assert(tonumber(port), "Invalid URL format");

	end

	return {

		scheme = scheme:lower();

		username = username; password = password;

		host = host; port = port;

		database = #database > 0 and database or nil;

	};

end

local engine = {};

function engine:connect()

	if self.conn then return true; end

	local params = self.params;

	assert(params.driver == "SQLite3", "Only sqlite3 is supported");

	local dbh, err = lsqlite3.open(params.database);

	if not dbh then return nil, err2str[err]; end

	self.conn = dbh;

	self.prepared = {};

	local ok, err = self:set_encoding();

	if not ok then

		return ok, err;

	end

	local ok, err = self:onconnect();

	if ok == false then

		return ok, err;

	end

	return true;

end

function engine:onconnect()

	-- Override from create_engine()

end

function engine:execute(sql, ...)

	local success, err = self:connect();

	if not success then return success, err; end

	local prepared = self.prepared;

	local stmt = prepared[sql];

	if not stmt then

		local err;

		stmt, err = self.conn:prepare(sql);

		if not stmt then return stmt, err; end

		prepared[sql] = stmt;

	end

	local ret = stmt:bind_values(...);

	if ret ~= lsqlite3.OK then return nil, self.conn:errmsg(); end

	return stmt;

end

local result_mt = {

	__index = {

	affected = function(self) return self.__affected; end;

	rowcount = function(self) return self.__rowcount; end;

	},

};

local function iterator(table)

	local i=0;

	return function()

		i=i+1;

		local item=table[i];

		if item ~= nil then

			return item;

		end

	end

end

local function debugquery(where, sql, ...)

	local i = 0; local a = {...}

	sql = sql:gsub("\n?\t+", " ");

	log("debug", "[%s] %s", where, (sql:gsub("%?", function ()

		i = i + 1;

		local v = a[i];

		if type(v) == "string" then

			v = ("'%s'"):format(v:gsub("'", "''"));

		end

		return tostring(v);

	end)));

end

function engine:execute_query(sql, ...)

	local prepared = self.prepared;

	local stmt = prepared[sql];

	if stmt and stmt:isopen() then

		prepared[sql] = nil; -- Can't be used concurrently

	else

		stmt = assert(self.conn:prepare(sql));

	end

	local ret = stmt:bind_values(...);

	if ret ~= lsqlite3.OK then error(self.conn:errmsg()); end

	local data, ret = {}

	while stmt:step() == ROW do

		t_insert(data, stmt:get_values());

	end

	-- FIXME Error handling, BUSY, ERROR, MISUSE

	if stmt:reset() == lsqlite3.OK then

		prepared[sql] = stmt;

	end

	return setmetatable({ __data = data }, { __index = result_mt.__index, __call = iterator(data) });

end

function engine:execute_update(sql, ...)

	local prepared = self.prepared;

	local stmt = prepared[sql];

	if not stmt or not stmt:isopen() then

		stmt = assert(self.conn:prepare(sql));

	else

		prepared[sql] = nil;

	end

	local ret = stmt:bind_values(...);

	if ret ~= lsqlite3.OK then error(self.conn:errmsg()); end

	local rowcount = 0;

	repeat

		ret = stmt:step();

		if ret == lsqlite3.ROW then

			rowcount = rowcount + 1;

		end

	until ret ~= lsqlite3.ROW;

	local affected = self.conn:changes();

	if stmt:reset() == lsqlite3.OK then

		prepared[sql] = stmt;

	end

	return setmetatable({ __affected = affected, __rowcount = rowcount }, result_mt);

end

engine.insert = engine.execute_update;

engine.select = engine.execute_query;

engine.delete = engine.execute_update;

engine.update = engine.execute_update;

local function debugwrap(name, f)

	return function (self, sql, ...)

		debugquery(name, sql, ...)

		return f(self, sql, ...)

	end

end

function engine:debug(enable)

	self._debug = enable;

	if enable then

		engine.insert = debugwrap("insert", engine.execute_update);

		engine.select = debugwrap("select", engine.execute_query);

		engine.delete = debugwrap("delete", engine.execute_update);

		engine.update = debugwrap("update", engine.execute_update);

	else

		engine.insert = engine.execute_update;

		engine.select = engine.execute_query;

		engine.delete = engine.execute_update;

		engine.update = engine.execute_update;

	end

end

function engine:_(word)

	local ret = self.conn:exec(word);

	if ret ~= lsqlite3.OK then return nil, self.conn:errmsg(); end

	return true;

end

function engine:_transaction(func, ...)

	if not self.conn then

		local a,b = self:connect();

		if not a then return a,b; end

	end

	--assert(not self.__transaction, "Recursive transactions not allowed");

	local ok, err = self:_"BEGIN";

	if not ok then return ok, err; end

	self.__transaction = true;

	local success, a, b, c = xpcall(func, debug_traceback, ...);

	self.__transaction = nil;

	if success then

		log("debug", "SQL transaction success [%s]", tostring(func));

		local ok, err = self:_"COMMIT";

		if not ok then return ok, err; end -- commit failed

		return success, a, b, c;

	else

		log("debug", "SQL transaction failure [%s]: %s", tostring(func), a);

		if self.conn then self:_"ROLLBACK"; end

		return success, a;

	end

end

function engine:transaction(...)

	local ok, ret = self:_transaction(...);

	if not ok then

		local conn = self.conn;

		if not conn or not conn:isopen() then

			self.conn = nil;

			ok, ret = self:_transaction(...);

		end

	end

	return ok, ret;

end

function engine:_create_index(index)

	local sql = "CREATE INDEX IF NOT EXISTS \""..index.name.."\" ON \""..index.table.."\" (";

	for i=1,#index do

		sql = sql.."\""..index[i].."\"";

		if i ~= #index then sql = sql..", "; end

	end

	sql = sql..");"

	if index.unique then

		sql = sql:gsub("^CREATE", "CREATE UNIQUE");

	end

	if self._debug then

		debugquery("create", sql);

	end

	return self:execute(sql);

end

function engine:_create_table(table)

	local sql = "CREATE TABLE IF NOT EXISTS \""..table.name.."\" (";

	for i,col in ipairs(table.c) do

		local col_type = col.type;

		sql = sql.."\""..col.name.."\" "..col_type;

		if col.nullable == false then sql = sql.." NOT NULL"; end

		if col.primary_key == true then sql = sql.." PRIMARY KEY"; end

		if col.auto_increment == true then

			sql = sql.." AUTOINCREMENT";

		end

		if i ~= #table.c then sql = sql..", "; end

	end

	sql = sql.. ");"

	if self._debug then

		debugquery("create", sql);

	end

	local success,err = self:execute(sql);

	if not success then return success,err; end

	for i,v in ipairs(table.__table__) do

		if is_index(v) then

			self:_create_index(v);

		end

	end

	return success;

end

function engine:set_encoding() -- to UTF-8

	return self:transaction(function()

			for encoding in self:select"PRAGMA encoding;" do

				if encoding[1] == "UTF-8" then

				self.charset = "utf8";

			end

		end

	end);

end

local engine_mt = { __index = engine };

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 function create_engine(_, params, onconnect)

	assert(params.driver == "SQLite3", "Only SQLite3 is supported without LuaDBI");

	return setmetatable({ url = db2uri(params), params = params, onconnect = onconnect }, engine_mt);

end