const axios = require('axios');
const fs = require('fs').promises;
const path = require('path');
const archiver = require('archiver');
const yauzl = require('yauzl');
const { promisify } = require('util');

class ContentDBClient {
  constructor() {
    this.baseURL = 'https://content.luanti.org/api';
    this.client = axios.create({
      baseURL: this.baseURL,
      timeout: 30000,
      headers: {
        'User-Agent': 'LuHost/1.0',
        'Accept': 'application/json'
      },
      validateStatus: (status) => {
        // Only treat 200-299 as success, but don't throw on 404
        return (status >= 200 && status < 300) || status === 404;
      }
    });
  }

  // Search packages (mods, games, texture packs)
  async searchPackages(query = '', type = '', sort = 'score', order = 'desc', limit = 20, offset = 0) {
    try {
      const params = {
        q: query,
        type: type, // mod, game, txp (texture pack)
        sort: sort, // score, name, created_at, approved_at, downloads
        order: order, // asc, desc
        limit: Math.min(limit, 50), // API limit
        offset: offset
      };

      const response = await this.client.get('/packages/', { params });
      return response.data;
    } catch (error) {
      throw new Error(`Failed to search ContentDB: ${error.message}`);
    }
  }

  // Get package details
  async getPackage(author, name) {
    try {
      const response = await this.client.get(`/packages/${author}/${name}/`);
      
      // Ensure we got JSON back
      if (typeof response.data !== 'object') {
        throw new Error('Invalid response format from ContentDB');
      }
      
      return response.data;
    } catch (error) {
      if (error.response?.status === 404) {
        throw new Error('Package not found');
      }
      
      // Handle cases where the response isn't JSON
      if (error.message.includes('JSON') || error.message.includes('Unexpected token')) {
        throw new Error('ContentDB returned invalid data format');
      }
      
      throw new Error(`Failed to get package details: ${error.message}`);
    }
  }

  // Get package releases
  async getPackageReleases(author, name) {
    try {
      const response = await this.client.get(`/packages/${author}/${name}/releases/`);
      return response.data;
    } catch (error) {
      throw new Error(`Failed to get package releases: ${error.message}`);
    }
  }

  // Download package
  async downloadPackage(author, name, targetPath, version = null) {
    try {
      // Get package info first
      const packageInfo = await this.getPackage(author, name);
      
      // Get releases to find download URL
      const releases = await this.getPackageReleases(author, name);
      
      if (!releases || releases.length === 0) {
        throw new Error('No releases found for this package');
      }

      // Find the specified version or use the latest
      let release;
      if (version) {
        release = releases.find(r => r.id === version || r.title === version);
        if (!release) {
          throw new Error(`Version ${version} not found`);
        }
      } else {
        // Use the first release (should be latest)
        release = releases[0];
      }

      if (!release.url) {
        throw new Error('No download URL found for this release');
      }

      // Construct full download URL if needed
      let downloadUrl = release.url;
      if (downloadUrl.startsWith('/')) {
        downloadUrl = 'https://content.luanti.org' + downloadUrl;
      }

      // Download the package with retry logic
      let downloadResponse;
      let retryCount = 0;
      const maxRetries = 3;
      
      while (retryCount <= maxRetries) {
        try {
          console.log(`ContentDB: Attempting download from ${downloadUrl} (attempt ${retryCount + 1}/${maxRetries + 1})`);
          downloadResponse = await axios.get(downloadUrl, {
            responseType: 'stream',
            timeout: 60000, // 1 minute timeout per attempt
            headers: {
              'User-Agent': 'LuHost/1.0',
              'Accept': '*/*',
              'Connection': 'keep-alive'
            },
            // Increase buffer limits to handle larger downloads
            maxContentLength: 100 * 1024 * 1024, // 100MB
            maxBodyLength: 100 * 1024 * 1024
          });
          break; // Success, exit retry loop
        } catch (downloadError) {
          retryCount++;
          console.warn(`ContentDB: Download attempt ${retryCount} failed:`, downloadError.message);
          
          if (retryCount > maxRetries) {
            // All retries exhausted
            const errorMsg = downloadError.code === 'ECONNRESET' || downloadError.message.includes('closed') 
              ? 'Connection was closed by the server. This may be due to network issues or server load. Please try again later.'
              : `Download failed: ${downloadError.message}`;
            throw new Error(errorMsg);
          }
          
          // Wait before retrying (exponential backoff)
          const delayMs = Math.pow(2, retryCount - 1) * 1000; // 1s, 2s, 4s
          console.log(`ContentDB: Retrying in ${delayMs}ms...`);
          await new Promise(resolve => setTimeout(resolve, delayMs));
        }
      }

      // Create target directory
      await fs.mkdir(targetPath, { recursive: true });

      // If it's a zip file, extract it
      if (release.url.endsWith('.zip')) {
        const tempZipPath = path.join(targetPath, 'temp.zip');
        
        // Save zip file temporarily
        const writer = require('fs').createWriteStream(tempZipPath);
        downloadResponse.data.pipe(writer);

        await new Promise((resolve, reject) => {
          writer.on('finish', resolve);
          writer.on('error', reject);
        });

        // Extract zip file
        try {
          await this.extractZipFile(tempZipPath, targetPath);
          console.log(`ContentDB: Successfully extracted zip to ${targetPath}`);
        } catch (extractError) {
          console.error(`ContentDB: Extraction failed:`, extractError);
          // Clean up temp file before rethrowing
          try {
            await fs.unlink(tempZipPath);
          } catch (cleanupError) {
            console.warn(`ContentDB: Failed to cleanup temp file:`, cleanupError.message);
          }
          throw extractError;
        }
        
        // Remove temp zip file
        try {
          await fs.unlink(tempZipPath);
          console.log(`ContentDB: Cleaned up temp zip file`);
        } catch (cleanupError) {
          console.warn(`ContentDB: Failed to remove temp zip file:`, cleanupError.message);
          // Don't throw - extraction succeeded, cleanup failure is not critical
        }
      } else {
        // For non-zip files, save directly
        const fileName = path.basename(release.url) || 'download';
        const filePath = path.join(targetPath, fileName);
        const writer = require('fs').createWriteStream(filePath);
        downloadResponse.data.pipe(writer);

        await new Promise((resolve, reject) => {
          writer.on('finish', resolve);
          writer.on('error', reject);
        });
      }

      return {
        package: packageInfo,
        release: release,
        downloadPath: targetPath
      };
    } catch (error) {
      throw new Error(`Failed to download package: ${error.message}`);
    }
  }

  // Extract zip file
  async extractZipFile(zipPath, targetPath) {
    return new Promise((resolve, reject) => {
      yauzl.open(zipPath, { lazyEntries: true }, (err, zipfile) => {
        if (err) {
          reject(err);
          return;
        }

        const entries = [];
        
        // First pass: collect all entries to analyze structure
        zipfile.on('entry', (entry) => {
          entries.push(entry);
          zipfile.readEntry();
        });
        
        zipfile.on('end', async () => {
          try {
            // Analyze if we have a common root directory that should be stripped
            let commonRoot = null;
            let shouldStripRoot = false;
            
            if (entries.length > 0) {
              // Find files (not directories) to analyze structure
              const fileEntries = entries.filter(e => !e.fileName.endsWith('/') && e.fileName.trim() !== '');
              
              if (fileEntries.length > 0) {
                // Check if all files are in the same top-level directory
                const firstPath = fileEntries[0].fileName;
                const firstSlash = firstPath.indexOf('/');
                
                if (firstSlash > 0) {
                  const potentialRoot = firstPath.substring(0, firstSlash);
                  
                  // Check if ALL file entries start with this root directory
                  const allInSameRoot = fileEntries.every(entry => 
                    entry.fileName.startsWith(potentialRoot + '/')
                  );
                  
                  if (allInSameRoot) {
                    commonRoot = potentialRoot;
                    shouldStripRoot = true;
                    console.log(`ContentDB: Detected common root directory "${commonRoot}", will strip it during extraction`);
                  }
                }
              }
            }
            
            zipfile.close();
            
            // Second pass: reopen zip and extract files sequentially
            yauzl.open(zipPath, { lazyEntries: true }, (reopenErr, newZipfile) => {
              if (reopenErr) {
                reject(reopenErr);
                return;
              }
              
              let entryIndex = 0;
              
              const processNextEntry = () => {
                if (entryIndex >= entries.length) {
                  newZipfile.close();
                  resolve();
                  return;
                }
                
                const entry = entries[entryIndex++];
                let fileName = entry.fileName;
                
                // Strip common root if detected
                if (shouldStripRoot && commonRoot) {
                  if (fileName === commonRoot || fileName === commonRoot + '/') {
                    processNextEntry(); // Skip the root directory itself
                    return;
                  }
                  if (fileName.startsWith(commonRoot + '/')) {
                    fileName = fileName.substring(commonRoot.length + 1);
                  }
                }
                
                // Skip empty filenames
                if (!fileName || fileName.trim() === '') {
                  processNextEntry();
                  return;
                }
                
                const entryPath = path.join(targetPath, fileName);
                
                // Ensure the entry path is within target directory (security)
                const normalizedPath = path.normalize(entryPath);
                if (!normalizedPath.startsWith(path.normalize(targetPath))) {
                  processNextEntry();
                  return;
                }

                if (fileName.endsWith('/')) {
                  // Directory entry
                  fs.mkdir(normalizedPath, { recursive: true })
                    .then(() => processNextEntry())
                    .catch(reject);
                } else {
                  // File entry
                  newZipfile.openReadStream(entry, async (streamErr, readStream) => {
                    if (streamErr) {
                      newZipfile.close();
                      reject(streamErr);
                      return;
                    }

                    try {
                      // Ensure parent directory exists
                      const parentDir = path.dirname(normalizedPath);
                      await fs.mkdir(parentDir, { recursive: true });
                      
                      const writeStream = require('fs').createWriteStream(normalizedPath);
                      readStream.pipe(writeStream);
                      
                      writeStream.on('finish', () => {
                        processNextEntry();
                      });
                      
                      writeStream.on('error', (writeError) => {
                        newZipfile.close();
                        reject(writeError);
                      });
                    } catch (mkdirError) {
                      newZipfile.close();
                      reject(mkdirError);
                    }
                  });
                }
              };
              
              newZipfile.on('error', (zipError) => {
                newZipfile.close();
                reject(zipError);
              });
              
              processNextEntry();
            });
              
          } catch (error) {
            zipfile.close();
            reject(error);
          }
        });

        zipfile.on('error', (error) => {
          zipfile.close();
          reject(error);
        });
        
        zipfile.readEntry();
      });
    });
  }

  // Get popular packages
  async getPopularPackages(type = '', limit = 10) {
    return this.searchPackages('', type, 'downloads', 'desc', limit, 0);
  }

  // Get recently updated packages
  async getRecentPackages(type = '', limit = 10) {
    return this.searchPackages('', type, 'approved_at', 'desc', limit, 0);
  }

  // Check for updates for installed packages
  async checkForUpdates(installedPackages) {
    const updates = [];
    
    for (const pkg of installedPackages) {
      try {
        // Try to find the package on ContentDB
        // This requires matching local package names to ContentDB packages
        // which might not always be straightforward
        
        // For now, we'll implement a basic search-based approach
        const searchResults = await this.searchPackages(pkg.name, '', 'score', 'desc', 5);
        
        if (searchResults && searchResults.length > 0) {
          // Try to find exact match
          const match = searchResults.find(result => 
            result.name.toLowerCase() === pkg.name.toLowerCase() ||
            result.title.toLowerCase() === pkg.name.toLowerCase()
          );
          
          if (match) {
            const releases = await this.getPackageReleases(match.author, match.name);
            if (releases && releases.length > 0) {
              updates.push({
                local: pkg,
                remote: match,
                latestRelease: releases[0],
                hasUpdate: true // We could implement version comparison here
              });
            }
          }
        }
      } catch (error) {
        // Skip packages that can't be found or checked
        console.warn(`Could not check updates for ${pkg.name}:`, error.message);
      }
    }
    
    return updates;
  }

  // Get package dependencies
  async getPackageDependencies(author, name) {
    try {
      const packageInfo = await this.getPackage(author, name);
      return {
        hard_dependencies: packageInfo.hard_dependencies || [],
        optional_dependencies: packageInfo.optional_dependencies || []
      };
    } catch (error) {
      throw new Error(`Failed to get dependencies: ${error.message}`);
    }
  }

  // Install package with dependencies
  async installPackageWithDeps(author, name, targetBasePath, resolveDeps = true) {
    const installResults = {
      main: null,
      dependencies: [],
      errors: []
    };

    try {
      // Install main package
      const mainPackagePath = path.join(targetBasePath, name);
      const mainResult = await this.downloadPackage(author, name, mainPackagePath);
      installResults.main = mainResult;

      // Install dependencies if requested
      if (resolveDeps) {
        const deps = await this.getPackageDependencies(author, name);
        
        for (const dep of deps.hard_dependencies) {
          try {
            const depPath = path.join(targetBasePath, dep.name);
            const depResult = await this.downloadPackage(dep.author, dep.name, depPath);
            installResults.dependencies.push(depResult);
          } catch (error) {
            installResults.errors.push(`Failed to install dependency ${dep.name}: ${error.message}`);
          }
        }
      }

      return installResults;
    } catch (error) {
      installResults.errors.push(error.message);
      return installResults;
    }
  }
}

module.exports = ContentDBClient;