import uuid
from datetime import datetime

from fastapi import APIRouter, Depends, HTTPException, Query, Request
from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession

from app.database import get_db
from app.models.folder import Folder
from app.models.project import Project
from app.schemas.folder import FolderCreate, FolderListResponse, FolderResponse, FolderUpdate
from app.routers.auth import get_current_agent

router = APIRouter(tags=["folders"])


def build_folder_path(project_id: str, folder_id: str, parent_id: str | None, parent_path: str | None) -> str:
    if parent_id and parent_path:
        return f"{parent_path}/{folder_id}"
    return f"/{project_id}/{folder_id}"


@router.get("/api/v1/projects/{project_id}/folders", response_model=FolderListResponse)
async def list_folders(
    request: Request,
    project_id: str,
    parent_id: str | None = Query(None),
    db: AsyncSession = Depends(get_db),
):
    agent = await get_current_agent(request, db)

    proj_result = await db.execute(
        select(Project).where(
            Project.id == project_id,
            Project.agent_id == agent.id,
            Project.is_deleted == False,
        )
    )
    if not proj_result.scalar_one_or_none():
        raise HTTPException(status_code=404, detail="Project not found")

    query = select(Folder).where(
        Folder.project_id == project_id,
        Folder.parent_id == parent_id,
        Folder.is_deleted == False,
    ).order_by(Folder.name)

    result = await db.execute(query)
    folders = result.scalars().all()
    return FolderListResponse(folders=[FolderResponse.model_validate(f) for f in folders])


@router.post("/api/v1/projects/{project_id}/folders", response_model=FolderResponse, status_code=201)
async def create_folder(
    request: Request,
    project_id: str,
    payload: FolderCreate,
    db: AsyncSession = Depends(get_db),
):
    agent = await get_current_agent(request, db)

    proj_result = await db.execute(
        select(Project).where(
            Project.id == project_id,
            Project.agent_id == agent.id,
            Project.is_deleted == False,
        )
    )
    if not proj_result.scalar_one_or_none():
        raise HTTPException(status_code=404, detail="Project not found")

    parent_path = None
    if payload.parent_id:
        parent_result = await db.execute(
            select(Folder).where(
                Folder.id == payload.parent_id,
                Folder.project_id == project_id,
                Folder.is_deleted == False,
            )
        )
        parent = parent_result.scalar_one_or_none()
        if not parent:
            raise HTTPException(status_code=400, detail="Parent folder not found")
        parent_path = parent.path

    folder_id = str(uuid.uuid4())
    path = build_folder_path(project_id, folder_id, payload.parent_id, parent_path)

    folder = Folder(
        id=folder_id,
        name=payload.name,
        project_id=project_id,
        parent_id=payload.parent_id,
        path=path,
    )
    db.add(folder)
    await db.flush()
    return FolderResponse.model_validate(folder)


@router.get("/api/v1/folders/{folder_id}", response_model=FolderResponse)
async def get_folder(
    request: Request,
    folder_id: str,
    db: AsyncSession = Depends(get_db),
):
    agent = await get_current_agent(request, db)

    result = await db.execute(
        select(Folder).where(
            Folder.id == folder_id,
            Folder.is_deleted == False,
        )
    )
    folder = result.scalar_one_or_none()
    if not folder:
        raise HTTPException(status_code=404, detail="Folder not found")

    proj_result = await db.execute(
        select(Project).where(
            Project.id == folder.project_id,
            Project.agent_id == agent.id,
            Project.is_deleted == False,
        )
    )
    if not proj_result.scalar_one_or_none():
        raise HTTPException(status_code=404, detail="Folder not found")

    return FolderResponse.model_validate(folder)


@router.put("/api/v1/folders/{folder_id}", response_model=FolderResponse)
async def update_folder(
    request: Request,
    folder_id: str,
    payload: FolderUpdate,
    db: AsyncSession = Depends(get_db),
):
    agent = await get_current_agent(request, db)

    result = await db.execute(
        select(Folder).where(
            Folder.id == folder_id,
            Folder.is_deleted == False,
        )
    )
    folder = result.scalar_one_or_none()
    if not folder:
        raise HTTPException(status_code=404, detail="Folder not found")

    proj_result = await db.execute(
        select(Project).where(
            Project.id == folder.project_id,
            Project.agent_id == agent.id,
            Project.is_deleted == False,
        )
    )
    if not proj_result.scalar_one_or_none():
        raise HTTPException(status_code=403, detail="Forbidden")

    if payload.name is not None:
        folder.name = payload.name
    if payload.parent_id is not None:
        if payload.parent_id == folder_id:
            raise HTTPException(status_code=400, detail="Cannot set folder as its own parent")
        parent_result = await db.execute(
            select(Folder).where(
                Folder.id == payload.parent_id,
                Folder.project_id == folder.project_id,
                Folder.is_deleted == False,
            )
        )
        parent = parent_result.scalar_one_or_none()
        if not parent:
            raise HTTPException(status_code=400, detail="Parent folder not found")
        folder.parent_id = payload.parent_id
        folder.path = f"{parent.path}/{folder.id}"
    folder.updated_at = datetime.utcnow()

    await db.flush()
    return FolderResponse.model_validate(folder)


@router.delete("/api/v1/folders/{folder_id}", status_code=204)
async def delete_folder(
    request: Request,
    folder_id: str,
    db: AsyncSession = Depends(get_db),
):
    agent = await get_current_agent(request, db)

    result = await db.execute(
        select(Folder).where(
            Folder.id == folder_id,
            Folder.is_deleted == False,
        )
    )
    folder = result.scalar_one_or_none()
    if not folder:
        raise HTTPException(status_code=404, detail="Folder not found")

    proj_result = await db.execute(
        select(Project).where(
            Project.id == folder.project_id,
            Project.agent_id == agent.id,
            Project.is_deleted == False,
        )
    )
    if not proj_result.scalar_one_or_none():
        raise HTTPException(status_code=403, detail="Forbidden")

    folder.is_deleted = True
    folder.deleted_at = datetime.utcnow()
    folder.deleted_by = agent.id
    await db.flush()
    return None


@router.post("/api/v1/folders/{folder_id}/restore", response_model=FolderResponse)
async def restore_folder(
    request: Request,
    folder_id: str,
    db: AsyncSession = Depends(get_db),
):
    agent = await get_current_agent(request, db)

    result = await db.execute(
        select(Folder).where(
            Folder.id == folder_id,
            Folder.is_deleted == True,
        )
    )
    folder = result.scalar_one_or_none()
    if not folder:
        raise HTTPException(status_code=404, detail="Folder not found")

    proj_result = await db.execute(
        select(Project).where(
            Project.id == folder.project_id,
            Project.agent_id == agent.id,
            Project.is_deleted == False,
        )
    )
    if not proj_result.scalar_one_or_none():
        raise HTTPException(status_code=403, detail="Forbidden")

    folder.is_deleted = False
    folder.deleted_at = None
    folder.deleted_by = None
    await db.flush()
    return FolderResponse.model_validate(folder)