import { createHash } from "node:crypto";
import { lstat, readFile, realpath } from "node:fs/promises";
import path from "node:path";

import type { BuildManifestArtifact } from "../../src/contracts/release-artifacts.ts";
import { moduleInventoryArtifactSchema } from "../contracts/release-artifacts.ts";

type VerifyBuildManifestOutputsDependencies = Readonly<{
  repositoryRoot?: string;
  readBytes?: (target: string) => Promise<Buffer>;
  realpathPath?: (target: string) => Promise<string>;
  assertRegularFile?: (target: string) => Promise<void>;
  assertDirectory?: (target: string) => Promise<void>;
}>;

export const CANONICAL_VITE_MANIFEST_PATH = "dist/.vite/manifest.json";

function isSafeRelativePath(value: string): boolean {
  return (
    value.length > 0 &&
    !path.posix.isAbsolute(value) &&
    !path.win32.isAbsolute(value) &&
    !value.includes("\\") &&
    !value.includes("\0") &&
    path.posix.normalize(value) === value &&
    value !== ".." &&
    !value.startsWith("../")
  );
}

function isWithinRoot(root: string, target: string): boolean {
  const relative = path.relative(root, target);
  return (
    relative === "" ||
    (relative !== ".." &&
      !relative.startsWith(`..${path.sep}`) &&
      !path.isAbsolute(relative))
  );
}

function belongsToApprovedRoot(value: string, approvedRoot: string): boolean {
  return value.startsWith(`${approvedRoot}/`);
}

async function defaultAssertRegularFile(target: string): Promise<void> {
  const metadata = await lstat(target);
  if (!metadata.isFile() || metadata.isSymbolicLink()) {
    throw new TypeError("not a regular file");
  }
}

async function defaultAssertDirectory(target: string): Promise<void> {
  const metadata = await lstat(target);
  if (!metadata.isDirectory() || metadata.isSymbolicLink()) {
    throw new TypeError("not a directory");
  }
}

export async function verifyBuildManifestOutputs(
  manifest: BuildManifestArtifact,
  dependencies: VerifyBuildManifestOutputsDependencies = {},
): Promise<string[]> {
  const repositoryRoot = path.resolve(dependencies.repositoryRoot ?? process.cwd());
  const readBytes = dependencies.readBytes ?? readFile;
  const realpathPath = dependencies.realpathPath ?? realpath;
  const assertRegularFile = dependencies.assertRegularFile ?? defaultAssertRegularFile;
  const assertDirectory = dependencies.assertDirectory ?? defaultAssertDirectory;
  const mismatches: string[] = [];
  const resolvedRoot = await realpathPath(repositoryRoot);
  const approvedRoots = new Map<string, Promise<string | null>>();

  function resolveApprovedRoot(relativeRoot: string): Promise<string | null> {
    const existing = approvedRoots.get(relativeRoot);
    if (existing) return existing;
    const pending = (async () => {
      const absoluteRoot = path.resolve(repositoryRoot, relativeRoot);
      try {
        await assertDirectory(absoluteRoot);
        const resolvedApprovedRoot = await realpathPath(absoluteRoot);
        return isWithinRoot(resolvedRoot, resolvedApprovedRoot)
          ? resolvedApprovedRoot
          : null;
      } catch {
        return null;
      }
    })();
    approvedRoots.set(relativeRoot, pending);
    return pending;
  }

  async function confinedPath(
    label: string,
    relativePath: string,
    kind: "file" | "directory",
    approvedRoot?: string,
  ): Promise<string | null> {
    if (
      !isSafeRelativePath(relativePath) ||
      (approvedRoot !== undefined &&
        !belongsToApprovedRoot(relativePath, approvedRoot))
    ) {
      mismatches.push(`buildManifest:${label}:path`);
      return null;
    }
    const absolutePath = path.resolve(repositoryRoot, relativePath);
    if (!isWithinRoot(repositoryRoot, absolutePath)) {
      mismatches.push(`buildManifest:${label}:path`);
      return null;
    }
    try {
      if (kind === "file") await assertRegularFile(absolutePath);
      else await assertDirectory(absolutePath);
      const resolvedPath = await realpathPath(absolutePath);
      const resolvedApprovedRoot = approvedRoot
        ? await resolveApprovedRoot(approvedRoot)
        : resolvedRoot;
      if (
        resolvedApprovedRoot === null ||
        !isWithinRoot(resolvedRoot, resolvedPath) ||
        !isWithinRoot(resolvedApprovedRoot, resolvedPath)
      ) {
        mismatches.push(`buildManifest:${label}:path`);
        return null;
      }
      return absolutePath;
    } catch {
      mismatches.push(`buildManifest:${label}:missing`);
      return null;
    }
  }

  if (manifest.outputs.directory !== "dist") {
    mismatches.push("buildManifest:directory:path");
  } else {
    await confinedPath("directory", manifest.outputs.directory, "directory");
  }
  if (manifest.outputs.viteManifest !== CANONICAL_VITE_MANIFEST_PATH) {
    mismatches.push("buildManifest:viteManifest:path");
  } else {
    await confinedPath(
      "viteManifest",
      manifest.outputs.viteManifest,
      "file",
      "dist",
    );
  }
  await confinedPath(
    "runtimeConfigSchema",
    manifest.outputs.runtimeConfigSchema,
    "file",
    "dist",
  );
  for (const [chunkId, chunkPath] of Object.entries(manifest.outputs.routeChunks)) {
    if (!isSafeRelativePath(chunkPath)) {
      mismatches.push(`buildManifest:routeChunk:${chunkId}:path`);
      continue;
    }
    await confinedPath(
      `routeChunk:${chunkId}`,
      path.posix.join(manifest.outputs.directory, chunkPath),
      "file",
      "dist",
    );
  }
  const moduleInventoryPath = await confinedPath(
    "moduleInventory",
    manifest.outputs.moduleInventory,
    "file",
    "artifacts/quality",
  );
  if (moduleInventoryPath) {
    try {
      const bytes = await readBytes(moduleInventoryPath);
      const digest = createHash("sha256").update(bytes).digest("hex");
      if (digest !== manifest.moduleInventoryHash) {
        mismatches.push("buildManifest:moduleInventoryHash");
      }
      try {
        moduleInventoryArtifactSchema.parse(JSON.parse(bytes.toString("utf8")));
      } catch {
        mismatches.push("buildManifest:moduleInventory:invalid");
      }
    } catch {
      mismatches.push("buildManifest:moduleInventory:missing");
    }
  }
  return mismatches;
}