from rest_framework.permissions import BasePermission, SAFE_METHODS


class IsCourseInstructorOrAdmin(BasePermission):
    """
    Grants permission to course creators, institution admins, regional admins, and super admins.
    Allows read-only access to anyone for safe methods.
    """
    def has_permission(self, request, view):
        if request.method in SAFE_METHODS:
            return True
        return bool(request.user and request.user.is_authenticated and request.user.is_active)

    def has_object_permission(self, request, view, obj):
        if request.method in SAFE_METHODS:
            return True

        if not request.user or not request.user.is_authenticated:
            return False

        if getattr(request.user, 'is_super_admin', False) or getattr(request.user, 'is_regional_admin', False):
            return True

        # If obj is a Course
        if hasattr(obj, 'created_by') and obj.created_by == request.user:
            return True

        if hasattr(obj, 'institution') and obj.institution:
            if obj.institution.is_editor(request.user):
                return True

        # If obj is CourseModule or Lesson
        if hasattr(obj, 'course'):
            course = obj.course
            if course.created_by == request.user:
                return True
            if course.institution and course.institution.is_editor(request.user):
                return True

        if hasattr(obj, 'module'):
            course = obj.module.course
            if course.created_by == request.user:
                return True
            if course.institution and course.institution.is_editor(request.user):
                return True

        return False


class IsEnrolledOrPreview(BasePermission):
    """
    Allows access if the lesson is marked as preview, or if the user is enrolled, or course admin.
    """
    def has_permission(self, request, view):
        return bool(request.user and request.user.is_authenticated and request.user.is_active)