//! Integration tests for the compiler binary against the Hello World program.

use std::process::Command;

/// `CARGO_BIN_EXE_rust-langrpg` is injected by Cargo for integration tests and
/// always points at the freshly-built binary under `target/`.
const BIN: &str = env!("CARGO_BIN_EXE_rust-langrpg");

/// Absolute path to hello.rpg, resolved at compile time relative to the crate
/// root so the test works regardless of the working directory.
const HELLO_RPG: &str = concat!(env!("CARGO_MANIFEST_DIR"), "/hello.rpg");

// ─────────────────────────────────────────────────────────────────────────────
// Helper
// ─────────────────────────────────────────────────────────────────────────────

fn run(args: &[&str]) -> std::process::Output {
    Command::new(BIN)
        .args(args)
        .output()
        .unwrap_or_else(|e| panic!("failed to spawn '{}': {e}", BIN))
}

// ─────────────────────────────────────────────────────────────────────────────
// Tests
// ─────────────────────────────────────────────────────────────────────────────

/// The compiler should exit 0 when given hello.rpg (no -o flag — tree is
/// discarded but the parse must still succeed).
#[test]
fn hello_rpg_exits_ok() {
    let out = run(&[HELLO_RPG]);
    assert!(
        out.status.success(),
        "expected exit 0 for hello.rpg\nstderr: {}",
        String::from_utf8_lossy(&out.stderr),
    );
}

/// When -o is supplied the output file must be created and contain a non-empty
/// parse tree.
#[test]
fn hello_rpg_writes_tree() {
    let out_path = std::env::temp_dir().join("hello_rpg_test_tree.txt");

    let out = run(&["-o", out_path.to_str().unwrap(), HELLO_RPG]);

    assert!(
        out.status.success(),
        "compiler failed with -o flag\nstderr: {}",
        String::from_utf8_lossy(&out.stderr),
    );

    let tree = std::fs::read_to_string(&out_path)
        .unwrap_or_else(|e| panic!("could not read output file '{}': {e}", out_path.display()));

    assert!(
        !tree.trim().is_empty(),
        "output file is empty — expected a parse tree",
    );

    // The tree should reference at least the top-level <program> non-terminal.
    assert!(
        tree.contains("program"),
        "parse tree does not mention <program>:\n{tree}",
    );
}

/// The compiler must print the file name to stderr as "ok: hello.rpg" (or the
/// full path) when the parse succeeds.
#[test]
fn hello_rpg_reports_ok_on_stderr() {
    let out = run(&[HELLO_RPG]);

    let stderr = String::from_utf8_lossy(&out.stderr);
    assert!(
        stderr.starts_with("ok:"),
        "expected stderr to start with 'ok:'\ngot: {stderr}",
    );
}