from datetime import datetime
from typing import List

from sqlalchemy.orm import Session

from app.models import Module, ModuleProgress, ProgressStatus


def ensure_module_progress(db: Session, user_id: int, course_id: int) -> List[ModuleProgress]:
    modules = db.query(Module).filter(Module.course_id == course_id).order_by(Module.order_index).all()
    progress_list: List[ModuleProgress] = []
    for module in modules:
        progress = (
            db.query(ModuleProgress)
            .filter(ModuleProgress.user_id == user_id, ModuleProgress.module_id == module.id)
            .first()
        )
        if not progress:
            progress = ModuleProgress(user_id=user_id, module_id=module.id, status=ProgressStatus.locked)
            db.add(progress)
            db.flush()
        progress_list.append(progress)
    db.commit()
    return progress_list


def recompute_progress(db: Session, user_id: int, course_id: int) -> None:
    modules = db.query(Module).filter(Module.course_id == course_id).order_by(Module.order_index).all()
    progresses = {
        p.module_id: p
        for p in db.query(ModuleProgress).filter(ModuleProgress.user_id == user_id).all()
    }

    last_completed_index = -1
    for idx, module in enumerate(modules):
        progress = progresses.get(module.id)
        if not progress:
            progress = ModuleProgress(user_id=user_id, module_id=module.id, status=ProgressStatus.locked)
            db.add(progress)
            progresses[module.id] = progress
        if progress.status == ProgressStatus.completed:
            last_completed_index = idx

    for idx, module in enumerate(modules):
        progress = progresses[module.id]
        if progress.status == ProgressStatus.completed:
            continue
        if idx == last_completed_index + 1:
            progress.status = ProgressStatus.unlocked
        else:
            progress.status = ProgressStatus.locked

    db.commit()


def complete_content_module(db: Session, user_id: int, module: Module) -> ModuleProgress:
    progress = (
        db.query(ModuleProgress)
        .filter(ModuleProgress.user_id == user_id, ModuleProgress.module_id == module.id)
        .first()
    )
    if not progress:
        progress = ModuleProgress(user_id=user_id, module_id=module.id, status=ProgressStatus.unlocked)
        db.add(progress)
    progress.status = ProgressStatus.completed
    progress.completed_at = datetime.utcnow()
    db.commit()
    return progress