use crsn::asm::data::{Rd, Wr, DataDispEquals};
use crsn::asm::error::CrsnError;
use crsn::asm::instr::op::OpKind;
use crsn::asm::parse::arg_parser::TokenParser;
use crsn::module::ParseRes;
use crsn::sexp::SourcePosition;

use crate::defs::ArithOp;


pub(crate) fn parse<'a>(op_pos: &SourcePosition, keyword: &str, mut args: TokenParser<'a>) -> Result<ParseRes<'a, OpKind>, CrsnError> {
    Ok(ParseRes::ext(match keyword {
        "cmp" => {
            let parsed = ArithOp::Compare { a: args.next_rd()?, b: args.next_rd()? };
            args.ensure_empty("two input arguments")?;
            parsed
        }

        "rcmp" => {
            let parsed = ArithOp::RangeTest { val: args.next_rd()?, a: args.next_rd()?, b: args.next_rd()? };
            args.ensure_empty("3 arguments (value, min, max)")?;
            parsed
        }

        "tst" => {
            let arg = args.next_rd()?;
            args.ensure_empty("1 input argument")?;
            ArithOp::Test { a: arg }
        }

        "rng" => {
            let parsed = match args.len() {
                1 => {
                    ArithOp::Rng {
                        dst: args.next_wr()?,
                        min: Rd::immediate(0),
                        max: Rd::immediate(u64::MAX),
                    }
                }
                2 => {
                    ArithOp::Rng {
                        dst: args.next_wr()?,
                        min: Rd::immediate(0),
                        max: args.next_rd()?,
                    }
                }
                3 => {
                    ArithOp::Rng {
                        dst: args.next_wr()?,
                        min: args.next_rd()?,
                        max: args.next_rd()?,
                    }
                }
                _ => {
                    return Err(CrsnError::Parse("Rng requires 1, 2 or 3 arguments".into(), op_pos.clone()));
                }
            };
            args.ensure_empty("1 (dst) or 3 (dst, min, max) arguments")?;
            parsed
        }

        "inc" => {
            let (dst, a) = args.parse_wr_rd()?;
            ArithOp::Add { dst, a, b: Rd::immediate(1) }
        }

        "dec" => {
            let (dst, a) = args.parse_wr_rd()?;
            ArithOp::Sub { dst, a, b: Rd::immediate(1) }
        }

        "add" => {
            let (dst, a, b) = args.parse_wr_rd_rd()?;
            ArithOp::Add { dst, a, b }
        }

        "sub" => {
            let (dst, a, b) = args.parse_wr_rd_rd()?;
            ArithOp::Sub { dst, a, b }
        }

        "mul" => {
            let (dst, a, b) = args.parse_wr_rd_rd()?;
            ArithOp::Mul { dst, a, b }
        }

        "divr" => {
            match args.len() {
                3 => {
                    let dst = args.next_rdwr()?;
                    let rem = args.next_wr()?;
                    let div = args.next_rd()?;
                    ArithOp::Div {
                        dst: dst.wr(),
                        rem,
                        a: dst.rd(),
                        div,
                    }
                }
                4 => {
                    ArithOp::Div {
                        dst: args.next_wr()?,
                        rem: args.next_wr()?,
                        a: args.next_rd()?,
                        div: args.next_rd()?,
                    }
                }
                _ => {
                    return Err(CrsnError::Parse("DivR requires 3 or 4 arguments".into(), op_pos.clone()));
                }
            }
        }

        "div" => {
            let (dst, a, div) = args.parse_wr_rd_rd()?;
            ArithOp::Div { dst, rem: Wr::discard(), a, div }
        }

        "mod" => {
            let (dst, a, div) = args.parse_wr_rd_rd()?;
            ArithOp::Mod { dst, a, div }
        }

        "and" => {
            let (dst, a, b) = args.parse_wr_rd_rd()?;
            ArithOp::And { dst, a, b }
        }

        "or" => {
            let (dst, a, b) = args.parse_wr_rd_rd()?;
            ArithOp::Or { dst, a, b }
        }

        "xor" => {
            let (dst, a, b) = args.parse_wr_rd_rd()?;
            ArithOp::Xor { dst, a, b }
        }

        "cpl" => {
            let (dst, a) = args.parse_wr_rd()?;
            ArithOp::Cpl { dst, a }
        }

        "rol" => {
            let (dst, a, n) = args.parse_wr_rd_rd_or_n(1)?;
            ArithOp::Rol { dst, a, n }
        }

        "ror" => {
            let (dst, a, n) = args.parse_wr_rd_rd_or_n(1)?;
            ArithOp::Ror { dst, a, n }
        }

        "lsl" | "asl" => {
            let (dst, a, n) = args.parse_wr_rd_rd_or_n(1)?;
            ArithOp::Lsl { dst, a, n }
        }

        "lsr" => {
            let (dst, a, n) = args.parse_wr_rd_rd_or_n(1)?;
            ArithOp::Lsr { dst, a, n }
        }

        "asr" => {
            let (dst, a, n) = args.parse_wr_rd_rd_or_n(1)?;
            ArithOp::Asr { dst, a, n }
        }

        "sw32" => {
            let (dst, src) = args.parse_wr_rd()?;
            ArithOp::Sw32 { dst, src }
        }

        "sw16" => {
            let (dst, src) = args.parse_wr_rd()?;
            ArithOp::Sw16 { dst, src }
        }

        "sw8" => {
            let (dst, src) = args.parse_wr_rd()?;
            ArithOp::Sw8 { dst, src }
        }

        "rev" => {
            let (dst, src) = args.parse_wr_rd()?;
            ArithOp::Rev { dst, src }
        }

        "rbit" => {
            let (dst, src) = args.parse_wr_rd()?;
            ArithOp::Rbit { dst, src }
        }

        other => {
            if let Some((dst, src, mask)) = args.parse_masked_wr_rd(other, "clz")? {
                if !dst.disp_equals(src) && mask.dst_pos != 0 {
                    return Err(CrsnError::Parse(
                        "Invalid offsets - permissible formats are (RW:src_offs) and (Wr Rd:src_offs) ".into(),
                        op_pos.clone()));
                }
                return Ok(ParseRes::ext(ArithOp::Clz {
                    dst,
                    src,
                    mask
                }));
            }

            if let Some((dst, src, mask)) = args.parse_masked_wr_rd(other, "clo")? {
                if !dst.disp_equals(src) && mask.dst_pos != 0 {
                    return Err(CrsnError::Parse(
                        "Invalid offsets - permissible formats are (RW:src_offs) and (Wr Rd:src_offs)".into(),
                        op_pos.clone()));
                }
                return Ok(ParseRes::ext(ArithOp::Clo {
                    dst,
                    src,
                    mask
                }));
            }

            if let Some((dst, src, mask)) = args.parse_masked_wr_rd(other, "se")? {
                if mask.src_pos != 0 || mask.dst_pos != 0 {
                    return Err(CrsnError::Parse(
                        "Offsets do not make sense for SignExtend".into(),
                        op_pos.clone()));
                }
                return Ok(ParseRes::ext(ArithOp::SignExtend {
                    dst,
                    src,
                    mask
                }));
            }

            return Ok(ParseRes::Unknown(args));
        }
    }))
}