import { mkdir, readFile, writeFile } from "node:fs/promises";
import { resolve } from "node:path";
import { Ajv } from "ajv";
import standaloneCode from "ajv/dist/standalone/index.js";
import {
  helloCapabilitiesSchema,
  requestSchema,
  responseSchema,
} from "../src/protocol/schema-definitions.js";

const root = resolve(import.meta.dirname, "..");
const manifestSchema = JSON.parse(
  await readFile(resolve(root, "src/conformance/adapter-manifest.schema.json"), "utf8"),
) as Record<string, unknown>;
const customSuiteManifestSchema = JSON.parse(
  await readFile(resolve(root, "src/custom/suite-manifest.schema.json"), "utf8"),
) as Record<string, unknown>;

const ajv = new Ajv({
  allErrors: true,
  strict: true,
  code: { source: true, esm: true, optimize: true },
});

ajv.addSchema(requestSchema, "adapter-request");
ajv.addSchema(responseSchema, "adapter-response");
ajv.addSchema(helloCapabilitiesSchema, "adapter-hello-capabilities");
ajv.addSchema(manifestSchema, "adapter-manifest");
ajv.addSchema(customSuiteManifestSchema, "custom-suite-manifest");

const ajvRuntimeUnicodeLength =
  /const (func\d+) = require\("ajv\/dist\/runtime\/ucs2length"\)\.default;/g;
const inlineUnicodeLength = (name: string) =>
  `function ${name}(value){let length=0;for(let index=0;index<value.length;index++){length++;const code=value.charCodeAt(index);if(code>=0xd800&&code<=0xdbff&&index+1<value.length){const next=value.charCodeAt(index+1);if((next&0xfc00)===0xdc00){index++;}}}return length;}`;
const generated = standaloneCode(ajv, {
  validateAdapterRequest: "adapter-request",
  validateAdapterResponse: "adapter-response",
  validateAdapterHelloCapabilities: "adapter-hello-capabilities",
  validateAdapterManifest: "adapter-manifest",
  validateCustomSuiteManifest: "custom-suite-manifest",
}).replace(ajvRuntimeUnicodeLength, (_match, name: string) => inlineUnicodeLength(name));

if (generated.includes('require("ajv/')) {
  const dependencies = generated.match(/require\("ajv\/[^"]+"\)/g) ?? [];
  throw new Error(
    `Generated validators contain unexpected Ajv runtime dependencies: ${[
      ...new Set(dependencies),
    ].join(", ")}`,
  );
}

const header = `// Generated by scripts/generate-validators.ts. Do not edit.\n// @ts-nocheck\n`;
const output = `${header}${generated}\n`;
const outputDirectory = resolve(root, "src/generated");
const outputPath = resolve(outputDirectory, "validators.ts");

if (process.argv.includes("--check")) {
  let existing: string;
  try {
    existing = await readFile(outputPath, "utf8");
  } catch {
    throw new Error("Generated validators are missing; run pnpm generate:validators");
  }
  if (existing !== output) {
    throw new Error("Generated validators are stale; run pnpm generate:validators");
  }
} else {
  await mkdir(outputDirectory, { recursive: true });
  await writeFile(outputPath, output, "utf8");
}