//! End-to-End-Test: lade Beispielmodul, kompiliere zu Binary, führe es aus.
//!
//! Dieses Test schützt die wichtigste Eigenschaft der gesamten Pipeline:
//! AST → typecheck → LLVM IR → clang → Binary → korrekter stdout.

use std::path::Path;
use std::process::Command;

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

fn build_and_run(example: &str) -> String {
    // Workspace-Root liegt zwei Ebenen über dem Crate-Manifest.
    let manifest_dir = env!("CARGO_MANIFEST_DIR");
    let workspace = Path::new(manifest_dir).parent().unwrap().parent().unwrap();
    let src = workspace.join("examples").join(example);
    let tmp = std::env::temp_dir().join(format!(
        "ailang_e2e_{}_{}",
        example.replace('.', "_"),
        std::process::id()
    ));
    std::fs::create_dir_all(&tmp).unwrap();
    let out = tmp.join("bin");
    let status = Command::new(ail_bin())
        .args(["build", src.to_str().unwrap(), "-o"])
        .arg(&out)
        .status()
        .expect("ail build failed to run");
    assert!(status.success(), "ail build failed for {example}");
    let output = Command::new(&out).output().expect("execute binary");
    assert!(
        output.status.success(),
        "binary {} exited non-zero",
        out.display()
    );
    String::from_utf8(output.stdout).expect("stdout utf8")
}

#[test]
fn sum_1_to_10_is_55() {
    let stdout = build_and_run("sum.ail.json");
    assert_eq!(stdout.trim(), "55");
}

/// Schützt das Block-Tracking im Codegen: max3 hat verschachtelte `if`s,
/// und falsches phi-Block-Tracking würde hier zu falschem Ergebnis führen.
#[test]
fn max3_picks_largest() {
    let stdout = build_and_run("max3.ail.json");
    assert_eq!(stdout.trim(), "17");
}

#[test]
fn hello_world_str_lit() {
    let stdout = build_and_run("hello.ail.json");
    assert_eq!(stdout.trim(), "Hallo, AILang.");
}

/// Schützt ADT-Codegen + Match: rekursive Liste, sum_list via match auf Cons/Nil.
#[test]
fn list_sum_via_match() {
    let stdout = build_and_run("list.ail.json");
    assert_eq!(stdout.trim(), "42");
}

/// Schützt `ail diff`: ein modifizierter Body ändert den Hash von `sum`,
/// während `main` unverändert bleibt. Erwartet Exit-Code 1, `changed`
/// enthält genau `sum`, `unchanged` enthält `main`, `added`/`removed` leer.
#[test]
fn diff_detects_changed_def() {
    let manifest_dir = env!("CARGO_MANIFEST_DIR");
    let workspace = Path::new(manifest_dir).parent().unwrap().parent().unwrap();
    let src_a = workspace.join("examples").join("sum.ail.json");

    // Variante: lade sum.ail.json, mutiere den `then`-Zweig (statt 0 nun 1)
    // in der `sum`-Definition. `main` bleibt bitidentisch.
    let raw = std::fs::read(&src_a).expect("read sum.ail.json");
    let mut module: serde_json::Value = serde_json::from_slice(&raw).expect("parse sum.ail.json");
    {
        let defs = module
            .get_mut("defs")
            .and_then(|d| d.as_array_mut())
            .expect("defs array");
        for def in defs.iter_mut() {
            if def.get("name").and_then(|n| n.as_str()) == Some("sum") {
                // Ersetze den then-Zweig literal 0 → literal 1.
                let new_then = serde_json::json!({
                    "t": "lit",
                    "lit": { "kind": "int", "value": 1 }
                });
                def["body"]["then"] = new_then;
            }
        }
    }

    let tmp = std::env::temp_dir().join(format!(
        "ailang_diff_changed_{}",
        std::process::id()
    ));
    std::fs::create_dir_all(&tmp).unwrap();
    let path_b = tmp.join("sum_v2.ail.json");
    std::fs::write(&path_b, serde_json::to_vec_pretty(&module).unwrap())
        .expect("write sum_v2.ail.json");

    let output = Command::new(ail_bin())
        .args([
            "diff",
            src_a.to_str().unwrap(),
            path_b.to_str().unwrap(),
            "--json",
        ])
        .output()
        .expect("ail diff failed to run");

    let code = output.status.code().expect("process terminated by signal");
    assert_eq!(
        code,
        1,
        "expected exit code 1 for differing modules; stderr: {}",
        String::from_utf8_lossy(&output.stderr)
    );

    let stdout = String::from_utf8(output.stdout).expect("stdout utf8");
    let v: serde_json::Value =
        serde_json::from_str(stdout.trim()).expect("stdout must be valid JSON");

    let added = v["added"].as_array().expect("added array");
    let removed = v["removed"].as_array().expect("removed array");
    let changed = v["changed"].as_array().expect("changed array");
    let unchanged = v["unchanged"].as_array().expect("unchanged array");

    assert!(added.is_empty(), "expected added empty: {added:?}");
    assert!(removed.is_empty(), "expected removed empty: {removed:?}");
    assert_eq!(changed.len(), 1, "expected one changed entry: {changed:?}");
    assert_eq!(
        changed[0].get("name").and_then(|n| n.as_str()),
        Some("sum")
    );
    assert_ne!(
        changed[0].get("hash_a").and_then(|n| n.as_str()),
        changed[0].get("hash_b").and_then(|n| n.as_str()),
        "hash_a and hash_b must differ for a changed def"
    );

    assert!(
        unchanged.iter().any(|e| e.get("name").and_then(|n| n.as_str()) == Some("main")),
        "expected `main` in unchanged: {unchanged:?}"
    );
}

/// Diff eines Moduls mit sich selbst: Exit 0, alle Listen außer `unchanged` leer.
#[test]
fn diff_no_changes_exit_zero() {
    let manifest_dir = env!("CARGO_MANIFEST_DIR");
    let workspace = Path::new(manifest_dir).parent().unwrap().parent().unwrap();
    let src = workspace.join("examples").join("sum.ail.json");

    let output = Command::new(ail_bin())
        .args([
            "diff",
            src.to_str().unwrap(),
            src.to_str().unwrap(),
            "--json",
        ])
        .output()
        .expect("ail diff failed to run");

    let code = output.status.code().expect("process terminated by signal");
    assert_eq!(
        code,
        0,
        "expected exit code 0 for identical modules; stderr: {}",
        String::from_utf8_lossy(&output.stderr)
    );

    let stdout = String::from_utf8(output.stdout).expect("stdout utf8");
    let v: serde_json::Value =
        serde_json::from_str(stdout.trim()).expect("stdout must be valid JSON");

    assert!(v["added"].as_array().unwrap().is_empty());
    assert!(v["removed"].as_array().unwrap().is_empty());
    assert!(v["changed"].as_array().unwrap().is_empty());
    assert!(
        !v["unchanged"].as_array().unwrap().is_empty(),
        "self-diff should report unchanged defs"
    );
}

/// Schützt das `--json`-Diagnostic-Format für Tooling-Konsumenten.
/// `broken_unbound.ail.json` referenziert eine nicht-existente Variable;
/// erwartet wird Exit-Code 1 und mindestens ein Diagnostic mit
/// `severity == "error"` und `code == "unbound-var"`.
#[test]
fn check_json_unbound_var() {
    let manifest_dir = env!("CARGO_MANIFEST_DIR");
    let workspace = Path::new(manifest_dir).parent().unwrap().parent().unwrap();
    let src = workspace.join("examples").join("broken_unbound.ail.json");

    let output = Command::new(ail_bin())
        .args(["check", src.to_str().unwrap(), "--json"])
        .output()
        .expect("ail check --json failed to run");

    let code = output.status.code().expect("process terminated by signal");
    assert_eq!(code, 1, "expected exit code 1, stderr: {}", String::from_utf8_lossy(&output.stderr));

    let stdout = String::from_utf8(output.stdout).expect("stdout utf8");
    let diags: serde_json::Value =
        serde_json::from_str(stdout.trim()).expect("stdout must be valid JSON");
    let arr = diags.as_array().expect("diagnostics must be a JSON array");
    assert!(
        arr.iter().any(|d| {
            d.get("severity").and_then(|v| v.as_str()) == Some("error")
                && d.get("code").and_then(|v| v.as_str()) == Some("unbound-var")
        }),
        "expected at least one error diagnostic with code unbound-var; got: {stdout}"
    );
}