import { createHash, generateKeyPairSync, KeyObject, sign } from "node:crypto";
import { describe, expect, test } from "vitest";
import { canonicalPluginSignaturePayload, parseTrustedPublicKeys, verifyPluginSignature } from "./signature.js";

function ed25519Keypair(): { privateKey: KeyObject; publicKeyHex: string } {
  const { privateKey, publicKey } = generateKeyPairSync("ed25519");
  const spki = publicKey.export({ format: "der", type: "spki" }) as Buffer;
  // SPKI prefix is 12 bytes; raw key is the last 32 bytes.
  const rawKey = spki.subarray(spki.length - 32);
  return { privateKey, publicKeyHex: rawKey.toString("hex") };
}

function signBuffer(privateKey: KeyObject, wasm: Uint8Array): string {
  return sign(null, Buffer.from(wasm), privateKey).toString("hex");
}

function signManifestPayload(privateKey: KeyObject, manifest: Record<string, unknown>, wasmSha256: string): string {
  return sign(null, Buffer.from(canonicalPluginSignaturePayload(manifest, wasmSha256), "utf8"), privateKey).toString("hex");
}

describe("verifyPluginSignature", () => {
  const wasm = new Uint8Array([0x00, 0x61, 0x73, 0x6d, 0x01, 0x00, 0x00, 0x00]);
  const wasmHash = createHash("sha256").update(wasm).digest("hex");

  test("returns ok when signature, hash and trust all match", () => {
    const { privateKey, publicKeyHex } = ed25519Keypair();
    const signatureHex = signBuffer(privateKey, wasm);

    const result = verifyPluginSignature({
      wasmBuffer: wasm,
      expectedWasmSha256: wasmHash,
      signatureHex,
      publicKeyHex,
      trustedPublicKeysHex: [publicKeyHex],
    });

    expect(result.ok).toBe(true);
  });

  test("returns ok for the canonical manifest-plus-wasm hash payload signed by the CLI", () => {
    const { privateKey, publicKeyHex } = ed25519Keypair();
    const manifest = {
      schemaVersion: 1,
      id: "de.toolctrl.test",
      version: "1.0.0",
      name: "Test",
      entry: "plugin.wasm",
      wasmSha256: wasmHash,
      signature: "0".repeat(128),
      signedBy: publicKeyHex,
      capabilities: [{ name: "log" }],
      hooks: [{ name: "workflow.executed", export: "onWorkflowExecuted" }],
    };
    const signatureHex = signManifestPayload(privateKey, manifest, wasmHash);

    const result = verifyPluginSignature({
      wasmBuffer: wasm,
      expectedWasmSha256: wasmHash,
      signatureHex,
      publicKeyHex,
      trustedPublicKeysHex: [publicKeyHex],
      manifest,
    });

    expect(result.ok).toBe(true);
  });

  test("fails when manifest content changes after signing", () => {
    const { privateKey, publicKeyHex } = ed25519Keypair();
    const manifest = { id: "de.toolctrl.test", version: "1.0.0", capabilities: [{ name: "log" }] };
    const signatureHex = signManifestPayload(privateKey, manifest, wasmHash);

    const result = verifyPluginSignature({
      wasmBuffer: wasm,
      expectedWasmSha256: wasmHash,
      signatureHex,
      publicKeyHex,
      trustedPublicKeysHex: [publicKeyHex],
      manifest: { ...manifest, capabilities: [{ name: "audit" }] },
    });

    expect(result.ok).toBe(false);
    if (!result.ok) expect(result.reason).toBe("signature_invalid");
  });

  test("fails with binary_hash_mismatch when wasm bytes differ from manifest hash", () => {
    const { privateKey, publicKeyHex } = ed25519Keypair();
    const signatureHex = signBuffer(privateKey, wasm);
    const tampered = new Uint8Array([...wasm, 0xff]);

    const result = verifyPluginSignature({
      wasmBuffer: tampered,
      expectedWasmSha256: wasmHash,
      signatureHex,
      publicKeyHex,
      trustedPublicKeysHex: [publicKeyHex],
    });

    expect(result.ok).toBe(false);
    if (!result.ok) expect(result.reason).toBe("binary_hash_mismatch");
  });

  test("fails with public_key_not_trusted when the signing key is not in the allowlist", () => {
    const { privateKey, publicKeyHex } = ed25519Keypair();
    const { publicKeyHex: otherKey } = ed25519Keypair();
    const signatureHex = signBuffer(privateKey, wasm);

    const result = verifyPluginSignature({
      wasmBuffer: wasm,
      expectedWasmSha256: wasmHash,
      signatureHex,
      publicKeyHex,
      trustedPublicKeysHex: [otherKey],
    });

    expect(result.ok).toBe(false);
    if (!result.ok) expect(result.reason).toBe("public_key_not_trusted");
  });

  test("fails with signature_invalid when the signature is tampered", () => {
    const { privateKey, publicKeyHex } = ed25519Keypair();
    const valid = signBuffer(privateKey, wasm);
    // Flip a hex char while staying in [0-9a-f] to keep the format-check happy.
    const tampered = (valid[0] === "0" ? "1" : "0") + valid.slice(1);

    const result = verifyPluginSignature({
      wasmBuffer: wasm,
      expectedWasmSha256: wasmHash,
      signatureHex: tampered,
      publicKeyHex,
      trustedPublicKeysHex: [publicKeyHex],
    });

    expect(result.ok).toBe(false);
    if (!result.ok) expect(result.reason).toBe("signature_invalid");
  });

  test("fails with malformed_input on non-hex signature", () => {
    const { publicKeyHex } = ed25519Keypair();
    const result = verifyPluginSignature({
      wasmBuffer: wasm,
      expectedWasmSha256: wasmHash,
      signatureHex: "not-hex",
      publicKeyHex,
      trustedPublicKeysHex: [publicKeyHex],
    });

    expect(result.ok).toBe(false);
    if (!result.ok) expect(result.reason).toBe("malformed_input");
  });
});

describe("parseTrustedPublicKeys", () => {
  test("returns an empty list for missing / empty env", () => {
    expect(parseTrustedPublicKeys(undefined)).toEqual([]);
    expect(parseTrustedPublicKeys("")).toEqual([]);
  });

  test("splits a CSV and lowercases hex entries", () => {
    const a = "aa".repeat(32);
    const b = "BB".repeat(32);
    expect(parseTrustedPublicKeys(`${a},${b}`)).toEqual([a, b.toLowerCase()]);
  });

  test("silently drops non-hex / wrong-length entries", () => {
    const valid = "cc".repeat(32);
    expect(parseTrustedPublicKeys(`junk,${valid},also-bad`)).toEqual([valid]);
  });
});