use yaxpeax_arch::Decoder;
use yaxpeax_power::{InstDecoder, DecodeError};
use crate::{ParsedInstr, ParsedOperand};
use crate::tools;

fn yax_decode(bytes: &[u8]) -> String {
    let decoder = InstDecoder::default()
        .with_be(false);

    let mut reader = yaxpeax_arch::U8Reader::new(&bytes);
    let decode_res = decoder.decode(&mut reader);
    format!("{}", decode_res.unwrap())
}

fn compare_objdump(bytes: &[u8]) {
    let objdump_text = tools::objdump(bytes).unwrap();
    eprintln!("objdump says: {:?}", objdump_text);
    let yax_text = yax_decode(bytes);
    eprintln!("yax says: {:?}", yax_text);
    assert_eq!(
        ParsedInstr::from_str(objdump_text.as_str()).unwrap(),
        ParsedInstr::from_str(yax_text.as_str()).unwrap(),
    );
}

#[test]
fn test_general() {
    // this is `bdzflr+ 4*cr7+gt`. on gekko, there was no bh field, but objdump prints one anyway.
    // yax doesn't, so the operand count mismatches, and objdump is sad. also, how does this get a
    // + in the modern hinting scheme?
    // compare_objdump(&[0x20, 0x18, 0x7d, 0x4c]);

    compare_objdump(&[0x04, 0x06, 0xe0, 0x13]);
    compare_objdump(&[0x44, 0xfe, 0x00, 0x10]);
    compare_objdump(&[0x64, 0x01, 0x00, 0x7f]);
    compare_objdump(&[0x24, 0x01, 0x60, 0x7d]);
    compare_objdump(&[0x82, 0x13, 0xc6, 0x4c]);

    compare_objdump(&[0x3d, 0x60, 0x82, 0x70]);

    compare_objdump(&[0x21, 0x04, 0x06, 0x4e]);
}

// a blanket ppc64le test won't run because it will decode vsx instructions which yax doesn't
// know..
#[ignore]
#[test]
fn test_vs_objdump() {
    eprintln!("objdump says {}", tools::objdump(&[0x82, 0x51, 0x0d, 0x4c]).unwrap());
    let decoder = InstDecoder::default()
        .with_be(false);
    let mut reader = yaxpeax_arch::U8Reader::new(&[0x82, 0x51, 0x0d, 0x4c]);
    let decode_res = decoder.decode(&mut reader).unwrap();
    eprintln!("i       says {}", decode_res);
}

// a blanket ppc64le test won't run because it will decode vsx instructions which yax doesn't
// know..
#[ignore]
#[test]
fn differential_objdump_ppc64le() {
    use crate::ParsedInstr;

    let decoder = InstDecoder::default()
        .with_be(false);

    let ranges: [std::ops::Range<u32>; 3] = [
        0x7c_00_00_00..0x7d_00_00_00,
        0xec_00_00_00..0xed_00_00_00,
        0xfc_00_00_00..0xfd_00_00_00,
    ];
    for range in ranges {
    for word in range { // u32::MAX {
        let bytes = word.to_le_bytes();

        if word & 0x0000_1fff == 0 {
            eprintln!("{:#x?}", bytes);
        }

        let objdump_text = tools::objdump(&bytes).unwrap();

        let mut reader = yaxpeax_arch::U8Reader::new(&bytes);
        let decode_res = decoder.decode(&mut reader);
        let instr = match decode_res {
            Err(e) => {
                // if objdump failed to decode and we failed to decode, move on; we agree!
                if objdump_text.contains("\t.long ") {
                    continue;
                }
                let parsed_objdump = match ParsedInstr::from_str(&objdump_text) {
                    Ok(parse) => parse,
                    Err(e) => {
                        panic!("couldn't parse objdump ({}), because {}", objdump_text, e);
                    }
                };
                eprintln!("objdump says: {:?}", parsed_objdump);

                if e == DecodeError::IncompleteDecoder {
                    // attn and friends
                    continue;
                }
                panic!("failed to decode {:02x}{:02x}{:02x}{:02x}: {}", bytes[0], bytes[1], bytes[2], bytes[3], e);
            },
            Ok(instr) => instr,
        };
        let displayed = format!("{}", instr);

        if objdump_text.contains("\t.long ") {
            // objdump rejected but we did not. the vast majority of this is objdump being picky
            // about the low bit (rc, lk etc) of the word, but manuals say it's a don't-care.
            // that's not *All* cases, so this is overly broad to try helping the overall SNR...
            continue;
        }

        let parsed_objdump = ParsedInstr::from_str(&objdump_text).expect("can parse objdump");
        let parsed_yax = ParsedInstr::from_str(&displayed).expect("can parse decoder output");

        if !acceptable_match(&parsed_objdump, &parsed_yax) {
            eprintln!("miss {:02x}{:02x}{:02x}{:02x}: {} vs {}", bytes[0], bytes[1], bytes[2], bytes[3], objdump_text, displayed);
//            missed += 1;
        } else {
//            eprintln!("you: {}, me: {}", objdump_text, displayed);
        }
    }
    }
}

fn acceptable_match(objdump: &ParsedInstr, yax: &ParsedInstr) -> bool {
    if objdump == yax {
        return true;
    }

    if objdump.mnemonic == yax.mnemonic && (yax.mnemonic == "mtfsfi" || yax.mnemonic == "mtfsfi.") {
        // TDOO: for the first operand, yax prints "fpscrf", but objdump just prints an immediate..
        // so just compare the second. would be better to assert the same numeric value at least?
        if objdump.operands[1] == yax.operands[1] {
            return true;
        }
    }

    if objdump.mnemonic == yax.mnemonic && ["fre", "frsqrte", "fre.", "frsqrte."].contains(&yax.mnemonic.as_str()) {
        // TODO: objdump prints a third immediate sometimes if bit 15 is set, an immediate 0 or 1
        // which yax ignores.
        if yax.operands == objdump.operands[..2] {
            return true;
        }
    }

    if objdump.operands.len() == yax.operands.len() {
        static LEGACY_MNEMONICS: &'static [(&'static str, &'static str)] = &[

            ("lswi", "lsi"),
            ("lswx", "lsx"),

            ("lwbrx", "lbrx"),
            ("l", "lwz"),
            ("lu", "lwzu"),
            ("lux", "lwzux"),

            ("stsi", "stswi"),
            ("stsx", "stswx"),

            ("stu", "stwu"),
            ("stux", "stwux"),
            ("stx", "stwx"),

            ("lsx", "lswx"),
            ("lsi", "lswi"),
        ];
        for (old, new) in LEGACY_MNEMONICS.iter() {
            if objdump.mnemonic == *old && yax.mnemonic == *new {
                return true;
            }
        }
    }

    if objdump.mnemonic == yax.mnemonic && objdump.operands.len() == yax.operands.len() {
        if objdump.operands.len() == 2 {
            if objdump.operands[0] == yax.operands[0] &&
                objdump.operands[1] == ParsedOperand::Immediate(0) &&
                yax.operands[1] == ParsedOperand::Reg(0) {
                return true;
            } else if objdump.operands[1] == yax.operands[1] &&
                objdump.operands[0] == ParsedOperand::Immediate(0) &&
                yax.operands[0] == ParsedOperand::Reg(0) {
                return true;
            }
        } else if yax.operands.len() == 4 {
            // objdump is at *least* 3 operands ...
            if objdump.operands[0] == yax.operands[0] &&
                objdump.operands[2] == yax.operands[2] &&
                objdump.operands[3] == yax.operands[3] {
                if objdump.operands[1] == ParsedOperand::Immediate(0) &&
                    yax.operands[1] == ParsedOperand::Reg(0) {
                    return true;
                }
            }
        } else if objdump.operands.len() == 3 {
            if objdump.operands[0] == yax.operands[0] &&
                objdump.operands[2] == yax.operands[2] &&
                objdump.operands[1] == ParsedOperand::Immediate(0) &&
                yax.operands[1] == ParsedOperand::Reg(0) {
                return true;
            }
        }
    }

    if yax.mnemonic == objdump.mnemonic && ["lwarx", "ldarx"].contains(&yax.mnemonic.as_str()) {
        // objdump is at *least* 3 operands ...
        if objdump.operands[0] == yax.operands[0] &&
            objdump.operands[2] == yax.operands[2] &&
            objdump.operands.len() == 3 &&
            yax.operands[3] == ParsedOperand::Immediate(0) {

            if objdump.operands[1] == ParsedOperand::Immediate(0) &&
                yax.operands[1] == ParsedOperand::Reg(0) {
                return true;
            }
        }
    }

    if yax.mnemonic == objdump.mnemonic &&
        yax.mnemonic == "dcbtls" &&
        yax.operands[1] == ParsedOperand::Reg(0) &&
        yax.operands[0] == objdump.operands[0] &&
        yax.operands[2] == objdump.operands[1] {
            return true;
    }

    if (yax.mnemonic == objdump.mnemonic && yax.mnemonic == "mbar") ||
        (yax.mnemonic == "eieio" && objdump.mnemonic == "mbar") {
        // yax prints TH, objdump doesn't print it
        if objdump.operands.len() == 0 &&  yax.operands.len() <= 1 {
            return true;
        }
    }

    false
}

#[test]
fn compare_objdump_acceptable_match() {
    assert!(acceptable_match(
        &ParsedInstr::from_str("stvewx  v0,0,r0").unwrap(),
        &ParsedInstr::from_str("stvewx vr0, r0, r0").unwrap(),
    ));

    assert!(acceptable_match(
        &ParsedInstr::from_str("fre f0,f13,1").unwrap(),
        &ParsedInstr::from_str("fre fr0, fr13").unwrap(),
    ));

    assert!(acceptable_match(
        &ParsedInstr::from_str("mbar").unwrap(),
        &ParsedInstr::from_str("eieio").unwrap(),
    ));

    assert!(acceptable_match(
        &ParsedInstr::from_str("mbar").unwrap(),
        &ParsedInstr::from_str("mbar 0").unwrap(),
    ));
}