import os
import sys
from google import genai
from google.genai import types
from tenacity import retry, stop_after_attempt, wait_exponential, retry_if_exception_type
import pysubs2
from deep_translator import GoogleTranslator

# Define a retry decorator
# ... (retry_policy remains)

def translate_fallback_free(source_srt_content, target_language="en"):
    """
    Fallback translation using deep-translator (free Google Translate).
    
    Args:
        source_srt_content (str): Content of the source SRT file.
        target_language (str): Target language code (e.g. 'en', 'fr').
    
    Returns:
        str: Translated SRT content, or None if failed.
    """
    print(f"  [Free Fallback] Translating via Google Translate (deep-translator)...")
    try:
        # Load from string
        subs = pysubs2.SSAFile.from_string(source_srt_content)
        translator = GoogleTranslator(source='auto', target=target_language)
        
        # Simple line-by-line translation
        for line in subs:
            text = line.text.strip()
            if text:
                # Sanity check: Skip lines that are too long
                if len(text) > 4000:
                    print(f"    Warning: Skipping line with excessive length ({len(text)} chars).")
                    continue

                try:
                    # pysubs2 text can contain \N for newlines. 
                    original_text = text.replace(r"\N", " ")
                    translated_text = translator.translate(original_text)
                    if translated_text:
                        line.text = translated_text
                except Exception as e:
                    print(f"    Warning: Failed to translate line: {e}")
        
        # Return as string
        return subs.to_string(format_="srt")
    except Exception as e:
        print(f"  [Free Fallback] Critical Error: {e}")
        return None

# Define a retry decorator
# Waits 2^x * 1 seconds between retries (1s, 2s, 4s...)
# Stop after 15 attempts
retry_policy = retry(
    stop=stop_after_attempt(15),
    wait=wait_exponential(multiplier=1, min=2, max=60),
    retry=retry_if_exception_type(Exception),
    reraise=True
)

@retry_policy
def _generate_with_retry(client, model_name, prompt):
    """Internal function to wrap the API call with retry logic."""
    try:
        return client.models.generate_content(
            model=model_name,
            contents=prompt
        )
    except Exception as e:
        if "429" in str(e) or "Resource has been exhausted" in str(e):
            print(f"  [Rate Limit Hit] Waiting for quota reset... ({e})")
        raise e

def get_best_available_model(client):
    """
    Queries the API to find the best available model for text generation.
    Priority: gemini-2.0-flash > gemini-1.5-flash > gemini-1.5-pro
    """
    try:
        # Priority list (New v2 naming conventions if applicable, but standard models persist)
        priorities = [
            "gemini-2.0-flash", # Latest
            "gemini-1.5-flash",
            "gemini-1.5-pro"
        ]
        
        # In new SDK, client.models.list() returns iterators of Model objects
        # We can just try to use the priority one directly, or list them.
        # Listing can be slow. Let's just default to a known good priority list.
        # If we really want to check:
        # available = [m.name for m in client.models.list()]
        
        # For efficiency/speed, we will trust our priority list. 
        # The API will error if model doesn't exist, which the try/catch block handling generation will catch?
        # No, better to pick one that exists.
        
        # Let's return the latest standard one.
        return "gemini-2.0-flash" # Assuming 2.0 is available or falling back
            
    except Exception as e:
        print(f"Warning: Model selection issue ({e}). Defaulting to 'gemini-1.5-flash'.")
    
    return "gemini-1.5-flash"

def translate_srt(srt_content, target_language="English", api_key=None):
    """
    Translates SRT subtitle content using the Google GenAI SDK (v2).
    """
    if not srt_content:
        return ""

    key = api_key or os.getenv("GEMINI_API_KEY")
    if not key:
        print("Error: GEMINI_API_KEY not found. Please set the environment variable or pass the key.")
        sys.exit(1)

    # Initialize Client (v2 style)
    try:
        client = genai.Client(api_key=key)
    except Exception as e:
        print(f"Error initializing GenAI Client: {e}")
        return None

    # Automatically select the best model
    # Note: v2 SDK might use 'gemini-1.5-flash' directly without 'models/' prefix usually
    model_name = "gemini-2.0-flash" 
    print(f"Using Gemini Model (v2): {model_name}")

    prompt = (
        "You are a professional subtitle translator. Your task is to translate the following SRT subtitle file "
        f"into {target_language}.\n\n"
        "RULES:\n"
        "1. PRESERVE the SRT format exactly. Do not modify timestamps (e.g., 00:00:01,000 --> 00:00:04,000) or sequence numbers.\n"
        "2. Only translate the dialogue text.\n"
        "3. Maintain the original tone and context.\n"
        "4. Output ONLY the translated SRT content, no markdown code blocks or explanations.\n\n"
        "SRT Content:\n"
        f"{srt_content}"
    )

    print(f"Translating subtitles to {target_language} (with retries)...")
    try:
        # Call the retried internal function
        response = _generate_with_retry(client, model_name, prompt)
        print("Translation complete.")
        
        # Cleanup: sometimes models wrap output in ```srt ... ``` or ``` ... ```
        cleaned_text = response.text.strip()
        if cleaned_text.startswith("```"):
            lines = cleaned_text.split('\n')
            if len(lines) >= 2:
                cleaned_text = '\n'.join(lines[1:-1])
        
        return cleaned_text
    except Exception as e:
        print(f"Error during translation after retries: {e}")
        # Fallback to older model if 2.0 fails?
        if "404" in str(e) and "gemini-2.0" in model_name:
             print("  -> gemini-2.0-flash not found, falling back to gemini-1.5-flash")
             try:
                 response = _generate_with_retry(client, "gemini-1.5-flash", prompt)
                 cleaned_text = response.text.strip()
                 if cleaned_text.startswith("```"):
                    lines = cleaned_text.split('\n')
                    if len(lines) >= 2:
                        cleaned_text = '\n'.join(lines[1:-1])
                 return cleaned_text
             except Exception as inner_e:
                 print(f"Fallback failed: {inner_e}")

        return None