from app.db import get_db_connection
from app.schemas import MessageResponse, ConversationResponse
from datetime import datetime

class ChatService:
    """Handle chat messages and conversations"""
    
    @staticmethod
    def send_message(sender_id: int, conversation_id: int, content: str) -> MessageResponse:
        """Send a message in a conversation"""
        with get_db_connection() as conn:
            cur = conn.cursor()
            
            # Verify user is in this conversation
            cur.execute(
                "SELECT user_id_1, user_id_2 FROM conversations WHERE id = %s",
                (conversation_id,)
            )
            row = cur.fetchone()
            if not row or (sender_id != row[0] and sender_id != row[1]):
                raise ValueError("Not authorized to message in this conversation")
            
            # Insert message
            cur.execute(
                "INSERT INTO messages (conversation_id, sender_id, content) VALUES (%s, %s, %s) RETURNING id, created_at",
                (conversation_id, sender_id, content)
            )
            result = cur.fetchone()
            message_id = result[0]
            created_at = result[1]
            
            # Update conversation updated_at
            cur.execute(
                "UPDATE conversations SET updated_at = CURRENT_TIMESTAMP WHERE id = %s",
                (conversation_id,)
            )
            conn.commit()
        
        return MessageResponse(
            id=message_id,
            conversation_id=conversation_id,
            sender_id=sender_id,
            content=content,
            created_at=created_at.isoformat()
        )
    
    @staticmethod
    def get_conversations(user_id: int) -> list:
        """Get all conversations for a user"""
        with get_db_connection() as conn:
            cur = conn.cursor()
            cur.execute(
                """SELECT id, user_id_1, user_id_2, created_at, updated_at
                   FROM conversations
                   WHERE user_id_1 = %s OR user_id_2 = %s
                   ORDER BY updated_at DESC""",
                (user_id, user_id)
            )
            
            conversations = []
            for row in cur.fetchall():
                conv_id, user_1, user_2, created_at, updated_at = row
                other_user_id = user_2 if user_1 == user_id else user_1
                
                # Get other user's display name
                cur.execute("SELECT display_name FROM profiles WHERE user_id = %s", (other_user_id,))
                profile_row = cur.fetchone()
                other_user_name = profile_row[0] if profile_row else "Unknown"
                
                # Get latest message
                cur.execute(
                    "SELECT content FROM messages WHERE conversation_id = %s ORDER BY created_at DESC LIMIT 1",
                    (conv_id,)
                )
                msg_row = cur.fetchone()
                latest_msg = msg_row[0] if msg_row else ""
                
                conversations.append(ConversationResponse(
                    id=conv_id,
                    user_id_1=user_1,
                    user_id_2=user_2,
                    other_user_id=other_user_id,
                    other_user_display_name=other_user_name,
                    latest_message=latest_msg,
                    created_at=created_at.isoformat()
                ))
            
            return conversations
    
    @staticmethod
    def get_messages(user_id: int, conversation_id: int, limit: int = 50) -> list:
        """Get messages from a conversation"""
        with get_db_connection() as conn:
            cur = conn.cursor()
            
            # Verify user is in this conversation
            cur.execute(
                "SELECT user_id_1, user_id_2 FROM conversations WHERE id = %s",
                (conversation_id,)
            )
            row = cur.fetchone()
            if not row or (user_id != row[0] and user_id != row[1]):
                raise ValueError("Not authorized to view this conversation")
            
            # Fetch messages
            cur.execute(
                """SELECT id, conversation_id, sender_id, content, created_at
                   FROM messages
                   WHERE conversation_id = %s
                   ORDER BY created_at DESC
                   LIMIT %s""",
                (conversation_id, limit)
            )
            
            messages = []
            for row in cur.fetchall():
                messages.append(MessageResponse(
                    id=row[0],
                    conversation_id=row[1],
                    sender_id=row[2],
                    content=row[3],
                    created_at=row[4].isoformat()
                ))
            
            return list(reversed(messages))  # Return in chronological order