use std::hint::black_box;
use std::time::Instant;

#[derive(Debug)]
enum ReferenceFailure {
    Fault(Fault),
    Failed(String, Fault),
}

fn state_reference(value: &STATE_TYPE) -> Result<i64, Fault> {
    Ok(match value {
        STATE_TYPE::Variant0 => 0,
        STATE_TYPE::Variant1(number) => *number,
        STATE_TYPE::Variant2(text) => text.chars().count() as i64,
    })
}

fn nullable_reference(value: &Option<String>) -> Result<i64, Fault> {
    Ok(match value {
        None => -1,
        Some(text) if text == "zero" => 0,
        Some(text) => text.chars().count() as i64,
    })
}

fn operation_reference(value: i64) -> Result<i64, ReferenceFailure> {
    if value >= 0 {
        Ok(value)
    } else {
        Err(ReferenceFailure::Failed(
            "negative".into(),
            &FaultInfo {
                message: "Result.Failed",
                source: "reference.dever",
                line: 1,
                column: 1,
            },
        ))
    }
}

fn propagate_reference(value: i64) -> Result<i64, ReferenceFailure> {
    Ok(operation_reference(value)?)
}

fn capture_reference(value: i64) -> Result<RESULT_TYPE, Fault> {
    match propagate_reference(value) {
        Ok(number) => Ok(RESULT_TYPE::Variant0(number)),
        Err(ReferenceFailure::Failed(message, _origin)) => Ok(RESULT_TYPE::Variant1(message)),
        Err(ReferenceFailure::Fault(fault)) => Err(fault),
    }
}

fn change_reference(value: &STATE_TYPE) -> Result<STATE_TYPE, Fault> {
    Ok(match value {
        STATE_TYPE::Variant2(text) => {
            let mut result = String::with_capacity(text.len() + "新".len());
            result.push_str(text);
            result.push_str("新");
            STATE_TYPE::Variant2(result)
        }
        _ => value.clone(),
    })
}

fn score(value: RESULT_TYPE) -> usize {
    match value {
        RESULT_TYPE::Variant0(number) => number as usize,
        RESULT_TYPE::Variant1(message) => message.len(),
    }
}

fn sample(
    name: &str,
    sample: usize,
    implementation: &str,
    count: usize,
    mut operation: impl FnMut(usize) -> usize,
) {
    let start = Instant::now();
    let mut checksum = 0usize;
    for position in 0..count {
        checksum = checksum.wrapping_add(black_box(operation(black_box(position))));
    }
    println!(
        "{name},{sample},{implementation},{},{checksum}",
        start.elapsed().as_nanos()
    );
}

fn main() {
    let states = [
        STATE_TYPE::Variant0,
        STATE_TYPE::Variant1(42),
        STATE_TYPE::Variant2("雪山树林".repeat(16)),
    ];
    let texts = [None, Some("zero".into()), Some("雪山树林".repeat(16))];
    for state in &states {
        assert_eq!(
            GENERATED_STATE(state).unwrap(),
            state_reference(state).unwrap()
        );
        assert_eq!(
            GENERATED_CHANGE(state).unwrap(),
            change_reference(state).unwrap()
        );
    }
    for text in &texts {
        assert_eq!(
            GENERATED_NULLABLE(text).unwrap(),
            nullable_reference(text).unwrap()
        );
    }
    for value in [i64::MIN, -1, 0, 1, i64::MAX] {
        assert_eq!(
            GENERATED_PROPAGATE(value).map_err(|_| ()),
            propagate_reference(value).map_err(|_| ())
        );
        assert_eq!(
            GENERATED_CAPTURE(value).unwrap(),
            capture_reference(value).unwrap()
        );
    }
    println!("case,sample,implementation,elapsed_ns,checksum");
    for iteration in 0..9 {
        for generated in if iteration % 2 == 0 {
            [true, false]
        } else {
            [false, true]
        } {
            let implementation = if generated { "dever" } else { "rust" };
            if generated {
                sample(
                    "choice_payload",
                    iteration,
                    implementation,
                    1_000_000,
                    |position| GENERATED_STATE(black_box(&states[position % 3])).unwrap() as usize,
                );
                sample(
                    "nullable_text",
                    iteration,
                    implementation,
                    1_000_000,
                    |position| {
                        GENERATED_NULLABLE(black_box(&texts[position % 3])).unwrap() as usize
                    },
                );
                sample(
                    "default_failure",
                    iteration,
                    implementation,
                    500_000,
                    |position| {
                        black_box(GENERATED_PROPAGATE((position % 8) as i64 - 1)).unwrap_or(7)
                            as usize
                    },
                );
                sample(
                    "capture_failure",
                    iteration,
                    implementation,
                    500_000,
                    |position| {
                        score(black_box(
                            GENERATED_CAPTURE((position % 8) as i64 - 1).unwrap(),
                        ))
                    },
                );
                sample(
                    "choice_copy",
                    iteration,
                    implementation,
                    300_000,
                    |_| match black_box(GENERATED_CHANGE(black_box(&states[2])).unwrap()) {
                        STATE_TYPE::Variant2(text) => text.len(),
                        _ => unreachable!(),
                    },
                );
            } else {
                sample(
                    "choice_payload",
                    iteration,
                    implementation,
                    1_000_000,
                    |position| state_reference(black_box(&states[position % 3])).unwrap() as usize,
                );
                sample(
                    "nullable_text",
                    iteration,
                    implementation,
                    1_000_000,
                    |position| {
                        nullable_reference(black_box(&texts[position % 3])).unwrap() as usize
                    },
                );
                sample(
                    "default_failure",
                    iteration,
                    implementation,
                    500_000,
                    |position| {
                        black_box(propagate_reference((position % 8) as i64 - 1)).unwrap_or(7)
                            as usize
                    },
                );
                sample(
                    "capture_failure",
                    iteration,
                    implementation,
                    500_000,
                    |position| {
                        score(black_box(
                            capture_reference((position % 8) as i64 - 1).unwrap(),
                        ))
                    },
                );
                sample(
                    "choice_copy",
                    iteration,
                    implementation,
                    300_000,
                    |_| match black_box(change_reference(black_box(&states[2])).unwrap()) {
                        STATE_TYPE::Variant2(text) => text.len(),
                        _ => unreachable!(),
                    },
                );
            }
        }
    }
}