use std::convert::TryFrom;
use std::fmt::{Debug, Display, Formatter};
use std::fmt;

pub use rd::Rd;
pub use rd::RdObj;
pub use reg::Register;
pub use wr::Wr;
pub use rdwr::RdWr;

use crate::asm::data::literal::{as_signed, is_negative, Value};

use super::error::AsmError;

pub mod literal;
pub mod reg;

mod rd;
mod wr;
mod rdwr;

/// Data source disposition
#[derive(Debug, Clone, Copy, Eq, PartialEq)]
pub enum DataDisp {
    /// Constant value
    Immediate(Value),
    /// Object pointer with immediate value
    ImmObject(Value),
    /// Register
    Register(Register),
    /// Object pointer in register
    RegObject(Register),
    /// Discard the written value
    Discard,
}

impl Display for DataDisp {
    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
        match self {
            DataDisp::Immediate(v) => {
                write!(f, "{}", as_signed(*v))
            }
            DataDisp::Register(r) => {
                write!(f, "{}", r)
            }
            DataDisp::RegObject(r) => {
                write!(f, "@{}", r)
            }
            DataDisp::ImmObject(r) => {
                write!(f, "@{:#x}", r)
            }
            DataDisp::Discard => {
                write!(f, "_")
            }
        }
    }
}

impl From<RdData> for DataDisp {
    fn from(s: RdData) -> Self {
        match s {
            RdData::Immediate(x) => DataDisp::Immediate(x),
            RdData::Register(x) => DataDisp::Register(x),
            RdData::RegObject(x) => DataDisp::RegObject(x),
            RdData::ImmObject(x) => DataDisp::ImmObject(x),
        }
    }
}

impl From<WrData> for DataDisp {
    fn from(s: WrData) -> Self {
        match s {
            WrData::Register(x) => DataDisp::Register(x),
            WrData::RegObject(x) => DataDisp::RegObject(x),
            WrData::ImmObject(x) => DataDisp::ImmObject(x),
            WrData::Discard => DataDisp::Discard,
        }
    }
}

impl From<Rd> for DataDisp {
    fn from(s: Rd) -> Self {
        s.0.into()
    }
}

impl From<Wr> for DataDisp {
    fn from(s: Wr) -> Self {
        s.0.into()
    }
}

impl From<RdWr> for DataDisp {
    fn from(s: RdWr) -> Self {
        s.0.into()
    }
}

impl From<&Rd> for DataDisp {
    fn from(s: &Rd) -> Self {
        s.0.into()
    }
}

impl From<&Wr> for DataDisp {
    fn from(s: &Wr) -> Self {
        s.0.into()
    }
}

impl From<&RdWr> for DataDisp {
    fn from(s: &RdWr) -> Self {
        s.0.into()
    }
}

pub trait DataDispEquals : Into<DataDisp> {
    fn disp_equals<T : Into<DataDisp>>(self, other : T) -> bool;
}

impl<T : Into<DataDisp>> DataDispEquals for T {
    fn disp_equals<X : Into<DataDisp>>(self, other : X) -> bool {
        self.into() == other.into()
    }
}

/// Data source disposition
#[derive(Debug, Clone, Copy, Eq, PartialEq)]
pub enum RdData {
    /// Constant value
    Immediate(Value),
    /// Pointer into memory, address immediate
    ImmObject(Value),
    /// Register
    Register(Register),
    /// Pointer into memory, stored in a numbered register
    RegObject(Register),
}

impl Display for RdData {
    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
        match self {
            RdData::Immediate(v) => {
                if is_negative(*v) {
                    write!(f, "{}", as_signed(*v))
                } else {
                    write!(f, "{}", *v)
                }
            }
            RdData::Register(r) => write!(f, "{}", r),
            RdData::RegObject(r) => write!(f, "@{}", r),
            RdData::ImmObject(v) => write!(f, "@{:#x}", v),
        }
    }
}

impl TryFrom<DataDisp> for RdData {
    type Error = AsmError;

    fn try_from(value: DataDisp) -> Result<Self, Self::Error> {
        match value {
            DataDisp::Immediate(x) => Ok(RdData::Immediate(x)),
            DataDisp::ImmObject(x) => Ok(RdData::ImmObject(x)),
            DataDisp::Register(x) => Ok(RdData::Register(x)),
            DataDisp::RegObject(x) => Ok(RdData::RegObject(x)),
            DataDisp::Discard => Err(AsmError::DiscardAsValue),
        }
    }
}

/// Data destination disposition
#[derive(Debug, Clone, Copy, Eq, PartialEq)]
pub enum WrData {
    /// Pointer into memory, address immediate
    ImmObject(Value),
    /// Register
    Register(Register),
    /// Pointer into memory, stored in a numbered register
    RegObject(Register),
    /// Discard the written value
    Discard,
}

impl WrData {
    pub fn is_readable(self) -> bool {
        self != Self::Discard
    }
}

impl Display for WrData {
    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
        match self {
            WrData::Discard => f.write_str("_"),
            WrData::Register(r) => write!(f, "{}", r),
            WrData::RegObject(r) => write!(f, "@{}", r),
            WrData::ImmObject(v) => write!(f, "@{:#x}", v),
        }
    }
}

impl From<WrData> for RdData {
    fn from(s: WrData) -> Self {
        match s {
            WrData::ImmObject(x) => RdData::ImmObject(x),
            WrData::Register(x) => RdData::Register(x),
            WrData::RegObject(x) => RdData::RegObject(x),
            WrData::Discard => RdData::Immediate(0), // this should not be allowed by the assembler
        }
    }
}

impl TryFrom<DataDisp> for WrData {
    type Error = AsmError;

    fn try_from(value: DataDisp) -> Result<Self, Self::Error> {
        match value {
            DataDisp::Immediate(_x) => Err(AsmError::ValueAsOutput),
            DataDisp::ImmObject(x) => Ok(WrData::ImmObject(x)),
            DataDisp::Register(x) => Ok(WrData::Register(x)),
            DataDisp::RegObject(x) => Ok(WrData::RegObject(x)),
            DataDisp::Discard => Ok(WrData::Discard),
        }
    }
}