//! Header probes (extensions/format-probes.md): the committed corpus `format-probe-conformance/`
//! regenerates byte for byte from its external vectors and holds no other generated file,
//! every vector, binding and fact gets its stated outcome, the extension's §2.4 and §12 tables
//! are the reference's probes and codes, and projection.md §4 lists only codes of §12.
#![cfg(feature = "format_probe")]

use std::collections::BTreeMap;
use std::path::{Path, PathBuf};
use wai::format_probe::{corpus, Refusal, PROBES};

fn wai_dir() -> PathBuf {
    PathBuf::from(env!("CARGO_MANIFEST_DIR")).join("..")
}

fn walk(root: &Path, dir: &Path, out: &mut BTreeMap<String, Vec<u8>>) {
    for e in std::fs::read_dir(dir).expect("a corpus directory").flatten() {
        let p = e.path();
        if p.is_dir() {
            walk(root, &p, out);
        } else {
            let rel = p.strip_prefix(root).unwrap().to_string_lossy().replace('\\', "/");
            out.insert(rel, std::fs::read(&p).unwrap());
        }
    }
}

fn committed() -> BTreeMap<String, Vec<u8>> {
    let root = wai_dir().join("format-probe-conformance");
    let mut out = BTreeMap::new();
    for sub in ["ext", "gen"] {
        walk(&root, &root.join(sub), &mut out);
    }
    out.insert("vectors.json".into(), std::fs::read(root.join("vectors.json")).expect("vectors.json"));
    out
}

#[test]
fn the_corpus_regenerates_and_every_outcome_holds() {
    let files = committed();
    assert!(files.keys().filter(|k| k.starts_with("ext/")).count() >= 9, "the external vectors");
    let fails = corpus::verify(&files);
    assert!(fails.is_empty(), "{}: run `wai_format_probe gen`", fails.join("\n"));
}

fn section(text: &str, heading: &str) -> String {
    let at = text.find(&format!("\n{heading}")).unwrap_or_else(|| panic!("{heading}"));
    let end = text[at + 1..].find("\n## ").map_or(text.len(), |e| at + 1 + e);
    text[at..end].to_string()
}

/// §2.4 lists exactly the probes and bases of `PROBES`, in order; §12 exactly the codes of
/// `Refusal::ALL`, in order.
#[test]
fn the_extension_lists_the_probes_and_the_codes() {
    let text = std::fs::read_to_string(wai_dir().join("extensions/format-probes.md")).expect("the extension");
    let rows: Vec<(String, String)> = section(&text, "## 2. Common rules")
        .lines()
        .filter(|l| l.starts_with("| `wai."))
        .map(|l| {
            let cells: Vec<&str> = l.split('|').map(str::trim).collect();
            (cells[1].trim_matches('`').to_string(), cells[2].to_string())
        })
        .collect();
    let want: Vec<(String, String)> = PROBES.iter().map(|(c, b)| (c.to_string(), b.label().to_string())).collect();
    assert_eq!(rows, want, "§2.4's table and PROBES differ");
    let codes: Vec<String> = section(&text, "## 12. Refusals")
        .lines()
        .filter(|l| l.starts_with("| `"))
        .filter_map(|l| l.split('`').nth(1).map(String::from))
        .collect();
    let want: Vec<String> = Refusal::ALL.iter().map(|r| r.code().to_string()).collect();
    assert_eq!(codes, want, "§12's table and Refusal::ALL differ");
    // projection.md states the codes its reader and its binding check give.
    let proj = std::fs::read_to_string(wai_dir().join("extensions/projection.md")).expect("projection.md");
    let checks = section(&proj, "## 4. Checks");
    for r in [Refusal::NoSignature, Refusal::LengthMismatch, Refusal::ReservedValue, Refusal::DescriptorInvalid] {
        assert!(checks.contains(&format!("`{}`", r.code())), "projection.md §4 does not state {}", r.code());
    }
    assert!(section(&proj, "## 5. Binding to the rendition").contains("`layer_absent`"));
}

fn sha256_hex(b: &[u8]) -> String {
    use sha2::{Digest, Sha256};
    Sha256::digest(b).iter().map(|x| format!("{x:02x}")).collect()
}

/// Planted faults in the AV2, AC-4, IAMF and IVAS vectors (format-probes §14 to §17): a
/// stated profile, level, version, bit rate or codec string changed, or a header byte changed
/// with the file's digest restated so that only the outcome can catch it. `corpus::verify`
/// must report each.
#[test]
fn planted_faults_in_the_av2_ac4_iamf_and_ivas_vectors_are_caught() {
    use serde_json::{json, Value};
    let files = committed();
    let doc: Value = serde_json::from_slice(&files["vectors.json"]).unwrap();
    let find = |doc: &Value, name: &str| doc["vectors"].as_array().unwrap().iter().position(|v| v["name"] == name).unwrap_or_else(|| panic!("{name}"));
    let stated = [
        ("main420_10_1080p", "/outcome/accept/profile", json!(1)),
        ("main420_10_1080p", "/outcome/accept/level", json!("4.1")),
        ("main420_10_1080p", "/outcome/accept/codec", json!("av02.0.08M.10")),
        ("v2_crc_24fps", "/outcome/accept/codec", json!("ac-4.02.01.04")),
        ("v2_crc_24fps", "/outcome/accept/presentation/version", json!(2)),
        ("opus_simple", "/outcome/accept/codec", json!("iamf.000.000.opus")),
        ("opus_simple", "/outcome/accept/primary_profile", json!(1)),
        ("stereo_32k_two_frames_cmr", "/outcome/accept/codec", json!("sevs")),
        ("stereo_32k_two_frames_cmr", "/outcome/accept/frames/0/bitrate", json!(24400)),
    ];
    let mut caught = 0;
    for (name, ptr, value) in stated {
        let mut d = doc.clone();
        let i = find(&d, name);
        *d["vectors"][i].pointer_mut(ptr).unwrap_or_else(|| panic!("{name}{ptr}")) = value;
        let mut f = files.clone();
        f.insert("vectors.json".into(), serde_json::to_vec_pretty(&d).unwrap());
        assert!(!corpus::verify(&f).is_empty(), "{name}{ptr} restated, and nothing fails");
        caught += 1;
    }
    // Header bytes: the AV2 profile's last bit, the AC-4 frame rate index, the IAMF primary
    // profile, the IVAS ToC byte's bit rate.
    let bytes = [("main420_10_1080p", 4, 0x04u8, false), ("v0_single_44k", 5, 0x01, false), ("opus_simple", 6, 0x01, true), ("stereo_32k_two_frames_cmr", 1, 0x07, false)];
    for (name, at, x, set) in bytes {
        let mut d = doc.clone();
        let i = find(&d, name);
        let file = d["vectors"][i]["file"].as_str().unwrap().to_string();
        let mut f = files.clone();
        let mut b = f[&file].clone();
        b[at] = if set { x } else { b[at] ^ x };
        d["vectors"][i]["sha256"] = json!(sha256_hex(&b));
        f.insert(file, b);
        f.insert("vectors.json".into(), serde_json::to_vec_pretty(&d).unwrap());
        let fails = corpus::verify(&f);
        assert!(fails.iter().any(|m| m.starts_with(&format!("{name}: stated"))), "{name} byte {at}: {fails:?}");
        caught += 1;
    }
    assert_eq!(caught, 13);
}