"""
Translation Module
==================
Handles text translation between English and Hindi using deep-translator.

Functions:
    - detect_language: Auto-detect if text is English or Hindi
    - translate_text: Translate text between languages
"""

from deep_translator import GoogleTranslator
from typing import Literal


def detect_language(text: str) -> Literal["en", "hi"]:
    """
    Detect if the input text is English or Hindi.
    
    Uses Unicode range detection for Devanagari script (Hindi).
    
    Args:
        text: Input text string to analyze
        
    Returns:
        'hi' if Hindi/Devanagari characters found, 'en' otherwise
        
    Example:
        >>> detect_language("Hello World")
        'en'
        >>> detect_language("नमस्ते")
        'hi'
    """
    # Check for Devanagari Unicode range (U+0900 to U+097F)
    for char in text:
        if '\u0900' <= char <= '\u097F':
            return "hi"
    return "en"


def translate_text(
    text: str, 
    source_lang: Literal["auto", "en", "hi"], 
    target_lang: Literal["en", "hi"]
) -> str:
    """
    Translate text from source language to target language.
    
    Uses Google Translator via deep-translator library for accurate
    translations between English and Hindi.
    
    Args:
        text: The text to translate
        source_lang: Source language code ('auto', 'en', or 'hi')
        target_lang: Target language code ('en' or 'hi')
        
    Returns:
        Translated text string
        
    Raises:
        ValueError: If text is empty
        
    Example:
        >>> translate_text("Hello", "en", "hi")
        'नमस्ते'
        >>> translate_text("नमस्ते", "auto", "en")
        'Hello'
    """
    # Validate input
    if not text or not text.strip():
        return ""
    
    # Auto-detect source language if needed
    if source_lang == "auto":
        source_lang = detect_language(text)
    
    # Skip translation if source and target are the same
    if source_lang == target_lang:
        return text
    
    # Perform translation using Google Translator
    translator = GoogleTranslator(source=source_lang, target=target_lang)
    translated = translator.translate(text)
    
    return translated