import type { KeyLike } from "node:crypto";
import {
  canonicalJsonDigest,
  isSha256Hex,
  verifyEd25519Envelope,
  type Sha256Hex,
} from "./canonical-digest.ts";
import {
  type ApprovalEnvelope,
  type ApprovalTrustPolicy,
  verifyApprovalLedger,
  verifyApprovalEnvelope,
} from "./approval-envelope.ts";
import { computeProductionInputRoot } from "./production-input-root.ts";

export const APPROVAL_PROJECTION_ATTESTATION_SCHEMA =
  "portfolio-approval-projection-attestation/v1" as const;
export const APPROVAL_PROJECTION_ATTESTATION_SCOPE =
  APPROVAL_PROJECTION_ATTESTATION_SCHEMA;

export interface ContentApprovalRecord {
  recordType: string;
  publicRecordId: string;
  approvedPublicRecordHash: string;
  envelope: ApprovalEnvelope;
}

export interface AssetApprovalRecord {
  assetId: string;
  approvedManifestRecordHash: string;
  sanitizedOutputHash: string;
  envelope: ApprovalEnvelope;
}

export interface ApprovalClosure {
  approvedRecordRoot: Sha256Hex;
  approvedAssetRoot: Sha256Hex;
  approvalProofSetDigest: Sha256Hex;
  earliestApprovalExpiry: string | null;
}

export interface ApprovalProjectionAttestationPayload {
  schema: typeof APPROVAL_PROJECTION_ATTESTATION_SCHEMA;
  keyId: string;
  issuerEpoch: number;
  scope: typeof APPROVAL_PROJECTION_ATTESTATION_SCOPE;
  approvedRecordRoot: string;
  approvedAssetRoot: string;
  approvalProofSetDigest: string;
  inputDigests: {
    PortfolioContent: string;
    PublicAssetManifest: string;
    PreparedAssetSet: string;
    SiteConfig: string;
  };
  productionInputRoot: string;
  liveLedgerHeadHash: string;
  liveLedgerRevision: number;
  policyVersion: string;
  issuedAt: string;
  expiresAt: string;
  earliestApprovalExpiry: string;
}

export interface ApprovalProjectionAttestationEnvelope {
  schema: "portfolio-approval-projection-attestation-envelope/v1";
  payload: ApprovalProjectionAttestationPayload;
  signature: {
    algorithm: "Ed25519";
    encoding: "base64url-nopad";
    value: string;
  };
}

const encoder = new TextEncoder();
function utf8TupleCompare(left: string[], right: string[]): number {
  for (let field = 0; field < Math.max(left.length, right.length); field += 1) {
    const a = encoder.encode(left[field] ?? "");
    const b = encoder.encode(right[field] ?? "");
    for (let index = 0; index < Math.min(a.length, b.length); index += 1) {
      if (a[index] !== b[index]) return (a[index] ?? 0) - (b[index] ?? 0);
    }
    if (a.length !== b.length) return a.length - b.length;
  }
  return 0;
}

export function computeApprovalClosure(input: {
  contentRecords: ContentApprovalRecord[];
  assetRecords: AssetApprovalRecord[];
  trust: ApprovalTrustPolicy;
}): ApprovalClosure {
  const latestLedger = verifyApprovalLedger(input.trust);
  const ids = new Set<string>();
  const expiries: string[] = [];
  const contentTuples = input.contentRecords
    .map((record) => {
      const typedId = record.publicRecordId;
      if (ids.has(typedId)) throw new Error("Duplicate content approval ID.");
      ids.add(typedId);
      if (!isSha256Hex(record.approvedPublicRecordHash))
        throw new Error("Content record hash is invalid.");
      const payload = verifyApprovalEnvelope(record.envelope, input.trust);
      if (
        payload.recordClass !== "content" ||
        payload.recordType !== record.recordType ||
        payload.publicRecordIdOrAssetId !== record.publicRecordId ||
        payload.approvedPublicRecordHashOrManifestRecordHash !==
          record.approvedPublicRecordHash ||
        payload.sanitizedOutputHashOrNull !== null
      ) {
        throw new Error(
          "Content approval does not bind the exact emitted record.",
        );
      }
      expiries.push(payload.expiresAt);
      const envelopeDigest = canonicalJsonDigest(
        "portfolio-approval-envelope-digest/v1",
        record.envelope,
      );
      return [
        record.recordType,
        record.publicRecordId,
        record.approvedPublicRecordHash,
        envelopeDigest,
      ] as const;
    })
    .sort((a, b) => utf8TupleCompare([a[0], a[1]], [b[0], b[1]]));

  const assetTuples = input.assetRecords
    .map((record) => {
      const typedId = record.assetId;
      if (ids.has(typedId)) throw new Error("Duplicate asset approval ID.");
      ids.add(typedId);
      if (
        !isSha256Hex(record.approvedManifestRecordHash) ||
        !isSha256Hex(record.sanitizedOutputHash)
      )
        throw new Error("Asset record hash is invalid.");
      const payload = verifyApprovalEnvelope(record.envelope, input.trust);
      if (
        payload.recordClass !== "asset" ||
        payload.recordType !== "" ||
        payload.publicRecordIdOrAssetId !== record.assetId ||
        payload.approvedPublicRecordHashOrManifestRecordHash !==
          record.approvedManifestRecordHash ||
        payload.sanitizedOutputHashOrNull !== record.sanitizedOutputHash
      ) {
        throw new Error(
          "Asset approval does not bind the exact emitted record and bytes.",
        );
      }
      expiries.push(payload.expiresAt);
      const envelopeDigest = canonicalJsonDigest(
        "portfolio-approval-envelope-digest/v1",
        record.envelope,
      );
      return [
        record.assetId,
        record.approvedManifestRecordHash,
        record.sanitizedOutputHash,
        envelopeDigest,
      ] as const;
    })
    .sort((a, b) => utf8TupleCompare([a[0]], [b[0]]));

  const proofList = [
    ...contentTuples.map(
      (tuple) => ["content", tuple[0], tuple[1], tuple[3]] as const,
    ),
    ...assetTuples.map((tuple) => ["asset", "", tuple[0], tuple[3]] as const),
  ].sort((a, b) => utf8TupleCompare([a[0], a[1], a[2]], [b[0], b[1], b[2]]));

  const supplied = new Set([
    ...input.contentRecords.map(
      (record) => `content\0${record.recordType}\0${record.publicRecordId}`,
    ),
    ...input.assetRecords.map((record) => `asset\0\0${record.assetId}`),
  ]);
  const required = new Set(
    [...latestLedger.entries()]
      .filter(
        ([, envelope]) =>
          envelope.payload.decision === "approve" &&
          Date.parse(input.trust.now) < Date.parse(envelope.payload.expiresAt),
      )
      .map(([typedId]) => typedId),
  );
  if (
    supplied.size !== required.size ||
    [...supplied].some((typedId) => !required.has(typedId))
  ) {
    throw new Error(
      "Approval records are not the exact latest authenticated approved ledger projection.",
    );
  }

  return {
    approvedRecordRoot: canonicalJsonDigest("portfolio-record-closure/v1", {
      records: contentTuples,
    }),
    approvedAssetRoot: canonicalJsonDigest("portfolio-asset-closure/v1", {
      assets: assetTuples,
    }),
    approvalProofSetDigest: canonicalJsonDigest(
      "portfolio-approval-proof-set/v1",
      { envelopes: proofList },
    ),
    earliestApprovalExpiry: expiries.sort()[0] ?? null,
  };
}

export function verifyApprovalProjectionAttestation(
  envelopeValue: unknown,
  trust: {
    now: string;
    latestLedgerHeadHash: string;
    latestLedgerRevision: number;
    trustedKey: {
      keyId: string;
      issuerEpoch: number;
      scope: typeof APPROVAL_PROJECTION_ATTESTATION_SCOPE;
      publicKey: KeyLike;
      revoked?: boolean;
    };
  },
): ApprovalProjectionAttestationPayload {
  if (
    envelopeValue === null ||
    typeof envelopeValue !== "object" ||
    Array.isArray(envelopeValue)
  )
    throw new Error("Projection envelope is invalid.");
  const envelope = envelopeValue as Record<string, unknown>;
  if (
    JSON.stringify(Object.keys(envelope).sort()) !==
    JSON.stringify(["payload", "schema", "signature"])
  )
    throw new Error("Projection envelope contains unknown fields.");
  if (
    envelope.schema !== "portfolio-approval-projection-attestation-envelope/v1"
  )
    throw new Error("Projection envelope schema is invalid.");
  if (
    envelope.payload === null ||
    typeof envelope.payload !== "object" ||
    Array.isArray(envelope.payload)
  )
    throw new Error("Projection payload is invalid.");
  const payload =
    envelope.payload as unknown as ApprovalProjectionAttestationPayload;
  const payloadFields = [
    "schema",
    "keyId",
    "issuerEpoch",
    "scope",
    "approvedRecordRoot",
    "approvedAssetRoot",
    "approvalProofSetDigest",
    "inputDigests",
    "productionInputRoot",
    "liveLedgerHeadHash",
    "liveLedgerRevision",
    "policyVersion",
    "issuedAt",
    "expiresAt",
    "earliestApprovalExpiry",
  ].sort();
  if (
    JSON.stringify(Object.keys(payload).sort()) !==
    JSON.stringify(payloadFields)
  )
    throw new Error("Projection payload contains missing or unknown fields.");
  if (
    payload.schema !== APPROVAL_PROJECTION_ATTESTATION_SCHEMA ||
    payload.scope !== APPROVAL_PROJECTION_ATTESTATION_SCOPE
  )
    throw new Error("Projection payload schema/scope is invalid.");
  if (
    trust.trustedKey.revoked ||
    trust.trustedKey.scope !== payload.scope ||
    trust.trustedKey.keyId !== payload.keyId ||
    trust.trustedKey.issuerEpoch !== payload.issuerEpoch
  ) {
    throw new Error("Projection key, scope, or issuer epoch is not trusted.");
  }
  for (const digest of [
    payload.approvedRecordRoot,
    payload.approvedAssetRoot,
    payload.approvalProofSetDigest,
    payload.productionInputRoot,
    payload.liveLedgerHeadHash,
  ]) {
    if (!isSha256Hex(digest))
      throw new Error("Projection digest field is invalid.");
  }
  const inputKeys = Object.keys(payload.inputDigests).sort();
  if (
    JSON.stringify(inputKeys) !==
      JSON.stringify([
        "PortfolioContent",
        "PreparedAssetSet",
        "PublicAssetManifest",
        "SiteConfig",
      ]) ||
    Object.values(payload.inputDigests).some((digest) => !isSha256Hex(digest))
  )
    throw new Error("Projection input digest closure is invalid.");
  const expectedRoot = computeProductionInputRoot({
    portfolioContentDigest: payload.inputDigests.PortfolioContent,
    publicAssetManifestDigest: payload.inputDigests.PublicAssetManifest,
    preparedAssetSetDigest: payload.inputDigests.PreparedAssetSet,
    siteConfigDigest: payload.inputDigests.SiteConfig,
  });
  if (expectedRoot !== payload.productionInputRoot)
    throw new Error("Projection does not bind the exact four-input root.");
  if (
    payload.liveLedgerHeadHash !== trust.latestLedgerHeadHash ||
    payload.liveLedgerRevision !== trust.latestLedgerRevision
  )
    throw new Error("Projection live-ledger state is stale.");
  for (const [label, value] of [
    ["now", trust.now],
    ["issuedAt", payload.issuedAt],
    ["expiresAt", payload.expiresAt],
    ["earliestApprovalExpiry", payload.earliestApprovalExpiry],
  ] as const) {
    if (
      !/^\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}(?:\.\d{1,3})?Z$/u.test(value) ||
      Number.isNaN(Date.parse(value))
    )
      throw new Error(`${label} timestamp is invalid.`);
  }
  if (
    Date.parse(payload.issuedAt) > Date.parse(trust.now) ||
    Date.parse(trust.now) >= Date.parse(payload.expiresAt) ||
    Date.parse(payload.expiresAt) > Date.parse(payload.earliestApprovalExpiry)
  )
    throw new Error("Projection is outside its trusted expiry bounds.");
  return verifyEd25519Envelope(
    envelope as unknown as ApprovalProjectionAttestationEnvelope,
    trust.trustedKey,
  );
}