//! End-to-end tests for the Eq/Ord prelude shipped in milestone 23.
//!
//! These tests compile a `.ail.json` workspace via the `ail build`
//! subcommand, run the resulting native binary, and assert on stdout.
//! Together they protect:
//!
//! 1. Polymorphic-helper composition over the prelude free fns at
//!    three primitive types (`eq_ord_polymorphic_runs_end_to_end`).
//!    Property: a user-defined `forall a. Ord a => …` helper that
//!    calls `gt`/`not` is monomorphised correctly at Int / Bool / Str.
//! 2. User-ADT integration with the unified mono pass
//!    (`eq_ord_user_adt_runs_end_to_end`). Property: `instance Eq T`
//!    + `instance Ord T` for a user-defined `T` produces working
//!    mono symbols when invoked through the prelude.
//! 3. Mono-symbol body-hash stability for `eq__IntBox`
//!    (`eq_ord_user_adt_eq_intbox_hash_stable`). Property: the user
//!    instance body that the unified pass emits for IntBox is
//!    bit-stable across refactors; drift here means either a
//!    legitimate emission change (re-record) or a regression
//!    (investigate). Mirrors `crates/ail/tests/mono_hash_stability.rs`.

use ailang_check::{check_workspace, monomorphise_workspace};
use ailang_core::ast::Def;
use ailang_core::hash::def_hash;
use ailang_core::workspace::load_workspace;
use std::path::PathBuf;
use std::process::Command;

fn fixture_path(name: &str) -> PathBuf {
    PathBuf::from(env!("CARGO_MANIFEST_DIR"))
        .join("../../examples")
        .join(name)
}

fn build_and_run(fixture: &str) -> String {
    let src = fixture_path(fixture);
    let out = std::env::temp_dir().join(format!("ail_{}.bin", fixture.replace('.', "_")));

    let build = Command::new(env!("CARGO_BIN_EXE_ail"))
        .args(["build", src.to_str().unwrap(), "-o", out.to_str().unwrap()])
        .output()
        .expect("ail build");
    assert!(
        build.status.success(),
        "ail build failed:\nstdout: {}\nstderr: {}",
        String::from_utf8_lossy(&build.stdout),
        String::from_utf8_lossy(&build.stderr),
    );

    let run = Command::new(&out).output().expect("run binary");
    assert!(
        run.status.success(),
        "binary exited non-zero:\nstdout: {}\nstderr: {}",
        String::from_utf8_lossy(&run.stdout),
        String::from_utf8_lossy(&run.stderr),
    );
    String::from_utf8_lossy(&run.stdout).trim().to_string()
}

#[test]
fn eq_ord_polymorphic_runs_end_to_end() {
    let stdout = build_and_run("eq_ord_polymorphic.ail.json");
    // Helper `at_most(3, 5)` at Int = true → 1
    // `at_most(true, false)` at Bool = false → 0
    // `at_most("abc", "abd")` at Str = true → 1
    // `io/print_int` emits one int per line, so stdout is "1\n0\n1"
    // after `.trim()` strips the trailing newline.
    assert_eq!(stdout, "1\n0\n1", "expected 1\\n0\\n1, got {stdout:?}");
}

#[test]
fn eq_ord_user_adt_runs_end_to_end() {
    let stdout = build_and_run("eq_ord_user_adt.ail.json");
    // eq(MkIntBox 3, MkIntBox 3) = true → 1
    // eq(MkIntBox 3, MkIntBox 5) = false → 0
    // `io/print_int` emits one int per line; trimmed stdout is "1\n0".
    assert_eq!(stdout, "1\n0", "expected 1\\n0, got {stdout:?}");
}

#[test]
fn eq_ord_user_adt_eq_intbox_hash_stable() {
    let ws = load_workspace(&fixture_path("eq_ord_user_adt.ail.json")).expect("load");
    let diags = check_workspace(&ws);
    assert!(diags.is_empty(), "typecheck failed: {diags:#?}");
    let mono = monomorphise_workspace(&ws).expect("mono");

    // The mono symbol for `eq` at a user-defined ADT uses the
    // `<method>__<8-hex-prefix>` mangling per DESIGN.md
    // §"Mangling scheme" (primitives use the bare type name; compound
    // / user-defined types use the 8-hex BLAKE3 prefix of the
    // canonical type bytes). We look up the single `eq__` symbol
    // synthesised at `IntBox` — there is only one user instance,
    // so the find-by-prefix is unambiguous in this fixture.
    let eq_intbox = mono
        .modules
        .values()
        .flat_map(|m| m.defs.iter())
        .find_map(|d| match d {
            Def::Fn(f) if f.name.starts_with("eq__") && f.name != "eq__Int"
                && f.name != "eq__Bool" && f.name != "eq__Str" =>
            {
                Some(f)
            }
            _ => None,
        })
        .expect("eq__<IntBox-hash> not synthesised");

    // The 8-hex-prefix in the mono-symbol name is the BLAKE3 prefix
    // of the canonical IntBox type bytes (DESIGN.md §"Mangling
    // scheme"). Drift here means either the canonical-form encoding
    // changed or the type's canonical bytes changed — both warrant
    // investigation before re-pinning.
    assert_eq!(
        eq_intbox.name, "eq__cde77856",
        "eq__IntBox mono-symbol name drifted — type-mangling regression?"
    );

    // The body hash pins the unified mono pass's IntBox eq emission.
    // Drift means either a legitimate refactor (re-record) or a
    // regression in user-instance body propagation (investigate).
    let h = def_hash(&Def::Fn(eq_intbox.clone()));
    assert_eq!(
        h, "9daaffa7528d2a1c",
        "eq__IntBox body hash drifted — see mono_hash_stability.rs for the resolution pattern"
    );
}