from __future__ import annotations

import uuid
from typing import Literal

from sqlalchemy.orm import Session

from app.core.errors import AppError
from app.models import Project
from app.schemas.project import ProjectCreate, ProjectRead, ProjectUpdate


class ProjectService:
    @staticmethod
    def list_projects(
        db: Session,
        limit: int = 50,
        offset: int = 0,
        name: str | None = None,
        project_status: Literal["active", "archived", "all"] = "active",
    ) -> tuple[list[ProjectRead], int]:
        query = db.query(Project).filter(Project.status != "deleted")
        if project_status != "all":
            query = query.filter(Project.status == project_status)
        if name:
            query = query.filter(Project.name == name.strip())
        query = query.order_by(Project.created_at.desc())
        total = query.count()
        items = query.offset(offset).limit(limit).all()
        return [ProjectRead.model_validate(item) for item in items], total

    @staticmethod
    def create_project(db: Session, payload: ProjectCreate) -> ProjectRead:
        project = Project(
            name=payload.name.strip(),
            description=(payload.description or "").strip() or None,
            region=payload.region or "Belgium and Belgian North Sea",
        )
        db.add(project)
        db.commit()
        db.refresh(project)
        return ProjectRead.model_validate(project)

    @staticmethod
    def get_project(db: Session, project_id: uuid.UUID) -> ProjectRead | None:
        project = db.get(Project, project_id)
        if not project or project.status == "deleted":
            return None
        return ProjectRead.model_validate(project)

    @staticmethod
    def update_project(db: Session, project_id: uuid.UUID, payload: ProjectUpdate) -> ProjectRead | None:
        project = db.get(Project, project_id)
        if not project or project.status == "deleted":
            return None

        payload_data = payload.model_dump(exclude_unset=True)
        changed = False
        for key, value in payload_data.items():
            if value is None:
                continue
            setattr(project, key, value)
            changed = True
        if not changed:
            raise AppError(code="NO_CHANGES", message="No updatable fields provided", status_code=422)

        db.add(project)
        db.commit()
        db.refresh(project)
        return ProjectRead.model_validate(project)

    @staticmethod
    def delete_project(db: Session, project_id: uuid.UUID) -> bool:
        project = db.get(Project, project_id)
        if not project or project.status == "deleted":
            return False
        project.status = "deleted"
        db.add(project)
        db.commit()
        return True