import os
import requests
import threading
import time
import urllib.parse
import re
from typing import Dict, Optional


class HttpDownloader:
    def __init__(self):
        self.download = None
        self.thread = None
        self.stop_download = False
        self.download_info = None

    def start_download(self, url: str, save_path: str, header: str, out: str = None, allow_multiple_connections: bool = False):
        """Start a download with the given parameters"""
        # Parse header string into dictionary
        headers = {}
        if header:
            for line in header.split('\n'):
                if ':' in line:
                    key, value = line.split(':', 1)
                    headers[key.strip()] = value.strip()
        
        # Determine output filename
        if out:
            filename = out
        else:
            # Extract filename from URL
            raw_filename = self._extract_filename_from_url(url)
            if not raw_filename:
                filename = 'download'
            else:
                filename = raw_filename
            
        # Create full path
        if not os.path.exists(save_path):
            os.makedirs(save_path)
        
        full_path = os.path.join(save_path, filename)
        
        # Initialize download info
        self.download_info = {
            'url': url,
            'save_path': save_path,
            'full_path': full_path,
            'headers': headers,
            'filename': filename,
            'folderName': filename,
            'fileSize': 0,
            'progress': 0,
            'downloadSpeed': 0,
            'status': 'waiting',
            'bytesDownloaded': 0,
            'start_time': time.time()
        }
        
        # Start download in a separate thread
        self.stop_download = False
        self.thread = threading.Thread(target=self._download_worker)
        self.thread.daemon = True
        self.thread.start()
        
    def _download_worker(self):
        """Worker thread that performs the actual download"""
        url = self.download_info['url']
        full_path = self.download_info['full_path']
        headers = self.download_info['headers']
        
        try:
            # Start with a HEAD request to get file size
            head_response = requests.head(url, headers=headers, allow_redirects=True)
            total_size = int(head_response.headers.get('content-length', 0))
            self.download_info['fileSize'] = total_size
            
            # Open the request as a stream
            self.download_info['status'] = 'active'
            response = requests.get(url, headers=headers, stream=True, allow_redirects=True)
            response.raise_for_status()
            
            # If we didn't get file size from HEAD request, try from GET
            if total_size == 0:
                total_size = int(response.headers.get('content-length', 0))
                self.download_info['fileSize'] = total_size
            
            downloaded = 0
            start_time = time.time()
            last_update_time = start_time
            bytes_since_last_update = 0
            
            with open(full_path, 'wb') as f:
                for chunk in response.iter_content(chunk_size=8192):
                    if self.stop_download:
                        self.download_info['status'] = 'paused'
                        return
                    
                    if chunk:
                        f.write(chunk)
                        downloaded += len(chunk)
                        bytes_since_last_update += len(chunk)
                        
                        # Update progress and speed every 0.5 seconds
                        current_time = time.time()
                        if current_time - last_update_time >= 0.5:
                            elapsed = current_time - last_update_time
                            speed = bytes_since_last_update / elapsed if elapsed > 0 else 0
                            
                            self.download_info['bytesDownloaded'] = downloaded
                            self.download_info['progress'] = downloaded / total_size if total_size > 0 else 0
                            self.download_info['downloadSpeed'] = speed
                            
                            last_update_time = current_time
                            bytes_since_last_update = 0
            
            # Download completed
            self.download_info['status'] = 'complete'
            self.download_info['progress'] = 1.0
            self.download_info['bytesDownloaded'] = total_size
            
        except requests.exceptions.RequestException as e:
            self.download_info['status'] = 'error'
            print(f"Download error: {str(e)}")
    
    def pause_download(self):
        """Pause the current download (actually stops it)"""
        if self.thread and self.thread.is_alive():
            self.stop_download = True
            if self.download_info:
                self.download_info['status'] = 'paused'
    
    def cancel_download(self):
        """Cancel the current download and reset the download object"""
        self.pause_download()
        if self.download_info:
            # Attempt to delete the partial file
            try:
                if os.path.exists(self.download_info['full_path']):
                    os.remove(self.download_info['full_path'])
            except:
                pass
            self.download_info['status'] = 'removed'
        self.download_info = None
    
    def _extract_filename_from_url(self, url: str) -> str:
        """Extract a clean filename from URL, handling URL encoding and query parameters"""
        # Parse the URL to get the path
        parsed_url = urllib.parse.urlparse(url)
        
        # Extract the path component
        path = parsed_url.path
        
        # Get the last part of the path (filename with potential URL encoding)
        encoded_filename = os.path.basename(path)
        
        # URL decode the filename
        decoded_filename = urllib.parse.unquote(encoded_filename)
        
        # Remove query parameters if present
        if '?' in decoded_filename:
            decoded_filename = decoded_filename.split('?')[0]
            
        # If we get an empty string, use the domain as a fallback
        if not decoded_filename:
            return 'download'
            
        return decoded_filename
    
    def get_download_status(self) -> Optional[Dict]:
        """Get the current status of the download"""
        if not self.download_info:
            return None
        
        return {
            'folderName': self.download_info['filename'],
            'fileSize': self.download_info['fileSize'],
            'progress': self.download_info['progress'],
            'downloadSpeed': self.download_info['downloadSpeed'],
            'numPeers': 0,  # Not applicable for HTTP
            'numSeeds': 0,  # Not applicable for HTTP
            'status': self.download_info['status'],
            'bytesDownloaded': self.download_info['bytesDownloaded'],
        }