from youtube_transcript_api import YouTubeTranscriptApi
from youtube_transcript_api.formatters import TextFormatter
from deep_translator import GoogleTranslator
from yt_dlp import YoutubeDL
import os
import re

def extract_video_id(url):
    """
    Extracts the video ID from a YouTube URL.
    """
    match = re.search(r"(?:v=|\/)([0-9A-Za-z_-]{11}).*", url)
    return match.group(1) if match else None

def get_subtitles(video_url):
    """
    Gets English subtitles using youtube-transcript-api.
    Tries manual subtitles first, then auto-generated.
    """
    video_id = extract_video_id(video_url)
    if not video_id:
        raise ValueError("Invalid YouTube URL")

    try:
        # Try manually added subtitles in English
        subtitles = YouTubeTranscriptApi.get_transcript(video_id, languages=['en'])
        return subtitles
    except Exception as e:
        print("🚫 Error getting manual transcript:", e)

        try:
            # Try auto-generated English subtitles
            subtitles = YouTubeTranscriptApi.get_transcript(video_id, languages=['en'])
            return subtitles
        except Exception as fallback_error:
            print("❌ Fallback also failed:", fallback_error)
            raise RuntimeError("Subtitles not available.")



def format_transcript(transcript):
    """
    Returns a plain text version of subtitles
    """
    formatter = TextFormatter()
    return formatter.format_transcript(transcript)

def split_text(text, max_chars=5000):
    """
    Splits text into chunks within API limit
    """
    chunks = []
    while len(text) > max_chars:
        split_at = text[:max_chars].rfind(".") + 1  # split at sentence boundary
        chunks.append(text[:split_at].strip())
        text = text[split_at:].strip()
    if text:
        chunks.append(text)
    return chunks

def translate_text(text, target_lang):
    """
    Translate text into target language using deep-translator
    """
    translated = []
    chunks = split_text(text)
    for chunk in chunks:
        try:
            translated_chunk = GoogleTranslator(source='auto', target=target_lang.lower()).translate(chunk)
            translated.append(translated_chunk)
        except Exception as e:
            print(f"❌ Error translating chunk: {e}")
            translated.append("[Translation Failed]")
    return "\n\n".join(translated)

def VideoToSubtitle(video_url, language):
    """
    Main function to fetch and translate subtitles.
    """
    print(f"🔍 Processing Video: {video_url}, Language: {language}")
    subtitles = get_subtitles(video_url)
    english_text = format_transcript(subtitles)
    translated_text = translate_text(english_text, language)
    return english_text, translated_text