//! CLI roundtrip: every `examples/*.ail.json` survives
//! `ail render` → tempfile → `ail parse` with BLAKE3 hash
//! identity on canonical bytes.
//!
//! This is the user-facing-surface defence line. Crate-internal
//! roundtrip tests in `ailang-surface` cover the same property
//! at the library level; this test additionally protects the
//! `ail render` and `ail parse` CLI wrappers from drift (output
//! formatting, exit codes, stdout framing).
//!
//! Pure reader: the test writes only to a `tempfile::TempDir`
//! that lives outside the repo and is cleaned up by Drop. No
//! committed content is mutated.

use std::path::{Path, PathBuf};
use std::process::Command;

fn ail_bin() -> &'static str {
    env!("CARGO_BIN_EXE_ail")
}

fn workspace_root() -> PathBuf {
    let manifest_dir = env!("CARGO_MANIFEST_DIR");
    Path::new(manifest_dir).parent().unwrap().parent().unwrap().to_path_buf()
}

fn examples_dir() -> PathBuf {
    workspace_root().join("examples")
}

fn list_json_fixtures() -> Vec<PathBuf> {
    let dir = examples_dir();
    let mut paths: Vec<PathBuf> = std::fs::read_dir(&dir)
        .unwrap_or_else(|e| panic!("read_dir({}): {e}", dir.display()))
        .filter_map(|entry| entry.ok())
        .map(|e| e.path())
        .filter(|p| {
            p.file_name()
                .and_then(|n| n.to_str())
                .map(|n| n.ends_with(".ail.json"))
                .unwrap_or(false)
        })
        .collect();
    paths.sort();
    paths
}

fn strip_trailing_newlines(mut v: Vec<u8>) -> Vec<u8> {
    while v.last() == Some(&b'\n') {
        v.pop();
    }
    v
}

/// Run the full render → parse pipeline for one fixture. Returns
/// Ok(()) on hash-identity, Err(reason) otherwise.
fn roundtrip_one(fixture: &Path, tmpdir: &Path) -> Result<(), String> {
    // Step A: load the original fixture and compute canonical bytes
    //         (independent of how the JSON file is formatted on disk).
    let original_module = ailang_core::load_module(fixture)
        .map_err(|e| format!("load_module: {e}"))?;
    let bytes_orig = ailang_core::canonical::to_bytes(&original_module);
    let h_orig = blake3::hash(&bytes_orig);

    // Step B: `ail render <fixture>` → captured stdout = ail text.
    let render_out = Command::new(ail_bin())
        .args(["render", fixture.to_str().unwrap()])
        .output()
        .map_err(|e| format!("spawn ail render: {e}"))?;
    if !render_out.status.success() {
        return Err(format!(
            "ail render exit={:?}\nstderr: {}",
            render_out.status.code(),
            String::from_utf8_lossy(&render_out.stderr),
        ));
    }

    // Step C: write the rendered .ail into the tempdir.
    let stem = fixture
        .file_name()
        .and_then(|n| n.to_str())
        .and_then(|n| n.strip_suffix(".ail.json"))
        .unwrap_or("fixture");
    let tmp_ail = tmpdir.join(format!("{stem}.round.ail"));
    std::fs::write(&tmp_ail, &render_out.stdout)
        .map_err(|e| format!("write tempfile {}: {e}", tmp_ail.display()))?;

    // Step D: `ail parse <tmp_ail>` → captured stdout = canonical
    //         bytes + trailing newline.
    let parse_out = Command::new(ail_bin())
        .args(["parse", tmp_ail.to_str().unwrap()])
        .output()
        .map_err(|e| format!("spawn ail parse: {e}"))?;
    if !parse_out.status.success() {
        return Err(format!(
            "ail parse exit={:?}\nstderr: {}",
            parse_out.status.code(),
            String::from_utf8_lossy(&parse_out.stderr),
        ));
    }
    let bytes_round = strip_trailing_newlines(parse_out.stdout);
    let h_round = blake3::hash(&bytes_round);

    if h_orig != h_round {
        let s_orig = String::from_utf8_lossy(&bytes_orig).into_owned();
        let s_round = String::from_utf8_lossy(&bytes_round).into_owned();
        return Err(format!(
            "BLAKE3 mismatch:\n  orig: {}\n  round: {}\noriginal bytes: {s_orig}\nround bytes:    {s_round}",
            h_orig.to_hex(),
            h_round.to_hex(),
        ));
    }
    Ok(())
}

#[test]
fn cli_render_then_parse_preserves_canonical_bytes_on_every_fixture() {
    let fixtures = list_json_fixtures();
    assert!(
        !fixtures.is_empty(),
        "no .ail.json fixtures found under {}",
        examples_dir().display()
    );

    let tmpdir = tempfile::TempDir::new().expect("create tempdir");
    let mut failures = Vec::<String>::new();
    let mut passed = 0usize;

    for fixture in &fixtures {
        match roundtrip_one(fixture, tmpdir.path()) {
            Ok(()) => passed += 1,
            Err(msg) => failures.push(format!("{}: {msg}", fixture.display())),
        }
    }

    if !failures.is_empty() {
        panic!(
            "CLI roundtrip failed for {} of {} fixtures (passed: {}):\n{}",
            failures.len(),
            fixtures.len(),
            passed,
            failures.join("\n\n")
        );
    }
    eprintln!("CLI roundtrip ok for {passed} fixtures");
}