package updates

import (
	"github.com/go-gormigrate/gormigrate/v2"
	"gorm.io/gorm"
)

// MakeCourseIDNullable returns the 20261002234500_make_course_id_nullable
// gormigrate entry: class sessions and readings may have no course while
// the course form that creates them is not saved yet. The relation managers
// on the course form hold such rows in deferred_bindings, and the first save
// of the course sets course_id; deferred:purge deletes abandoned ones.
func MakeCourseIDNullable() *gormigrate.Migration {
	return &gormigrate.Migration{
		ID: "20261002234500_make_course_id_nullable",
		Migrate: func(tx *gorm.DB) error {
			return execAll(tx, `ALTER TABLE jz_bm_class_sessions ALTER COLUMN course_id DROP NOT NULL;
ALTER TABLE jz_bm_readings ALTER COLUMN course_id DROP NOT NULL`)
		},
		Rollback: func(tx *gorm.DB) error {
			return execAll(tx, `DELETE FROM jz_bm_class_sessions WHERE course_id IS NULL;
DELETE FROM jz_bm_readings WHERE course_id IS NULL;
ALTER TABLE jz_bm_class_sessions ALTER COLUMN course_id SET NOT NULL;
ALTER TABLE jz_bm_readings ALTER COLUMN course_id SET NOT NULL`)
		},
	}
}