# main.py
from fastapi import FastAPI, Query, HTTPException
from fastapi.responses import FileResponse
from gtts import gTTS, gTTSError  # Import gTTSError for specific error handling
import uuid
import os  # Import os module for path operations
import tempfile # Import tempfile for better temporary file handling

# --- Configuration ---
# Use tempfile to get a cross-platform temporary directory
TEMP_DIR = tempfile.gettempdir()
# Ensure the temporary directory exists
os.makedirs(TEMP_DIR, exist_ok=True)

# --- FastAPI App Initialization ---
app = FastAPI(
    title="gTTS API",
    description="A simple API to convert text to speech using Google Text-to-Speech (gTTS). Supports multiple languages including Tamil, Sinhala, and many others.",
    version="1.2.0", # Increment version for documentation changes
)

# --- API Endpoints ---

@app.get("/", tags=["General"])
def read_root():
    """
    Root endpoint providing a welcome message.
    """
    return {"message": "Welcome to the gTTS API. Use the /tts endpoint to generate speech."}

@app.get("/tts", tags=["Text-to-Speech"])
def text_to_speech(
    text: str = Query(
        ..., # Ellipsis makes the parameter required
        min_length=1,
        max_length=500, # Adjust max length as needed
        title="Text to Convert",
        description="The text you want to convert into speech (1-500 characters)."
    ),
    lang: str = Query(
        "en", # Default language is English
        min_length=2,
        max_length=10, # Allow for language codes like 'en-us', 'zh-CN' etc.
        title="Language Code",
        description="The BCP 47 language code for the speech synthesis (e.g., 'en', 'es', 'ta', 'si', 'ja', 'zh-CN'). See gTTS documentation for supported languages."
    )
):
    """
    Converts the provided text into an MP3 audio file using the specified language.

    - **text**: The text to synthesize (required).
    - **lang**: The language code (e.g., 'en', 'es', 'fr', 'ta', 'si'). Defaults to 'en'. **Crucially, gTTS must support this language code.**
    """
    try:
        # Generate a unique filename in the configured temporary directory
        filename = os.path.join(TEMP_DIR, f"{uuid.uuid4().hex}.mp3")

        # Create gTTS object with text and language
        # Use slow=False for normal speed speech
        tts_object = gTTS(text=text, lang=lang, slow=False)

        # Save the audio file
        tts_object.save(filename)

        # Return the audio file as a response
        # The 'filename' parameter sets the download name for the browser
        return FileResponse(
            path=filename,
            media_type="audio/mpeg",
            filename=f"speech_{lang}.mp3" # Suggest a filename like speech_en.mp3 or speech_ta.mp3
            # Consider adding background task for cleanup as mentioned in previous examples
        )

    except gTTSError as e:
        # Handle specific gTTS errors (like invalid language code, network issues)
        detail_message = f"gTTS Error: {str(e)}. Ensure the language code '{lang}' is supported and text is appropriate for the language."
        # Check common error patterns
        if "400 (Bad Request)" in str(e) or "Language not supported" in str(e):
             raise HTTPException(status_code=400, detail=detail_message)
        elif "500 (Internal Server Error)" in str(e) or "Failed to connect" in str(e):
             # Treat these as potential temporary Google service issues
             raise HTTPException(status_code=503, detail=f"Service Error: {str(e)}. Could be a temporary issue with the TTS service.")
        else: # Other gTTS errors
             raise HTTPException(status_code=503, detail=detail_message) # 503 Service Unavailable likely

    except ValueError as e:
        # Potentially handle other value errors if gTTS raises them for certain inputs
         raise HTTPException(status_code=400, detail=f"Input Error: {str(e)}")

    except Exception as e:
        # Catch any other unexpected errors
        # Log the error for debugging
        # import logging
        # logging.exception(f"An unexpected error occurred during TTS generation for lang='{lang}'")
        raise HTTPException(status_code=500, detail=f"Internal Server Error: An unexpected error occurred.")

# --- How to Run (Instructions) ---
# 1. Save this code as `main.py`.
# 2. Install necessary libraries:
#    pip install fastapi "uvicorn[standard]" gTTS
# 3. Run the FastAPI server using Uvicorn:
#    uvicorn main:app --reload
#
# --- How to Use - Examples ---
# Open your browser or use a tool like curl/Postman.
# Access the TTS endpoint with the 'text' and 'lang' query parameters.
# NOTE: Text containing non-ASCII characters needs to be URL-encoded. Most browsers do this automatically.
#
# - English (en - Default):
#   Text: "Hello, world!"
#   URL: http://127.0.0.1:8000/tts?text=Hello%2C%20world%21
#
# - Spanish (es):
#   Text: "Hola Mundo"
#   URL: http://127.0.0.1:8000/tts?text=Hola%20Mundo&lang=es
#
# - French (fr):
#   Text: "Bonjour le monde"
#   URL: http://127.0.0.1:8000/tts?text=Bonjour%20le%20monde&lang=fr
#
# - German (de):
#   Text: "Hallo Welt"
#   URL: http://127.0.0.1:8000/tts?text=Hallo%20Welt&lang=de
#
# - Tamil (ta):
#   Text: "வணக்கம் உலகம்"
#   URL: http://127.0.0.1:8000/tts?text=%E0%AE%B5%E0%AE%A3%E0%AE%95%E0%AF%8D%E0%AE%95%E0%AE%AE%E0%AF%8D%20%E0%AE%89%E0%AE%B2%E0%AE%95%E0%AE%AE%E0%AF%8D&lang=ta
#
# - Sinhala (si):
#   Text: "හෙලෝ ලෝකය"
#   URL: http://127.0.0.1:8000/tts?text=%E0%B7%84%E0%B7%99%E0%B6%BD%E0%B7%9D%20%E0%B6%BD%E0%B7%9D%E0%B6%9A%E0%B6%BA&lang=si
#
# - Japanese (ja):
#   Text: "こんにちは世界"
#   URL: http://127.0.0.1:8000/tts?text=%E3%81%93%E3%82%93%E3%81%AB%E3%81%A1%E3%81%AF%E4%B8%96%E7%95%8C&lang=ja
#
# - Chinese (Mandarin, Simplified) (zh-CN):
#   Text: "你好世界"
#   URL: http://127.0.0.1:8000/tts?text=%E4%BD%A0%E5%A5%BD%E4%B8%96%E7%95%8C&lang=zh-CN
#
# - Russian (ru):
#   Text: "Привет мир"
#   URL: http://127.0.0.1:8000/tts?text=%D0%9F%D1%80%D0%B8%D0%B2%D0%B5%D1%82%20%D0%BC%D0%B8%D1%80&lang=ru
#
# - Hindi (hi):
#   Text: "नमस्ते दुनिया"
#   URL: http://127.0.0.1:8000/tts?text=%E0%A4%A8%E0%A4%AE%E0%A4%B8%E0%A5%8D%E0%A4%A4%E0%A5%87%20%E0%A4%A6%E0%A5%81%E0%A4%A8%E0%A4%BF%E0%A4%AF%E0%A4%BE&lang=hi
#
# - Arabic (ar):
#   Text: "مرحبا بالعالم"
#   URL: http://127.0.0.1:8000/tts?text=%D9%85%D8%B1%D8%AD%D8%A8%D8%A7%20%D8%A8%D8%A7%D9%84%D8%B9%D8%A7%D9%84%D9%85&lang=ar
#
# Find more supported language codes in the gTTS documentation or common lists of BCP 47 codes.
# The API will return an MP3 file download or playback depending on your browser/client.
# If you provide an unsupported language code, you should get a 400 Bad Request error.