"""
Dataset Handler Module

Handles dataset import and exploration functionality for ACE-Step training.
This module provides a placeholder implementation for dataset operations
when the full training dataset dependencies are not available.

Note: Full dataset functionality requires Text2MusicDataset which may not be
included in the basic installation to reduce dependencies.
"""
from typing import Optional, Tuple, Any, Dict


class DatasetHandler:
    """
    Dataset Handler for Dataset Explorer functionality.
    
    Provides interface for dataset import and exploration features in the Gradio UI.
    When training dependencies are not available, returns appropriate fallback responses.
    """
    
    def __init__(self):
        """Initialize dataset handler with empty state"""
        self.dataset = None
        self.dataset_imported = False
    
    def import_dataset(self, dataset_type: str) -> str:
        """
        Import dataset (currently disabled in base installation)
        
        Args:
            dataset_type: Type of dataset to import (e.g., "train", "test", "validation")
            
        Returns:
            Status message indicating dataset import is disabled
            
        Note:
            This is a placeholder implementation. Full dataset support requires:
            - Text2MusicDataset dependency
            - Training data files  
            - Additional configuration
        """
        self.dataset_imported = False
        return f"⚠️ Dataset import is currently disabled. Text2MusicDataset dependency not available."
    
    def get_item_data(self, *args, **kwargs) -> Tuple:
        """
        Get dataset item data (placeholder implementation)
        
        Args:
            *args: Variable arguments (ignored in placeholder)
            **kwargs: Keyword arguments (ignored in placeholder)
            
        Returns:
            Tuple of placeholder values matching the expected return format:
            (caption, lyrics, language, bpm, keyscale, ref_audio, src_audio, codes,
             status_msg, instruction, duration, timesig, audio1, audio2, audio3, 
             metadata, task_type)
             
        Note:
            Returns empty/default values since dataset is not available.
            Real implementation would return actual dataset samples.
        """
        return (
            "",           # caption: empty string
            "",           # lyrics: empty string  
            "",           # language: empty string
            "",           # bpm: empty string
            "",           # keyscale: empty string
            None,         # ref_audio: no audio file
            None,         # src_audio: no audio file
            None,         # codes: no audio codes
            "❌ Dataset not available",  # status_msg: error indicator
            "",           # instruction: empty string
            0,            # duration: zero
            "",           # timesig: empty string
            None,         # audio1: no audio
            None,         # audio2: no audio
            None,         # audio3: no audio
            {},           # metadata: empty dict
            "text2music"  # task_type: default task
        )