//! Joule Code conformance harness (SPEC §8).
//!
//! Loads the published wire vectors and runs the four suites:
//! C1 content addressing, C2 signing, C3 receipt, C4 cascade. Each vector is
//! reported PASS / FAIL / SKIP. SKIP marks a positive crypto vector whose
//! derived field is a placeholder pending regeneration against this library
//! (see `conformance/v1/regeneration.md`); the structural and negative checks,
//! the real Ed25519 known-answer vectors, and the entire cascade suite run for
//! real. Any FAIL makes the run non-zero (CI-ready).

use std::collections::BTreeMap;
use std::path::Path;

use ed25519_dalek::{Signature, Verifier, VerifyingKey};
use joule_code_cargo::{Anchor, CargoError, CodingOp, Edit};
use joule_code_receipt::{Energy, Provenance, Receipt, ReceiptError};
use joule_code_cascade::Cascade;
use joule_code_schema::{ContentId, Tier};
use serde::Deserialize;

/// The outcome of a run over one or more suites.
#[derive(Default, Debug)]
pub struct Report {
    pub pass: u32,
    pub fail: u32,
    pub skip: u32,
    pub lines: Vec<String>,
}

impl Report {
    fn pass(&mut self, name: &str) {
        self.pass += 1;
        self.lines.push(format!("  PASS {name}"));
    }
    fn fail(&mut self, name: &str, why: &str) {
        self.fail += 1;
        self.lines.push(format!("  FAIL {name}: {why}"));
    }
    fn skip(&mut self, name: &str, why: &str) {
        self.skip += 1;
        self.lines.push(format!("  SKIP {name}: {why}"));
    }
    /// Merge another report into this one.
    pub fn absorb(&mut self, other: Report) {
        self.pass += other.pass;
        self.fail += other.fail;
        self.skip += other.skip;
        self.lines.extend(other.lines);
    }
}

fn is_placeholder(s: &str) -> bool {
    s.contains("PLACEHOLDER")
}

// ---------- JSON mirrors of the vector files ----------

#[derive(Deserialize)]
struct OpVector {
    name: String,
    op: OpJson,
    expected_op_id: Option<String>,
    error: Option<String>,
}

#[derive(Deserialize)]
struct OpJson {
    alg: u8,
    prior: String,
    edits: Vec<EditJson>,
    author: String,
    intent: String,
    tier: Tier,
}

#[derive(Deserialize)]
struct EditJson {
    path: String,
    anchor: AnchorJson,
    replacement_hex: String,
}

#[derive(Deserialize)]
enum AnchorJson {
    ByteRange { start: u64, end: u64 },
    Hunk { hunk_id: String },
}

impl OpJson {
    fn to_op(&self) -> Result<CodingOp, String> {
        let mut author = [0u8; 32];
        let bytes = hex::decode(&self.author).map_err(|e| e.to_string())?;
        if bytes.len() != 32 {
            return Err("author key must be 32 bytes".into());
        }
        author.copy_from_slice(&bytes);
        let edits = self
            .edits
            .iter()
            .map(|e| {
                Ok(Edit {
                    path: e.path.clone(),
                    anchor: match &e.anchor {
                        AnchorJson::ByteRange { start, end } => Anchor::ByteRange {
                            start: *start,
                            end: *end,
                        },
                        AnchorJson::Hunk { hunk_id } => Anchor::Hunk {
                            hunk_id: ContentId(hunk_id.clone()),
                        },
                    },
                    replacement: hex::decode(&e.replacement_hex).map_err(|x| x.to_string())?,
                })
            })
            .collect::<Result<Vec<_>, String>>()?;
        Ok(CodingOp {
            alg: self.alg,
            prior: ContentId(self.prior.clone()),
            edits,
            author,
            intent: self.intent.clone(),
            tier: self.tier,
        })
    }
}

#[derive(Deserialize)]
struct SigVector {
    name: String,
    verifying_key: Option<String>,
    message_hex: Option<String>,
    signature: Option<String>,
    /// Present for op-binding cases: the signature preimage is `op_id ‖ prior`.
    op_id: Option<String>,
    prior: Option<String>,
    expected_verify: bool,
}

#[derive(Deserialize)]
struct ReceiptVector {
    name: String,
    receipt: ReceiptJson,
    steward: Option<String>,
    endpoint_verifying_key: Option<String>,
    expected_envelope: Option<String>,
    expected_verify: bool,
    error: Option<String>,
}

#[derive(Deserialize)]
struct ReceiptJson {
    op_id: String,
    tier: Tier,
    energy: EnergyJson,
    sequence: u64,
    nonce: String,
}

#[derive(Deserialize)]
struct EnergyJson {
    measured_uj: Option<u64>,
    estimated_uj: u64,
    provenance: Provenance,
}

#[derive(Deserialize)]
struct CascadeVector {
    name: String,
    stages: Vec<Tier>,
    stage_closes: BTreeMap<String, bool>,
    expected_closing_tier: Option<Tier>,
}

fn parse_tier(s: &str) -> Option<Tier> {
    match s {
        "L0" => Some(Tier::L0),
        "L1" => Some(Tier::L1),
        "L2" => Some(Tier::L2),
        "L3" => Some(Tier::L3),
        "L4" => Some(Tier::L4),
        _ => None,
    }
}

// Map a CargoError to the stable error token used in the vectors.
fn cargo_error_token(e: &CargoError) -> &'static str {
    match e {
        CargoError::EditsOverlap => "edits_overlap",
        CargoError::EditsMisordered => "edits_misordered",
        CargoError::UnknownAlgorithm(_) => "unknown_algorithm",
        CargoError::NoEdits => "no_edits",
        _ => "other",
    }
}

fn receipt_error_token(e: &ReceiptError) -> &'static str {
    match e {
        ReceiptError::HwShuntRequiresMeasured => "hwshunt_requires_measured",
        ReceiptError::EstimatorMustNotCarryMeasured => "estimator_must_not_carry_measured",
        _ => "other",
    }
}

// ---------- the four suites ----------

/// C1 — content addressing. Recompute `op_id`; honor expected errors.
pub fn verify_coding_ops(json: &str) -> Result<Report, String> {
    let vectors: Vec<OpVector> = serde_json::from_str(json).map_err(|e| e.to_string())?;
    let mut r = Report::default();
    for v in vectors {
        let op = match v.op.to_op() {
            Ok(op) => op,
            Err(e) => {
                r.fail(&v.name, &format!("malformed vector: {e}"));
                continue;
            }
        };
        match (op.op_id(), v.error.as_deref()) {
            // Expected an error and got the right one.
            (Err(e), Some(expected)) => {
                if cargo_error_token(&e) == expected {
                    r.pass(&v.name);
                } else {
                    r.fail(&v.name, &format!("wrong error: got {}, want {expected}", cargo_error_token(&e)));
                }
            }
            // Expected an error, got an id.
            (Ok(_), Some(expected)) => r.fail(&v.name, &format!("expected error {expected}, got an op_id")),
            // Expected success.
            (Ok(id), None) => match v.expected_op_id {
                Some(expected) if is_placeholder(&expected) => {
                    r.skip(&v.name, &format!("op_id pending regen (computed {id})"));
                }
                Some(expected) => {
                    if id.as_str() == expected {
                        r.pass(&v.name);
                    } else {
                        r.fail(&v.name, &format!("op_id mismatch: got {id}, want {expected}"));
                    }
                }
                None => r.fail(&v.name, "no expected_op_id and no error"),
            },
            (Err(e), None) => r.fail(&v.name, &format!("unexpected error: {e}")),
        }
    }
    Ok(r)
}

/// C2 — signing. Real Ed25519 known-answer cases run; op-binding cases whose
/// signature is a placeholder are skipped pending regeneration.
pub fn verify_signatures(json: &str) -> Result<Report, String> {
    let vectors: Vec<SigVector> = serde_json::from_str(json).map_err(|e| e.to_string())?;
    let mut r = Report::default();
    for v in vectors {
        let (Some(vk_hex), Some(sig_hex)) = (&v.verifying_key, &v.signature) else {
            r.skip(&v.name, "no key/signature");
            continue;
        };
        if is_placeholder(sig_hex) {
            r.skip(&v.name, "signature pending regen");
            continue;
        }
        let ok = (|| -> Result<bool, String> {
            let vk_bytes: [u8; 32] = hex::decode(vk_hex)
                .map_err(|e| e.to_string())?
                .try_into()
                .map_err(|_| "vk len".to_string())?;
            let sig_bytes: [u8; 64] = hex::decode(sig_hex)
                .map_err(|e| e.to_string())?
                .try_into()
                .map_err(|_| "sig len".to_string())?;
            // KAT cases verify a raw message; op-binding cases verify over the
            // preimage `op_id ‖ prior` (joule-code-cargo's signing preimage).
            let msg: Vec<u8> = if let Some(msg_hex) = &v.message_hex {
                hex::decode(msg_hex).map_err(|e| e.to_string())?
            } else if let (Some(op_id), Some(prior)) = (&v.op_id, &v.prior) {
                let mut pre = op_id.as_bytes().to_vec();
                pre.extend_from_slice(prior.as_bytes());
                pre
            } else {
                return Err("vector has neither message_hex nor op_id+prior".into());
            };
            let vk = VerifyingKey::from_bytes(&vk_bytes).map_err(|e| e.to_string())?;
            Ok(vk.verify(&msg, &Signature::from_bytes(&sig_bytes)).is_ok())
        })();
        match ok {
            Ok(got) if got == v.expected_verify => r.pass(&v.name),
            Ok(got) => r.fail(&v.name, &format!("verify={got}, expected {}", v.expected_verify)),
            Err(e) => r.fail(&v.name, &e),
        }
    }
    Ok(r)
}

/// C3 — receipt. The provenance↔measured coupling runs for real; positive
/// signature reproduction is skipped pending regeneration.
pub fn verify_receipts(json: &str) -> Result<Report, String> {
    let vectors: Vec<ReceiptVector> = serde_json::from_str(json).map_err(|e| e.to_string())?;
    let mut r = Report::default();
    for v in vectors {
        let energy = Energy {
            measured_uj: v.receipt.energy.measured_uj,
            estimated_uj: v.receipt.energy.estimated_uj,
            provenance: v.receipt.energy.provenance,
        };
        match (energy.check_provenance(), v.error.as_deref()) {
            (Err(e), Some(expected)) => {
                if receipt_error_token(&e) == expected {
                    r.pass(&v.name);
                } else {
                    r.fail(&v.name, &format!("wrong error: got {}, want {expected}", receipt_error_token(&e)));
                }
            }
            (Ok(()), Some(expected)) => r.fail(&v.name, &format!("expected error {expected}, got valid")),
            (Err(e), None) => r.fail(&v.name, &format!("unexpected provenance error: {e}")),
            (Ok(()), None) => {
                // Coupling holds; verify the JCR-1 COSE_Sign1 envelope for real.
                let Some(env_hex) = v.expected_envelope.as_deref() else {
                    r.fail(&v.name, "positive vector missing expected_envelope");
                    continue;
                };
                if is_placeholder(env_hex) {
                    r.skip(&v.name, "coupling OK; envelope pending regen");
                    continue;
                }
                match verify_receipt_envelope(&v, energy, env_hex) {
                    Ok(ok) if ok == v.expected_verify => r.pass(&v.name),
                    Ok(ok) => r.fail(&v.name, &format!("verify={ok}, expected {}", v.expected_verify)),
                    Err(e) => r.fail(&v.name, &e),
                }
            }
        }
    }
    Ok(r)
}

/// Reconstruct the [`Receipt`] from a vector and verify its JCR-1 COSE_Sign1
/// envelope against the endpoint key + steward (SPEC §6).
fn verify_receipt_envelope(v: &ReceiptVector, energy: Energy, env_hex: &str) -> Result<bool, String> {
    let steward = v.steward.as_deref().ok_or("missing steward")?;
    let vk_hex = v
        .endpoint_verifying_key
        .as_deref()
        .ok_or("missing endpoint_verifying_key")?;
    let vk_bytes: [u8; 32] = hex::decode(vk_hex)
        .map_err(|e| e.to_string())?
        .try_into()
        .map_err(|_| "endpoint key len".to_string())?;
    let envelope = hex::decode(env_hex).map_err(|e| e.to_string())?;
    let nonce: [u8; 8] = hex::decode(&v.receipt.nonce)
        .map_err(|e| e.to_string())?
        .try_into()
        .map_err(|_| "nonce len".to_string())?;
    let receipt = Receipt {
        op_id: ContentId(v.receipt.op_id.clone()),
        tier: v.receipt.tier,
        energy,
        sequence: v.receipt.sequence,
        nonce,
    };
    Ok(receipt.verify_envelope(&envelope, steward, &vk_bytes).is_ok())
}

/// C4 — cascade. Fully checkable: select the closing tier under
/// stop-at-first-close and compare to the vector.
pub fn verify_cascade(json: &str) -> Result<Report, String> {
    let vectors: Vec<CascadeVector> = serde_json::from_str(json).map_err(|e| e.to_string())?;
    let mut r = Report::default();
    for v in vectors {
        let closes = |t: Tier| -> bool {
            v.stage_closes
                .iter()
                .any(|(k, &c)| parse_tier(k) == Some(t) && c)
        };
        let got = Cascade::select_closing_tier(&v.stages, closes);
        if got == v.expected_closing_tier {
            r.pass(&v.name);
        } else {
            r.fail(
                &v.name,
                &format!("closing tier got {got:?}, expected {:?}", v.expected_closing_tier),
            );
        }
    }
    Ok(r)
}

// ---------- C5: the JCP-gated cascade ----------

#[derive(Deserialize)]
struct GatedStageVector {
    tier: String,
    closes: bool,
}

#[derive(Deserialize)]
struct GatedExpect {
    closing_tiers: Vec<Option<String>>,
    spent_uj: u64,
    verdicts: Vec<String>,
    deny_reasons: Vec<String>,
}

#[derive(Deserialize)]
struct GatedVector {
    name: String,
    stages: Vec<GatedStageVector>,
    granted_actions: Vec<String>,
    budget_uj: u64,
    runs: u32,
    expected: GatedExpect,
}

/// Scripted stage for C5: closes (or not) at its tier.
struct Scripted {
    tier: Tier,
    closes: bool,
}

impl joule_code_cascade::Stage for Scripted {
    fn tier(&self) -> Tier {
        self.tier
    }
    fn try_resolve(
        &self,
        _req: &joule_code_cascade::Request,
    ) -> Option<joule_code_cascade::Resolution> {
        if !self.closes {
            return None;
        }
        Some(joule_code_cascade::Resolution {
            op: None,
            answer: Some(format!("closed at {:?}", self.tier)),
            receipt: Receipt {
                op_id: ContentId::of_bytes(b"c5-op"),
                tier: self.tier,
                energy: Energy {
                    measured_uj: None,
                    estimated_uj: joule_code_jcp::tier_cost_estimate(self.tier),
                    provenance: Provenance::Estimator,
                },
                sequence: 0,
                nonce: [0; 8],
            },
        })
    }
}

/// C5 — the JCP-gated cascade (SPEC §5.1). Runs the REAL jcp runtime: per
/// vector, issue a grant naming `granted_actions` with `budget_uj` over the
/// fixed fixture identities, wrap the scripted stages with the gate, run the
/// cascade `runs` times, and compare closing tiers, total debit, and the
/// sealed receipt verdicts (deny reasons included — a denial is evidence, not
/// a silent skip).
///
/// Fixture constants (third-party implementations must use the same):
/// issuer key = [1;32], agent key = [2;32], steward key = [7;32],
/// steward did = "did:example:joule-code",
/// resource = ContentId::of_bytes(b"repo:joule-code"),
/// request = { prior: "tree-hash", intent: "rename the function" },
/// per-tier costs = `tier_cost_estimate` (SPEC §1.1 class markers).
pub fn verify_gated_cascade(json: &str) -> Result<Report, String> {
    use ed25519_dalek::SigningKey;
    use jcp_schema::{Capability, Did, Grant};

    let vectors: Vec<GatedVector> = serde_json::from_str(json).map_err(|e| e.to_string())?;
    let mut r = Report::default();
    let issuer = SigningKey::from_bytes(&[1; 32]);
    let agent = SigningKey::from_bytes(&[2; 32]);
    let steward_sk = SigningKey::from_bytes(&[7; 32]);
    let steward = "did:example:joule-code";
    let steward_vk = steward_sk.verifying_key().to_bytes();
    let tree = jcp_schema::ContentId::of_bytes(b"repo:joule-code");

    'vectors: for v in vectors {
        let grant = Grant {
            issuer: Did::from_verifying_key(&issuer.verifying_key()),
            subject: Did::from_verifying_key(&agent.verifying_key()),
            capability: Capability::new(tree, v.granted_actions.iter().map(String::as_str)),
            budget_uj: v.budget_uj,
            budget_funds: None,
            caveats: Vec::new(),
            expiry: 0,
            parent: None,
            delegate_depth: None,
            nonce: [0; 16],
        };
        let chain = match jcp_grant::issue(&issuer, grant) {
            Ok(sg) => vec![sg],
            Err(e) => {
                r.fail(&v.name, &format!("grant issue: {e:?}"));
                continue;
            }
        };
        let gate = joule_code_jcp::JcpGate::new(
            chain,
            Did::from_verifying_key(&agent.verifying_key()),
            steward_sk.clone(),
            steward,
        );
        let mut stages: Vec<Box<dyn joule_code_cascade::Stage>> = Vec::new();
        for s in &v.stages {
            let Some(tier) = parse_tier(&s.tier.to_uppercase()) else {
                r.fail(&v.name, &format!("bad tier {:?}", s.tier));
                continue 'vectors;
            };
            stages.push(Box::new(gate.wrap(Scripted { tier, closes: s.closes })));
        }
        let cascade = Cascade::new(stages);
        let req = joule_code_cascade::Request {
            prior: "tree-hash".into(),
            intent: "rename the function".into(),
        };

        let mut closings: Vec<Option<String>> = Vec::new();
        for _ in 0..v.runs {
            closings.push(
                cascade
                    .resolve(&req)
                    .map(|res| format!("{:?}", res.receipt.tier).to_lowercase()),
            );
        }
        let expected_closings: Vec<Option<String>> = v
            .expected
            .closing_tiers
            .iter()
            .map(|t| t.as_ref().map(|s| s.to_lowercase()))
            .collect();
        if closings != expected_closings {
            r.fail(&v.name, &format!("closings got {closings:?}, want {expected_closings:?}"));
            continue;
        }
        if gate.spent() != v.expected.spent_uj {
            r.fail(&v.name, &format!("spent got {}, want {}", gate.spent(), v.expected.spent_uj));
            continue;
        }
        let mut verdicts = Vec::new();
        let mut deny_reasons = Vec::new();
        for sealed in gate.receipts() {
            match jcp_receipt::extract(&sealed, steward, &steward_vk) {
                Ok(rec) => {
                    verdicts.push(rec.verdict.clone());
                    if let Some(reason) = rec.deny_reason {
                        deny_reasons.push(reason);
                    }
                }
                Err(e) => {
                    r.fail(&v.name, &format!("receipt extract: {e:?}"));
                    continue 'vectors;
                }
            }
        }
        if verdicts != v.expected.verdicts {
            r.fail(&v.name, &format!("verdicts got {verdicts:?}, want {:?}", v.expected.verdicts));
            continue;
        }
        if deny_reasons != v.expected.deny_reasons {
            r.fail(&v.name, &format!("deny reasons got {deny_reasons:?}, want {:?}", v.expected.deny_reasons));
            continue;
        }
        r.pass(&v.name);
    }
    Ok(r)
}

/// Verify a whole pack directory (the five suite files).
pub fn verify_pack(dir: &Path) -> Result<Report, String> {
    let mut report = Report::default();
    type Suite = (&'static str, fn(&str) -> Result<Report, String>);
    let suites: &[Suite] = &[
        ("coding_op_vectors.json", verify_coding_ops),
        ("signature_vectors.json", verify_signatures),
        ("receipt_vectors.json", verify_receipts),
        ("cascade_vectors.json", verify_cascade),
        ("gated_cascade_vectors.json", verify_gated_cascade),
    ];
    for (file, f) in suites {
        let path = dir.join(file);
        report.lines.push(format!("[{file}]"));
        let json = std::fs::read_to_string(&path)
            .map_err(|e| format!("{}: {e}", path.display()))?;
        report.absorb(f(&json)?);
    }
    Ok(report)
}