--[[

DB Tables:

	Prosody - key-value, map

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

	ProsodyArchive - list

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

Mapping:

	Roster - Prosody

		| host | user | "roster" | "contactjid" | item-subkey | type | value |

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

	Account - Prosody

		| host | user | "accounts" | "username" | NULL | 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 json = { stringify = function(s) return require"util.serialization".serialize(s) end, parse = require"util.serialization".deserialize };

local connection = ...;

local host,user,store = module.host;

do -- process options to get a db connection

	local DBI = require "DBI";

	local params = module:get_option("sql") or { driver = "SQLite3", database = "prosody.sqlite" };

	assert(params and params.driver and params.database, "invalid params");

	prosody.unlock_globals();

	local dbh, err = DBI.Connect(

		params.driver, params.database,

		params.username, params.password,

		params.host, params.port

	);

	prosody.lock_globals();

	assert(dbh, err);

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

	connection = dbh;

	if params.driver == "SQLite3" then -- auto initialize

		local ok = assert(stmt:execute());

		local count = stmt:fetch()[1];

		if count == 0 then

			assert(stmt:execute());

			assert(connection:commit());

			module:log("debug", "Initialized new SQLite3 database");

		end

		--print("===", json.stringify())

	end

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.stringify(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.parse(value);

	end

end

local function getsql(sql, ...)

	-- do prepared statement stuff

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

	if not stmt then return nil, err; end

	-- run query

	if not ok then return nil, err; end

	return stmt;

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(...)

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

	return ...;

end

local function commit(...)

	if not connection:commit() then return nil, "SQL commit failed"; end

	return ...;

end

local keyval_store = {};

keyval_store.__index = keyval_store;

function keyval_store:get(username)

	user,store = username,self.store;

	if not stmt then return 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 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 haveany and result or nil;

end

function keyval_store:set(username, data)

	user,store = username,self.store;

	-- start transaction

	if data and next(data) ~= nil then

		local extradata = {};

		for key, value in pairs(data) do

				local t, value = serialize(value);

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

				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

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

		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;

	if not stmt then return nil, err; end

	local haveany;

	local result = {};

	for row in stmt:rows(true) do

		haveany = true;

		local k = row.subkey;

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

		if 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 haveany and result or nil;

end

function map_store:set(username, key, data)

	user,store = username,self.store;

	-- start transaction

	if data and next(data) ~= nil then

		local extradata = {};

		for subkey, value in pairs(data) do

				local t, value = serialize(value);

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

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

			else

				extradata[subkey] = value;

			end

		end

		if next(extradata) ~= nil then

			local t, extradata = serialize(extradata);

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

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

		end

	end

	return commit(true);

end

local list_store = {};

list_store.__index = list_store;

function list_store:scan(username, from, to, jid, typ)

	user,store = username,self.store;

	local cols = {"from", "to", "jid", "typ"};

	local vals = { from ,  to ,  jid ,  typ };

	local stmt, err;

	query = query.." ORDER BY time";

	return nil, "not-implemented"

end

local driver = { name = "sql" };

function driver:open(store, typ)

	if not typ then -- default key-value store

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

	end

	return nil, "unsupported-store";

end

module:add_item("data-driver", driver);