use crate::eval::interpret;
use crate::eval::Options;
use pretty_assertions::assert_eq;

use test_generator::test_resources;

fn eval_test(code_path: &str, expect_success: bool) {
    let base = code_path
        .strip_suffix("nix")
        .expect("test files always end in .nix");
    let exp_path = format!("{}exp", base);
    let exp_xml_path = std::path::PathBuf::from(format!("{}exp.xml", base));

    let code = std::fs::read_to_string(code_path).expect("should be able to read test code");

    if exp_xml_path.exists() {
        // We can't test them at the moment because we don't have XML output yet.
        // Checking for success / failure only is a bit disingenious.
        return;
    }

    match interpret(&code, Some(code_path.into()), Options::test_options()) {
        Ok(result) => {
            let result_str = format!("{}", result);
            if let Ok(exp) = std::fs::read_to_string(exp_path) {
                if expect_success {
                    assert_eq!(
                        result_str,
                        exp.trim(),
                        "{code_path}: result value representation (left) must match expectation (right)"
                    );
                } else {
                    assert_ne!(
                        result_str,
                        exp.trim(),
                        "{code_path}: test passed unexpectedly!  consider moving it out of notyetpassing"
                    );
                }
            } else {
                if expect_success {
                    panic!("{code_path}: should be able to read test expectation");
                } else {
                    panic!(
                        "{code_path}: test should have failed, but succeeded with output {}",
                        result
                    );
                }
            }
        }
        Err(e) => {
            if expect_success {
                panic!(
                    "{code_path}: evaluation of eval-okay test should succeed, but failed with {:?}",
                    e
                );
            }
        }
    }
}

// identity-* tests contain Nix code snippets which should evaluate to
// themselves exactly (i.e. literals).
#[test_resources("src/tests/tvix_tests/identity-*.nix")]
fn identity(code_path: &str) {
    let code = std::fs::read_to_string(code_path).expect("should be able to read test code");

    let result = interpret(&code, None, Options::test_options())
        .expect("evaluation of identity test should succeed");
    let result_str = format!("{}", result);

    assert_eq!(
        result_str,
        code.trim(),
        "result value representation (left) must match expectation (right)"
    )
}

// eval-okay-* tests contain a snippet of Nix code, and an expectation
// of the produced string output of the evaluator.
//
// These evaluations are always supposed to succeed, i.e. all snippets
// are guaranteed to be valid Nix code.
#[test_resources("src/tests/tvix_tests/eval-okay-*.nix")]
fn eval_okay(code_path: &str) {
    eval_test(code_path, true)
}

// eval-okay-* tests from the original Nix test suite.
#[cfg(feature = "nix_tests")]
#[test_resources("src/tests/nix_tests/eval-okay-*.nix")]
fn nix_eval_okay(code_path: &str) {
    eval_test(code_path, true)
}

// eval-okay-* tests from the original Nix test suite which do not yet pass for tvix
//
// Eventually there will be none of these left, and this function
// will disappear :) Until then, to run these tests, use `cargo test
// --features expected_failures`.
//
// Please don't submit failing tests unless they're in
// notyetpassing; this makes the test suite much more useful for
// regression testing, since there should always be zero non-ignored
// failing tests.
//
// Unfortunately test_generator is unmaintained, so the PRs to make
// it understand #[ignored] has been sitting for two years, so we
// can't use `cargo test --include-ignored`, which is the normal way
// of handling this situation.
//
//   https://github.com/frehberg/test-generator/pull/10
//   https://github.com/frehberg/test-generator/pull/8
#[test_resources("src/tests/nix_tests/notyetpassing/eval-okay-*.nix")]
fn nix_eval_okay_currently_failing(code_path: &str) {
    eval_test(code_path, false)
}

// eval-fail-* tests contain a snippet of Nix code, which is
// expected to fail evaluation.  The exact type of failure
// (assertion, parse error, etc) is not currently checked.
#[test_resources("src/tests/tvix_tests/eval-fail-*.nix")]
fn eval_fail(code_path: &str) {
    eval_test(code_path, false)
}

// eval-fail-* tests from the original Nix test suite.
#[cfg(feature = "nix_tests")]
#[test_resources("src/tests/nix_tests/eval-fail-*.nix")]
fn nix_eval_fail(code_path: &str) {
    eval_test(code_path, false)
}