use crate::ast::*;
use crate::lalrpop::parser::InstructionError;

use lalrpop_util::ErrorRecovery;
use std::rc::Rc;

grammar<'err>(errors: &'err mut Vec<ErrorRecovery<usize, Token<'input>, InstructionError>>);

extern {
    type Error = InstructionError;
}

pub Instr: Box<Instruction<'input>> = {
    "(" "seq" <l:Instr> <r:Instr> ")" => Box::new(Instruction::Seq(Seq(l, r))),
    "(" "par" <l:Instr> <r:Instr> ")" => Box::new(Instruction::Par(Par(l, r))),
    "(" "xor" <l:Instr> <r:Instr> ")" => Box::new(Instruction::Xor(Xor(l, r))),

    "(" "call" <p:PeerPart> <f:FPart> <args:Args> <output:Output> ")" =>
        Box::new(Instruction::Call(Call{peer_part: p, function_part: f, args, output})),

    "(" "fold" <iterable:Alphanumeric> <iterator:Alphanumeric> <i:Instr> ")" => {
        let instruction = Rc::new(*i);
        Box::new(Instruction::Fold(Fold{ iterable, iterator, instruction }))
    },

    "(" "next" <i:Alphanumeric> ")" => Box::new(Instruction::Next(Next(i))),
    "(" "null" ")" => Box::new(Instruction::Null(Null)),
    ! => { errors.push(<>); Box::new(Instruction::Error) },
}

Args: Vec<Value<'input>> = {
    "[" <args:(<Arg>)*> "]" => args
}


FPart: FunctionPart<'input> = {
    <f:Function> => FunctionPart::FuncName(f),
    "(" <sid:ServiceId> <f:Function> ")" => FunctionPart::ServiceIdWithFuncName(sid, f),
}


PeerPart: PeerPart<'input> = {
    <pid:PeerId> => PeerPart::PeerPk(pid),
    "(" <pid:PeerId> <sid:ServiceId> ")" => PeerPart::PeerPkWithServiceId(pid, sid),
}

// TODO: make output one of _ () "" and absence
Output: CallOutput<'input> = {
    <o:Alphanumeric> => CallOutput::Scalar(o),
    <o:ACCUMULATOR> => CallOutput::Accumulator(&o[..o.len()-2]),
};

Function = Value;
PeerId = Value;
ServiceId = Value;
Arg = Value;

Value: Value<'input> = {
    "\"" "\"" => Value::Literal(""), // TODO: signal absence somehow?
    "\"" <v: Alphanumeric> "\"" => Value::Literal(v),
    <v:Alphanumeric> => Value::Variable(v),
    <v:JSON_PATH> => {
        let mut path = v.splitn(2, ".");
        let variable = path.next().expect("must contain dot");
        let path = path.next().expect("contain component after dot");
        Value::JsonPath { variable, path }
    },
    CURRENT_PEER_ID => Value::CurrentPeerId,
}



Alphanumeric = ALPHANUMERIC;

match {
    r"[\w_-]+" => ALPHANUMERIC,
    r"[\w_-]+\[\]" => ACCUMULATOR,
    r#"[\w_-]+\.*\$([\w._-]*(\[[\w"]+\])*)+"# => JSON_PATH,
    r#"%current_peer_id%"# => CURRENT_PEER_ID,
    "seq",
    "call",
    "null",
    "par",
    "xor",
    "fold",
    "next",
} else {
    _
}