//! Consume the published `joule-ui-conformance/v1` pack.
//!
//! The in-crate tests call the fixture functions (`c1_errors()`, `c4_chain()`, …),
//! so they check the library against itself and never touch the published bytes.
//! The pack was written by `gen_vectors` and read back by nothing — a third party
//! told to reproduce these facts "from the published vectors alone" had no evidence
//! that the reference implementation still did.
//!
//! This test works from the files on disk. Where the pack carries an input, the
//! input comes from the pack; where it records an output, the *whole* recorded
//! output is compared, not a count or an `is_ok()`.

use joule_ui_conformance::{Budget, STEWARD_SEED, StepMeter};
use joule_ui_core::{Registry, ValidationError, Widget, validate};
use joule_ui_interaction::{
    ContentId, Interaction, InteractionLog, SealedInteraction, run_interaction, verify_chain,
};
use serde::de::DeserializeOwned;
use serde_json::Value;
use std::path::PathBuf;

fn pack_dir() -> PathBuf {
    let d = PathBuf::from(env!("CARGO_MANIFEST_DIR")).join("../../../conformance/v1");
    d.canonicalize().expect("the conformance pack must exist next to the spec")
}

fn raw(name: &str) -> Vec<u8> {
    std::fs::read(pack_dir().join(name)).unwrap_or_else(|e| panic!("read {name}: {e}"))
}

fn doc(name: &str) -> Value {
    serde_json::from_slice(&raw(name)).unwrap_or_else(|e| panic!("{name} must parse: {e}"))
}

fn field<T: DeserializeOwned>(v: &Value, key: &str) -> T {
    serde_json::from_value(v[key].clone()).unwrap_or_else(|e| panic!("field `{key}`: {e}"))
}

fn unhex(s: &str) -> Vec<u8> {
    assert!(s.len() % 2 == 0, "odd-length hex");
    (0..s.len())
        .step_by(2)
        .map(|i| u8::from_str_radix(&s[i..i + 2], 16).expect("hex digit"))
        .collect()
}

/// Every file the manifest lists is present and matches its content address. A pack
/// edited without regenerating the manifest fails here rather than being trusted.
#[test]
fn manifest_addresses_every_file_in_the_pack() {
    let m = doc("MANIFEST.json");
    assert_eq!(m["pack"], "joule-ui-conformance/v1");
    let classes: Vec<String> = field(&m, "classes");
    assert_eq!(classes, ["C1", "C2", "C3", "C4"]);

    let files = m["files"].as_object().expect("manifest lists files");
    assert_eq!(files.len(), 4, "one file per class — a wrong path must not check nothing");
    for (name, want) in files {
        let got = ContentId::of_bytes(&raw(name)).0;
        assert_eq!(&got, want.as_str().unwrap(), "{name} does not match its manifest address");
    }
}

/// C1 — the registry and both surfaces come from the pack; `validate` must reproduce
/// the *exhaustive* recorded error list exactly, in order.
#[test]
fn c1_validation_reproduces_the_exhaustive_error_list() {
    let c1 = doc("c1-validation.json");
    let registry: Registry = field(&c1, "registry");
    let valid: Widget = field(&c1, "valid_surface");
    let invalid: Widget = field(&c1, "invalid_surface");
    let want_valid: Vec<ValidationError> = field(&c1, "expected_valid_errors");
    let want_invalid: Vec<ValidationError> = field(&c1, "expected_invalid_errors");

    // Guard the pack itself, so a vacuous regeneration cannot pass as conformance.
    assert!(want_valid.is_empty(), "the valid surface must record no errors");
    assert!(want_invalid.len() >= 3, "the invalid surface plants three faults");

    assert_eq!(validate(&valid, &registry), want_valid);
    assert_eq!(validate(&invalid, &registry), want_invalid);
}

/// C2 — a metered, allowed interaction, rebuilt from the pack's surface, action,
/// inputs and meter step.
///
/// Two things the pack does not carry are taken from where they must come from: the
/// actor from the recorded interaction itself, and the handler from the spec — the
/// pack records only its output's content address, which cannot be inverted. Because
/// that address is compared, a different handler output still fails.
#[test]
fn c2_interaction_is_reproduced_from_the_pack() {
    let c2 = doc("c2-interaction.json");
    let c1 = doc("c1-validation.json");
    let surface_id: ContentId = field(&c2, "surface_id");
    let action: String = field(&c2, "action");
    let inputs: String = field(&c2, "inputs_utf8");
    let step: u64 = field(&c2, "meter_step_uj");
    let want: Interaction = field(&c2, "expected_interaction");

    // Cross-file: C2's surface id is the address of C1's valid surface, so the two
    // classes are checked against the same published surface rather than each alone.
    let valid: Widget = field(&c1, "valid_surface");
    assert_eq!(
        surface_id,
        ContentId::of_bytes(serde_json::to_string(&valid).unwrap().as_bytes()),
        "C2 surface_id must address C1's valid surface"
    );

    let meter = StepMeter::new(step);
    let got = run_interaction(
        &surface_id,
        &action,
        &want.actor,
        inputs.as_bytes(),
        &meter,
        None,
        || serde_json::to_vec(&Widget::leaf("Image").prop("intensity", 7.0)).unwrap(),
    );
    assert_eq!(got, want);
    assert_eq!(got.energy.uj(), step, "one interaction reads exactly one meter step");
}

/// C3 — a zero budget from the pack denies the action before the handler runs.
#[test]
fn c3_denial_happens_before_the_handler() {
    let c3 = doc("c3-authorization.json");
    let surface_id: ContentId = field(&c3, "surface_id");
    let action: String = field(&c3, "action");
    let budget_uj: u64 = field(&c3, "budget_uj");
    let want_ran: bool = field(&c3, "expected_handler_ran");
    let want: Interaction = field(&c3, "expected_interaction");

    assert!(!want_ran, "the pack must record that the handler did not run");
    assert_eq!(want.outputs, ContentId::genesis(), "a denial's outputs are the genesis sentinel");

    let meter = StepMeter::new(4200);
    let mut budget = Budget { remaining: budget_uj };
    let mut ran = false;
    let got = run_interaction(
        &surface_id,
        &action,
        &want.actor,
        br#"{"intensity":7}"#,
        &meter,
        Some(&mut budget),
        || {
            ran = true;
            b"never".to_vec()
        },
    );
    assert_eq!(ran, want_ran, "the handler ran despite the denial");
    assert_eq!(got, want);
}

/// C4 — the sealed chain, deserialized from the pack, verified end to end.
#[test]
fn c4_published_chain_verifies_under_the_published_steward() {
    let c4 = doc("c4-chain.json");
    let chain: Vec<SealedInteraction> = field(&c4, "chain");
    let steward_hex: String = field(&c4, "steward_verifying_key_hex");
    let want_count: usize = field(&c4, "expected_verify_ok_count");
    let breaks_at: usize = field(&c4, "expected_excise_index_1_breaks_at");

    assert_eq!(chain.len(), 3, "the pack records a three-link chain");
    assert_eq!(verify_chain(&chain), Ok(want_count));

    // The published key is the documented fixed seed (it attests nothing, by design).
    let steward = unhex(&steward_hex);
    let seed_vk = ed25519_dalek::SigningKey::from_bytes(&STEWARD_SEED).verifying_key().to_bytes();
    assert_eq!(steward, seed_vk, "published steward key must be the documented seed's");

    // `verify_chain` checks each link against the key the link *carries*. Authenticity
    // needs the carried key to be the steward's — see the forged-chain test below.
    for (i, link) in chain.iter().enumerate() {
        assert_eq!(link.signer, steward, "link {i} is not signed by the published steward");
    }

    // allow, allow, deny — as the pack's note states.
    let verdicts: Vec<bool> = chain.iter().map(|l| l.interaction.verdict.is_allow()).collect();
    assert_eq!(verdicts, [true, true, false]);

    let mut excised = chain.clone();
    excised.remove(1);
    assert_eq!(verify_chain(&excised), Err(breaks_at));
}

/// Tampering with the published bytes breaks the chain at the tampered link.
#[test]
fn c4_tampering_with_a_published_link_is_detected_at_that_link() {
    let chain: Vec<SealedInteraction> = field(&doc("c4-chain.json"), "chain");

    let mut content = chain.clone();
    content[1].interaction.action = "exfiltrate".into();
    assert_eq!(verify_chain(&content), Err(1), "a rewritten action must not verify");

    let mut sig = chain.clone();
    sig[2].signature[0] ^= 0x01;
    assert_eq!(verify_chain(&sig), Err(2), "a flipped signature bit must not verify");

    let mut order = chain.clone();
    order.swap(0, 1);
    assert_eq!(verify_chain(&order), Err(0), "reordered links must not verify");
}

/// Why the steward check above is not optional.
///
/// Re-sealing the same interactions under an unrelated key yields a chain that
/// `verify_chain` accepts in full: every signature is valid for the key its link
/// carries, `seq` counts from zero, and each `prev` links correctly. Only comparing
/// the signer against the published steward rejects it.
#[test]
fn c4_a_re_signed_chain_passes_verify_chain_but_not_the_steward_binding() {
    let chain: Vec<SealedInteraction> = field(&doc("c4-chain.json"), "chain");
    let steward = unhex(field::<String>(&doc("c4-chain.json"), "steward_verifying_key_hex").as_str());

    let mut forger = InteractionLog::new(ed25519_dalek::SigningKey::from_bytes(&[0x42; 32]));
    for link in &chain {
        forger.record(link.interaction.clone());
    }
    let forged = forger.entries();

    assert_eq!(verify_chain(forged), Ok(3), "integrity alone accepts the forgery");
    assert!(
        forged.iter().all(|l| l.signer != steward),
        "the forgery must be distinguishable only by its signer"
    );
}