//! Byte-exact conformance against the frozen TCE vectors produced by the
//! reference implementation. The vectors file lives in the relay repo at
//! ~/niko_trust/testdata/vectors/tce_vectors.json and is the normative ground
//! truth. If the file is absent the tests are skipped (keeps this crate
//! self-contained).

use std::collections::BTreeMap;
use std::path::{Path, PathBuf};

use niko_trust_gui::address::Address;
use niko_trust_gui::protocol::{self, Decision, MAX_CLOCK_SKEW};
use niko_trust_gui::signer::{self, Signer};
use niko_trust_gui::tce::number::canonical_number;
use niko_trust_gui::tce::value::Value;
use serde_json::Value as Json;

fn vectors_path() -> PathBuf {
    if let Ok(p) = std::env::var("NIKO_VECTORS") {
        return PathBuf::from(p);
    }
    let d = std::env::var("CARGO_MANIFEST_DIR").unwrap_or_else(|_| ".".into());
    Path::new(&d).join("../niko_trust/testdata/vectors/tce_vectors.json")
}

fn load_vectors() -> Option<Json> {
    let p = vectors_path();
    if !p.exists() {
        eprintln!("skipping: vectors file not found at {}", p.display());
        return None;
    }
    let raw = std::fs::read_to_string(&p).expect("read vectors");
    serde_json::from_str(&raw).map(Some).expect("parse vectors json")
}

fn pubkey_of(addr: &str) -> [u8; 32] {
    let a = Address::parse(addr).expect("valid address");
    *a.pubkey()
}

fn seed_for_pubkey(parties: &Json, pubkey_hex: &str) -> [u8; 32] {
    for (_name, p) in parties.as_object().unwrap() {
        if p["pubkey_hex"].as_str() == Some(pubkey_hex) {
            let s = hex::decode(p["seed_hex"].as_str().unwrap()).unwrap();
            return s.try_into().unwrap();
        }
    }
    panic!("party not found for pubkey {pubkey_hex}")
}

fn signer_for(parties: &Json, pubkey_hex: &str) -> Signer {
    Signer::from_seed(seed_for_pubkey(parties, pubkey_hex)).expect("signer")
}

fn hex_bytes(s: &str) -> Vec<u8> {
    hex::decode(s).expect("hex")
}

fn value_from_json(v: &Json) -> Value {
    match v {
        Json::Null => Value::Null,
        Json::Bool(b) => Value::Bool(*b),
        Json::String(s) => Value::Str(s.clone()),
        Json::Number(n) => Value::Number(n.to_string()),
        other => panic!("unsupported value in vector json: {other}"),
    }
}

fn map_from_json(v: &Json) -> BTreeMap<String, Value> {
    let mut m = BTreeMap::new();
    for (k, val) in v.as_object().unwrap() {
        m.insert(k.clone(), value_from_json(val));
    }
    m
}

fn nonce_from_json(v: &Json) -> [u8; 16] {
    hex_bytes(v.as_str().unwrap()).try_into().unwrap()
}

fn hash_from_json(v: &Json) -> [u8; 32] {
    hex_bytes(v.as_str().unwrap()).try_into().unwrap()
}

fn check_vector(parties: &Json, v: &Json) {
    let tce_expected = hex_bytes(v["tce_hex"].as_str().unwrap());
    let object_id = v["object_id_hex"].as_str().unwrap();
    let signer_key = v["signer_pubkey_hex"].as_str().unwrap();
    let _ = v["signature_hex"];
    let j = &v["json"];
    let typ = j["type"].as_str().unwrap();
    let signer = signer_for(parties, signer_key);

    // Build the typed object from the json view.
    let encoded: Vec<u8> = match typ {
        "identity" => protocol::encode_identity(&protocol::Identity {
            pubkey: signer.pubkey(),
            alias: j["alias"].as_str().unwrap().to_string(),
            created_at: j["created_at"].as_u64().unwrap(),
        })
        .unwrap(),
        "claim" => protocol::encode_claim(&protocol::Claim {
            issuer: signer.pubkey(),
            subject: pubkey_of(j["subject"].as_str().unwrap()),
            claims: map_from_json(&j["claims"]),
            created_at: j["created_at"].as_u64().unwrap(),
            expires_at: j["expires_at"].as_u64().unwrap(),
            serial: j["serial"].as_u64().unwrap(),
            nonce: nonce_from_json(&j["nonce"]),
        })
        .unwrap(),
        "revocation" => protocol::encode_revocation(&protocol::Revocation {
            issuer: signer.pubkey(),
            claim_id: hash_from_json(&j["claim_id"]),
            reason: j["reason"].as_str().unwrap().to_string(),
            created_at: j["created_at"].as_u64().unwrap(),
            nonce: nonce_from_json(&j["nonce"]),
        })
        .unwrap(),
        "approval_request" => protocol::encode_approval_request(&protocol::ApprovalRequest {
            sender: signer.pubkey(),
            recipient: pubkey_of(j["recipient"].as_str().unwrap()),
            action: j["action"].as_str().unwrap().to_string(),
            payload: map_from_json(&j["payload"]),
            message: j["message"].as_str().unwrap().to_string(),
            created_at: j["created_at"].as_u64().unwrap(),
            expires_at: j["expires_at"].as_u64().unwrap(),
            nonce: nonce_from_json(&j["nonce"]),
        })
        .unwrap(),
        "approval_response" => {
            let decision = match j["decision"].as_str().unwrap() {
                "allow" => Decision::Allow,
                "deny" => Decision::Deny,
                other => panic!("bad decision {other}"),
            };
            protocol::encode_approval_response(&protocol::ApprovalResponse {
                request_hash: hash_from_json(&j["request_hash"]),
                responder: signer.pubkey(),
                decision,
                created_at: j["created_at"].as_u64().unwrap(),
                nonce: nonce_from_json(&j["nonce"]),
            })
            .unwrap()
        }
        "auth_assertion" => protocol::encode_auth_assertion(&protocol::AuthAssertion {
            pubkey: signer.pubkey(),
            challenge: hash_from_json(&j["challenge"]),
            scope: j["scope"].as_str().unwrap().to_string(),
            audience: j["audience"].as_str().unwrap().to_string(),
            created_at: j["created_at"].as_u64().unwrap(),
        })
        .unwrap(),
        other => panic!("unknown vector type {other}"),
    };

    assert_eq!(encoded, tce_expected, "vector {}: encoded bytes differ", v["name"]);
    assert_eq!(
        hex::encode(niko_trust_gui::crypto::sha256(&encoded)),
        object_id,
        "vector {}: object id differs",
        v["name"]
    );

    // Deterministic Ed25519 must reproduce the reference signature.
    let sig = signer.sign(&encoded);
    assert_eq!(hex::encode(sig), v["signature_hex"], "vector {}: signature differs", v["name"]);

    // Rule checks on the decoded form.
    let _ = MAX_CLOCK_SKEW;

    // decode -> re-encode round trip must be byte-identical.
    let reencoded: Vec<u8> = match typ {
        "identity" => {
            let d = protocol::decode_identity(&tce_expected).unwrap();
            protocol::encode_identity(&d).unwrap()
        }
        "claim" => {
            let d = protocol::decode_claim(&tce_expected).unwrap();
            protocol::encode_claim(&d).unwrap()
        }
        "revocation" => {
            let d = protocol::decode_revocation(&tce_expected).unwrap();
            protocol::encode_revocation(&d).unwrap()
        }
        "approval_request" => {
            let d = protocol::decode_approval_request(&tce_expected).unwrap();
            protocol::encode_approval_request(&d).unwrap()
        }
        "approval_response" => {
            let d = protocol::decode_approval_response(&tce_expected).unwrap();
            protocol::encode_approval_response(&d).unwrap()
        }
        "auth_assertion" => {
            let d = protocol::decode_auth_assertion(&tce_expected).unwrap();
            protocol::encode_auth_assertion(&d).unwrap()
        }
        _ => unreachable!(),
    };
    assert_eq!(reencoded, tce_expected, "vector {}: decode/re-encode differs", v["name"]);

    // Signature verification over the exact bytes with the embedded key.
    let verify_pub = match typ {
        "claim" => pubkey_of(j["issuer"].as_str().unwrap()),
        "approval_response" => signer.pubkey(),
        "revocation" => signer.pubkey(),
        "approval_request" => signer.pubkey(),
        "auth_assertion" => signer.pubkey(),
        "identity" => signer.pubkey(),
        _ => unreachable!(),
    };
    let sig_vec = hex_bytes(v["signature_hex"].as_str().unwrap());
    let sig_arr: [u8; 64] = sig_vec.try_into().unwrap();
    signer::verify(&verify_pub, &tce_expected, &sig_arr).expect("signature must verify");
}

#[test]
fn frozen_tce_vectors_byte_exact() {
    let Some(doc) = load_vectors() else { return };
    let parties = &doc["parties"];
    for v in doc["vectors"].as_array().unwrap() {
        check_vector(parties, v);
    }
    assert!(doc["vectors"].as_array().unwrap().len() >= 9);
}

#[test]
fn number_canonicalization_vectors() {
    let Some(doc) = load_vectors() else { return };
    let nc = &doc["number_canonicalization"];
    for (input, want) in nc["accept"].as_object().unwrap() {
        assert_eq!(
            canonical_number(input).ok(),
            Some(want.as_str().unwrap().to_string()),
            "accept {input}"
        );
    }
    for (input, _reason) in nc["reject"].as_object().unwrap() {
        assert!(canonical_number(input).is_err(), "reject {input}");
    }
}

#[test]
fn strict_decoder_rejects() {
    let Some(doc) = load_vectors() else { return };
    // Every reject vector is hex bytes that a strict decoder must refuse as a
    // Claim (the reference uses a claim context for these). Failing to decode
    // is the assertion.
    for r in doc["rejects"].as_array().unwrap() {
        let name = r["name"].as_str().unwrap();
        // Some reject rows are prose descriptions without bytes; only rows
        // carrying tce_hex are byte-checkable here.
        let Some(b) = r["tce_hex"].as_str().map(hex_bytes) else {
            continue;
        };
        assert!(
            niko_trust_gui::protocol::decode_claim(&b).is_err(),
            "reject vector {name} must fail to decode"
        );
    }
}