-module(store_sql).
%%-author('Daniil Churikov').
%%-author('Max Davidenko').


-include_lib("kvs/include/sql.hrl").
-include_lib("kvs/include/metainfo.hrl").


-export([
  start/0,
  stop/0,
  version/0,
  join/0,
  join/1,
  initialize/0,
  insert/3,
  select_pk/3,
  select/3,
  update_pk/3,
  update_pk_diff/4,
  update/4,
  delete_pk/3,
  delete/3,
  prepare_insert/3,
  prepare_select/3,
  prepare_update/4,
  prepare_delete/3,
  build/1,
  e2l/1,
  skip/3,
  qdata/4,
  returning/3,
  where/2,
  predicate/2,
  op_to_bin/1,
  order_by/1,
  build_return/1,
  build_where/1,
  build_order_by/1,
  predicate_val/1,
  set_predicate_val/2,
  map2/3,
  intersperse/2,
  intersperse2/4,
  put/1,
  sql_put/1,
  get/2,
  sql_get/2,
  proplistToRecord/2,
  convertBindingVal/1,
  mapResult/2,
  extendedQuery/2,
  connection/0
]).


-define(SETTINGS, #sql_settings{placeholder = fun (_, Pos, _) -> PosBin = integer_to_binary(Pos), <<"$", PosBin/binary>> end}).


start() -> ok.
stop() -> ok.

version() -> {version,"KVS SQL 1.0.0"}.
join() -> ok.
join(_) -> ok.
initialize() -> ok.

insert(E, Table, S) ->
    SkipFun = fun(#column{ro = RO}, V) -> RO orelse V == '$skip' end,
    Q = prepare_insert(skip(SkipFun, Table#table.columns, e2l(E)), Table, S),
    if
        Q#query.values /= [] ->
            Query = build(Q),
            BinFold = fun(Elem, Acc) ->
                <<Acc/binary, Elem/binary>>
            end,
            NewBody = lists:foldl(BinFold, <<>>, lists:flatten(Query#query.body)),
            NewVals = lists:map(fun convertBindingVal/1, Query#query.values),
            {ok, Query#query{body = NewBody, values = NewVals}};
        true ->
            {error, empty_insert}
    end.

select_pk(E, Table, S) ->
    SkipFun = fun(#column{key = Key}, _) -> not Key end,
    Q = prepare_select(skip(SkipFun, Table#table.columns, e2l(E)), Table, S),
    if
        Q#query.values /= [] ->
            Query = build(Q),
            BinFold = fun(Elem, Acc) ->
                <<Acc/binary, Elem/binary>>
            end,
            NewBody = lists:foldl(BinFold, <<>>, lists:flatten(Query#query.body)),
            NewVals = lists:map(fun convertBindingVal/1, Query#query.values),
            {ok, Query#query{body = NewBody, values = NewVals}};
    true -> {error, pk_miss} end.

select(E, Table, S) ->
    SkipFun = fun(_, V) -> V == '$skip' end,
    Query = build(prepare_select(skip(SkipFun, Table#table.columns, e2l(E)), Table, S)),
    BinFold = fun(Elem, Acc) ->
        <<Acc/binary, Elem/binary>>
    end,
    NewBody = lists:foldl(BinFold, <<>>, lists:flatten(Query#query.body)),
    NewVals = lists:map(fun convertBindingVal/1, Query#query.values),
    {ok, Query#query{body = NewBody, values = NewVals}}.

update_pk(E, Table = #table{columns = MekaoCols}, S) ->
    SetSkipFun = fun(#column{ro = RO}, V) -> RO orelse V == '$skip' end,
    WhereSkipFun = fun(#column{key = Key}, _) -> not Key end,
    Vals = e2l(E),
    Q = prepare_update(skip(SetSkipFun, MekaoCols, Vals),
                       skip(WhereSkipFun, MekaoCols, Vals),Table, S),
    if (Q#query.body)#sql_update.set == [] -> {error, empty_update};
       (Q#query.body)#sql_update.where == [] -> {error, pk_miss};
       true ->
           Query = build(Q),
           BinFold = fun(Elem, Acc) ->
               <<Acc/binary, Elem/binary>>
           end,
           NewBody = lists:foldl(BinFold, <<>>, lists:flatten(Query#query.body)),
           NewVals = lists:map(fun convertBindingVal/1, Query#query.values),
           {ok, Query#query{body = NewBody, values = NewVals}}
    end.

update_pk_diff(E1, E2, Table = #table{columns = MekaoCols}, S) ->
    Vals1 = e2l(E1),
    Vals2 = e2l(E2),
    DiffVals = map2(
        fun (V, V) -> '$skip';
            (_, V2) -> V2 end, Vals1, Vals2),
    SetSkipFun = fun(#column{ro = RO}, V) -> RO orelse V == '$skip' end,
    WhereSkipFun = fun(#column{key = Key}, _) -> not Key end,
    Q = prepare_update(skip(SetSkipFun, MekaoCols, DiffVals),
                       skip(WhereSkipFun, MekaoCols, Vals1),Table, S),
    if (Q#query.body)#sql_update.set == [] -> {error, empty_update};
       (Q#query.body)#sql_update.where == [] -> {error, pk_miss};
        true ->
            Query = build(Q),
            BinFold = fun(Elem, Acc) ->
                <<Acc/binary, Elem/binary>>
            end,
            NewBody = lists:foldl(BinFold, <<>>, lists:flatten(Query#query.body)),
            NewVals = lists:map(fun convertBindingVal/1, Query#query.values),
            {ok, Query#query{body = NewBody, values = NewVals}}
    end.

update(E, Selector, Table = #table{columns = MekaoCols}, S) ->
    SetSkipFun = fun(#column{ro = RO}, V) -> RO orelse V == '$skip' end,
    WhereSkipFun = fun(_, V) -> V == '$skip' end,
    Q = prepare_update(skip(SetSkipFun, MekaoCols, e2l(E)),
                       skip(WhereSkipFun, MekaoCols, e2l(Selector)),Table, S),
    if (Q#query.body)#sql_update.set == [] -> {error, empty_update};
        true ->
            Query = build(Q),
            BinFold = fun(Elem, Acc) ->
                <<Acc/binary, Elem/binary>>
            end,
            NewBody = lists:foldl(BinFold, <<>>, lists:flatten(Query#query.body)),
            NewVals = lists:map(fun convertBindingVal/1, Query#query.values),
            {ok, Query#query{body = NewBody, values = NewVals}}
    end.

delete_pk(E, Table, S) ->
    SkipFun = fun(#column{key = Key}, _) -> not Key end,
    Q = prepare_delete(skip(SkipFun, Table#table.columns, e2l(E)), Table, S),
    if Q#query.values /= [] ->
        Query = build(Q),
        BinFold = fun(Elem, Acc) ->
            <<Acc/binary, Elem/binary>>
        end,
        NewBody = lists:foldl(BinFold, <<>>, lists:flatten(Query#query.body)),
        NewVals = lists:map(fun convertBindingVal/1, Query#query.values),
        {ok, Query#query{body = NewBody, values = NewVals}};
       true -> {error, pk_miss} end.

delete(Selector, Table, S) ->
    SkipFun = fun(_, V) -> V == '$skip' end,
    Q = prepare_delete(skip(SkipFun, Table#table.columns, e2l(Selector)), Table, S),
    Query = build(Q),
    BinFold = fun(Elem, Acc) ->
        <<Acc/binary, Elem/binary>>
    end,
    NewBody = lists:foldl(BinFold, <<>>, lists:flatten(Query#query.body)),
    NewVals = lists:map(fun convertBindingVal/1, Query#query.values),
    {ok, Query#query{body = NewBody, values = NewVals}}.

prepare_insert(E, Table, S) ->
    {Cols, PHs, Types, Vals} = qdata(1, e2l(E), Table#table.columns, S),
    Q = #sql_insert{table=atom_to_binary(Table#table.name, utf8),columns=intersperse(Cols, <<", ">>),
                   values=intersperse(PHs, <<", ">>),returning=returning(insert, Table, S)},
    #query{body=Q,types=Types,values=Vals,next_ph_num=length(PHs) + 1}.

prepare_select(E, Table, S) ->
    #table{columns = MekaoCols,order_by = OrderBy} = Table,
    {Where, {_, PHs, Types, Vals}} = where(qdata(1, e2l(E), MekaoCols, S), S),
    AllCols = intersperse(MekaoCols, <<", ">>, fun(#column{name = Name}) -> Name end),
    Q = #sql_select{table=atom_to_binary(Table#table.name, utf8),columns=AllCols,where=Where,order_by=order_by(OrderBy)},
    #query{body=Q,types=Types,values=Vals,next_ph_num = length(PHs) + 1}.

prepare_update(SetE, WhereE, Table = #table{columns = MekaoCols}, S) ->
    {SetCols, SetPHs, SetTypes, SetVals} = qdata(1, e2l(SetE), MekaoCols, S),
    SetPHsLen = length(SetPHs),
    {Where, {_, WherePHs, WhereTypes, WhereVals}} = where(qdata(SetPHsLen + 1, e2l(WhereE), MekaoCols, S), S),
    WherePHsLen = length(WherePHs),
    Set = intersperse2(fun (C, PH) -> [C, <<" = ">>, PH] end,<<", ">>, SetCols, SetPHs),
    Q = #sql_update{table=atom_to_binary(Table#table.name, utf8),set=Set,where=Where,returning=returning(update, Table, S)},
    #query{body=Q,types=SetTypes++WhereTypes,values=SetVals++WhereVals,next_ph_num = SetPHsLen + WherePHsLen + 1}.

prepare_delete(E, Table, S) ->
    {Where, {_, PHs, Types, Vals}} = where(qdata(1, e2l(E), Table#table.columns, S), S),
    Q = #sql_delete{table=atom_to_binary(Table#table.name, utf8),where=Where,returning=returning(delete, Table, S)},
    #query{body=Q,types=Types,values=Vals,next_ph_num = length(PHs) + 1}.

build(Q = #query{body = Select}) when is_record(Select, sql_select) ->
    #sql_select{columns=Columns,table=Table,where=Where,order_by=OrderBy} = Select,
    Q#query{body = [<<"SELECT ">>, Columns, <<" FROM ">>, Table, build_where(Where),build_order_by(OrderBy)]};
build(Q = #query{body = Insert}) when is_record(Insert, sql_insert) ->
    #sql_insert{table=Table,columns=Columns,values=Values,returning=Return} = Insert,
    Q#query{body = [<<"INSERT INTO ">>, Table, <<" (">>, Columns, <<") VALUES (">>,Values, <<")">>, build_return(Return)]};
build(Q = #query{body = Update}) when is_record(Update, sql_update) ->
    #sql_update{table=Table,set=Set,where=Where,returning=Return} = Update,
    Q#query{body = [<<"UPDATE ">>, Table, <<" SET ">>, Set,build_where(Where), build_return(Return)]};
build(Q = #query{body = Delete}) when is_record(Delete, sql_delete) ->
    #sql_delete{table=Table,where=Where,returning=Return} = Delete,
    Q#query{body = [<<"DELETE FROM ">>, Table, build_where(Where),build_return(Return)]}.

e2l(Vals) when is_list(Vals) -> Vals;
e2l(E) when is_tuple(E) -> [_EntityName | Vals] = tuple_to_list(E), Vals.

skip(SkipFun, Cols, Vals) -> map2(fun(C, V) -> Skip = SkipFun(C, V),if Skip -> '$skip'; true -> V end end, Cols, Vals).

qdata(_, [], [], _) -> {[], [], [], []};
qdata(Num, ['$skip' | Vals], [_Col | Cols], S) -> qdata(Num, Vals, Cols, S);
qdata(Num, [Pred | Vals], [Col | Cols], S) ->
    #column{type = T, name = CName, transform = TrFun} = Col,
    V = predicate_val(Pred),
    NewV = if TrFun == undefined -> V;
                            true -> TrFun(V) end,
    PH = (S#sql_settings.placeholder)(Col, Num, NewV),
    NewPred = set_predicate_val(Pred, NewV), {ResCols, ResPHs, ResTypes, ResVals} = qdata(Num + 1, Vals, Cols, S),
    {[CName | ResCols], [PH | ResPHs], [T | ResTypes], [NewPred | ResVals]}.

returning(_QType, _Table, #sql_settings{returning = undefined}) -> [];
returning(QType, Table, #sql_settings{returning = RetFun}) -> RetFun(QType, Table).

where(QData = {[], [], [], []}, _S) -> {[], QData};
where({[C], [PH], [T], [V]}, S) ->
    {W, {NewC, NewPH, NewT, NewV}} = predicate({C, PH, T, V}, S),
    {[W], {[NewC], [NewPH], [NewT], [NewV]}};
where({[C | Cs], [PH | PHs], [T | Types], [V | Vals]}, S) ->
    {W, {NewC, NewPH, NewT, NewV}} = predicate({C, PH, T, V}, S),
    {Ws, {NewCs, NewPHs, NewTypes, NewVals}} = where({Cs, PHs, Types, Vals}, S),
    {[W, <<" AND ">> | Ws], {[NewC | NewCs], [NewPH | NewPHs], [NewT | NewTypes], [NewV | NewVals]}}.

%% TODO: add NOT, IN, ANY, ALL, BETWEEN, LIKE handling
predicate({C, PH, T, {'$predicate', Op, V}}, S) when Op == '='; Op == '<>' ->
    IsNull = (S#sql_settings.is_null)(V),
    if not IsNull -> {[C, op_to_bin(Op), PH], {C, PH, T, V}};
    Op == '=' -> {[C, <<" IS NULL">>], {C, PH, T, V}};
    Op == '<>' -> {[C, <<" IS NOT NULL">>], {C, PH, T, V}} end;
predicate({C, PH, T, {'$predicate', OP, V}},  _S) -> {[C, op_to_bin(OP), PH],  {C, PH, T, V}};
predicate({C, PH, T, V}, S) -> predicate({C, PH, T, {'$predicate', '=', V}}, S).

op_to_bin('=')  -> <<" = ">>;
op_to_bin('<>') -> <<" <> ">>;
op_to_bin('>')  -> <<" > ">>;
op_to_bin('>=') -> <<" >= ">>;
op_to_bin('<')  -> <<" < ">>;
op_to_bin('<=') -> <<" <= ">>.

order_by(undefined) -> [];
order_by([]) -> [];
order_by([O]) -> [order_by_1(O)];
order_by([O | OrderBy]) -> [order_by_1(O), <<", ">> | order_by(OrderBy)].
order_by_1(E) when not is_tuple(E) -> order_by_1({E, {default, default}});
order_by_1({Pos, Opts}) when is_integer(Pos) -> order_by_1({integer_to_list(Pos - 1), Opts});
order_by_1({Expr, Opts}) when is_list(Expr); is_binary(Expr) -> [Expr, order_by_opts(Opts)].
order_by_opts({Ordering, Nulls}) ->
    O = case Ordering of
        default -> <<"">>;
        asc -> <<" ASC">>;
        desc -> <<" DESC">> end,
    case Nulls of
        default -> O;
        nulls_first -> <<O/binary," NULLS FIRST">>;
        nulls_last -> <<O/binary, " NULLS LAST">> end.

build_return([]) -> <<>>;
build_return(Return) -> [<<" ">> | Return].
build_where([]) -> <<>>;
build_where(Where) -> [<<" WHERE ">> | Where].
build_order_by([]) -> <<>>;
build_order_by(OrderBy) -> [<<" ORDER BY ">>, OrderBy].

predicate_val({'$predicate', _, V}) -> V;
predicate_val(V) -> V.

set_predicate_val({'$predicate', Op, _}, NewV) -> {'$predicate', Op, NewV};
set_predicate_val(_, NewV) -> NewV.

map2(_Fun, [], []) -> [];
map2(Fun, [V1 | L1], [V2 | L2]) -> [Fun(V1, V2) | map2(Fun, L1, L2)].

intersperse(List, Sep) -> intersperse(List, Sep, fun (X) -> X end).
intersperse([], _, _) -> [];
intersperse([Item], _, Fun) -> [Fun(Item)];
intersperse([Item | Items], Sep, Fun) -> [Fun(Item), Sep | intersperse(Items, Sep, Fun)].

intersperse2(_Fun, _Sep, [], []) -> [];
intersperse2(Fun, _Sep, [I1], [I2]) -> [Fun(I1, I2)];
intersperse2(Fun, Sep, [I1 | I1s], [I2 | I2s]) -> [Fun(I1, I2), Sep | intersperse2(Fun, Sep, I1s, I2s)].

put(Records) when is_list(Records) -> lists:foreach(fun sql_put/1, Records);
put(Record) -> sql_put(Record).

sql_put(Record) ->
    Table = kvs:table(element(1, Record)),
    io:format("Trying to put ~p ~n", [Record]),
    {ok, Query} = insert(Record, Table, ?SETTINGS),
    io:format("Query [~p], vals [~p] ~n", [Query#query.body, Query#query.values]),
    PutRes = extendedQuery(Query#query.body, Query#query.values),
    case PutRes of
        {ok, _} -> ok;
        _ -> PutRes end.

get(Table, Key) ->
    io:format("Trying to get from ~p by ~p ~n", [Table, Key]),
    TableSpec = kvs:table(Table),
    SkipVals = lists:duplicate(length(TableSpec#table.fields) - 1, '$skip'),
    RecList = [Table | [Key | SkipVals]],
    Record = list_to_tuple(RecList),
    sql_get(TableSpec, Record).

sql_get(TableSpec, Record) ->
    io:format("Record is: ~p ~n", [Record]),
    {ok, Query} = select(Record, TableSpec, ?SETTINGS),
    io:format("Query is: ~p ~n", [Query#query.body]),
    QueryRes = extendedQuery(Query#query.body, Query#query.values),
    case QueryRes of
        {ok, []} -> {error, not_found};
        {ok, Rows} -> [Row | _] = Rows, {ok, proplistToRecord(element(1, Record), Row)};
        {ok, _Count, Rows} -> [Row | _] = Rows,{ok, proplistToRecord(element(1, Record), Row)};
        _ -> QueryRes end.

proplistToRecord(Tag, Proplist) ->
    ValsExt = fun(Elem) ->
        {_, Val} = Elem,
        Val
    end,
    Vals = lists:map(ValsExt, Proplist),
    RecList = [Tag | Vals],
    list_to_tuple(RecList).

convertBindingVal(Val) when is_integer(Val) -> Val;
convertBindingVal(Val) when is_float(Val) -> Val;
convertBindingVal(Val) -> term_to_binary(Val).

mapResult([], _Rows) -> [];
mapResult(_Columns, []) -> [];
mapResult(Columns, Rows) ->
  ColumnsExtractor = fun(Elem) -> Elem#column.name end,
  ColsNames = lists:map(ColumnsExtractor, Columns),
  ResultsMapper = fun(Row) -> lists:zip(ColsNames, tuple_to_list(Row)) end,
  lists:map(ResultsMapper, Rows).

extendedQuery(SQL, Params) ->
  QueryRes = case Params of
    [] -> pgsql:equery(connection(), SQL);
     _ -> pgsql:equery(connection(), SQL, Params) end,
  _Reply = case QueryRes of
    {ok, Columns, Rows} -> {ok, mapResult(Columns, Rows)};
    {ok, Count, Columns, Rows} -> {ok, Count, mapResult(Columns, Rows)};
    _ -> QueryRes end.

connection() ->
  case wf:cache(pgsql_conn) of
       unefined ->  Host = kvs:config(pgsql,host,"localhost"),
                    Port = kvs:config(pgsql,port, 5432),
                    User = kvs:config(pgsql,user, "user"),
                    Pass = kvs:config(pgsql,pass, "pass"),
                    Db   = kvs:config(pgsql,db, "test"),
                    Timeout = kvs:config(pgsql,timeout,5000),
                    {ok, Conn} = pgsql:connect(Host, User, Pass,
                              [{database, Db}, {port, Port}, {timeout, Timeout}]),
                    wf:cache(pgsql_conn,Conn),
                    Conn;
      Connection -> Connection end.