use std::ops::Rem;

use num_traits::PrimInt;

use crsn::asm::instr::Cond;
use crsn::asm::instr::op::{EvalRes, OpTrait};
use crsn::runtime::fault::Fault;
use crsn::runtime::run_thread::{state::RunState, ThreadInfo};

use crate::defs::ArithOp;

impl OpTrait for ArithOp {
    fn execute(&self, _ti: &ThreadInfo, state: &mut RunState) -> Result<EvalRes, Fault> {
        let eres = EvalRes::default();
        match self {
            ArithOp::Test { a } => {
                state.clear_status();
                let res = state.read(*a)?;
                state.update_status(res);
            }
            ArithOp::Compare { a, b } => {
                state.clear_status();
                let x = state.read(*a)?;
                let y = state.read(*b)?;
                state.set_flag(Cond::Equal, x == y);
                state.set_flag(Cond::Lower, x < y);
                state.set_flag(Cond::Greater, x > y);
                // Test flags are set when both arguments have the property
                if x == y {
                    state.update_status(x);
                }
            }
            ArithOp::Add { dst, a, b } => {
                state.clear_status();
                let x = state.read(*a)?;
                let y = state.read(*b)?;
                let (res, ov) = if let Some(v) = x.checked_add(y) {
                    (v, false)
                } else {
                    (x.wrapping_add(y), true)
                };
                state.update_status(res);
                state.set_flag(Cond::Overflow, ov);
                state.write(*dst, res)?;
            }
            ArithOp::Sub { dst, a, b } => {
                state.clear_status();
                let x = state.read(*a)?;
                let y = state.read(*b)?;
                let (res, ov) = if let Some(v) = x.checked_sub(y) {
                    (v, false)
                } else {
                    (x.wrapping_sub(y), true)
                };
                state.update_status(res);
                state.set_flag(Cond::Overflow, ov);
                state.write(*dst, res)?;
            }
            ArithOp::Mul { dst, a, b } => {
                state.clear_status();
                let x = state.read(*a)?;
                let y = state.read(*b)?;
                let (res, ov) = if let Some(v) = x.checked_mul(y) {
                    (v, false)
                } else {
                    (x.wrapping_mul(y), true)
                };
                state.update_status(res);
                state.set_flag(Cond::Overflow, ov);
                state.write(*dst, res)?;
            }
            ArithOp::Div { dst, rem, a, div } => {
                state.clear_status();
                let x = state.read(*a)?;
                let d = state.read(*div)?;
                if d == 0 {
                    state.set_flag(Cond::Invalid, true);
                } else {
                    let (res, remainder, ov) = if let Some(v) = x.checked_div(d) {
                        (v, x.rem(d), false)
                    } else {
                        (x.wrapping_div(d), x.wrapping_rem(d), true)
                    };
                    state.update_status(res);
                    state.set_flag(Cond::Overflow, ov);
                    state.write(*dst, res)?;
                    state.write(*rem, remainder)?;
                }
            }
            ArithOp::Mod { dst, a, div } => {
                state.clear_status();
                let x = state.read(*a)?;
                let d = state.read(*div)?;
                if d == 0 {
                    state.set_flag(Cond::Invalid, true);
                } else {
                    let (remainder, ov) = if let Some(v) = x.checked_rem(d) {
                        (v, false)
                    } else {
                        (x.wrapping_rem(d), true)
                    };
                    state.update_status(remainder);
                    state.set_flag(Cond::Overflow, ov);
                    state.write(*dst, remainder)?;
                }
            }
            ArithOp::And { dst, a, b } => {
                state.clear_status();
                let x = state.read(*a)?;
                let y = state.read(*b)?;
                let res = x & y;
                state.update_status(res);
                state.write(*dst, res)?;
            }
            ArithOp::Or { dst, a, b } => {
                state.clear_status();
                let x = state.read(*a)?;
                let y = state.read(*b)?;
                let res = x | y;
                state.update_status(res);
                state.write(*dst, res)?;
            }
            ArithOp::Xor { dst, a, b } => {
                state.clear_status();
                let x = state.read(*a)?;
                let y = state.read(*b)?;
                let res = x ^ y;
                state.update_status(res);
                state.write(*dst, res)?;
            }
            ArithOp::Cpl { dst, a } => {
                state.clear_status();
                let x = state.read(*a)?;
                let res = !x;
                state.update_status(res);
                state.write(*dst, res)?;
            }
            ArithOp::Rol { dst, a, n } => {
                state.clear_status();
                let x = state.read(*a)?;
                let y = state.read(*n)?;
                if y > u32::MAX as u64 {
                    state.set_flag(Cond::Invalid, true);
                } else {
                    let res = x.rotate_left(y as u32);
                    state.update_status(res);
                    state.write(*dst, res)?;
                }
            }
            ArithOp::Ror { dst, a, n } => {
                state.clear_status();
                let x = state.read(*a)?;
                let y = state.read(*n)?;
                if y > u32::MAX as u64 {
                    state.set_flag(Cond::Invalid, true);
                } else {
                    let res = x.rotate_right(y as u32);
                    state.update_status(res);
                    state.write(*dst, res)?;
                }
            }
            ArithOp::Lsl { dst, a, n } => {
                state.clear_status();
                let x = state.read(*a)?;
                let y = state.read(*n)?;
                let res = x << y;
                state.update_status(res);
                state.write(*dst, res)?;
            }
            ArithOp::Lsr { dst, a, n } => {
                state.clear_status();
                let x = state.read(*a)?;
                let y = state.read(*n)?;
                let res = x >> y;
                state.update_status(res);
                state.write(*dst, res)?;
            }
            ArithOp::Asr { dst, a, n } => {
                state.clear_status();
                let x = state.read(*a)?;
                let y = state.read(*n)?;
                if y > u32::MAX as u64 {
                    state.set_flag(Cond::Invalid, true);
                } else {
                    let res = x.signed_shr(y as u32);
                    state.update_status(res);
                    state.write(*dst, res)?;
                }
            }
        }

        Ok(eres)
    }
    //
}