"""Projects CRUD + per-project stats."""
from fastapi import APIRouter, Depends, Query
from sqlalchemy import func, or_, select
from sqlalchemy.ext.asyncio import AsyncSession

from app.db.engine import get_db
from app.models.procurement import Project, Quote, User
from app.schemas.procurement import ProjectCreate, ProjectUpdate
from app.services.quote_service import project_stats
from app.utils.errors import ConflictError, NotFoundError
from app.utils.pagination import paginate, sort_query
from app.utils.serialization import to_date, to_iso

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


async def _pm_map(db: AsyncSession, projects: list[Project]) -> dict:
    """project_id -> pm brief (v2.6: the single PM of the project)."""
    pm_ids = {p.pm_user_id for p in projects if p.pm_user_id}
    if not pm_ids:
        return {}
    users = (await db.execute(select(User).where(User.id.in_(pm_ids)))).scalars().all()
    return {u.id: u for u in users}


async def project_to_dict(db: AsyncSession, project: Project) -> dict:
    d = {
        "id": str(project.id),
        "name": project.name,
        "description": project.description,
        "start_date": to_date(project.start_date),
        "pm_user_id": str(project.pm_user_id) if project.pm_user_id else None,
        "created_at": to_iso(project.created_at),
    }
    if project.pm_user_id:
        pm = await db.get(User, project.pm_user_id)
        if pm:
            d["pm_name"] = f"{pm.first_name} {pm.last_name}".strip() or pm.casdoor_id
    return d


@router.get("")
async def list_projects(
    page: int = Query(1, ge=1),
    page_size: int = Query(20, ge=1, le=100),
    q: str | None = None,
    sort: str | None = None,
    db: AsyncSession = Depends(get_db),
):
    stmt = select(Project)
    if q:
        stmt = stmt.where(or_(Project.name.ilike(f"%{q}%"), Project.description.ilike(f"%{q}%")))
    stmt = sort_query(stmt, Project, sort)
    items, meta = await paginate(stmt, page, page_size, db)
    pm_map = await _pm_map(db, items)
    data = []
    for p in items:
        d = {
            "id": str(p.id),
            "name": p.name,
            "description": p.description,
            "start_date": to_date(p.start_date),
            "pm_user_id": str(p.pm_user_id) if p.pm_user_id else None,
            "created_at": to_iso(p.created_at),
        }
        pm = pm_map.get(p.pm_user_id)
        if pm:
            d["pm_name"] = f"{pm.first_name} {pm.last_name}".strip() or pm.casdoor_id
        data.append(d)
    return {"data": data, "meta": meta}


@router.post("", status_code=201)
async def create_project(payload: ProjectCreate, db: AsyncSession = Depends(get_db)):
    project = Project(
        name=payload.name,
        description=payload.description,
        start_date=payload.start_date,
    )
    db.add(project)
    await db.flush()
    return {"data": await project_to_dict(db, project)}


@router.get("/{project_id}")
async def get_project(project_id, db: AsyncSession = Depends(get_db)):
    project = await db.get(Project, project_id)
    if project is None:
        raise NotFoundError("پروژه یافت نشد")
    return {"data": await project_to_dict(db, project)}


@router.patch("/{project_id}")
async def update_project(project_id, payload: ProjectUpdate, db: AsyncSession = Depends(get_db)):
    project = await db.get(Project, project_id)
    if project is None:
        raise NotFoundError("پروژه یافت نشد")
    if payload.name is not None:
        project.name = payload.name
    if payload.description is not None:
        project.description = payload.description
    if payload.start_date is not None:
        project.start_date = payload.start_date
    await db.flush()
    return {"data": await project_to_dict(db, project)}


@router.delete("/{project_id}")
async def delete_project(project_id, db: AsyncSession = Depends(get_db)):
    project = await db.get(Project, project_id)
    if project is None:
        raise NotFoundError("پروژه یافت نشد")
    # Recommendation (P2-24): block instead of silently unlinking quotes (SET NULL).
    linked = await db.scalar(select(func.count()).select_from(Quote).where(Quote.project_id == project_id))
    if linked:
        raise ConflictError("این پروژه دارای پیشنهاد است و قابل حذف نیست")
    await db.delete(project)
    await db.flush()
    return {"data": {"id": str(project_id), "deleted": True}}


@router.get("/{project_id}/stats")
async def get_project_stats(project_id, db: AsyncSession = Depends(get_db)):
    return {"data": await project_stats(db, project_id)}