import fs from "node:fs";
import { builtinModules } from "node:module";
import path from "node:path";
import { fileURLToPath } from "node:url";
import { build as analyzeBuild } from "esbuild";

const BUILTIN_MODULES = new Set([...builtinModules, ...builtinModules.map((name) => `node:${name}`)]);
const OPAQUE_REQUIRE_PATTERN = /\brequireFromHere\(\s*["'`]([^"'`]+)["'`]\s*\)/gu;

// A dynamic import whose specifier is held in a local string variable is opaque to esbuild, so the two
// halves are matched separately and paired by position afterwards. Spanning both halves in one pattern
// (declaration, then a lazy `[\s\S]{0,500}?` gap, then the import) overflows the regex stack on a bundled
// server artifact, where a single generated line can run into the megabytes.
const OPAQUE_STRING_BINDING_PATTERN = /\b(?:const|let|var)\s+([$_A-Za-z][\w$]*)\s*=\s*["'`]([^"'`]+)["'`]\s*;/gu;
// The comment body uses an unrolled loop rather than a lazy span so it cannot backtrack across the file.
const OPAQUE_DYNAMIC_IMPORT_PATTERN = /\bimport\(\s*(?:\/\*[^*]*(?:\*(?!\/)[^*]*)*\*\/\s*)?([$_A-Za-z][\w$]*)\s*\)/gu;
/** How far after its declaration the variable may be imported and still count as the same binding. */
const OPAQUE_BINDING_MAX_DISTANCE = 500;

export const RUNTIME_CLOSURE_TARGETS = {
  web: {
    entryPoints: [
      "build/server-runtime/server.js",
      "apps/web/build/server/index.js",
      "apps/web/build-portal/server/index.js",
      "packages/db/dist/deploy-permission-catalog-sync.server.js",
    ],
    manifestPath: "runtime/web/package.json",
  },
  api: {
    entryPoints: ["apps/api/dist/server.js"],
    manifestPath: "runtime/api/package.json",
  },
  worker: {
    entryPoints: [
      "apps/worker/dist/index.js",
      "apps/worker/dist/health.js",
      "apps/worker/dist/jobs/plugin-sandbox-worker.js",
      "apps/worker/dist/jobs/file-preview-decoder-process.js",
    ],
    manifestPath: "runtime/worker/package.json",
  },
  mcp: {
    entryPoints: ["apps/mcp/dist/server.js"],
    manifestPath: "runtime/mcp/package.json",
  },
  hocuspocus: {
    entryPoints: ["apps/hocuspocus/dist/index.js"],
    manifestPath: "runtime/hocuspocus/package.json",
  },
  "portal-domain-controller": {
    entryPoints: ["apps/portal-domain-controller/dist/index.js"],
    manifestPath: "runtime/portal-domain-controller/package.json",
  },
};

export function packageNameFromSpecifier(specifier) {
  if (!specifier || specifier.startsWith(".") || specifier.startsWith("/") || specifier.startsWith("#") || BUILTIN_MODULES.has(specifier)) {
    return null;
  }
  const segments = specifier.split("/");
  return specifier.startsWith("@") ? segments.slice(0, 2).join("/") : segments[0];
}

export async function collectRuntimePackageImports(rootDir, entryPoints) {
  const packageNames = new Set();
  const absoluteEntryPoints = entryPoints.map((entryPoint) => path.join(rootDir, entryPoint));

  for (const [index, entryPoint] of absoluteEntryPoints.entries()) {
    if (!fs.existsSync(entryPoint)) {
      throw new Error(`missing runtime artifact entry point: ${entryPoints[index]}`);
    }
  }

  const analysis = await analyzeBuild({
    absWorkingDir: rootDir,
    bundle: true,
    entryPoints: absoluteEntryPoints,
    format: "esm",
    logLevel: "silent",
    metafile: true,
    outdir: path.join(rootDir, ".runtime-closure-analysis"),
    packages: "external",
    platform: "node",
    write: false,
  });

  for (const input of Object.values(analysis.metafile.inputs)) {
    for (const imported of input.imports) {
      const packageName = packageNameFromSpecifier(imported.path);
      if (imported.external && packageName) packageNames.add(packageName);
    }
  }

  for (const inputPath of Object.keys(analysis.metafile.inputs)) {
    const absoluteInputPath = path.isAbsolute(inputPath) ? inputPath : path.join(rootDir, inputPath);
    if (!fs.existsSync(absoluteInputPath) || !/\.[cm]?js$/u.test(absoluteInputPath)) continue;
    const source = fs.readFileSync(absoluteInputPath, "utf8");
    for (const specifier of collectOpaquePackageSpecifiers(source)) {
      const packageName = packageNameFromSpecifier(specifier);
      if (packageName) packageNames.add(packageName);
    }
  }

  return [...packageNames].sort();
}

export function collectOpaquePackageSpecifiers(source) {
  const specifiers = [];
  for (const match of source.matchAll(OPAQUE_REQUIRE_PATTERN)) {
    if (match[1]) specifiers.push(match[1]);
  }

  // Declarations first, keyed by name and kept in source order, so each import can be paired with the
  // nearest preceding one. Re-assigning the same name later shadows the earlier value, as it would at runtime.
  const bindings = new Map();
  for (const match of source.matchAll(OPAQUE_STRING_BINDING_PATTERN)) {
    if (!match[1] || !match[2]) continue;
    const declarations = bindings.get(match[1]) ?? [];
    declarations.push({ specifier: match[2], endIndex: match.index + match[0].length });
    bindings.set(match[1], declarations);
  }

  for (const match of source.matchAll(OPAQUE_DYNAMIC_IMPORT_PATTERN)) {
    const declarations = bindings.get(match[1]);
    if (!declarations) continue;
    const declaration = lastDeclarationWithinReach(declarations, match.index);
    if (declaration) specifiers.push(declaration.specifier);
  }

  return specifiers;
}

function lastDeclarationWithinReach(declarations, importIndex) {
  for (let index = declarations.length - 1; index >= 0; index -= 1) {
    const declaration = declarations[index];
    if (declaration.endIndex > importIndex) continue;
    return importIndex - declaration.endIndex <= OPAQUE_BINDING_MAX_DISTANCE ? declaration : null;
  }
  return null;
}

export async function verifyRuntimeClosure(rootDir, targetName, targetConfig = RUNTIME_CLOSURE_TARGETS[targetName]) {
  if (!targetConfig) throw new Error(`unknown runtime closure target: ${targetName}`);

  const manifest = JSON.parse(fs.readFileSync(path.join(rootDir, targetConfig.manifestPath), "utf8"));
  const declaredDependencies = Object.keys(manifest.dependencies ?? {}).sort();
  const importedPackages = await collectRuntimePackageImports(rootDir, targetConfig.entryPoints);
  const missingDependencies = importedPackages.filter((packageName) => !declaredDependencies.includes(packageName));

  return {
    targetName,
    manifestPath: targetConfig.manifestPath,
    declaredDependencies,
    importedPackages,
    missingDependencies,
  };
}

export function parseRuntimeSelection(args) {
  const selected = [];

  for (let index = 0; index < args.length; index += 1) {
    const argument = args[index];
    let targetName;

    if (argument === "--") {
      continue;
    } else if (argument === "--runtime") {
      targetName = args[index + 1];
      index += 1;
    } else if (argument.startsWith("--runtime=")) {
      targetName = argument.slice("--runtime=".length);
    } else {
      throw new Error(`unknown runtime closure argument: ${argument}`);
    }

    if (!targetName) throw new Error("--runtime requires a target name");
    if (!(targetName in RUNTIME_CLOSURE_TARGETS)) {
      throw new Error(`unknown runtime closure target: ${targetName}`);
    }
    if (!selected.includes(targetName)) selected.push(targetName);
  }

  return selected.length > 0 ? selected : Object.keys(RUNTIME_CLOSURE_TARGETS);
}

export async function verifyRuntimeClosures(
  rootDir = path.resolve(path.dirname(fileURLToPath(import.meta.url)), ".."),
  targetNames = Object.keys(RUNTIME_CLOSURE_TARGETS)
) {
  return Promise.all(targetNames.map((targetName) => verifyRuntimeClosure(rootDir, targetName)));
}

async function runCli() {
  let targetNames;
  try {
    targetNames = parseRuntimeSelection(process.argv.slice(2));
  } catch (error) {
    console.error(`FAIL ${(error instanceof Error && error.message) || String(error)}`);
    process.exitCode = 1;
    return;
  }

  const results = await verifyRuntimeClosures(undefined, targetNames);
  let failed = false;

  for (const result of results) {
    if (result.missingDependencies.length > 0) {
      failed = true;
      console.error(`FAIL runtime=${result.targetName} missing=${result.missingDependencies.join(",")}`);
    } else {
      console.log(`PASS runtime=${result.targetName} imports=${result.importedPackages.length} dependencies=${result.declaredDependencies.length}`);
    }
  }

  if (failed) process.exitCode = 1;
}

if (process.argv[1] && path.resolve(process.argv[1]) === fileURLToPath(import.meta.url)) await runCli();