"""
Ticket Storage Utility
======================
Modular storage system for ticket data with caching support.
"""
import json
import os
from datetime import datetime
from typing import Dict, Optional, Any, List
from threading import Lock

from .models import TicketData, GuildTicketConfig, TicketStatus


class TicketStorage:
    """
    Thread-safe storage manager for ticket data.
    
    Features:
    - Automatic file creation
    - In-memory caching with write-through
    - Backup creation before writes
    - Data validation on load
    """
    
    def __init__(self, base_path: str = "data/tickets"):
        self.base_path = base_path
        self.config_path = os.path.join(base_path, "config.json")
        self.tickets_path = os.path.join(base_path, "tickets")
        self.backup_path = os.path.join(base_path, "backups")
        self.cache: Dict[str, Any] = {}
        self.cache_lock = Lock()
        self._ensure_directories()
    
    def _ensure_directories(self) -> None:
        """Create necessary directories"""
        for path in [self.base_path, self.tickets_path, self.backup_path]:
            os.makedirs(path, exist_ok=True)
    
    def _create_backup(self, file_path: str) -> str:
        """Create a timestamped backup of a file"""
        if not os.path.exists(file_path):
            return ""
        
        timestamp = datetime.now().strftime("%Y%m%d_%H%M%S")
        filename = os.path.basename(file_path)
        backup_file = os.path.join(self.backup_path, f"{timestamp}_{filename}")
        
        try:
            with open(file_path, 'r', encoding='utf-8') as src:
                with open(backup_file, 'w', encoding='utf-8') as dst:
                    dst.write(src.read())
            return backup_file
        except Exception:
            return ""
    
    def _get_cache_key(self, guild_id: int, key_type: str) -> str:
        """Generate a cache key"""
        return f"{guild_id}_{key_type}"
    
    # --- Config Methods ---
    
    def load_config(self, guild_id: int) -> GuildTicketConfig:
        """Load guild ticket configuration"""
        cache_key = self._get_cache_key(guild_id, "config")
        
        with self.cache_lock:
            if cache_key in self.cache:
                return self.cache[cache_key]
        
        try:
            if os.path.exists(self.config_path):
                with open(self.config_path, 'r', encoding='utf-8') as f:
                    all_configs = json.load(f)
                
                config_data = all_configs.get(str(guild_id), {})
                config = GuildTicketConfig.from_dict(config_data)
                config.guild_id = guild_id
            else:
                config = GuildTicketConfig(guild_id=guild_id)
        except (json.JSONDecodeError, KeyError) as e:
            print(f"[TicketStorage] Error loading config for guild {guild_id}: {e}")
            config = GuildTicketConfig(guild_id=guild_id)
        
        with self.cache_lock:
            self.cache[cache_key] = config
        
        return config
    
    def save_config(self, guild_id: int, config: GuildTicketConfig) -> bool:
        """Save guild ticket configuration"""
        cache_key = self._get_cache_key(guild_id, "config")
        
        try:
            # Create backup
            self._create_backup(self.config_path)
            
            # Load all configs
            all_configs = {}
            if os.path.exists(self.config_path):
                with open(self.config_path, 'r', encoding='utf-8') as f:
                    all_configs = json.load(f)
            
            # Update config
            all_configs[str(guild_id)] = config.to_dict()
            
            # Save
            with open(self.config_path, 'w', encoding='utf-8') as f:
                json.dump(all_configs, f, indent=4, ensure_ascii=False)
            
            # Update cache
            with self.cache_lock:
                self.cache[cache_key] = config
            
            return True
        except Exception as e:
            print(f"[TicketStorage] Error saving config for guild {guild_id}: {e}")
            return False
    
    # --- Ticket Methods ---
    
    def get_ticket_path(self, channel_id: int) -> str:
        """Get the file path for a ticket"""
        return os.path.join(self.tickets_path, f"{channel_id}.json")
    
    def load_ticket(self, channel_id: int) -> Optional[TicketData]:
        """Load a ticket by channel ID"""
        cache_key = self._get_cache_key(channel_id, "ticket")
        
        with self.cache_lock:
            if cache_key in self.cache:
                return self.cache[cache_key]
        
        path = self.get_ticket_path(channel_id)
        
        try:
            if os.path.exists(path):
                with open(path, 'r', encoding='utf-8') as f:
                    data = json.load(f)
                ticket = TicketData.from_dict(data)
            else:
                return None
        except (json.JSONDecodeError, KeyError) as e:
            print(f"[TicketStorage] Error loading ticket {channel_id}: {e}")
            return None
        
        with self.cache_lock:
            self.cache[cache_key] = ticket
        
        return ticket
    
    def save_ticket(self, ticket: TicketData) -> bool:
        """Save a ticket"""
        cache_key = self._get_cache_key(ticket.channel_id, "ticket")
        
        try:
            # Create backup
            self._create_backup(self.get_ticket_path(ticket.channel_id))
            
            path = self.get_ticket_path(ticket.channel_id)
            
            with open(path, 'w', encoding='utf-8') as f:
                json.dump(ticket.to_dict(), f, indent=4, ensure_ascii=False)
            
            with self.cache_lock:
                self.cache[cache_key] = ticket
            
            return True
        except Exception as e:
            print(f"[TicketStorage] Error saving ticket {ticket.channel_id}: {e}")
            return False
    
    def delete_ticket(self, channel_id: int) -> bool:
        """Delete a ticket file"""
        cache_key = self._get_cache_key(channel_id, "ticket")
        path = self.get_ticket_path(channel_id)
        
        try:
            if os.path.exists(path):
                # Create backup before delete
                self._create_backup(path)
                os.remove(path)
            
            with self.cache_lock:
                self.cache.pop(cache_key, None)
            
            return True
        except Exception as e:
            print(f"[TicketStorage] Error deleting ticket {channel_id}: {e}")
            return False
    
    def get_guild_tickets(self, guild_id: int, status: Optional[TicketStatus] = None) -> List[TicketData]:
        """Get all tickets for a guild, optionally filtered by status"""
        tickets = []
        
        if not os.path.exists(self.tickets_path):
            return tickets
        
        for filename in os.listdir(self.tickets_path):
            if not filename.endswith('.json'):
                continue
            
            try:
                channel_id = int(filename.replace('.json', ''))
                ticket = self.load_ticket(channel_id)
                
                if ticket and ticket.guild_id == guild_id:
                    if status is None or ticket.status == status:
                        tickets.append(ticket)
            except (ValueError, TypeError):
                continue
        
        return tickets
    
    def get_user_tickets(self, guild_id: int, user_id: int, open_only: bool = True) -> List[TicketData]:
        """Get all tickets for a user"""
        tickets = self.get_guild_tickets(guild_id)
        user_tickets = [t for t in tickets if t.user_id == user_id]
        
        if open_only:
            user_tickets = [t for t in user_tickets if t.is_open]
        
        return user_tickets
    
    def count_user_tickets(self, guild_id: int, user_id: int, category_id: Optional[str] = None) -> int:
        """Count tickets for a user, optionally in a specific category"""
        tickets = self.get_user_tickets(guild_id, user_id, open_only=True)
        
        if category_id:
            tickets = [t for t in tickets if t.category_id == category_id]
        
        return len(tickets)
    
    # --- Bulk Operations ---
    
    def get_all_guild_ids(self) -> List[int]:
        """Get all guild IDs with ticket configurations"""
        if not os.path.exists(self.config_path):
            return []
        
        try:
            with open(self.config_path, 'r', encoding='utf-8') as f:
                configs = json.load(f)
            return [int(gid) for gid in configs.keys()]
        except (json.JSONDecodeError, ValueError):
            return []
    
    def cleanup_cache(self, max_size: int = 1000) -> int:
        """Clear cache if it exceeds max size"""
        with self.cache_lock:
            if len(self.cache) <= max_size:
                return 0
            
            # Clear all non-config keys (keep recent)
            removed = 0
            keys_to_remove = [k for k in self.cache.keys() if not k.endswith("_config")]
            
            for key in keys_to_remove[:len(keys_to_remove) - max_size]:
                del self.cache[key]
                removed += 1
            
            return removed
    
    def invalidate_cache(self, guild_id: Optional[int] = None) -> None:
        """Invalidate cache for a guild or all"""
        with self.cache_lock:
            if guild_id is None:
                self.cache.clear()
            else:
                keys_to_remove = [k for k in self.cache.keys() if k.startswith(str(guild_id))]
                for key in keys_to_remove:
                    del self.cache[key]
    
    # --- Statistics ---
    
    def get_storage_stats(self) -> Dict[str, Any]:
        """Get storage statistics"""
        stats = {
            "total_tickets": 0,
            "total_backups": 0,
            "config_size_bytes": 0,
            "cache_size": 0,
            "tickets_by_status": {}
        }
        
        # Count tickets
        if os.path.exists(self.tickets_path):
            for filename in os.listdir(self.tickets_path):
                if filename.endswith('.json'):
                    stats["total_tickets"] += 1
        
        # Count backups
        if os.path.exists(self.backup_path):
            stats["total_backups"] = len(os.listdir(self.backup_path))
        
        # Config size
        if os.path.exists(self.config_path):
            stats["config_size_bytes"] = os.path.getsize(self.config_path)
        
        # Cache size
        with self.cache_lock:
            stats["cache_size"] = len(self.cache)
        
        return stats


# Singleton instance
_storage_instance: Optional[TicketStorage] = None


def get_storage() -> TicketStorage:
    """Get the singleton storage instance"""
    global _storage_instance
    if _storage_instance is None:
        _storage_instance = TicketStorage()
    return _storage_instance


def reset_storage() -> None:
    """Reset the storage instance (for testing)"""
    global _storage_instance
    _storage_instance = None