import { readFileSync, readdirSync, writeFileSync } from "node:fs";
import { dirname, join, relative, resolve } from "node:path";
import { fileURLToPath } from "node:url";

const __filename = fileURLToPath(import.meta.url);
const __dirname = dirname(__filename);
const repoRoot = resolve(__dirname, "..");

const featuresPath = join(repoRoot, "FEATURES.md");
const workflowToolsPath = join(repoRoot, "packages", "mcp-server", "src", "workflow-tools.ts");
const providersPath = join(repoRoot, "packages", "pi-ai", "src", "types.ts");
const extensionsRoot = join(repoRoot, "src", "resources", "extensions");
const searchToolPath = join(repoRoot, "src", "resources", "extensions", "search-the-web", "tool-search.ts");

export const START = "<!-- GENERATED_FEATURE_INVENTORY_START -->";
export const END = "<!-- GENERATED_FEATURE_INVENTORY_END -->";

function uniqueSorted(values) {
  return [...new Set(values)].sort((a, b) => a.localeCompare(b));
}

export function parseWorkflowToolNames() {
  const src = readFileSync(workflowToolsPath, "utf8");
  const matches = [...src.matchAll(/server\.tool\(\s*"([^"]+)"/g)].map((m) => m[1]);
  return uniqueSorted(matches);
}

export function parseKnownProviders() {
  const src = readFileSync(providersPath, "utf8");
  const match = src.match(/export type KnownProvider =([\s\S]*?);/);
  if (!match) throw new Error("Could not find KnownProvider in packages/pi-ai/src/types.ts");
  const providers = [...match[1].matchAll(/"([^"]+)"/g)].map((m) => m[1]);
  return uniqueSorted(providers);
}

export function parseBundledExtensions() {
  const entries = readdirSync(extensionsRoot, { withFileTypes: true })
    .filter((entry) => entry.isDirectory())
    .map((entry) => entry.name)
    .filter((name) => {
      try {
        const manifestPath = join(extensionsRoot, name, "extension-manifest.json");
        readFileSync(manifestPath, "utf8");
        return true;
      } catch {
        return false;
      }
    });
  return uniqueSorted(entries);
}

export function parseSearchProviders() {
  const src = readFileSync(searchToolPath, "utf8");
  const providers = [
    ...src.matchAll(/providers\.push\('([^']+)'\)/g),
    ...src.matchAll(/provider\?: '([^']+)'/g),
  ]
    .map((m) => m[1])
    .filter((p) => p !== "combosearch");
  return uniqueSorted(providers);
}

function formatBullets(values, formatter = (value) => `- \`${value}\``) {
  return values.map((value) => formatter(value)).join("\n");
}

export function buildSection() {
  const workflowTools = parseWorkflowToolNames();
  const extensions = parseBundledExtensions();
  const searchProviders = parseSearchProviders();
  const knownProviders = parseKnownProviders();

  return [
    "### Workflow Tools",
    "",
    "Generated from `packages/mcp-server/src/workflow-tools.ts`.",
    "",
    formatBullets(workflowTools),
    "",
    "### Bundled Extensions",
    "",
    "Generated from `src/resources/extensions/*/extension-manifest.json`.",
    "",
    formatBullets(
      extensions,
      (value) => `- \`${value}\` — [extension-manifest.json](${relative(repoRoot, join(extensionsRoot, value, "extension-manifest.json"))})`,
    ),
    "",
    "### Search Providers",
    "",
    "Generated from the `search-the-web` extension provider declarations.",
    "",
    formatBullets(searchProviders),
    "",
    "### Known Model Providers",
    "",
    "Generated from `packages/pi-ai/src/types.ts` (`KnownProvider`).",
    "",
    formatBullets(knownProviders),
    "",
  ].join("\n");
}

export function updateFeaturesContent(features) {
  const startIndex = features.indexOf(START);
  const endIndex = features.indexOf(END);

  if (startIndex === -1 || endIndex === -1 || endIndex < startIndex) {
    throw new Error("FEATURES.md is missing generated inventory markers");
  }

  const before = features.slice(0, startIndex + START.length);
  const after = features.slice(endIndex);
  const section = `\n\n${buildSection()}`;
  return `${before}${section}\n${after}`;
}

export function main() {
  const features = readFileSync(featuresPath, "utf8");
  const updated = updateFeaturesContent(features);
  writeFileSync(featuresPath, updated);
  process.stdout.write(`Updated ${relative(repoRoot, featuresPath)}\n`);
}

if (process.argv[1] && resolve(process.argv[1]) === __filename) {
  main();
}