"""
NovaAi – TTS-Engine-Hub
utils/cache.py
Version: v0.0.1

Description:
  Caching utilities for TTS requests (cache key generation, etc).

Author: Abby (ChatGPT)
Date: 2025-07-23
Canvas: utils/cache.py
"""

import hashlib
import os
import time

# Cache version - increment this to invalidate all cached files
# This is useful when fixing bugs that affect audio generation
# Version history:
# v1: Initial implementation with --stdin bug
# v2: Fixed Bug #1-7 (removed --stdin, added timeouts, better error handling)
CACHE_VERSION = "v2"

# Für die API: Wichtig! req muss mindestens die Felder .text, .engine, .model, .speaker, .format, .chunking haben.
def build_cache_key(req) -> str:
    """
    Build a cache key from all relevant TTS request parameters.
    Includes CACHE_VERSION to automatically invalidate cache when bugs are fixed.
    """
    data = f"{CACHE_VERSION}|{req.text}|{req.engine}|{req.model}|{req.speaker}|{req.format}|{getattr(req, 'chunking', False)}"
    return hashlib.sha256(data.encode()).hexdigest()


def cleanup_old_cache_files(cache_dir: str, max_age_days: int = 7) -> int:
    """
    Remove cache files older than max_age_days.
    Returns the number of files deleted.

    This helps prevent the cache directory from growing indefinitely,
    especially after cache version changes that make old files obsolete.
    """
    if not os.path.isdir(cache_dir):
        return 0

    current_time = time.time()
    max_age_seconds = max_age_days * 24 * 60 * 60
    deleted_count = 0

    for filename in os.listdir(cache_dir):
        if not filename.startswith('tts_'):
            continue

        filepath = os.path.join(cache_dir, filename)

        try:
            file_age = current_time - os.path.getmtime(filepath)
            if file_age > max_age_seconds:
                os.remove(filepath)
                deleted_count += 1
        except (OSError, IOError):
            # Skip files we can't access
            continue

    return deleted_count