use super::*;

/// Creates a [Parsable] implementation for an enum whose variants
/// are named after other [Parsable] items
macro make_parsable($(#[$meta:meta])* $vis:vis enum $id:ident {$($(#[$vmeta:meta])*$v:ident),*$(,)?}) {
    $( #[$meta] )* $vis enum $id {$($(#[$vmeta])*$v($v),)* }
    impl ::msp430_asm::parser::parsable::Parsable for $id {
        fn parse<'text, T>(p: &Parser, stream: &mut T) -> Result<Self, ParseError>
        where T: TokenStream<'text> {
            $(if let Some(v) = Parsable::try_parse(p, stream)? { Ok(Self::$v(v)) } else )*
            { Err(ParseError::UnrecognizedDirective("".into())) }
        }
    }
    impl TryFrom<&str> for $id {
        type Error = ParseError;
        fn try_from(value: &str) -> Result<Self, Self::Error> {
            Parsable::parse(&Parser::default(), &mut Tokenizer::new(value).ignore(Type::Space).preprocessed())
        }
    }
}

make_parsable! {
    #[derive(Debug)]
    pub enum SyntaxFragment {
        Opcode,
        PrimaryOperand,
        Number,
    }
}

impl SyntaxFragment {
    pub fn info(&self) {
        match self {
            SyntaxFragment::Opcode(o) => Self::opcode_info(o),
            SyntaxFragment::PrimaryOperand(o) => Self::operand_info(o),
            SyntaxFragment::Number(n) => println!("The number {n}"),
        }
    }
    fn opcode_info(o: &Opcode) {
        let (desc, as_rust) = usage(o);
        println!("Usage: {o}{}\n{desc} ( {as_rust} )", params(o));
        footer!("https://mspgcc.sourceforge.net/manual/x223.html");
    }
    // TODO: re-enable full instruction decoding
    // fn encoding_info(e: &Encoding) {
    //     match e {
    //         Encoding::Single { dst, .. } => Self::operand_info(dst),
    //         Encoding::Jump { target } => println!("Jumps to (pc + {target})"),
    //         Encoding::Double { src, dst, .. } => {
    //             Self::operand_info(src);
    //             Self::operand_info(&dst.clone().into())
    //         }
    //     }
    // }
    fn operand_info(o: &PrimaryOperand) {
        match o {
            PrimaryOperand::Direct(r) => Self::register_info(r),
            PrimaryOperand::Indirect(r) => {
                Self::register_info(r);
                println!("Indirect addressing mode: use data pointed to by {r}");
            }
            PrimaryOperand::PostInc(r) => {
                Self::register_info(r);
                println!("Indirect post-increment mode: use data pointed to by {r}, then increment {r}");
            }
            PrimaryOperand::Indexed(r, n) => {
                Self::register_info(r);
                println!("Indexed mode: use the data at {r}[{n}]");
            }
            PrimaryOperand::Relative(_) => return,
            PrimaryOperand::Absolute(n) => println!("Absolute mode: use the data at absolute address {n}"),
            PrimaryOperand::Immediate(n) => println!("Immediate mode: the constant {n}"),
            PrimaryOperand::Four => println!("#4 mode: Immediate 4 is encoded @sr"),
            PrimaryOperand::Eight => println!("#8 mode: Immediate 8 is encoded @sr+"),
            PrimaryOperand::Zero => println!("#0 mode: Immediate 0 is encoded cg (r3)"),
            PrimaryOperand::One => println!("#1 mode: Immediate 1 is encoded _(cg), where _ is a nonexistent ext-word"),
            PrimaryOperand::Two => println!("#2 mode: Immediate 2 is encoded @cg"),
            PrimaryOperand::MinusOne => println!("#-1 mode: the all-ones constant, is encoded @cg+"),
        }
        footer!("https://mspgcc.sourceforge.net/manual/x82.html");
    }
    fn register_info(r: &Register) {
        use Register as Re;
        match r {
            Re::pc => println!("pc (r0) is the Program Counter. Post-increment addressing will increase it by 2."),
            Re::sp => println!("sp (r1) is the Stack Pointer. Post-increment addressing will increase it by 2."),
            Re::sr => println!(
                "sr (r2) is the Status Register. It has arithmetic flags: oVerflow, Negative, Zero, and Carry;\nInterrupt Enable; and toggles for various clock/sleep functions.\n8\t7\t6\t5\t4\t3\t2\t1\t0\nV\tSCG1\tSCG1\tOSCOFF\tCPUOFF\tGIE\tN\tZ\tC",
            ),
            Re::cg => println!("cg (r3) is the Constant Generator. It's hard-wired to zero."),
            Re::r4 | Re::r5 | Re::r6 | Re::r7 | Re::r8 | Re::r9 | Re::r10 | Re::r11 => {
                println!("{r} is a callee-saved general purpose register.")
            }
            Re::r12 | Re::r13 | Re::r14 | Re::r15 => {
                println!("{r} is a caller-saved general purpose register, allowed for return values.")
            }
        }
    }
}

// Gets parameter usage information from the opcode's EncodingParser
pub fn params(opcode: &Opcode) -> &'static str {
    match opcode.resolve().1 {
        EncodingParser::Jump { target: None } => " target (relative address or label)",
        EncodingParser::Single { width: None, dst: None } => "[.b] dst",
        EncodingParser::Single { dst: None, .. } => " dst",
        EncodingParser::Double { src: None, dst: None, .. } => "[.b] src, dst",
        EncodingParser::Double { src: None, .. } => "[.b] src",
        EncodingParser::Double { dst: None, .. } => "[.b] dst",
        EncodingParser::Double { .. } => "[.b]",
        EncodingParser::Reflexive { reg: None, .. } => "[.b] dst",
        _ => "",
    }
}

pub fn usage(opcode: &Opcode) -> (&'static str, &'static str) {
    match opcode {
        // Single
        Opcode::Rrc => ("Rotates dst right, through carry flag", "dst = (dst >> 1) | (sr[C] << 15)"),
        Opcode::Swpb => ("Swaps the high and low byte of dst", "dst.swap_bytes()"),
        Opcode::Rra => ("Shifts dst right, sign-extending the result", "dst >>= 1"),
        Opcode::Sxt => ("Sign-extends the 8-bit dst to 16-bits", "dst as i16 << 8 >> 8"),
        Opcode::Push => ("Pushes dst to the stack", "stack.push(dst)"),
        Opcode::Call => ("Calls a subroutine at an absolute address", "dst()"),
        Opcode::Reti => ("Return from interrupt handler", "{ sr = stack.pop(); pc = stack.pop() }"),
        // Jump
        Opcode::Jnz => ("Jump if the last result was not zero", "if !Z { pc += target }"),
        Opcode::Jz => ("Jump if the last result was zero", "if Z { pc += target }"),
        Opcode::Jnc => ("Jump if the last operation did not carry", "if !C { pc += target }"),
        Opcode::Jc => ("Jump if the last operation produced a carry bit", "if C { pc += target }"),
        Opcode::Jn => ("Jump if the last result was negative", "if N { pc += target }"),
        Opcode::Jge => ("Jump if the flags indicate src >= dst", "if sr[C] == sr[V] { pc += target }"),
        Opcode::Jl => ("Jump if the flags indicate src < dst", "if sr[C] != sr[V] { pc += target }"),
        Opcode::Jmp => ("Jump unconditionally", "pc += target"),
        // Double
        Opcode::Mov => ("Copy src into dst", "dst = src"),
        Opcode::Add => ("Add src to dst", "dst += src"),
        Opcode::Addc => ("Add src to dst with carry", "dst += src + sr[C]"),
        Opcode::Subc => ("Subtract src from dst with carry", "dst -= src - sr[C]"),
        Opcode::Sub => ("Subtract src from dst", "dst -= src"),
        Opcode::Cmp => ("Subtract src from dst, but discard the result, keeping the flags", "dst - src"),
        Opcode::Dadd => ("Add src to dst in Binary Coded Decimal", "dst = dst as BCD + src as BCD"),
        Opcode::Bit => ("Test if bits in src are set in dst", "(src & dst).cmp(0)"),
        Opcode::Bic => ("Clear bits in dst that are set in src, without changing flags", "dst &= !src"),
        Opcode::Bis => ("Set bits in dst that are set in src, without changing flags", "dst |= src"),
        Opcode::Xor => ("Bitwise Xor src into dst", "dst ^= src"),
        Opcode::And => ("Bitwise And src into dst", "dst &= src"),
        // Emulated
        Opcode::Nop => ("Does nothing", "{}"),
        Opcode::Pop => ("Pops a value from the stack", "dst = stack.pop()"),
        Opcode::Br => ("Branches to the absolute address in src", "pc = src"),
        Opcode::Ret => ("Returns from subroutine", "pc = stack.pop()"),
        Opcode::Clrc => ("Clears the carry flag", "sr[C] = 0"),
        Opcode::Setc => ("Sets the carry flag", "sr[C] = 1"),
        Opcode::Clrz => ("Clears the zero flag", "sr[Z] = 0"),
        Opcode::Setz => ("Sets the zero flag", "sr[Z] = 1"),
        Opcode::Clrn => ("Clears the negative flag", "sr[N] = 0"),
        Opcode::Setn => ("Sets the negative flag", "sr[N] = 1"),
        Opcode::Dint => ("Disables interrupts", "sr[GIE] = 0"),
        Opcode::Eint => ("Enables interrupts", "sr[GIE] = 1"),
        Opcode::Rla => ("Shifts dst to the left, padding with zeros", "dst <<= 1"),
        Opcode::Rlc => ("Rotates dst to the left, through carry flag", "dst = (dst << 1) + sr[C]"),
        Opcode::Inv => ("Inverts the bits in dst", "dst = !dst"),
        Opcode::Clr => ("Sets dst to 0", "dst = 0"),
        Opcode::Tst => ("Sets the status register flags (CNZV) using dst", ""),
        Opcode::Dec => ("Decrements dst", "dst -= 1"),
        Opcode::Decd => ("Decrements dst by 2 (one processor word)", "dst -= 2"),
        Opcode::Inc => ("Increments dst", "dst += 1"),
        Opcode::Incd => ("Increments dst by 2 (one processor word)", "dst += 2"),
        Opcode::Adc => ("Adds the carry bit to dst", "dst += sr[C]"),
        Opcode::Dadc => ("Adds the carry bit to dst, in Binary Coded Decimal", "dst as BCD = sr[C]"),
        Opcode::Sbc => ("Subtracts the carry bit from dst", "dst -= sr[C]"),
    }
}

const SINGLE: [Opcode; 7] =
    [Opcode::Rrc, Opcode::Swpb, Opcode::Rra, Opcode::Sxt, Opcode::Push, Opcode::Call, Opcode::Reti];

const JUMP: [Opcode; 8] =
    [Opcode::Jnz, Opcode::Jz, Opcode::Jnc, Opcode::Jc, Opcode::Jn, Opcode::Jge, Opcode::Jl, Opcode::Jmp];

#[rustfmt::skip]
const DOUBLE: [Opcode; 12] = [
    Opcode::Mov,  Opcode::Add,  Opcode::Addc, Opcode::Subc, Opcode::Sub,  Opcode::Cmp,
    Opcode::Dadd, Opcode::Bit,  Opcode::Bic,  Opcode::Bis,  Opcode::Xor,  Opcode::And,
];
#[rustfmt::skip]
const SIMULATED: [Opcode; 24] = [
    Opcode::Nop,  Opcode::Pop,  Opcode::Br,   Opcode::Ret,  Opcode::Clrc, Opcode::Setc,
    Opcode::Clrz, Opcode::Setz, Opcode::Clrn, Opcode::Setn, Opcode::Dint, Opcode::Eint,
    Opcode::Rla,  Opcode::Rlc,  Opcode::Inv,  Opcode::Clr,  Opcode::Tst,  Opcode::Dec,
    Opcode::Decd, Opcode::Inc,  Opcode::Incd, Opcode::Adc,  Opcode::Dadc, Opcode::Sbc,
];

pub fn list_opcodes() {
    let mut stdout = std::io::stdout().lock();
    header!(stdout, "Single-operand instructions:");
    let _ = write_opcode_list(&mut stdout, &SINGLE);
    header!(stdout, "Relative Jump instructions:");
    let _ = write_opcode_list(&mut stdout, &JUMP);
    header!(stdout, "Double-operand instructions:");
    let _ = write_opcode_list(&mut stdout, &DOUBLE);
    header!(stdout, "Simulated instructions:");
    let _ = write_opcode_list(&mut stdout, &SIMULATED);
}

fn write_opcode_list(mut f: impl std::io::Write, list: &[Opcode]) -> std::io::Result<()> {
    for (idx, opcode) in list.iter().enumerate() {
        write!(f, "{opcode}{}", if idx % 6 == 5 { "\n" } else { "\t" })?;
    }
    if list.len() % 6 != 0 {
        writeln!(f)?;
    }
    Ok(())
}

macro header ($f:ident, $($x: expr),+) {
    {write!($f, "{}",SetForegroundColor(Color::Cyan)).ok();write!($f, $($x),+).ok();writeln!($f, "{}",ResetAttributes).ok();}
}
macro footer ($($x: expr),+) {
    {print!("{}",SetForegroundColor(Color::DarkGray));print!($($x),+);println!("{}",ResetAttributes);}
}