import { promises as fs } from "node:fs";
import path from "node:path";

// Utility to normalize and validate paths within a contained root directory
const normalizePath = (inputPath, chrootDir) => {
  // Resolve chroot directory
  const chrootResolved = path.resolve(chrootDir);
  
  // Handle root path ("/") as the chroot directory itself
  if (inputPath === "/" || inputPath === "") {
    return chrootResolved;
  }

  // Resolve input path relative to chroot directory
  const resolved = path.join(chrootResolved, inputPath);
  const normalized = path.normalize(resolved);

  // Ensure the path is within chrootDir
  if (!normalized.startsWith(chrootResolved)) {
    throw new Error(`Path escapes root boundary: ${inputPath}`);
  }
  
  return normalized;
};

// Convert an absolute path under the contained root to a user-display path (root-relative)
const toDisplayPath = (absPath, chrootDir) => {
  const rel = path.relative(path.resolve(chrootDir), absPath);
  if (!rel || rel === "") return "/";
  return `/${rel}`;
};

// Main recursive directory listing function
async function listEntriesRecursive(startDir, chrootDir, maxDepth, includeHidden = false) {
  const results = [];
  const seen = new Set(); // Track paths to prevent symlink cycles

  async function walk(currentDir, currentDepth) {
    if (currentDepth > maxDepth) return;

    let dirents;
    try {
      dirents = await fs.readdir(currentDir, { withFileTypes: true });
    } catch (err) {
      throw new Error(`Failed to read directory: ${toDisplayPath(currentDir, chrootDir)}`);
    }

    for (const dirent of dirents) {
      // Skip hidden files/directories unless includeHidden is true
      if (!includeHidden && dirent.name.startsWith(".")) continue;

      const fullPath = path.join(currentDir, dirent.name);
      // Ensure fullPath is within chroot
      if (!fullPath.startsWith(path.resolve(chrootDir))) {
        continue; // Skip paths outside chroot
      }
      
      const relPath = path.relative(startDir, fullPath) || ".";

      // Prevent symlink cycles
      if (dirent.isSymbolicLink()) {
        const realPath = await fs.realpath(fullPath).catch(() => null);
        // Ensure realPath is within chroot
        if (realPath && !realPath.startsWith(path.resolve(chrootDir))) {
          continue; // Skip symlinks pointing outside chroot
        }
        if (realPath && seen.has(realPath)) continue;
        if (realPath) seen.add(realPath);
        results.push([relPath, "l", null]);
        continue; // Don't recurse into symlinks
      }

      if (dirent.isDirectory()) {
        seen.add(fullPath);
        results.push([relPath, "d", null]);
        if (currentDepth < maxDepth) {
          await walk(fullPath, currentDepth + 1);
        }
      } else if (dirent.isFile()) {
        let size = null;
        try {
          const stat = await fs.stat(fullPath);
          size = stat.size;
        } catch {
          // Size remains null if stat fails
        }
        results.push([relPath, "f", size]);
      } else {
        results.push([relPath, "o", null]);
      }
    }
  }

  await walk(startDir, 0);
  return results;
}

export default {
  type: "function",
  name: "list_files",
  description: "List files and directories recursively from the root with customizable options",
  parameters: {
    type: "object",
    properties: {
      path: {
        type: ["string", "null"],
        description: "Directory or file path relative to the root. Use '/' for the root. Defaults to root if not specified.",
      },
      depth: {
        type: ["integer", "null"],
        description: "Maximum subdirectory levels to traverse. Use -1 for unlimited depth. Defaults to 1.",
        minimum: -1,
      },
      includeHidden: {
        type: ["boolean", "null"],
        description: "Whether to include hidden files and directories (starting with '.'). Defaults to false.",
        default: false,
      }
    },
    required: [],
    additionalProperties: false,
  },
  strict: false,
};

export async function run(args) {
  const inputPath = args?.path || "";
  const depth = Number.isInteger(args?.depth) ? args.depth : 1;
  const includeHidden = args?.includeHidden ?? false;
  const chrootPath = '/workspaces/aiTools/root';

  if (!chrootPath) {
    return { err: "Root path is required" };
  }
  if (depth < -1) {
    return { err: `Depth must be >= -1, received ${args?.depth}` };
  }

  let chrootResolved;
  try {
    chrootResolved = path.resolve(chrootPath);
    // Auto-create the chroot base directory if it does not exist
    await fs.mkdir(chrootResolved, { recursive: true });
  } catch (err) {
    return { err: "Failed to initialize root directory" };
  }

  let resolvedBase;
  try {
    resolvedBase = normalizePath(inputPath, chrootResolved);
  } catch (err) {
    return { err: err.message };
  }

  let stat;
  try {
    stat = await fs.lstat(resolvedBase);
  } catch (err) {
    return { err: `Path does not exist${inputPath ? `: ${inputPath}` : ""}` };
  }

  const cwd = toDisplayPath(
    stat.isFile() ? path.dirname(resolvedBase) : resolvedBase,
    chrootResolved
  );

  // Handle single file case
  if (stat.isFile()) {
    const fileName = path.basename(resolvedBase);
    if (!includeHidden && fileName.startsWith(".")) {
      return { cwd, files: [] };
    }
    // Return structured object for easier machine parsing
    return { cwd, files: [{ path: fileName, type: 'f', size: stat.size }] };
  }

  // Handle non-directory case
  if (!stat.isDirectory()) {
    return { err: `Not a file or directory${inputPath ? `: ${inputPath}` : ""}` };
  }

  // Handle directory case
  try {
    const files = await listEntriesRecursive(resolvedBase, chrootResolved, depth === -1 ? Infinity : depth, includeHidden);
    // Map to structured objects and sort by path for consistent output
    const mapped = files
      .map(([p, t, s]) => ({ path: p, type: t, size: s }))
      .sort((a, b) => a.path.localeCompare(b.path));
    return {
      cwd,
      files: mapped,
    };
  } catch (err) {
    return { err: "Failed to list files" };
  }
}