/**
 * API endpoint for listing files and directories in a repository
 */

import { json } from '@sveltejs/kit';
import type { RequestHandler } from './$types';
import { fileManager, repoManager, nostrClient } from '$lib/services/service-registry.js';
import { createRepoGetHandler } from '$lib/utils/api-handlers.js';
import type { RepoRequestContext, RequestEvent } from '$lib/utils/api-context.js';
import { handleApiError, handleNotFoundError } from '$lib/utils/error-handler.js';
import { KIND } from '$lib/types/nostr.js';
import { join, resolve } from 'path';
import { existsSync } from 'fs';
import { repoCache, RepoCache } from '$lib/services/git/repo-cache.js';
import logger from '$lib/services/logger.js';
import { eventCache } from '$lib/services/nostr/event-cache.js';
import { fetchRepoAnnouncementsWithCache, findRepoAnnouncement } from '$lib/utils/nostr-utils.js';

// Resolve GIT_REPO_ROOT to absolute path (handles both relative and absolute paths)
const repoRootEnv = typeof process !== 'undefined' && process.env?.GIT_REPO_ROOT
  ? process.env.GIT_REPO_ROOT
  : '/repos';
const repoRoot = resolve(repoRootEnv);

export const GET: RequestHandler = createRepoGetHandler(
  async (context: RepoRequestContext) => {
    const repoPath = join(repoRoot, context.npub, `${context.repo}.git`);
    
    // If repo doesn't exist, try to fetch it on-demand
    if (!existsSync(repoPath)) {
      try {
        // Fetch repository announcement from Nostr (case-insensitive) with caching
        const allEvents = await fetchRepoAnnouncementsWithCache(nostrClient, context.repoOwnerPubkey, eventCache);
        const announcement = findRepoAnnouncement(allEvents, context.repo);

        if (announcement) {
          // Try API-based fetching first (no cloning)
          const { tryApiFetch } = await import('$lib/utils/api-repo-helper.js');
          const { extractCloneUrls: extractCloneUrlsHelper } = await import('$lib/utils/nostr-utils.js');
          const cloneUrlsForLogging = extractCloneUrlsHelper(announcement);
          
          logger.debug({ npub: context.npub, repo: context.repo, cloneUrlCount: cloneUrlsForLogging.length, cloneUrls: cloneUrlsForLogging, path: context.path }, 'Attempting API fallback for tree');
          
          const apiData = await tryApiFetch(announcement, context.npub, context.repo);
          
          if (apiData && apiData.files !== undefined) {
            // Return empty array if no files (legitimate for empty repos)
            // Only proceed if we have files to filter
            if (apiData.files.length === 0) {
              logger.debug({ npub: context.npub, repo: context.repo, path: context.path }, 'API fallback returned empty files array (repo may be empty)');
              return json([]);
            }
            logger.debug({ npub: context.npub, repo: context.repo, fileCount: apiData.files.length }, 'Successfully fetched files via API fallback');
            // Return API data directly without cloning
            const path = context.path || '';
            // Filter files by path if specified
            let filteredFiles: typeof apiData.files;
            if (path) {
              // Normalize path: ensure it ends with / for directory matching
              const normalizedPath = path.endsWith('/') ? path : `${path}/`;
              // Filter files that are directly in this directory (not in subdirectories)
              filteredFiles = apiData.files.filter(f => {
                // File must start with the normalized path
                if (!f.path.startsWith(normalizedPath)) {
                  return false;
                }
                // Get the relative path after the directory prefix
                const relativePath = f.path.slice(normalizedPath.length);
                // If relative path is empty, skip (this would be the directory itself)
                if (!relativePath) {
                  return false;
                }
                // Remove trailing slash from relative path for directories
                const cleanRelativePath = relativePath.endsWith('/') ? relativePath.slice(0, -1) : relativePath;
                // Check if it's directly in this directory (no additional / in the relative path)
                // This works for both files (e.g., "icon.svg") and directories (e.g., "subfolder")
                return !cleanRelativePath.includes('/');
              });
            } else {
              // Root directory: show only files and directories in root
              filteredFiles = apiData.files.filter(f => {
                // Remove trailing slash for directories
                const cleanPath = f.path.endsWith('/') ? f.path.slice(0, -1) : f.path;
                const pathParts = cleanPath.split('/');
                // Include only items in root (single path segment)
                return pathParts.length === 1;
              });
            }
            
            // Normalize type: API returns 'dir' but frontend expects 'directory'
            // Also update name to be just the filename/dirname for display
            const normalizedFiles = filteredFiles.map(f => {
              // Extract display name from path
              const cleanPath = f.path.endsWith('/') ? f.path.slice(0, -1) : f.path;
              const pathParts = cleanPath.split('/');
              const displayName = pathParts[pathParts.length - 1] || f.name;
              return {
                name: displayName,
                path: f.path,
                type: (f.type === 'dir' ? 'directory' : 'file') as 'file' | 'directory',
                size: f.size
              };
            });
            
            return json(normalizedFiles);
          }
          
          // API fetch failed - repo is not cloned and API fetch didn't work
          // Check if announcement has clone URLs to provide better error message
          const { extractCloneUrls } = await import('$lib/utils/nostr-utils.js');
          const cloneUrls = extractCloneUrls(announcement);
          const hasCloneUrls = cloneUrls.length > 0;
          
          logger.debug({ npub: context.npub, repo: context.repo, hasCloneUrls, cloneUrlCount: cloneUrls.length }, 'API fallback failed or no clone URLs available');
          
          throw handleNotFoundError(
            hasCloneUrls 
              ? 'Repository is not cloned locally and could not be fetched via API. Privileged users can clone this repository using the "Clone to Server" button.'
              : 'Repository is not cloned locally and has no external clone URLs for API fallback. Privileged users can clone this repository using the "Clone to Server" button.',
            { operation: 'listFiles', npub: context.npub, repo: context.repo }
          );
        } else {
          throw handleNotFoundError(
            'Repository announcement not found in Nostr',
            { operation: 'listFiles', npub: context.npub, repo: context.repo }
          );
        }
      } catch (err) {
        // Check if repo was created by another concurrent request
        if (existsSync(repoPath)) {
          // Repo exists now, clear cache and continue with normal flow
          repoCache.delete(RepoCache.repoExistsKey(context.npub, context.repo));
        } else {
          // If fetching fails, return 404
          throw handleNotFoundError(
            'Repository not found',
            { operation: 'listFiles', npub: context.npub, repo: context.repo }
          );
        }
      }
    }

    // Double-check repo exists (should be true if we got here)
    if (!existsSync(repoPath)) {
      throw handleNotFoundError(
        'Repository not found',
        { operation: 'listFiles', npub: context.npub, repo: context.repo }
      );
    }

    // Get default branch if no ref specified
    let ref = context.ref || 'HEAD';
    // If ref is a branch name, validate it exists or use default branch
    if (ref !== 'HEAD' && !ref.startsWith('refs/')) {
      try {
        const branches = await fileManager.getBranches(context.npub, context.repo);
        if (!branches.includes(ref)) {
          // Branch doesn't exist, use default branch
          ref = await fileManager.getDefaultBranch(context.npub, context.repo);
        }
      } catch {
        // If we can't get branches, fall back to HEAD
        ref = 'HEAD';
      }
    }
    const path = context.path || '';
    
    try {
      const files = await fileManager.listFiles(context.npub, context.repo, ref, path);
      
      // If repo exists but has no files (empty repo), try API fallback
      if (files.length === 0) {
        logger.debug({ npub: context.npub, repo: context.repo, path, ref }, 'Repo exists but is empty, attempting API fallback for tree');
        
        try {
          // Fetch repository announcement for API fallback
          const allEvents = await fetchRepoAnnouncementsWithCache(nostrClient, context.repoOwnerPubkey, eventCache);
          const announcement = findRepoAnnouncement(allEvents, context.repo);
          
          if (announcement) {
            const { tryApiFetch } = await import('$lib/utils/api-repo-helper.js');
            const apiData = await tryApiFetch(announcement, context.npub, context.repo);
            
            if (apiData && apiData.files && apiData.files.length > 0) {
              logger.info({ npub: context.npub, repo: context.repo, fileCount: apiData.files.length }, 'Successfully fetched files via API fallback for empty repo');
              
              // Filter files by path if specified (same logic as above)
              let filteredFiles: typeof apiData.files;
              if (path) {
                const normalizedPath = path.endsWith('/') ? path : `${path}/`;
                filteredFiles = apiData.files.filter(f => {
                  if (!f.path.startsWith(normalizedPath)) {
                    return false;
                  }
                  const relativePath = f.path.slice(normalizedPath.length);
                  if (!relativePath) {
                    return false;
                  }
                  const cleanRelativePath = relativePath.endsWith('/') ? relativePath.slice(0, -1) : relativePath;
                  return !cleanRelativePath.includes('/');
                });
              } else {
                filteredFiles = apiData.files.filter(f => {
                  const cleanPath = f.path.endsWith('/') ? f.path.slice(0, -1) : f.path;
                  const pathParts = cleanPath.split('/');
                  return pathParts.length === 1;
                });
              }
              
              // Normalize type and name
              const normalizedFiles = filteredFiles.map(f => {
                const cleanPath = f.path.endsWith('/') ? f.path.slice(0, -1) : f.path;
                const pathParts = cleanPath.split('/');
                const displayName = pathParts[pathParts.length - 1] || f.name;
                return {
                  name: displayName,
                  path: f.path,
                  type: (f.type === 'dir' ? 'directory' : 'file') as 'file' | 'directory',
                  size: f.size
                };
              });
              
              return json(normalizedFiles);
            }
          }
        } catch (apiErr) {
          logger.debug({ error: apiErr, npub: context.npub, repo: context.repo }, 'API fallback failed for empty repo, returning empty files');
        }
      }
      
      // Debug logging to help diagnose missing files
      logger.debug({ 
        npub: context.npub, 
        repo: context.repo, 
        path, 
        ref, 
        fileCount: files.length,
        files: files.map(f => ({ name: f.name, path: f.path, type: f.type }))
      }, '[Tree] Returning files from fileManager.listFiles');
      return json(files);
    } catch (err) {
      // If error occurs, try API fallback before giving up
      logger.debug({ error: err, npub: context.npub, repo: context.repo }, '[Tree] Error listing files, attempting API fallback');
      
      try {
        const allEvents = await fetchRepoAnnouncementsWithCache(nostrClient, context.repoOwnerPubkey, eventCache);
        const announcement = findRepoAnnouncement(allEvents, context.repo);
        
        if (announcement) {
          const { tryApiFetch } = await import('$lib/utils/api-repo-helper.js');
          const apiData = await tryApiFetch(announcement, context.npub, context.repo);
          
          if (apiData && apiData.files && apiData.files.length > 0) {
            logger.info({ npub: context.npub, repo: context.repo, fileCount: apiData.files.length }, 'Successfully fetched files via API fallback after error');
            
            // Filter and normalize files (same logic as above)
            const path = context.path || '';
            let filteredFiles: typeof apiData.files;
            if (path) {
              const normalizedPath = path.endsWith('/') ? path : `${path}/`;
              filteredFiles = apiData.files.filter(f => {
                if (!f.path.startsWith(normalizedPath)) return false;
                const relativePath = f.path.slice(normalizedPath.length);
                if (!relativePath) return false;
                const cleanRelativePath = relativePath.endsWith('/') ? relativePath.slice(0, -1) : relativePath;
                return !cleanRelativePath.includes('/');
              });
            } else {
              filteredFiles = apiData.files.filter(f => {
                const cleanPath = f.path.endsWith('/') ? f.path.slice(0, -1) : f.path;
                return cleanPath.split('/').length === 1;
              });
            }
            
            const normalizedFiles = filteredFiles.map(f => {
              const cleanPath = f.path.endsWith('/') ? f.path.slice(0, -1) : f.path;
              const pathParts = cleanPath.split('/');
              const displayName = pathParts[pathParts.length - 1] || f.name;
              return {
                name: displayName,
                path: f.path,
                type: (f.type === 'dir' ? 'directory' : 'file') as 'file' | 'directory',
                size: f.size
              };
            });
            
            return json(normalizedFiles);
          }
        }
      } catch (apiErr) {
        logger.debug({ error: apiErr, npub: context.npub, repo: context.repo }, 'API fallback failed after error');
      }
      
      // Log the actual error for debugging
      logger.error({ error: err, npub: context.npub, repo: context.repo, path: context.path }, '[Tree] Error listing files');
      
      // For optional paths (like "docs"), return empty array instead of 404
      // This allows components to gracefully handle missing directories
      const optionalPaths = ['docs'];
      if (context.path && optionalPaths.includes(context.path.toLowerCase())) {
        logger.debug({ npub: context.npub, repo: context.repo, path: context.path }, '[Tree] Optional path not found, returning empty array');
        return json([]);
      }
      
      // Check if it's a "not found" error for the repo itself
      if (err instanceof Error && (err.message.includes('Repository not found') || err.message.includes('not cloned'))) {
        throw handleNotFoundError(
          err.message,
          { operation: 'listFiles', npub: context.npub, repo: context.repo }
        );
      }
      
      // For other errors with optional paths, return empty array
      if (context.path && optionalPaths.includes(context.path.toLowerCase())) {
        return json([]);
      }
      
      // Otherwise, it's a server error
      throw handleApiError(
        err,
        { operation: 'listFiles', npub: context.npub, repo: context.repo },
        'Failed to list files'
      );
    }
  },
  { operation: 'listFiles', requireRepoExists: false, requireRepoAccess: true } // Handle on-demand fetching, but check access for private repos
);