use crsn::asm::data::literal::Value;
use crsn::asm::error::Error;
use crsn::asm::instr::Op;
use crsn::asm::parse::arg_parser::ArgParser;
use crsn::module::{CrsnExtension, ParseOpRes};
use crsn::runtime::fault::Fault;
use crsn::runtime::run_thread::{RunState, ThreadInfo};

use crate::defs::StackOp;

#[derive(Debug, Clone)]
pub struct StackOps {
    _internal: ()
}

impl StackOps {
    pub fn new() -> Box<dyn CrsnExtension> {
        Box::new(Self {
            _internal: ()
        })
    }
}

impl CrsnExtension for StackOps {
    fn name(&self) -> &'static str {
        "stacks"
    }

    fn parse_op(&self, keyword: &str, mut args: ArgParser) -> Result<ParseOpRes<Op>, Error> {
        Ok(ParseOpRes::parsed(match keyword {
            "stack" => {
                StackOp::NewStack {
                    dst: args.next_wr()?,
                }
            }

            "push" => {
                StackOp::Push {
                    obj: args.next_rdobj()?,
                    src: args.next_rd()?,
                }
            }

            "pop" => {
                StackOp::Pop {
                    dst: args.next_wr()?,
                    obj: args.next_rdobj()?,
                }
            }

            _other => {
                return Ok(ParseOpRes::Unknown(args));
            }
        }))
    }

    fn drop_obj(&self, _ti: &ThreadInfo, state: &mut RunState, handle: Value) -> Result<Option<()>, Fault>
    {
        crate::exec::drop_stack(state, handle)
    }
}