use std::time::Duration;

use sexp::Sexp;

use crate::asm::data::literal::{Addr, Value};
use crate::builtin::defs::{Barrier, BuiltinOp, LdsValue};
use crate::module::{EvalRes, OpTrait};
use crate::runtime::fault::Fault;
use crate::runtime::frame::StackFrame;
use crate::runtime::run_thread::{state::RunState, ThreadInfo};
use crate::asm::instr::cond::Flag;

impl OpTrait for BuiltinOp {
    fn execute(&self, info: &ThreadInfo, state: &mut RunState) -> Result<EvalRes, Fault> {
        let program = &info.program;
        let mut res = EvalRes::default();
        match self {
            BuiltinOp::Nop => {}
            BuiltinOp::Halt => {
                trace!("HALT - stop execution");
                return Err(Fault::Halt);
            }
            BuiltinOp::Label(_) | BuiltinOp::FarLabel(_) | BuiltinOp::Routine(_) => {
                /* this is nop, but without any cost - just markers */
                res.cycles = 0;
            }
            BuiltinOp::Barrier {
                kind: Barrier::Open(lbl),
                ..
            } => {
                match program.find_far_label(lbl) {
                    Ok(pos) => {
                        res.cycles = 0;
                        state.set_pc(pos);
                    }
                    Err(e) => {
                        return Err(e);
                    }
                }
            }
            BuiltinOp::Barrier {
                msg, ..
            } => {
                return Err(Fault::FaultInstr {
                    msg: msg.clone().unwrap_or_else(|| "BARRIER".into())
                });
            }
            BuiltinOp::Fault(msg) => {
                return Err(Fault::FaultInstr {
                    msg: msg.clone().unwrap_or_else(|| "FAULT".into())
                });
            }
            BuiltinOp::FarJump(name) => {
                match program.find_far_label(name) {
                    Ok(pos) => {
                        state.set_pc(pos);
                    }
                    Err(e) => {
                        return Err(e);
                    }
                }
            }
            BuiltinOp::Jump(_name) => {
                panic!("jump not translated to skip by assembler!");
            }
            BuiltinOp::Call(name, args) => {
                match program.find_routine(&name) {
                    Ok(pos) => {
                        let mut values = Vec::with_capacity(args.len());
                        for arg in args {
                            values.push(state.read(arg)?);
                        }

                        let mut frame2 = StackFrame::new(pos, &values);
                        std::mem::swap(&mut state.frame, &mut frame2);
                        state.call_stack.push(frame2);
                        res.advance = 0;
                    }
                    Err(e) => {
                        return Err(e);
                    }
                }
            }
            BuiltinOp::Ret(retvals) => {
                match state.call_stack.pop() {
                    Some(previous) => {
                        let mut values = Vec::with_capacity(retvals.len());
                        for arg in retvals {
                            values.push(state.read(arg)?);
                        }
                        state.frame = previous;
                        state.frame.set_retvals(&values);
                    }
                    None => {
                        return Err(Fault::CallStackUnderflow);
                    }
                }
            }
            BuiltinOp::Skip(val) => {
                let steps = state.read(val)?;
                res.advance = i64::from_ne_bytes(steps.to_ne_bytes());
                let pc = state.get_pc();
                program.validate_jump(pc, Addr((pc.0 as i64 + res.advance) as u64))?;
            }
            BuiltinOp::Load { dst, src } => {
                state.clear_status();
                let val = state.read(src)?;
                state.update_status(val);
                state.write(dst, val)?;
            }
            BuiltinOp::LoadMultiple { dst, src, count } => {
                state.clear_status();
                let mut count = state.read(count)?;
                let mut last = 0;
                while count > 0 {
                    last = state.read(src)?;
                    state.write(dst, last)?;
                    count -= 1;
                }
                state.update_status(last);
            }
            BuiltinOp::LoadBits { dst, a, b, mask: slice, } => {
                state.clear_status();
                let new = state.read(b)?;
                let old = state.read(a)?;
                let ones : u64 = (1 << slice.width) - 1;
                let val = (old & !(ones << slice.src_pos)) | (((new & (ones << slice.src2_pos)) >> slice.src2_pos) << slice.src_pos);
                state.update_status(val);
                state.write(dst, val)?;
            }
            BuiltinOp::LoadSequence { dst, value } => {
                match value {
                    LdsValue::Values(vals) => {
                        for val in vals {
                            let v = state.read(val)?;
                            state.write(dst, v)?;
                        }
                    }
                    LdsValue::Chars(string) => {
                        for val in string.chars() {
                            state.write(dst, val as Value)?;
                        }
                    }
                    LdsValue::Handle(h) => {
                        let hv = h.read(state)?;

                        let mut found = false;
                        for ex in info.program.extensions.iter() {
                            if ex.read_obj_all(state, *dst, hv)?.is_some() {
                                found = true;
                            }
                        }

                        if !found {
                            warn!("Object {:#x} to read does not exist!", hv);
                            state.set_flag(Flag::Invalid, true);
                        }
                    }
                }
            }
            BuiltinOp::Exchange { a, b, mask: slice } => {
                let aa = state.read(a)?;
                let bb = state.read(b)?;

                if slice.is_full() {
                    state.write(a, bb)?;
                    state.write(b, aa)?;
                } else {
                    let ones: u64 = (1 << slice.width) - 1;
                    let aa2 = (aa & !(ones << slice.dst_pos)) | (((bb & (ones << slice.src_pos)) >> slice.src_pos) << slice.dst_pos);
                    let bb2 = (bb & !(ones << slice.src_pos)) | (((aa & (ones << slice.dst_pos)) >> slice.dst_pos) << slice.src_pos);
                    state.write(a, aa2)?;
                    state.write(b, bb2)?;
                }
            }
            BuiltinOp::StoreFlags { dst } => {
                let packed = state.frame.status.store();
                state.write(dst, packed)?;
            }
            BuiltinOp::LoadFlags { src } => {
                let x = state.read(src)?;
                state.frame.status.load(x);
            }
            BuiltinOp::Sleep { count: micros, unit_us } => {
                std::thread::sleep(Duration::from_micros(state.read(micros)? * unit_us.micros()))
            }
            BuiltinOp::Delete(obj) => {
                let hv = obj.read(state)?;

                trace!("Del object: {:#x}", hv);
                let mut dropped = false;
                for ex in info.program.extensions.iter() {
                    if ex.drop_obj(info, state, hv)?.is_some() {
                        dropped = true;
                    }
                }
                if !dropped {
                    warn!("Object {:#x} to del does not exist!", hv);
                    state.set_flag(Flag::Invalid, true);
                }
            }
        }

        Ok(res)
    }

    fn is_compile_time_evaluable(&self) -> bool {
        match self {
            BuiltinOp::Load { .. } | BuiltinOp::LoadBits { .. } => true,
            _ => false
        }
    }

    fn to_sexp(&self) -> Sexp {
        super::parse::to_sexp(self)
    }
}