video-accessibility/backend/app/services/gemini.py

import json
import asyncio
from pathlib import Path
from typing import Any, Optional

import google.genai as genai

from ..core.config import settings
from ..core.logging import get_logger

logger = get_logger(__name__)

# Configure Gemini client
client = genai.Client(api_key=settings.gemini_api_key)

class GeminiService:
    def __init__(self):
        self.model_name = 'gemini-3-pro-preview'  # Gemini 3 Pro preview model
        self.prompts_dir = Path(__file__).parent.parent / "prompts"

    def _load_prompt(self, prompt_file: str) -> str:
        """Load prompt template from prompts directory"""
        prompt_path = self.prompts_dir / prompt_file
        try:
            return prompt_path.read_text()
        except FileNotFoundError:
            logger.error(f"Prompt file not found: {prompt_file}")
            raise

    async def _wait_for_file_active(self, file_name: str, max_wait_seconds: int = 300) -> bool:
        """Wait for uploaded file to become ACTIVE state"""
        wait_time = 1  # Start with 1 second
        total_waited = 0
        
        while total_waited < max_wait_seconds:
            try:
                # Get file status - use asyncio.to_thread to avoid blocking event loop
                file_info = await asyncio.to_thread(client.files.get, name=file_name)
                logger.info(f"File {file_name} status: {file_info.state} (waited {total_waited}s)")
                
                if file_info.state == "ACTIVE":
                    logger.info(f"File {file_name} is now ACTIVE!")
                    return True
                elif file_info.state == "FAILED":
                    logger.error(f"File {file_name} processing FAILED")
                    return False
                
                # Wait with exponential backoff (max 30s)
                logger.info(f"File not ready, waiting {wait_time}s...")
                await asyncio.sleep(wait_time)
                total_waited += wait_time
                wait_time = min(wait_time * 1.5, 30)  # Exponential backoff, max 30s
                
            except Exception as e:
                logger.error(f"Error checking file status: {e}")
                await asyncio.sleep(5)  # Wait 5s on error
                total_waited += 5
        
        logger.error(f"File {file_name} did not become ACTIVE within {max_wait_seconds}s")
        return False

    async def extract_accessibility(self, video_file_path: str) -> dict[str, Any]:
        """
        Extract captions and audio descriptions from video using Gemini 2.0
        Returns structured JSON with transcript, captions VTT, and audio description VTT
        """
        prompt = self._load_prompt("gemini_ingestion.md")
        uploaded_file = None

        try:
            logger.info(f"Starting Gemini processing for video: {video_file_path}")
            
            # Upload video file to Gemini using new API - use asyncio.to_thread to avoid blocking
            logger.info("Uploading video file to Gemini API...")
            uploaded_file = await asyncio.to_thread(
                client.files.upload,
                file=video_file_path,
                config={
                    "display_name": f"video_processing_{Path(video_file_path).name}",
                    "mime_type": "video/mp4"
                }
            )
            logger.info(f"Successfully uploaded file: {uploaded_file.name} (URI: {uploaded_file.uri})")
            
            # Wait for file to become ACTIVE before using it
            logger.info("Waiting for file to become ACTIVE...")
            file_ready = await self._wait_for_file_active(uploaded_file.name)
            if not file_ready:
                raise Exception("File failed to become ACTIVE within timeout")
            
            # Generate content using new API - use asyncio.to_thread to avoid blocking
            logger.info("Generating content with Gemini model...")
            response = await asyncio.to_thread(
                client.models.generate_content,
                model=self.model_name,
                contents=[
                    genai.types.Part.from_text(text=prompt),
                    genai.types.Part.from_uri(
                        file_uri=uploaded_file.uri,
                        mime_type=uploaded_file.mime_type
                    )
                ]
            )

            # Parse JSON response
            response_text = response.text.strip()
            logger.info(f"Received Gemini response (first 200 chars): {response_text[:200]}...")

            # Handle potential markdown formatting
            if response_text.startswith("```json"):
                response_text = response_text.replace("```json", "").replace("```", "").strip()
                logger.info("Cleaned markdown formatting from response")
            
            # Additional cleanup for common JSON issues
            response_text = response_text.strip()
            
            logger.info("Parsing JSON response...")
            try:
                result = json.loads(response_text)
            except json.JSONDecodeError as e:
                logger.error(f"JSON parse error at position {e.pos}: {e.msg}")
                # Log the problematic area
                start = max(0, e.pos - 100)
                end = min(len(response_text), e.pos + 100)
                problematic_text = response_text[start:end]
                logger.error(f"Problematic JSON area: ...{problematic_text}...")
                raise

            # Validate required fields
            required_fields = [
                "language", "confidence", "summary",
                "transcript_plaintext", "captions_vtt", "audio_description_vtt"
            ]

            for field in required_fields:
                if field not in result:
                    raise ValueError(f"Missing required field: {field}")

            # Validate VTT format
            if not result["captions_vtt"].startswith("WEBVTT"):
                raise ValueError("Invalid captions VTT format")

            if not result["audio_description_vtt"].startswith("WEBVTT"):
                raise ValueError("Invalid audio description VTT format")

            logger.info(
                f"Successfully extracted accessibility content with confidence: {result['confidence']}"
            )

            return result

        except json.JSONDecodeError as e:
            logger.error(f"Failed to parse Gemini JSON response: {e}")
            logger.error(f"Raw response that failed to parse: {response_text}")
            # Attempt self-healing
            return await self._self_heal_response(video_file_path, response_text)
        except Exception as e:
            logger.error(f"Gemini extraction failed with exception: {type(e).__name__}: {str(e)}")
            logger.error(f"Video file path: {video_file_path}")
            # Print to stdout for immediate visibility
            print(f"🚨 GEMINI ERROR: {type(e).__name__}: {str(e)}")
            raise
        finally:
            # Guaranteed cleanup of uploaded file regardless of success/failure/cancellation
            if uploaded_file:
                try:
                    await asyncio.to_thread(client.files.delete, name=uploaded_file.name)
                    logger.info(f"Successfully cleaned up uploaded file: {uploaded_file.name}")
                except Exception as e:
                    logger.warning(f"Failed to cleanup uploaded file {uploaded_file.name}: {e}")

    async def _self_heal_response(self, video_file_path: str, invalid_response: str) -> dict[str, Any]:
        """Attempt to self-heal invalid JSON response from Gemini"""
        logger.info("Attempting to self-heal JSON response without re-uploading video")
        
        # Try to fix common JSON issues first
        try:
            fixed_response = self._attempt_json_fix(invalid_response)
            if fixed_response:
                logger.info("Successfully fixed JSON without re-processing")
                return fixed_response
        except Exception as e:
            logger.warning(f"JSON fix attempt failed: {e}")
        
        # If simple fixes don't work, try a text-only self-heal prompt with more context
        self_heal_prompt = f"""
SYSTEM: You are a JSON repair service. Fix the malformed JSON below and return ONLY the corrected JSON.

CRITICAL REQUIREMENTS:
- The JSON MUST contain these exact fields: language, confidence, summary, transcript_plaintext, captions_vtt, audio_description_vtt
- If audio_description_vtt is truncated or missing, reconstruct it as a valid WebVTT with at least basic descriptions
- All VTT content must start with "WEBVTT" and have proper timestamp format (HH:MM:SS.mmm --> HH:MM:SS.mmm)
- Properly escape all quotes within strings using \"
- Fix unterminated strings by adding closing quotes
- Remove trailing commas
- Ensure all JSON is properly closed with }}

Fix the JSON and return it:

{invalid_response}
        """

        try:
            response = await asyncio.to_thread(
                client.models.generate_content,
                model=self.model_name,
                contents=[genai.types.Part.from_text(text=self_heal_prompt)]
            )

            response_text = response.text.strip()
            
            # Handle potential markdown formatting
            if response_text.startswith("```json"):
                response_text = response_text.replace("```json", "").replace("```", "").strip()

            result = json.loads(response_text)
            
            # Validate that all required fields are present after healing
            required_fields = [
                "language", "confidence", "summary",
                "transcript_plaintext", "captions_vtt", "audio_description_vtt"
            ]
            
            missing_fields = [field for field in required_fields if field not in result]
            if missing_fields:
                logger.error(f"Self-heal lost required fields: {missing_fields}")
                # If audio_description_vtt is missing, create a basic one
                if "audio_description_vtt" in missing_fields:
                    logger.info("Creating fallback audio_description_vtt")
                    result["audio_description_vtt"] = "WEBVTT\n\n00:00:00.000 --> 00:00:05.000\nVideo content with visual elements described."
                
                # If other critical fields are missing, raise an error
                remaining_missing = [f for f in missing_fields if f != "audio_description_vtt"]
                if remaining_missing:
                    raise ValueError(f"Self-heal failed to preserve required fields: {remaining_missing}")
            
            logger.info("Successfully self-healed Gemini response with all required fields")
            return result

        except Exception as e:
            logger.error(f"Self-heal attempt failed: {e}")
            raise ValueError("Failed to get valid JSON from Gemini after self-heal attempt")

    async def extract_accessibility_targeted(
        self,
        video_file_path: str,
        target_language: str
    ) -> dict[str, Any]:
        """
        Extract captions and audio descriptions from video using Gemini,
        generating content directly in the specified target language.

        Unlike extract_accessibility() which auto-detects language, this method
        takes an explicit target language and generates all outputs in that language.
        This is used for "video_native" translation mode which re-processes the video
        for each target language with full visual context.

        Args:
            video_file_path: Path to the video file
            target_language: BCP-47 language code (e.g., "es", "fr", "de")

        Returns:
            Structured JSON with transcript, captions VTT, and audio description VTT
            all in the target language
        """
        prompt_template = self._load_prompt("gemini_ingestion_targeted.md")
        prompt = prompt_template.replace("{TARGET_LANGUAGE}", target_language)
        uploaded_file = None

        try:
            logger.info(f"Starting Gemini targeted processing for video: {video_file_path}, target: {target_language}")

            # Upload video file to Gemini using new API
            logger.info("Uploading video file to Gemini API for targeted extraction...")
            uploaded_file = await asyncio.to_thread(
                client.files.upload,
                file=video_file_path,
                config={
                    "display_name": f"video_processing_targeted_{target_language}_{Path(video_file_path).name}",
                    "mime_type": "video/mp4"
                }
            )
            logger.info(f"Successfully uploaded file: {uploaded_file.name} (URI: {uploaded_file.uri})")

            # Wait for file to become ACTIVE before using it
            logger.info("Waiting for file to become ACTIVE...")
            file_ready = await self._wait_for_file_active(uploaded_file.name)
            if not file_ready:
                raise Exception("File failed to become ACTIVE within timeout")

            # Generate content using new API
            logger.info(f"Generating content with Gemini model for {target_language}...")
            response = await asyncio.to_thread(
                client.models.generate_content,
                model=self.model_name,
                contents=[
                    genai.types.Part.from_text(text=prompt),
                    genai.types.Part.from_uri(
                        file_uri=uploaded_file.uri,
                        mime_type=uploaded_file.mime_type
                    )
                ]
            )

            # Parse JSON response
            response_text = response.text.strip()
            logger.info(f"Received Gemini targeted response for {target_language} (first 200 chars): {response_text[:200]}...")

            # Handle potential markdown formatting
            if response_text.startswith("```json"):
                response_text = response_text.replace("```json", "").replace("```", "").strip()
                logger.info("Cleaned markdown formatting from response")

            response_text = response_text.strip()

            logger.info("Parsing JSON response...")
            try:
                result = json.loads(response_text)
            except json.JSONDecodeError as e:
                logger.error(f"JSON parse error at position {e.pos}: {e.msg}")
                start = max(0, e.pos - 100)
                end = min(len(response_text), e.pos + 100)
                problematic_text = response_text[start:end]
                logger.error(f"Problematic JSON area: ...{problematic_text}...")
                # Attempt self-healing
                return await self._self_heal_targeted_response(target_language, response_text)

            # Validate required fields
            required_fields = [
                "language", "confidence", "summary",
                "transcript_plaintext", "captions_vtt", "audio_description_vtt"
            ]

            for field in required_fields:
                if field not in result:
                    raise ValueError(f"Missing required field: {field}")

            # Validate VTT format
            if not result["captions_vtt"].startswith("WEBVTT"):
                raise ValueError("Invalid captions VTT format")

            if not result["audio_description_vtt"].startswith("WEBVTT"):
                raise ValueError("Invalid audio description VTT format")

            logger.info(
                f"Successfully extracted targeted accessibility content for {target_language} "
                f"with confidence: {result['confidence']}"
            )

            return result

        except json.JSONDecodeError as e:
            logger.error(f"Failed to parse Gemini JSON response: {e}")
            logger.error(f"Raw response that failed to parse: {response_text}")
            return await self._self_heal_targeted_response(target_language, response_text)
        except Exception as e:
            logger.error(f"Gemini targeted extraction failed for {target_language}: {type(e).__name__}: {str(e)}")
            logger.error(f"Video file path: {video_file_path}")
            print(f"🚨 GEMINI TARGETED ERROR ({target_language}): {type(e).__name__}: {str(e)}")
            raise
        finally:
            # Cleanup uploaded file
            if uploaded_file:
                try:
                    await asyncio.to_thread(client.files.delete, name=uploaded_file.name)
                    logger.info(f"Successfully cleaned up uploaded file: {uploaded_file.name}")
                except Exception as e:
                    logger.warning(f"Failed to cleanup uploaded file {uploaded_file.name}: {e}")

    async def _self_heal_targeted_response(
        self,
        target_language: str,
        invalid_response: str
    ) -> dict[str, Any]:
        """Attempt to self-heal invalid JSON response from targeted extraction"""
        logger.info(f"Attempting to self-heal targeted response for {target_language}")

        # Try to fix common JSON issues first
        try:
            fixed_response = self._attempt_json_fix(invalid_response)
            if fixed_response:
                logger.info("Successfully fixed JSON without re-processing")
                return fixed_response
        except Exception as e:
            logger.warning(f"JSON fix attempt failed: {e}")

        self_heal_prompt = f"""
SYSTEM: You are a JSON repair service. Fix the malformed JSON below and return ONLY the corrected JSON.

CRITICAL REQUIREMENTS:
- The JSON MUST contain these exact fields: language, confidence, summary, transcript_plaintext, captions_vtt, audio_description_vtt
- All content should be in {target_language}
- If audio_description_vtt is truncated or missing, reconstruct it as a valid WebVTT with at least basic descriptions in {target_language}
- All VTT content must start with "WEBVTT" and have proper timestamp format (HH:MM:SS.mmm --> HH:MM:SS.mmm)
- Properly escape all quotes within strings using \"
- Fix unterminated strings by adding closing quotes
- Remove trailing commas
- Ensure all JSON is properly closed with }}

Fix the JSON and return it:

{invalid_response}
        """

        try:
            response = await asyncio.to_thread(
                client.models.generate_content,
                model=self.model_name,
                contents=[genai.types.Part.from_text(text=self_heal_prompt)]
            )

            response_text = response.text.strip()

            if response_text.startswith("```json"):
                response_text = response_text.replace("```json", "").replace("```", "").strip()

            result = json.loads(response_text)

            required_fields = [
                "language", "confidence", "summary",
                "transcript_plaintext", "captions_vtt", "audio_description_vtt"
            ]

            missing_fields = [field for field in required_fields if field not in result]
            if missing_fields:
                logger.error(f"Self-heal lost required fields: {missing_fields}")
                if "audio_description_vtt" in missing_fields:
                    logger.info("Creating fallback audio_description_vtt")
                    result["audio_description_vtt"] = "WEBVTT\n\n00:00:00.000 --> 00:00:05.000\nVideo content with visual elements described."

                remaining_missing = [f for f in missing_fields if f != "audio_description_vtt"]
                if remaining_missing:
                    raise ValueError(f"Self-heal failed to preserve required fields: {remaining_missing}")

            logger.info(f"Successfully self-healed targeted response for {target_language}")
            return result

        except Exception as e:
            logger.error(f"Self-heal attempt failed for {target_language}: {e}")
            raise ValueError(f"Failed to get valid JSON from Gemini targeted extraction for {target_language}")

    def _attempt_json_fix(self, json_text: str) -> dict[str, Any] | None:
        """Attempt to fix common JSON syntax issues"""
        # Try to identify and fix common issues
        fixes_tried = []
        fixed_text = json_text
        import re
        
        # Fix 1: Remove trailing commas
        fixed_text = re.sub(r',(\s*[}\]])', r'\1', fixed_text)
        fixes_tried.append("removed trailing commas")
        
        # Fix 2: Try to fix unterminated strings by adding closing quote and brace
        if fixed_text.count('"') % 2 != 0:  # Odd number of quotes suggests unterminated string
            # Find the last quote and see if we need to close the JSON
            last_quote_pos = fixed_text.rfind('"')
            remainder = fixed_text[last_quote_pos + 1:].strip()
            
            # If there's no closing brace after the last quote, try to fix it
            if remainder and not remainder.endswith('}'):
                # Try to intelligently close the JSON
                if 'audio_description_vtt' in fixed_text[max(0, last_quote_pos - 100):]:
                    # This appears to be in the audio_description_vtt field
                    fixed_text += '"\n}'
                    fixes_tried.append("closed unterminated audio_description_vtt string")
                else:
                    fixed_text += '"'
                    fixes_tried.append("closed unterminated string")
        
        # Fix 3: Ensure JSON ends with closing brace
        if not fixed_text.rstrip().endswith('}'):
            fixed_text = fixed_text.rstrip() + '\n}'
            fixes_tried.append("added closing brace")
        
        try:
            result = json.loads(fixed_text)
            logger.info(f"JSON fixed with: {', '.join(fixes_tried)}")
            
            # Validate that we have the required fields
            required_fields = [
                "language", "confidence", "summary",
                "transcript_plaintext", "captions_vtt", "audio_description_vtt"
            ]
            
            missing_fields = [field for field in required_fields if field not in result]
            if missing_fields:
                logger.warning(f"Fixed JSON is missing required fields: {missing_fields}")
                return None  # Let the more advanced self-healing handle this
            
            return result
        except json.JSONDecodeError as e:
            logger.debug(f"JSON fix attempt failed: {e}")
            return None

    async def analyze_accessible_video_placement(
        self,
        video_file_path: str,
        ad_vtt_content: str,
        ad_cue_durations: list[float]
    ) -> dict[str, Any]:
        """
        Analyze video and determine optimal method for integrating audio descriptions.
        Returns placement instructions for each AD cue.

        Args:
            video_file_path: Path to the source video file
            ad_vtt_content: The audio description VTT content
            ad_cue_durations: List of actual TTS audio durations in seconds (matching VTT cue order)

        Returns:
            Dictionary with method choice and placement instructions for each AD cue
        """
        prompt_template = self._load_prompt("gemini_accessible_video.md")

        # Format prompt with AD VTT content and durations
        prompt = prompt_template.replace(
            "{AD_VTT_CONTENT}", ad_vtt_content
        ).replace(
            "{AD_CUE_DURATIONS}", json.dumps(ad_cue_durations)
        )

        uploaded_file = None

        try:
            logger.info(f"Starting accessible video analysis for: {video_file_path}")
            logger.info(f"AD cues to place: {len(ad_cue_durations)}")

            # Upload video file to Gemini
            logger.info("Uploading video file to Gemini API for accessible video analysis...")
            uploaded_file = await asyncio.to_thread(
                client.files.upload,
                file=video_file_path,
                config={
                    "display_name": f"accessible_video_analysis_{Path(video_file_path).name}",
                    "mime_type": "video/mp4"
                }
            )
            logger.info(f"Successfully uploaded file: {uploaded_file.name}")

            # Wait for file to become ACTIVE
            logger.info("Waiting for file to become ACTIVE...")
            file_ready = await self._wait_for_file_active(uploaded_file.name)
            if not file_ready:
                raise Exception("File failed to become ACTIVE within timeout")

            # Generate content with video and prompt
            logger.info("Analyzing video with Gemini for accessible video placement...")
            response = await asyncio.to_thread(
                client.models.generate_content,
                model=self.model_name,
                contents=[
                    genai.types.Part.from_text(text=prompt),
                    genai.types.Part.from_uri(
                        file_uri=uploaded_file.uri,
                        mime_type=uploaded_file.mime_type
                    )
                ]
            )

            # Parse JSON response
            response_text = response.text.strip()
            logger.info(f"Received accessible video analysis response (first 300 chars): {response_text[:300]}...")

            # Handle potential markdown formatting
            if response_text.startswith("```json"):
                response_text = response_text.replace("```json", "").replace("```", "").strip()

            try:
                result = json.loads(response_text)
            except json.JSONDecodeError as e:
                logger.error(f"JSON parse error in accessible video analysis: {e}")
                # Try self-healing for this response
                result = await self._self_heal_accessible_video_response(response_text)

            # Validate required fields
            required_fields = ["method", "method_rationale", "dialogue_density", "placements"]
            for field in required_fields:
                if field not in result:
                    raise ValueError(f"Missing required field in accessible video analysis: {field}")

            # Validate method value
            if result["method"] not in ["overlay", "pause_insert"]:
                raise ValueError(f"Invalid method value: {result['method']}")

            # Validate placements
            if len(result["placements"]) != len(ad_cue_durations):
                logger.warning(
                    f"Placement count mismatch: got {len(result['placements'])}, "
                    f"expected {len(ad_cue_durations)}"
                )

            logger.info(
                f"Accessible video analysis complete: method={result['method']}, "
                f"dialogue_density={result['dialogue_density']:.2f}, "
                f"placements={len(result['placements'])}"
            )

            return result

        except Exception as e:
            logger.error(f"Accessible video analysis failed: {type(e).__name__}: {str(e)}")
            raise
        finally:
            # Cleanup uploaded file
            if uploaded_file:
                try:
                    await asyncio.to_thread(client.files.delete, name=uploaded_file.name)
                    logger.info(f"Cleaned up uploaded file: {uploaded_file.name}")
                except Exception as e:
                    logger.warning(f"Failed to cleanup uploaded file {uploaded_file.name}: {e}")

    async def _self_heal_accessible_video_response(self, invalid_response: str) -> dict[str, Any]:
        """Attempt to self-heal invalid JSON response from accessible video analysis"""
        logger.info("Attempting to self-heal accessible video analysis response")

        self_heal_prompt = f"""
SYSTEM: You are a JSON repair service. Fix the malformed JSON below and return ONLY the corrected JSON.

CRITICAL REQUIREMENTS:
- The JSON MUST contain: method, method_rationale, dialogue_density, placements, total_added_duration, warnings
- method must be either "overlay" or "pause_insert"
- dialogue_density must be a number between 0 and 1
- placements must be an array of placement objects
- Fix any JSON syntax errors (trailing commas, unterminated strings, etc.)

Fix the JSON and return it:

{invalid_response}
        """

        try:
            response = await asyncio.to_thread(
                client.models.generate_content,
                model=self.model_name,
                contents=[genai.types.Part.from_text(text=self_heal_prompt)]
            )

            response_text = response.text.strip()
            if response_text.startswith("```json"):
                response_text = response_text.replace("```json", "").replace("```", "").strip()

            result = json.loads(response_text)
            logger.info("Successfully self-healed accessible video analysis response")
            return result

        except Exception as e:
            logger.error(f"Self-heal attempt for accessible video analysis failed: {e}")
            raise ValueError("Failed to get valid JSON from accessible video analysis after self-heal")

    async def transcreate_content(
        self,
        captions_vtt: str,
        ad_vtt: str,
        target_language: str,
        brief: Optional[str] = None
    ) -> dict[str, str]:
        """
        Transcreate English VTT content to target language with cultural adaptation
        """
        prompt_template = self._load_prompt("gemini_transcreation.md")

        # Format prompt with actual content
        prompt = prompt_template.format(
            TARGET_LANGUAGE=target_language
        )

        user_prompt = f"""
Input:
- captions_vtt_en: {captions_vtt}
- ad_vtt_en: {ad_vtt}
- brief: {brief or "No specific brand guidelines provided"}

Output:
JSON:
"""

        try:
            response = await asyncio.to_thread(
                client.models.generate_content,
                model=self.model_name,
                contents=[
                    genai.types.Part.from_text(text=prompt + "\n\n" + user_prompt)
                ]
            )

            response_text = response.text.strip()

            # Handle potential markdown formatting
            if response_text.startswith("```json"):
                response_text = response_text.replace("```json", "").replace("```", "").strip()

            result = json.loads(response_text)

            # Validate required fields
            if "captions_vtt" not in result or "audio_description_vtt" not in result:
                raise ValueError("Missing required VTT fields in transcreation response")

            logger.info(f"Successfully transcreated content to {target_language}")
            return result

        except json.JSONDecodeError as e:
            logger.error(f"Failed to parse transcreation JSON response: {e}")
            raise ValueError("Invalid JSON response from transcreation")
        except Exception as e:
            logger.error(f"Transcreation failed: {e}")
            raise

    async def translate_vtt(
        self,
        vtt_content: str,
        target_language: str,
        source_language: str = "en"
    ) -> str:
        """
        Translate VTT content using Gemini, preserving timing and structure.
        More cost-effective alternative to Google Translate API (6-36x cheaper).

        Args:
            vtt_content: The VTT file content to translate
            target_language: The language code to translate to (e.g., 'es', 'fr')
            source_language: The source language code (default: 'en')

        Returns:
            Translated VTT content with preserved timestamps
        """
        prompt = f"""Translate this WebVTT subtitle file from {source_language} to {target_language}.

CRITICAL REQUIREMENTS:
- Preserve ALL timestamps exactly as-is (do not modify any timing)
- Keep the WEBVTT header line
- Translate ONLY the text content between timestamps
- Maintain readable line lengths (~32-40 characters per line)
- Handle idioms and slang naturally in {target_language}
- Preserve any speaker labels (e.g., "[Speaker 1]:")
- Do NOT add any explanation or markdown - return ONLY the translated VTT

VTT Content to translate:
{vtt_content}"""

        try:
            response = await asyncio.to_thread(
                client.models.generate_content,
                model=self.model_name,
                contents=[genai.types.Part.from_text(text=prompt)]
            )

            result = response.text.strip()

            # Handle potential markdown formatting
            if result.startswith("```"):
                # Remove markdown code blocks
                lines = result.split("\n")
                # Filter out lines that are just ``` or ```vtt or ```webvtt
                filtered_lines = [
                    line for line in lines
                    if not line.strip().startswith("```")
                ]
                result = "\n".join(filtered_lines).strip()

            # Validate VTT format
            if not result.startswith("WEBVTT"):
                logger.warning("Gemini translation missing WEBVTT header, adding it")
                result = "WEBVTT\n\n" + result

            logger.info(f"Successfully translated VTT to {target_language} using Gemini")
            return result

        except Exception as e:
            logger.error(f"Gemini translation failed for {target_language}: {e}")
            raise


# Global service instance
gemini_service = GeminiService()