use std::fmt::{Debug, Display};
use crate::{
    FromIntegerLiteral, Literal, IntegerLit, IntegerType as Ty, IntegerBase, IntegerBase::*,
    test_util::{assert_parse_ok_eq, assert_roundtrip},
};


// ===== Utility functions =======================================================================

#[track_caller]
fn check<T: FromIntegerLiteral + PartialEq + Debug + Display>(
    input: &str,
    value: T,
    base: IntegerBase,
    main_part: &str,
    type_suffix: Option<Ty>,
) {
    let expected_integer = IntegerLit {
        raw: input,
        start_main_part: base.prefix().len(),
        end_main_part: base.prefix().len() + main_part.len(),
        base,
    };
    assert_parse_ok_eq(
        input, IntegerLit::parse(input), expected_integer.clone(), "IntegerLit::parse");
    assert_parse_ok_eq(
        input, Literal::parse(input), Literal::Integer(expected_integer), "Literal::parse");
    assert_roundtrip(expected_integer.to_owned(), input);
    assert_eq!(Ty::from_suffix(IntegerLit::parse(input).unwrap().suffix()), type_suffix);

    let actual_value = IntegerLit::parse(input)
        .unwrap()
        .value::<T>()
        .unwrap_or_else(|| panic!("unexpected overflow in `IntegerLit::value` for `{}`", input));
    if actual_value != value {
        panic!(
            "Parsing int literal `{}` should give value `{}`, but actually resulted in `{}`",
            input,
            value,
            actual_value,
        );
    }
}


// ===== Actual tests ===========================================================================

#[test]
fn parse_decimal() {
    check("0", 0u128, Decimal, "0", None);
    check("1", 1u8, Decimal, "1", None);
    check("8", 8u16, Decimal, "8", None);
    check("9", 9u32, Decimal, "9", None);
    check("10", 10u64, Decimal, "10", None);
    check("11", 11i8, Decimal, "11", None);
    check("123456789", 123456789i128, Decimal, "123456789", None);

    check("05", 5i16, Decimal, "05", None);
    check("00005", 5i32, Decimal, "00005", None);
    check("0123456789", 123456789i64, Decimal, "0123456789", None);

    check("123_456_789", 123_456_789, Decimal, "123_456_789", None);
    check("0___4", 4, Decimal, "0___4", None);
    check("0___4_3", 43, Decimal, "0___4_3", None);
    check("0___4_3", 43, Decimal, "0___4_3", None);
    check("123___________", 123, Decimal, "123___________", None);

    check(
        "340282366920938463463374607431768211455",
        340282366920938463463374607431768211455u128,
        Decimal,
        "340282366920938463463374607431768211455",
        None,
    );
    check(
        "340_282_366_920_938_463_463_374_607_431_768_211_455",
        340282366920938463463374607431768211455u128,
        Decimal,
        "340_282_366_920_938_463_463_374_607_431_768_211_455",
        None,
    );
    check(
        "3_40_282_3669_20938_463463_3746074_31768211_455___",
        340282366920938463463374607431768211455u128,
        Decimal,
        "3_40_282_3669_20938_463463_3746074_31768211_455___",
        None,
    );
}

#[test]
fn parse_binary() {
    check("0b0", 0b0, Binary, "0", None);
    check("0b000", 0b000, Binary, "000", None);
    check("0b1", 0b1, Binary, "1", None);
    check("0b01", 0b01, Binary, "01", None);
    check("0b101010", 0b101010, Binary, "101010", None);
    check("0b10_10_10", 0b10_10_10, Binary, "10_10_10", None);
    check("0b01101110____", 0b01101110____, Binary, "01101110____", None);

    check("0b10010u8", 0b10010u8, Binary, "10010", Some(Ty::U8));
    check("0b10010i8", 0b10010u8, Binary, "10010", Some(Ty::I8));
    check("0b10010u64", 0b10010u64, Binary, "10010", Some(Ty::U64));
    check("0b10010i64", 0b10010i64, Binary, "10010", Some(Ty::I64));
    check(
        "0b1011001_00110000_00101000_10100101u32",
        0b1011001_00110000_00101000_10100101u32,
        Binary,
        "1011001_00110000_00101000_10100101",
        Some(Ty::U32),
    );
}

#[test]
fn parse_octal() {
    check("0o0", 0o0, Octal, "0", None);
    check("0o1", 0o1, Octal, "1", None);
    check("0o6", 0o6, Octal, "6", None);
    check("0o7", 0o7, Octal, "7", None);
    check("0o17", 0o17, Octal, "17", None);
    check("0o123", 0o123, Octal, "123", None);
    check("0o7654321", 0o7654321, Octal, "7654321", None);
    check("0o7_53_1", 0o7_53_1, Octal, "7_53_1", None);
    check("0o66_", 0o66_, Octal, "66_", None);

    check("0o755u16", 0o755u16, Octal, "755", Some(Ty::U16));
    check("0o755i128", 0o755i128, Octal, "755", Some(Ty::I128));
}

#[test]
fn parse_hexadecimal() {
    check("0x0", 0x0, Hexadecimal, "0", None);
    check("0x1", 0x1, Hexadecimal, "1", None);
    check("0x9", 0x9, Hexadecimal, "9", None);

    check("0xa", 0xa, Hexadecimal, "a", None);
    check("0xf", 0xf, Hexadecimal, "f", None);
    check("0x17", 0x17, Hexadecimal, "17", None);
    check("0x1b", 0x1b, Hexadecimal, "1b", None);
    check("0x123", 0x123, Hexadecimal, "123", None);
    check("0xace", 0xace, Hexadecimal, "ace", None);
    check("0xfdb971", 0xfdb971, Hexadecimal, "fdb971", None);
    check("0xa_54_f", 0xa_54_f, Hexadecimal, "a_54_f", None);
    check("0x6d_", 0x6d_, Hexadecimal, "6d_", None);

    check("0xA", 0xA, Hexadecimal, "A", None);
    check("0xF", 0xF, Hexadecimal, "F", None);
    check("0x17", 0x17, Hexadecimal, "17", None);
    check("0x1B", 0x1B, Hexadecimal, "1B", None);
    check("0x123", 0x123, Hexadecimal, "123", None);
    check("0xACE", 0xACE, Hexadecimal, "ACE", None);
    check("0xFDB971", 0xFDB971, Hexadecimal, "FDB971", None);
    check("0xA_54_F", 0xA_54_F, Hexadecimal, "A_54_F", None);
    check("0x6D_", 0x6D_, Hexadecimal, "6D_", None);

    check("0xFdB97a1", 0xFdB97a1, Hexadecimal, "FdB97a1", None);
    check("0xfdB97A1", 0xfdB97A1, Hexadecimal, "fdB97A1", None);

    check("0x40u16", 0x40u16, Hexadecimal, "40", Some(Ty::U16));
    check("0xffi128", 0xffi128, Hexadecimal, "ff", Some(Ty::I128));
}

#[test]
fn starting_underscore() {
    check("0b_1", 1, Binary, "_1", None);
    check("0b_010i16", 0b_010, Binary, "_010", Some(Ty::I16));

    check("0o_5", 5, Octal, "_5", None);
    check("0o_750u128", 0o_750u128, Octal, "_750", Some(Ty::U128));

    check("0x_c", 0xc, Hexadecimal, "_c", None);
    check("0x_cf3i8", 0x_cf3, Hexadecimal, "_cf3", Some(Ty::I8));
}

#[test]
fn parse_overflowing_just_fine() {
    check("256u8", 256u16, Decimal, "256", Some(Ty::U8));
    check("123_456_789u8", 123_456_789u32, Decimal, "123_456_789", Some(Ty::U8));
    check("123_456_789u16", 123_456_789u32, Decimal, "123_456_789", Some(Ty::U16));

    check("123_123_456_789u8", 123_123_456_789u64, Decimal, "123_123_456_789", Some(Ty::U8));
    check("123_123_456_789u16", 123_123_456_789u64, Decimal, "123_123_456_789", Some(Ty::U16));
    check("123_123_456_789u32", 123_123_456_789u64, Decimal, "123_123_456_789", Some(Ty::U32));
}

#[test]
fn suffixes() {
    [
        ("123i8", Ty::I8),
        ("123i16", Ty::I16),
        ("123i32", Ty::I32),
        ("123i64", Ty::I64),
        ("123i128", Ty::I128),
        ("123u8", Ty::U8),
        ("123u16", Ty::U16),
        ("123u32", Ty::U32),
        ("123u64", Ty::U64),
        ("123u128", Ty::U128),
    ].iter().for_each(|&(s, ty)| {
        assert_eq!(Ty::from_suffix(IntegerLit::parse(s).unwrap().suffix()), Some(ty));
    });
}

#[test]
fn overflow_u128() {
    let inputs = [
        "340282366920938463463374607431768211456",
        "0x100000000000000000000000000000000",
        "0o4000000000000000000000000000000000000000000",
        "0b1000000000000000000000000000000000000000000000000000000000000000000\
            00000000000000000000000000000000000000000000000000000000000000",
        "340282366920938463463374607431768211456u128",
        "340282366920938463463374607431768211457",
        "3_40_282_3669_20938_463463_3746074_31768211_456___",
        "3_40_282_3669_20938_463463_3746074_31768211_455___1",
        "3_40_282_3669_20938_463463_3746074_31768211_455___0u128",
        "3402823669209384634633746074317682114570",
    ];

    for &input in &inputs {
        let lit = IntegerLit::parse(input).expect("failed to parse");
        assert!(lit.value::<u128>().is_none());
    }
}

#[test]
fn overflow_u8() {
    let inputs = [
        "256", "0x100", "0o400", "0b100000000",
        "257", "0x101", "0o401", "0b100000001",
        "300",
        "1548",
        "2548985",
        "256u128",
        "256u8",
        "2_5_6",
        "256_____1",
        "256__",
    ];

    for &input in &inputs {
        let lit = IntegerLit::parse(input).expect("failed to parse");
        assert!(lit.value::<u8>().is_none());
    }
}

#[test]
fn parse_err() {
    assert_err!(IntegerLit, "", Empty, None);
    assert_err_single!(IntegerLit::parse("a"), DoesNotStartWithDigit, 0);
    assert_err_single!(IntegerLit::parse(";"), DoesNotStartWithDigit, 0);
    assert_err_single!(IntegerLit::parse("0;"), UnexpectedChar, 1..2);
    assert_err!(IntegerLit, "0b", NoDigits, 2..2);
    assert_err_single!(IntegerLit::parse(" 0"), DoesNotStartWithDigit, 0);
    assert_err_single!(IntegerLit::parse("0 "), UnexpectedChar, 1);
    assert_err!(IntegerLit, "0b3", InvalidDigit, 2);
    assert_err_single!(IntegerLit::parse("_"), DoesNotStartWithDigit, 0);
    assert_err_single!(IntegerLit::parse("_3"), DoesNotStartWithDigit, 0);
    assert_err!(IntegerLit, "0x44.5", UnexpectedChar, 4..6);
    assert_err_single!(IntegerLit::parse("123em"), IntegerSuffixStartingWithE, 3);
}

#[test]
fn invalid_digits() {
    assert_err!(IntegerLit, "0b10201", InvalidDigit, 4);
    assert_err!(IntegerLit, "0b9", InvalidDigit, 2);
    assert_err!(IntegerLit, "0b07", InvalidDigit, 3);

    assert_err!(IntegerLit, "0o12380", InvalidDigit, 5);
    assert_err!(IntegerLit, "0o192", InvalidDigit, 3);

    assert_err_single!(IntegerLit::parse("a_123"), DoesNotStartWithDigit, 0);
    assert_err_single!(IntegerLit::parse("B_123"), DoesNotStartWithDigit, 0);
}

#[test]
fn no_valid_digits() {
    assert_err!(IntegerLit, "0x_", NoDigits, 2..3);
    assert_err!(IntegerLit, "0x__", NoDigits, 2..4);
    assert_err!(IntegerLit, "0x________", NoDigits, 2..10);
    assert_err!(IntegerLit, "0x_i8", NoDigits, 2..3);
    assert_err!(IntegerLit, "0x_u8", NoDigits, 2..3);
    assert_err!(IntegerLit, "0x_isize", NoDigits, 2..3);
    assert_err!(IntegerLit, "0x_usize", NoDigits, 2..3);

    assert_err!(IntegerLit, "0o_", NoDigits, 2..3);
    assert_err!(IntegerLit, "0o__", NoDigits, 2..4);
    assert_err!(IntegerLit, "0o________", NoDigits, 2..10);
    assert_err!(IntegerLit, "0o_i32", NoDigits, 2..3);
    assert_err!(IntegerLit, "0o_u32", NoDigits, 2..3);

    assert_err!(IntegerLit, "0b_", NoDigits, 2..3);
    assert_err!(IntegerLit, "0b__", NoDigits, 2..4);
    assert_err!(IntegerLit, "0b________", NoDigits, 2..10);
    assert_err!(IntegerLit, "0b_i128", NoDigits, 2..3);
    assert_err!(IntegerLit, "0b_u128", NoDigits, 2..3);
}

#[test]
fn non_standard_suffixes() {
    #[track_caller]
    fn check_suffix<T: FromIntegerLiteral + PartialEq + Debug + Display>(
        input: &str,
        value: T,
        base: IntegerBase,
        main_part: &str,
        suffix: &str,
    ) {
        check(input, value, base, main_part, None);
        assert_eq!(IntegerLit::parse(input).unwrap().suffix(), suffix);
    }

    check_suffix("5u7", 5, Decimal, "5", "u7");
    check_suffix("5u7", 5, Decimal, "5", "u7");
    check_suffix("5u9", 5, Decimal, "5", "u9");
    check_suffix("5u0", 5, Decimal, "5", "u0");
    check_suffix("33u12", 33, Decimal, "33", "u12");
    check_suffix("84u17", 84, Decimal, "84", "u17");
    check_suffix("99u80", 99, Decimal, "99", "u80");
    check_suffix("1234uu16", 1234, Decimal, "1234", "uu16");

    check_suffix("5i7", 5, Decimal, "5", "i7");
    check_suffix("5i9", 5, Decimal, "5", "i9");
    check_suffix("5i0", 5, Decimal, "5", "i0");
    check_suffix("33i12", 33, Decimal, "33", "i12");
    check_suffix("84i17", 84, Decimal, "84", "i17");
    check_suffix("99i80", 99, Decimal, "99", "i80");
    check_suffix("1234ii16", 1234, Decimal, "1234", "ii16");

    check_suffix("0ui32", 0, Decimal, "0", "ui32");
    check_suffix("1iu32", 1, Decimal, "1", "iu32");
    check_suffix("54321a64", 54321, Decimal, "54321", "a64");
    check_suffix("54321b64", 54321, Decimal, "54321", "b64");
    check_suffix("54321x64", 54321, Decimal, "54321", "x64");
    check_suffix("54321o64", 54321, Decimal, "54321", "o64");

    check_suffix("0a", 0, Decimal, "0", "a");
    check_suffix("0a3", 0, Decimal, "0", "a3");
    check_suffix("0z", 0, Decimal, "0", "z");
    check_suffix("0z3", 0, Decimal, "0", "z3");
    check_suffix("0b0a", 0, Binary, "0", "a");
    check_suffix("0b0A", 0, Binary, "0", "A");
    check_suffix("0b01f", 1, Binary, "01", "f");
    check_suffix("0b01F", 1, Binary, "01", "F");
    check_suffix("0o7a_", 7, Octal, "7", "a_");
    check_suffix("0o7A_", 7, Octal, "7", "A_");
    check_suffix("0o72f_0", 0o72, Octal, "72", "f_0");
    check_suffix("0o72F_0", 0o72, Octal, "72", "F_0");

    check_suffix("0x8cg", 0x8c, Hexadecimal, "8c", "g");
    check_suffix("0x8cG", 0x8c, Hexadecimal, "8c", "G");
    check_suffix("0x8c1h_", 0x8c1, Hexadecimal, "8c1", "h_");
    check_suffix("0x8c1H_", 0x8c1, Hexadecimal, "8c1", "H_");
    check_suffix("0x8czu16", 0x8c, Hexadecimal, "8c", "zu16");

    check_suffix("123_foo", 123, Decimal, "123_", "foo");
}