fn unicode_decode_checks() -> Bool {
    let ascii: Maybe<u32> = std.unicode.decodeAt("A", 0)
    if !ascii.has || ascii.value != 65 {
        return false
    }
    let accent: Maybe<u32> = std.unicode.decodeAt("xé", 1)
    if !accent.has || accent.value != 233 {
        return false
    }
    let emoji: Maybe<u32> = std.unicode.decodeAt("💯", 0)
    if !emoji.has || emoji.value != 128175 {
        return false
    }
    let continuation: Maybe<u32> = std.unicode.decodeAt("é", 1)
    if continuation.has {
        return false
    }
    var overlong: [2]u8 = [192_u8, 175_u8]
    let bad: Maybe<u32> = std.unicode.decodeAt(overlong, 0)
    if bad.has {
        return false
    }
    var surrogate: [3]u8 = [237_u8, 160_u8, 128_u8]
    let lone: Maybe<u32> = std.unicode.decodeAt(surrogate, 0)
    let next: Maybe<usize> = std.unicode.nextIndex("aé", 1)
    return !lone.has && next.has && next.value == 3
}

fn unicode_iteration_checks() -> Bool {
    let text: Span<u8> = std.mem.span("aé💯")
    var index: usize = 0
    var count: usize = 0
    while index < std.mem.len(text) {
        let width: Maybe<usize> = std.unicode.widthAt(text, index)
        if !width.has {
            return false
        }
        index = index + width.value
        count = count + 1
    }
    let total: Maybe<usize> = std.text.utf8Len(text)
    return count == 3 && (total.has && total.value == 3)
}

fn unicode_encode_checks() -> Bool {
    var two_storage: [4]u8 = [0; 4]
    let two_buffer: MutSpan<u8> = two_storage
    let two: Maybe<Span<u8>> = std.unicode.encode(two_buffer, 233)
    if !two.has || (std.mem.len(two.value) != 2 || (two.value[0] != 195_u8 || two.value[1] != 169_u8)) {
        return false
    }
    var four_storage: [4]u8 = [0; 4]
    let four_buffer: MutSpan<u8> = four_storage
    let four: Maybe<Span<u8>> = std.unicode.encode(four_buffer, 128175)
    if !four.has || std.mem.len(four.value) != 4 {
        return false
    }
    let echo: Maybe<u32> = std.unicode.decodeAt(four.value, 0)
    if !echo.has || echo.value != 128175 {
        return false
    }
    var reject_storage: [4]u8 = [0; 4]
    let reject_buffer: MutSpan<u8> = reject_storage
    let surrogate: Maybe<Span<u8>> = std.unicode.encode(reject_buffer, 55296)
    if surrogate.has {
        return false
    }
    var big_storage: [4]u8 = [0; 4]
    let big_buffer: MutSpan<u8> = big_storage
    let too_big: Maybe<Span<u8>> = std.unicode.encode(big_buffer, 1114112)
    if too_big.has {
        return false
    }
    let max_width: Maybe<usize> = std.unicode.encodedWidth(1114111)
    let bad_width: Maybe<usize> = std.unicode.encodedWidth(56000)
    let one_width: Maybe<usize> = std.unicode.encodedWidth(65)
    if !max_width.has || max_width.value != 4 {
        return false
    }
    if bad_width.has {
        return false
    }
    return one_width.has && one_width.value == 1
}

fn unicode_class_checks() -> Bool {
    return std.unicode.isDigit(53) && !std.unicode.isDigit(97) && std.unicode.isWord(95) && (std.unicode.isWord(122) && !std.unicode.isWord(233)) && std.unicode.isSpace(32) && (std.unicode.isSpace(8195) && (std.unicode.isSpace(12288) && !std.unicode.isSpace(65)))
}

fn unicode_status_checks() -> Bool {
    var truncated: [2]u8 = [226_u8, 130_u8]
    var continuation: [1]u8 = [128_u8]
    var overlong: [2]u8 = [192_u8, 175_u8]
    if std.unicode.decodeStatusAt("é", 0) != 0_u32 {
        return false
    }
    if std.unicode.decodeStatusAt(truncated, 0) != 4_u32 {
        return false
    }
    if std.unicode.decodeStatusAt(continuation, 0) != 2_u32 {
        return false
    }
    if std.unicode.decodeStatusAt(overlong, 0) != 6_u32 {
        return false
    }
    if std.unicode.invalidIndex("aé") != std.mem.len("aé") {
        return false
    }
    if std.unicode.invalidIndex(truncated) != 0 {
        return false
    }
    return std.mem.eql(std.unicode.statusName(4_u32), "truncated sequence")
}

pub fn main(world: World) -> Void raises {
    if unicode_decode_checks() && unicode_iteration_checks() && (unicode_encode_checks() && (unicode_class_checks() && unicode_status_checks())) {
        check world.out.write("std unicode ok\n")
    } else {
        check world.out.write("std unicode failed\n")
    }
}