use sexp::SourcePosition;

use crate::asm::data::{Rd, RdObj, Wr, RdWr};
use crate::asm::data::literal::{DebugMsg, Label, RoutineName, Value};
use crate::asm::instr::Op;
use crate::asm::instr::op::OpKind;
use std::fmt::{Display, Formatter};
use std::fmt;
use crate::asm::error::CrsnError;


#[derive(Debug)]
pub enum Barrier {
    /// Barrier that logically opens a section that cannot be jumped into, typically a routine
    Open(Label),
    /// Closing counterpart to the Open barrier
    Close(Label),
    /// Stand-alone barrier
    Standalone,
}

#[derive(Copy, Clone, Debug, Eq, PartialEq)]
pub enum SleepUnit {
    Usec, Msec, Sec
}

impl SleepUnit {
    pub fn micros(self) -> u64 {
        match self {
            SleepUnit::Usec => 1,
            SleepUnit::Msec => 1000,
            SleepUnit::Sec => 1000000,
        }
    }
}

#[derive(Clone, Debug, PartialEq)]
pub enum LdsValue {
    Values(Vec<Rd>),
    Handle(RdObj),
    Chars(String),
}

/// Instruction's bit mask
#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub struct BitMask {
    /// Operation bit width
    pub width: u32,
    /// Destination (or first operand's) offset
    pub dst_pos: u32,
    /// Source (or second operand's) offset
    pub src_pos: u32,
    /// Source 2 offset (if used)
    pub src2_pos: u32,
}

impl Display for BitMask {
    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
        if self.is_full() {
            return Ok(());
        }

        write!(f, "{}", self.width)?;
        if self.src_pos != 0 || self.dst_pos != 0 {
            write!(f, "/{}", self.dst_pos)?;
        }
        if self.src_pos != 0 {
            write!(f, "/{}", self.src_pos)?;
        }
        Ok(())
    }
}

impl Default for BitMask {
    fn default() -> Self {
        Self {
            width: 64,
            dst_pos: 0,
            src_pos: 0,
            src2_pos: 0,
        }
    }
}

impl BitMask {
    pub fn full() -> Self {
        Self::default()
    }

    pub fn validate(&self, pos: &SourcePosition) -> Result<(), CrsnError> {
        #[allow(non_snake_case)]
        let MAXWIDTH = (std::mem::size_of::<Value>() as u32)*8;

        if self.width == 0 || self.width > MAXWIDTH {
            return Err(CrsnError::Parse(format!("Bit width must be 1-{}", MAXWIDTH).into(), pos.clone()));
        }

        // Validation
        if self.src_pos + self.width > MAXWIDTH {
            return Err(CrsnError::Parse("Invalid source bit mask".into(), pos.clone()));
        }
        if self.src2_pos + self.width > MAXWIDTH {
            return Err(CrsnError::Parse("Invalid source 2 bit mask".into(), pos.clone()));
        }
        if self.dst_pos + self.width > MAXWIDTH {
            return Err(CrsnError::Parse("Invalid destination bit mask".into(), pos.clone()));
        }

        Ok(())
    }

    pub fn is_full(self) -> bool {
        self.width == 64
    }
}

#[derive(Debug)]
pub enum BuiltinOp {
    /// Do nothing (costs one cycle)
    Nop,
    /// Stop execution
    Halt,
    /// Sleep
    Sleep {
        count: Rd,
        unit_us: SleepUnit,
    },
    /// Mark a jump target.
    Label(Label),
    /// Jump to a label
    Jump(Label),
    /// Mark a far jump target (can be jumped to from another routine).
    /// This label is preserved in optimized code.
    FarLabel(Label),
    /// Jump to a label that can be in another function
    FarJump(Label),
    /// Call a routine with arguments.
    /// The arguments are passed as argX. Return values are stored in resX registers.
    Call(RoutineName, Vec<Rd>),
    /// Exit the current routine with return values
    Ret(Vec<Rd>),
    /// Mark a routine entry point (call target).
    /// The RoutineName struct includes its arity
    Routine(RoutineName),
    /// Skip backward or forward. The skip count can be defined by an argument.
    Skip(Rd),
    /// Deny jumps, skips and run across this address, producing a run-time fault.
    Barrier {
        kind: Barrier,
        msg: Option<DebugMsg>,
    },
    /// Generate a run-time fault with a debugger message
    Fault(Option<DebugMsg>),
    /// Deallocate an extension object.
    /// The object is released and the handle becomes invalid.
    Delete(RdObj),
    /// Move a value
    Load { dst: Wr, src: Rd },
    /// Move bits of a value
    LoadBits { dst: Wr, a: Rd, b: Rd, mask: BitMask },
    /// Move N values
    LoadMultiple { dst: Wr, src: Rd, count: Rd },
    /// Move values from a string or integer list
    LoadSequence { dst: Wr, value: LdsValue },
    /// Swap two registers
    Exchange { a: RdWr, b: RdWr, mask: BitMask },
    /// Swap if equal to a pattern
    CompareSwap { dst: RdWr, expected: Rd, src: Rd, mask: BitMask },
    /// Store runtime status to a register
    StoreFlags { dst: Wr },
    /// Load runtime status from a register
    LoadFlags { src: Rd },
}

impl BuiltinOp {
    pub fn into_op(self: BuiltinOp, pos: SourcePosition) -> Op {
        Op {
            kind: self.into(),
            pos,
            cond: None,
        }
    }
}

impl From<BuiltinOp> for OpKind {
    fn from(bo: BuiltinOp) -> Self {
        OpKind::BuiltIn(bo)
    }
}