use crate::asm::instr::op::{OpTrait, EvalRes};
use crate::runtime::fault::Fault;
use crate::runtime::frame::{StackFrame};

use crate::builtin::defs::BuiltinOp;
use crate::asm::data::literal::Addr;
use crate::runtime::run_thread::{ThreadInfo, RunState};

impl OpTrait for BuiltinOp {
    fn execute(&self, info: &ThreadInfo, state: &mut RunState) -> Result<EvalRes, Fault> {
        let frame = &mut state.frame;
        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(msg) => {
                return Err(Fault::Barrier {
                    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) => {
                        frame.pc = pos;
                    }
                    Err(e) => {
                        return Err(e);
                    }
                }
            }
            BuiltinOp::Jump(name) => {
                match program.find_local_label(frame.pc, name) {
                    Ok(pos) => {
                        frame.pc = pos;
                    }
                    Err(e) => {
                        return Err(e);
                    }
                }
            }
            BuiltinOp::JumpIf(cond, name) => {
                if frame.status.test(*cond) {
                    match program.find_local_label(frame.pc, name) {
                        Ok(pos) => {
                            frame.pc = pos;
                        }
                        Err(e) => {
                            return Err(e);
                        }
                    }
                }
            }
            BuiltinOp::FarJumpIf(cond, name) => {
                if frame.status.test(*cond) {
                    match program.find_far_label(name) {
                        Ok(pos) => {
                            frame.pc = pos;
                        }
                        Err(e) => {
                            return Err(e);
                        }
                    }
                }
            }
            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(frame.read(*arg)?);
                        }

                        let mut frame2 = StackFrame::new(pos, &values);
                        std::mem::swap(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(frame.read(*arg)?);
                        }
                        *frame = previous;
                        frame.set_retvals(&values);
                    }
                    None => {
                        return Err(Fault::CallStackUnderflow);
                    }
                }
            }
            BuiltinOp::Skip(val) => {
                let steps = frame.read(*val)?;
                res.advance = i64::from_ne_bytes(steps.to_ne_bytes());
                program.validate_jump(frame.pc, Addr((frame.pc.0 as i64 + res.advance) as u64))?;
            }
            BuiltinOp::SkipIf(cond, val) => {
                if frame.status.test(*cond) {
                    debug!("Skipping");
                    let steps = frame.read(*val)?;
                    res.advance = i64::from_ne_bytes(steps.to_ne_bytes());
                    program.validate_jump(frame.pc, Addr((frame.pc.0 as i64 + res.advance) as u64))?;
                }
            }
            BuiltinOp::Move { dst, src } => {
                frame.status.clear();
                let val = frame.read(*src)?;
                frame.status.update(val);
                frame.write(*dst, val)?;
            }
            BuiltinOp::StoreStatus { dst } => {
                let packed = frame.status.store();
                frame.write(*dst, packed)?;
            }
            BuiltinOp::LoadStatus { src } => {
                let x = frame.read(*src)?;
                frame.status.load(x);
            }
        }

        Ok(res)
    }
    //
}