//! #14 robustness gate: corrupt, truncated and mutated inputs must give a
//! recoverable `Err` (or a still-valid `Ok`), never a panic, hang or NaN body.
use paperdoll_renderer::{atlas::AtlasSet, equipment::Preset, preview, project};
use std::panic::{catch_unwind, AssertUnwindSafe};
use std::path::{Path, PathBuf};

fn fixture(rel: &str) -> PathBuf {
    Path::new(env!("CARGO_MANIFEST_DIR"))
        .join("tests/fixtures")
        .join(rel)
}

struct Temp(PathBuf);
impl Temp {
    fn new(tag: &str) -> Self {
        let p = std::env::temp_dir().join(format!("ppd-robust-{tag}-{}", std::process::id()));
        let _ = std::fs::remove_dir_all(&p);
        std::fs::create_dir_all(&p).unwrap();
        Temp(p)
    }
}
impl Drop for Temp {
    fn drop(&mut self) {
        let _ = std::fs::remove_dir_all(&self.0);
    }
}

/// Deterministic mutations: truncations, byte flips, zeroed and 0xFF runs.
fn mutations(bytes: &[u8], count: usize) -> Vec<Vec<u8>> {
    let mut out = vec![Vec::new(), bytes[..bytes.len() / 2].to_vec()];
    let mut seed = 0x9e37_79b9_u64;
    let mut next = || {
        seed = seed
            .wrapping_mul(6364136223846793005)
            .wrapping_add(1442695040888963407);
        (seed >> 33) as usize
    };
    for i in 0..count {
        let mut m = bytes.to_vec();
        match i % 4 {
            0 => m.truncate(next() % bytes.len()),
            1 => {
                for _ in 0..1 + next() % 8 {
                    let at = next() % m.len();
                    m[at] ^= 1 << (next() % 8);
                }
            }
            2 => {
                let at = next() % m.len();
                let end = (at + 1 + next() % 64).min(m.len());
                m[at..end].fill(0);
            }
            _ => {
                let at = next() % m.len();
                let end = (at + 1 + next() % 64).min(m.len());
                m[at..end].fill(0xff);
            }
        }
        out.push(m);
    }
    out
}

fn body_ok(body: &preview::PreviewCharacter) {
    assert!(body.positions.iter().flatten().all(|v| v.is_finite()));
    let n = body.positions.len() as u32;
    assert!(body.indices.iter().all(|i| *i < n));
}

fn fuzz_body(src: &str, ext: &str, count: usize) {
    let bytes = std::fs::read(fixture(src)).unwrap();
    let temp = Temp::new(&src.replace(['/', '.'], "-"));
    for (i, m) in mutations(&bytes, count).into_iter().enumerate() {
        let path = temp.0.join(format!("m{i}.{ext}"));
        std::fs::write(&path, &m).unwrap();
        let result = catch_unwind(AssertUnwindSafe(|| preview::load_body_file(&path)));
        match result {
            Ok(Ok(body)) => body_ok(&body),
            Ok(Err(e)) => assert!(!e.is_empty()),
            Err(_) => panic!("{src} mutation {i} panicked"),
        }
    }
}

#[test]
fn mutated_glb_bodies_never_panic() {
    fuzz_body("bodies/test-body-male.glb", "glb", 800);
    fuzz_body("bodies/static/static-body-male.glb", "glb", 80);
}

#[test]
fn mutated_fbx_body_never_panics() {
    fuzz_body("bodies/test-body-male.fbx", "fbx", 120);
}

#[test]
fn mutated_obj_body_never_panics() {
    let temp = Temp::new("obj");
    for f in ["static-body-albedo.png", "static-body-male.mtl"] {
        std::fs::copy(fixture(&format!("bodies/static/{f}")), temp.0.join(f)).unwrap();
    }
    let bytes = std::fs::read(fixture("bodies/static/static-body-male.obj")).unwrap();
    for (i, m) in mutations(&bytes, 120).into_iter().enumerate() {
        let path = temp.0.join(format!("m{i}.obj"));
        std::fs::write(&path, &m).unwrap();
        match catch_unwind(AssertUnwindSafe(|| preview::load_body_file(&path))) {
            Ok(Ok(body)) => body_ok(&body),
            Ok(Err(_)) => {}
            Err(_) => panic!("obj mutation {i} panicked"),
        }
    }
}

#[test]
fn mutated_equipment_preset_never_panics() {
    let bytes = std::fs::read(fixture("equipment/sword.ppe")).unwrap();
    for (i, m) in mutations(&bytes, 200).into_iter().enumerate() {
        if catch_unwind(AssertUnwindSafe(|| Preset::decode(&m))).is_err() {
            panic!("ppe mutation {i} panicked");
        }
    }
}

#[test]
fn mutated_project_manifest_is_a_recoverable_error() {
    let temp = Temp::new("ppd");
    let opened = project::create_project(&temp.0, "robust").unwrap();
    let text = std::fs::read(&opened.manifest_path).unwrap();
    for (i, m) in mutations(&text, 200).into_iter().enumerate() {
        let s = String::from_utf8_lossy(&m);
        if catch_unwind(AssertUnwindSafe(|| project::parse_manifest(&s))).is_err() {
            panic!("manifest mutation {i} panicked");
        }
    }
}

#[test]
fn garbage_ppda_is_an_error() {
    let temp = Temp::new("ppda");
    let cases: [&[u8]; 4] = [b"", b"{", b"{\"format\":3}", &[0xff; 64]];
    for (i, c) in cases.iter().enumerate() {
        let path = temp.0.join(format!("x{i}.ppda"));
        std::fs::write(&path, c).unwrap();
        assert!(AtlasSet::open(&path).is_err());
    }
    assert!(AtlasSet::open(&temp.0.join("missing.ppda")).is_err());
}

#[test]
fn non_finite_and_singular_gltf_transforms_are_errors() {
    let source = std::fs::read(fixture("bodies/static/static-body-male.glb")).unwrap();
    let json_len = u32::from_le_bytes(source[12..16].try_into().unwrap()) as usize;
    let doc: serde_json::Value = serde_json::from_slice(&source[20..20 + json_len]).unwrap();
    let temp = Temp::new("nan");
    let edits: [(&str, serde_json::Value); 2] = [
        ("scale0", serde_json::json!([0.0, 0.0, 0.0])),
        ("huge", serde_json::json!([3.0e38, 3.0e38, 3.0e38])),
    ];
    for (name, scale) in edits {
        let mut d = doc.clone();
        for node in d["nodes"].as_array_mut().unwrap() {
            if node.get("mesh").is_some() {
                node["scale"] = scale.clone();
            }
        }
        let mut json = serde_json::to_vec(&d).unwrap();
        while !json.len().is_multiple_of(4) {
            json.push(b' ');
        }
        let rest = &source[20 + json_len..];
        let mut out = source[0..8].to_vec();
        out.extend(((20 + json.len() + rest.len()) as u32).to_le_bytes());
        out.extend((json.len() as u32).to_le_bytes());
        out.extend(b"JSON");
        out.extend(&json);
        out.extend(rest);
        let path = temp.0.join(format!("{name}.glb"));
        std::fs::write(&path, out).unwrap();
        match preview::load_body_file(&path) {
            Err(_) => {}
            Ok(body) => panic!("{name}: loaded {} vertices", body.positions.len()),
        }
    }
}