"""
Admin Endpoints

API endpoints for administrative functions (user management, analytics, system settings)
"""

import logging
from typing import List
from fastapi import APIRouter, Depends, HTTPException, status
from sqlalchemy.ext.asyncio import AsyncSession
from sqlalchemy import select, func
from datetime import datetime, timedelta

from app.database import get_db
from app.core.middleware import get_current_active_user
from app.core.rbac import require_role, UserRole, Permission, require_permission
from app.models.user import User
from app.models.conversation import Conversation
from app.models.message import Message
from app.models.token_usage import TokenUsage
from pydantic import BaseModel, EmailStr

logger = logging.getLogger(__name__)

router = APIRouter(prefix="/admin", tags=["Admin"])


# Schemas
class UserListItem(BaseModel):
    """User list item for admin"""
    id: str
    email: EmailStr
    display_name: str
    role: str
    is_active: bool
    created_at: datetime
    last_login_at: datetime | None
    total_conversations: int
    total_tokens: int

    class Config:
        from_attributes = True


class UpdateUserRoleRequest(BaseModel):
    """Request to update user role"""
    role: str


class SystemAnalytics(BaseModel):
    """System-wide analytics"""
    total_users: int
    active_users: int
    total_conversations: int
    total_messages: int
    total_tokens_used: int
    total_cost_usd: float
    avg_tokens_per_user: float
    avg_messages_per_conversation: float


class UserAnalytics(BaseModel):
    """Per-user analytics"""
    user_id: str
    email: str
    display_name: str
    conversations_count: int
    messages_count: int
    tokens_used: int
    cost_usd: float
    last_activity: datetime | None


class MessageDetail(BaseModel):
    """Message detail for user details view"""
    id: str
    role: str
    content: str
    created_at: datetime
    token_count: int
    cost_usd: float


class ConversationDetail(BaseModel):
    """Conversation detail for user details view"""
    id: str
    title: str
    created_at: datetime
    last_message_at: datetime | None
    message_count: int
    total_tokens: int
    total_cost_usd: float
    messages: List[MessageDetail]


class UserDetails(BaseModel):
    """Detailed user information with conversations and messages"""
    user_id: str
    email: str
    display_name: str
    role: str
    is_active: bool
    created_at: datetime
    last_login_at: datetime | None
    total_conversations: int
    total_messages: int
    total_tokens: int
    prompt_tokens: int
    completion_tokens: int
    cached_tokens: int
    total_cost_usd: float
    avg_tokens_per_message: float
    conversations: List[ConversationDetail]


# Endpoints

@router.get("/users", response_model=List[UserListItem])
async def list_all_users(
    current_user: User = Depends(get_current_active_user),
    db: AsyncSession = Depends(get_db),
    skip: int = 0,
    limit: int = 100
):
    """
    List all users (admin only)

    Args:
        current_user: Current authenticated user
        db: Database session
        skip: Number of users to skip
        limit: Max number of users to return

    Returns:
        List of users with stats

    Raises:
        HTTPException: If user is not admin
    """
    require_permission(current_user.role, Permission.READ_ALL_USERS)

    # Query users with aggregated stats
    query = (
        select(
            User,
            func.count(Conversation.id).label("total_conversations"),
            func.sum(TokenUsage.total_tokens).label("total_tokens")
        )
        .outerjoin(Conversation, User.id == Conversation.user_id)
        .outerjoin(TokenUsage, User.id == TokenUsage.user_id)
        .group_by(User.id)
        .order_by(User.created_at.desc())
        .offset(skip)
        .limit(limit)
    )

    result = await db.execute(query)
    users_with_stats = result.all()

    return [
        UserListItem(
            id=str(user.id),
            email=user.email,
            display_name=user.display_name,
            role=user.role,
            is_active=user.is_active,
            created_at=user.created_at,
            last_login_at=user.last_login_at,
            total_conversations=total_conversations or 0,
            total_tokens=int(total_tokens or 0)
        )
        for user, total_conversations, total_tokens in users_with_stats
    ]


@router.put("/users/{user_id}/role")
async def update_user_role(
    user_id: str,
    request: UpdateUserRoleRequest,
    current_user: User = Depends(get_current_active_user),
    db: AsyncSession = Depends(get_db)
):
    """
    Update user role (admin only)

    Args:
        user_id: User ID to update
        request: New role
        current_user: Current authenticated user
        db: Database session

    Returns:
        Updated user info

    Raises:
        HTTPException: If user is not admin or user not found
    """
    require_permission(current_user.role, Permission.UPDATE_USER_ROLE)

    # Validate role
    try:
        new_role = UserRole(request.role)
    except ValueError:
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail=f"Invalid role. Must be one of: {[r.value for r in UserRole]}"
        )

    # Get user
    result = await db.execute(
        select(User).where(User.id == user_id)
    )
    user = result.scalar_one_or_none()

    if not user:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail="User not found"
        )

    # Update role
    user.role = new_role.value
    await db.commit()

    logger.info(f"Admin {current_user.id} updated user {user_id} role to {new_role.value}")

    return {
        "success": True,
        "user_id": str(user.id),
        "email": user.email,
        "new_role": user.role
    }


@router.put("/users/{user_id}/activate")
async def activate_user(
    user_id: str,
    current_user: User = Depends(get_current_active_user),
    db: AsyncSession = Depends(get_db)
):
    """
    Activate user account (admin only)

    Args:
        user_id: User ID to activate
        current_user: Current authenticated user
        db: Database session

    Returns:
        Success message

    Raises:
        HTTPException: If user is not admin or user not found
    """
    require_permission(current_user.role, Permission.READ_ALL_USERS)

    result = await db.execute(
        select(User).where(User.id == user_id)
    )
    user = result.scalar_one_or_none()

    if not user:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail="User not found"
        )

    user.is_active = True
    await db.commit()

    logger.info(f"Admin {current_user.id} activated user {user_id}")

    return {"success": True, "message": f"User {user.email} activated"}


@router.put("/users/{user_id}/deactivate")
async def deactivate_user(
    user_id: str,
    current_user: User = Depends(get_current_active_user),
    db: AsyncSession = Depends(get_db)
):
    """
    Deactivate user account (admin only)

    Args:
        user_id: User ID to deactivate
        current_user: Current authenticated user
        db: Database session

    Returns:
        Success message

    Raises:
        HTTPException: If user is not admin or user not found
    """
    require_permission(current_user.role, Permission.READ_ALL_USERS)

    result = await db.execute(
        select(User).where(User.id == user_id)
    )
    user = result.scalar_one_or_none()

    if not user:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail="User not found"
        )

    # Can't deactivate self
    if user.id == current_user.id:
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail="Cannot deactivate your own account"
        )

    user.is_active = False
    await db.commit()

    logger.info(f"Admin {current_user.id} deactivated user {user_id}")

    return {"success": True, "message": f"User {user.email} deactivated"}


@router.get("/analytics/system", response_model=SystemAnalytics)
async def get_system_analytics(
    current_user: User = Depends(get_current_active_user),
    db: AsyncSession = Depends(get_db)
):
    """
    Get system-wide analytics (admin only)

    Args:
        current_user: Current authenticated user
        db: Database session

    Returns:
        System analytics

    Raises:
        HTTPException: If user is not admin
    """
    require_permission(current_user.role, Permission.VIEW_ANALYTICS)

    # Get counts
    total_users = await db.scalar(select(func.count(User.id)))
    active_users = await db.scalar(
        select(func.count(User.id)).where(User.is_active == True)
    )
    total_conversations = await db.scalar(select(func.count(Conversation.id)))
    total_messages = await db.scalar(select(func.count(Message.id)))

    # Get token usage stats
    token_stats = await db.execute(
        select(
            func.sum(TokenUsage.total_tokens).label("total_tokens"),
            func.sum(TokenUsage.cost_usd).label("total_cost")
        )
    )
    token_row = token_stats.first()
    total_tokens = int(token_row.total_tokens or 0)
    total_cost = float(token_row.total_cost or 0.0)

    # Calculate averages
    avg_tokens_per_user = total_tokens / active_users if active_users > 0 else 0
    avg_messages_per_conv = total_messages / total_conversations if total_conversations > 0 else 0

    return SystemAnalytics(
        total_users=total_users or 0,
        active_users=active_users or 0,
        total_conversations=total_conversations or 0,
        total_messages=total_messages or 0,
        total_tokens_used=total_tokens,
        total_cost_usd=total_cost,
        avg_tokens_per_user=avg_tokens_per_user,
        avg_messages_per_conversation=avg_messages_per_conv
    )


@router.get("/analytics/users", response_model=List[UserAnalytics])
async def get_users_analytics(
    current_user: User = Depends(get_current_active_user),
    db: AsyncSession = Depends(get_db),
    days: int = 30,
    limit: int = 50
):
    """
    Get per-user analytics (admin only)

    Args:
        current_user: Current authenticated user
        db: Database session
        days: Number of days to analyze
        limit: Max number of users to return

    Returns:
        List of user analytics

    Raises:
        HTTPException: If user is not admin
    """
    require_permission(current_user.role, Permission.VIEW_ANALYTICS)

    since_date = datetime.utcnow() - timedelta(days=days)

    query = (
        select(
            User,
            func.count(Conversation.id).label("conversations_count"),
            func.count(Message.id).label("messages_count"),
            func.sum(TokenUsage.total_tokens).label("tokens_used"),
            func.sum(TokenUsage.cost_usd).label("cost_usd"),
            func.max(Conversation.last_message_at).label("last_activity")
        )
        .outerjoin(Conversation, User.id == Conversation.user_id)
        .outerjoin(Message, Conversation.id == Message.conversation_id)
        .outerjoin(TokenUsage, User.id == TokenUsage.user_id)
        .where(
            (Conversation.created_at >= since_date) | (Conversation.id == None)
        )
        .group_by(User.id)
        .order_by(func.sum(TokenUsage.total_tokens).desc().nullslast())
        .limit(limit)
    )

    result = await db.execute(query)
    users_analytics = result.all()

    return [
        UserAnalytics(
            user_id=str(user.id),
            email=user.email,
            display_name=user.display_name,
            conversations_count=conversations_count or 0,
            messages_count=messages_count or 0,
            tokens_used=int(tokens_used or 0),
            cost_usd=float(cost_usd or 0.0),
            last_activity=last_activity
        )
        for user, conversations_count, messages_count, tokens_used, cost_usd, last_activity in users_analytics
    ]


@router.get("/conversations/all")
async def get_all_conversations(
    current_user: User = Depends(get_current_active_user),
    db: AsyncSession = Depends(get_db),
    skip: int = 0,
    limit: int = 50
):
    """
    Get all conversations across all users (admin only)

    Args:
        current_user: Current authenticated user
        db: Database session
        skip: Number to skip
        limit: Max number to return

    Returns:
        List of conversations

    Raises:
        HTTPException: If user is not admin
    """
    require_permission(current_user.role, Permission.READ_ALL_CHATS)

    query = (
        select(Conversation, User)
        .join(User, Conversation.user_id == User.id)
        .order_by(Conversation.created_at.desc())
        .offset(skip)
        .limit(limit)
    )

    result = await db.execute(query)
    conversations = result.all()

    return [
        {
            "id": str(conv.id),
            "title": conv.title,
            "user_email": user.email,
            "user_display_name": user.display_name,
            "created_at": conv.created_at,
            "last_message_at": conv.last_message_at,
            "is_archived": conv.is_archived
        }
        for conv, user in conversations
    ]


@router.get("/users/{user_id}/details", response_model=UserDetails)
async def get_user_details(
    user_id: str,
    current_user: User = Depends(get_current_active_user),
    db: AsyncSession = Depends(get_db),
    limit_conversations: int = 20
):
    """
    Get detailed information for a specific user (admin only)

    Args:
        user_id: User ID to get details for
        current_user: Current authenticated user
        db: Database session
        limit_conversations: Max number of conversations to include

    Returns:
        Detailed user information with conversations and messages

    Raises:
        HTTPException: If user is not admin or user not found
    """
    require_permission(current_user.role, Permission.READ_ALL_CHATS)

    # Get user
    user_result = await db.execute(
        select(User).where(User.id == user_id)
    )
    user = user_result.scalar_one_or_none()

    if not user:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail="User not found"
        )

    # Get user's token usage stats
    token_stats = await db.execute(
        select(
            func.count(TokenUsage.id).label("total_messages"),
            func.sum(TokenUsage.total_tokens).label("total_tokens"),
            func.sum(TokenUsage.prompt_tokens).label("prompt_tokens"),
            func.sum(TokenUsage.completion_tokens).label("completion_tokens"),
            func.sum(TokenUsage.cached_tokens).label("cached_tokens"),
            func.sum(TokenUsage.cost_usd).label("total_cost_usd")
        ).where(TokenUsage.user_id == user_id)
    )
    stats_row = token_stats.first()

    total_messages = int(stats_row.total_messages or 0)
    total_tokens = int(stats_row.total_tokens or 0)
    prompt_tokens = int(stats_row.prompt_tokens or 0)
    completion_tokens = int(stats_row.completion_tokens or 0)
    cached_tokens = int(stats_row.cached_tokens or 0)
    total_cost_usd = float(stats_row.total_cost_usd or 0.0)
    avg_tokens_per_message = total_tokens / total_messages if total_messages > 0 else 0

    # Get user's conversations with message counts and token stats
    conv_query = (
        select(
            Conversation,
            func.count(Message.id).label("message_count"),
            func.sum(TokenUsage.total_tokens).label("total_tokens"),
            func.sum(TokenUsage.cost_usd).label("total_cost")
        )
        .outerjoin(Message, Conversation.id == Message.conversation_id)
        .outerjoin(TokenUsage, Conversation.id == TokenUsage.conversation_id)
        .where(Conversation.user_id == user_id)
        .group_by(Conversation.id)
        .order_by(Conversation.last_message_at.desc().nullslast())
        .limit(limit_conversations)
    )

    conv_result = await db.execute(conv_query)
    conversations_data = conv_result.all()

    # Build conversation details with messages
    conversations = []
    for conv, message_count, conv_tokens, conv_cost in conversations_data:
        # Get messages for this conversation
        msg_query = (
            select(Message, TokenUsage)
            .outerjoin(TokenUsage,
                (TokenUsage.conversation_id == Message.conversation_id) &
                (TokenUsage.message_id == Message.id))
            .where(Message.conversation_id == conv.id)
            .order_by(Message.created_at.asc())
        )

        msg_result = await db.execute(msg_query)
        messages_data = msg_result.all()

        messages = [
            MessageDetail(
                id=str(msg.id),
                role=msg.role,
                content=msg.content,
                created_at=msg.created_at,
                token_count=int(token.total_tokens) if token else 0,
                cost_usd=float(token.cost_usd) if token else 0.0
            )
            for msg, token in messages_data
        ]

        conversations.append(
            ConversationDetail(
                id=str(conv.id),
                title=conv.title,
                created_at=conv.created_at,
                last_message_at=conv.last_message_at,
                message_count=int(message_count or 0),
                total_tokens=int(conv_tokens or 0),
                total_cost_usd=float(conv_cost or 0.0),
                messages=messages
            )
        )

    # Get total conversation count
    total_conv_count = await db.scalar(
        select(func.count(Conversation.id))
        .where(Conversation.user_id == user_id)
    )

    logger.info(f"Admin {current_user.id} viewed details for user {user_id}")

    return UserDetails(
        user_id=str(user.id),
        email=user.email,
        display_name=user.display_name,
        role=user.role,
        is_active=user.is_active,
        created_at=user.created_at,
        last_login_at=user.last_login_at,
        total_conversations=total_conv_count or 0,
        total_messages=total_messages,
        total_tokens=total_tokens,
        prompt_tokens=prompt_tokens,
        completion_tokens=completion_tokens,
        cached_tokens=cached_tokens,
        total_cost_usd=total_cost_usd,
        avg_tokens_per_message=round(avg_tokens_per_message, 1),
        conversations=conversations
    )