#!/usr/bin/env python3
"""
SQLAlchemy and Pydantic models for GNSS Guard Server
"""

from datetime import datetime
from typing import Dict, Any, List, Optional
from sqlalchemy import Column, Integer, String, Float, Boolean, DateTime, ForeignKey, Text, Index
from sqlalchemy.orm import relationship, declarative_base
from pydantic import BaseModel, Field
import hashlib
import secrets

Base = declarative_base()


# =============================================================================
# SQLAlchemy Database Models
# =============================================================================

class Asset(Base):
    """Asset (client device) registered with the server"""
    __tablename__ = "assets"
    
    id = Column(Integer, primary_key=True, index=True)
    name = Column(String(255), unique=True, nullable=False, index=True)
    token_hash = Column(String(64), nullable=False)  # SHA-256 hash of token
    created_at = Column(DateTime, default=datetime.utcnow)
    is_active = Column(Boolean, default=True)
    description = Column(String(500), nullable=True)
    
    # Telegram notification settings (optional override for this asset)
    telegram_chat_id = Column(String(100), nullable=True)  # Override default chat ID
    telegram_enabled = Column(Boolean, default=True)  # Enable/disable notifications for this asset
    
    # Relationship to validation history
    validations = relationship("ValidationHistory", back_populates="asset", cascade="all, delete-orphan")
    
    # Relationship to notification state
    notification_state = relationship("AssetNotificationState", back_populates="asset", uselist=False, cascade="all, delete-orphan")
    
    @staticmethod
    def hash_token(token: str) -> str:
        """Hash a token using SHA-256"""
        return hashlib.sha256(token.encode()).hexdigest()
    
    @staticmethod
    def generate_token() -> str:
        """Generate a secure random token"""
        return secrets.token_urlsafe(32)
    
    def verify_token(self, token: str) -> bool:
        """Verify if provided token matches stored hash"""
        return self.token_hash == self.hash_token(token)


class AssetNotificationState(Base):
    """Tracks the previous notification state for each asset to detect changes"""
    __tablename__ = "asset_notification_state"
    
    id = Column(Integer, primary_key=True, index=True)
    asset_id = Column(Integer, ForeignKey("assets.id", ondelete="CASCADE"), unique=True, nullable=False)
    
    # Previous state (JSON arrays stored as text)
    prev_sources_missing = Column(Text, nullable=True)  # JSON array
    prev_sources_stale = Column(Text, nullable=True)  # JSON array
    prev_threshold_breached = Column(Boolean, default=False)
    
    # Last notification timestamp
    last_notification_at = Column(DateTime, nullable=True)
    
    # Asset online/offline tracking
    is_online = Column(Boolean, default=True)  # Whether asset is currently reporting
    last_validation_at = Column(DateTime, nullable=True)  # Last time we received validation data
    
    # Relationship
    asset = relationship("Asset", back_populates="notification_state")


class ValidationHistory(Base):
    """Historical validation records from assets"""
    __tablename__ = "validation_history"
    
    id = Column(Integer, primary_key=True, index=True)
    asset_id = Column(Integer, ForeignKey("assets.id", ondelete="CASCADE"), nullable=False)
    
    # Validation timestamps
    validation_timestamp = Column(String(50), nullable=False)  # ISO format
    validation_timestamp_unix = Column(Float, nullable=False, index=True)
    
    # Validation result
    is_valid = Column(Boolean, nullable=False)
    
    # JSON fields stored as text
    sources_missing = Column(Text, nullable=True)  # JSON array
    sources_stale = Column(Text, nullable=True)  # JSON array
    coordinate_differences = Column(Text, nullable=True)  # JSON object
    source_coordinates = Column(Text, nullable=True)  # JSON object
    validation_details = Column(Text, nullable=True)  # JSON object
    
    # Server-side metadata
    received_at = Column(DateTime, default=datetime.utcnow, index=True)
    
    # Relationship
    asset = relationship("Asset", back_populates="validations")
    
    # Indexes for common queries
    __table_args__ = (
        Index('ix_validation_asset_timestamp', 'asset_id', 'validation_timestamp_unix'),
    )


# =============================================================================
# Pydantic Request/Response Models
# =============================================================================

class AssetCreate(BaseModel):
    """Request model for creating a new asset"""
    name: str = Field(..., min_length=1, max_length=255)
    description: Optional[str] = Field(None, max_length=500)
    telegram_chat_id: Optional[str] = Field(None, max_length=100)  # Override default chat ID
    telegram_enabled: bool = True  # Enable notifications for this asset


class AssetResponse(BaseModel):
    """Response model for asset data"""
    id: int
    name: str
    is_active: bool
    created_at: datetime
    description: Optional[str] = None
    telegram_chat_id: Optional[str] = None
    telegram_enabled: bool = True
    
    class Config:
        from_attributes = True


class AssetWithToken(AssetResponse):
    """Response model for newly created asset (includes token)"""
    token: str  # Only returned when asset is created


class AssetImport(BaseModel):
    """Request model for importing an asset with a specific token"""
    name: str = Field(..., min_length=1, max_length=255)
    token: str = Field(..., min_length=32, max_length=128)
    description: Optional[str] = Field(None, max_length=500)
    telegram_chat_id: Optional[str] = Field(None, max_length=100)
    telegram_enabled: bool = True


class AssetBatchImport(BaseModel):
    """Request model for batch importing assets"""
    assets: List[AssetImport]


class ValidationSubmission(BaseModel):
    """Request model for submitting validation data"""
    validation_timestamp: str
    validation_timestamp_unix: float
    is_valid: bool
    sources_missing: List[str] = []
    sources_stale: List[str] = []
    coordinate_differences: Dict[str, Any] = {}
    source_coordinates: Dict[str, Any] = {}
    validation_details: Dict[str, Any] = {}


class ValidationBatchSubmission(BaseModel):
    """Request model for submitting multiple validation records"""
    records: List[ValidationSubmission]


class ValidationResponse(BaseModel):
    """Response model for validation data"""
    id: int
    asset_name: str
    validation_timestamp: str
    validation_timestamp_unix: float
    is_valid: bool
    sources_missing: List[str]
    sources_stale: List[str]
    coordinate_differences: Dict[str, Any]
    source_coordinates: Dict[str, Any]
    validation_details: Dict[str, Any]
    received_at: datetime
    
    class Config:
        from_attributes = True


class AssetStatus(BaseModel):
    """Current status of an asset (latest validation)"""
    asset_name: str
    is_online: bool  # Has reported in last 5 minutes
    last_seen: Optional[datetime] = None
    latest_validation: Optional[ValidationResponse] = None


class LoginRequest(BaseModel):
    """Request model for user login"""
    username: str
    password: str


class LoginResponse(BaseModel):
    """Response model for successful login"""
    message: str
    username: str