from typing import Annotated, Optional
from uuid import UUID
from fastapi import APIRouter, Depends, HTTPException, status, Query
from sqlalchemy.ext.asyncio import AsyncSession
from sqlalchemy import select, func, or_

from app.core.database import get_db
from app.models.tree import Tree
from app.models.user import User
from app.schemas.tree import TreeCreate, TreeUpdate, TreeResponse, TreeListResponse
from app.api.deps import get_current_user, require_engineer_or_admin, require_admin

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


@router.get("", response_model=list[TreeListResponse])
async def list_trees(
    db: Annotated[AsyncSession, Depends(get_db)],
    current_user: Annotated[User, Depends(get_current_user)],
    category: Optional[str] = Query(None, description="Filter by category"),
    is_active: Optional[bool] = Query(None, description="Filter by active status"),
    skip: int = Query(0, ge=0),
    limit: int = Query(100, ge=1, le=100)
):
    """List all trees with optional filters."""
    query = select(Tree)

    # Apply filters
    if category:
        query = query.where(Tree.category == category)
    if is_active is not None:
        query = query.where(Tree.is_active == is_active)

    # Only show active trees or trees owned by user (for now)
    # Later, add team-based filtering
    query = query.where(
        or_(
            Tree.is_active == True,
            Tree.author_id == current_user.id
        )
    )

    query = query.order_by(Tree.usage_count.desc(), Tree.updated_at.desc())
    query = query.offset(skip).limit(limit)

    result = await db.execute(query)
    trees = result.scalars().all()
    return trees


@router.get("/categories", response_model=list[str])
async def list_categories(
    db: Annotated[AsyncSession, Depends(get_db)],
    current_user: Annotated[User, Depends(get_current_user)]
):
    """List all unique categories."""
    query = select(Tree.category).where(
        Tree.category.isnot(None),
        Tree.is_active == True
    ).distinct()
    result = await db.execute(query)
    categories = [row[0] for row in result.all() if row[0]]
    return sorted(categories)


@router.get("/search", response_model=list[TreeListResponse])
async def search_trees(
    db: Annotated[AsyncSession, Depends(get_db)],
    current_user: Annotated[User, Depends(get_current_user)],
    q: str = Query(..., min_length=2, description="Search query"),
    limit: int = Query(20, ge=1, le=50)
):
    """Full-text search trees by name and description."""
    # Using PostgreSQL full-text search
    search_vector = func.to_tsvector('english', func.coalesce(Tree.name, '') + ' ' + func.coalesce(Tree.description, ''))
    search_query = func.plainto_tsquery('english', q)

    query = select(Tree).where(
        Tree.is_active == True,
        search_vector.op('@@')(search_query)
    ).order_by(
        func.ts_rank(search_vector, search_query).desc()
    ).limit(limit)

    result = await db.execute(query)
    trees = result.scalars().all()
    return trees


@router.get("/{tree_id}", response_model=TreeResponse)
async def get_tree(
    tree_id: UUID,
    db: Annotated[AsyncSession, Depends(get_db)],
    current_user: Annotated[User, Depends(get_current_user)]
):
    """Get a specific tree by ID."""
    result = await db.execute(select(Tree).where(Tree.id == tree_id))
    tree = result.scalar_one_or_none()

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

    # Check access: tree must be active OR user is the author
    if not tree.is_active and tree.author_id != current_user.id:
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="You don't have access to this tree"
        )

    return tree


@router.post("", response_model=TreeResponse, status_code=status.HTTP_201_CREATED)
async def create_tree(
    tree_data: TreeCreate,
    db: Annotated[AsyncSession, Depends(get_db)],
    current_user: Annotated[User, Depends(require_engineer_or_admin)]
):
    """Create a new tree (engineers and admins only)."""
    new_tree = Tree(
        name=tree_data.name,
        description=tree_data.description,
        category=tree_data.category,
        tree_structure=tree_data.tree_structure,
        author_id=current_user.id,
        team_id=current_user.team_id
    )
    db.add(new_tree)
    await db.commit()
    await db.refresh(new_tree)
    return new_tree


@router.put("/{tree_id}", response_model=TreeResponse)
async def update_tree(
    tree_id: UUID,
    tree_data: TreeUpdate,
    db: Annotated[AsyncSession, Depends(get_db)],
    current_user: Annotated[User, Depends(require_engineer_or_admin)]
):
    """Update an existing tree (engineers and admins only)."""
    result = await db.execute(select(Tree).where(Tree.id == tree_id))
    tree = result.scalar_one_or_none()

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

    # Check if user can edit: must be author or admin
    if tree.author_id != current_user.id and current_user.role != "admin":
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="You can only edit your own trees"
        )

    # Update fields
    update_data = tree_data.model_dump(exclude_unset=True)
    for field, value in update_data.items():
        setattr(tree, field, value)

    # Increment version if tree structure changed
    if "tree_structure" in update_data:
        tree.version += 1

    await db.commit()
    await db.refresh(tree)
    return tree


@router.delete("/{tree_id}", status_code=status.HTTP_204_NO_CONTENT)
async def delete_tree(
    tree_id: UUID,
    db: Annotated[AsyncSession, Depends(get_db)],
    current_user: Annotated[User, Depends(require_admin)]
):
    """Soft delete a tree (admin only). Sets is_active to False."""
    result = await db.execute(select(Tree).where(Tree.id == tree_id))
    tree = result.scalar_one_or_none()

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

    tree.is_active = False
    await db.commit()
    return None