htwkalender/backend/service/db/dbEvents.go

package db

import (
	"github.com/pocketbase/dbx"
	"github.com/pocketbase/pocketbase"
	"htwkalender/model"
)

func SaveEvents(seminarGroup []model.SeminarGroup, app *pocketbase.PocketBase) ([]model.Event, error) {
	var toBeSavedEvents model.Events
	var savedRecords model.Events
	// check if event is already in database and add to toBeSavedEvents if not
	for _, seminarGroup := range seminarGroup {
		for _, event := range seminarGroup.Events {
			event = event.SetCourse(seminarGroup.Course)
			dbGroup, err := findEventByDayWeekStartEndNameCourse(event, seminarGroup.Course, app)

			if dbGroup.UUID != "" && err.Error() == "sql: no rows in result set" && toBeSavedEvents.Contains(event) == false {
				toBeSavedEvents = append(toBeSavedEvents, event)
			}
		}
	}

	// create record for each event that's not already in the database
	for _, event := range toBeSavedEvents {
		event.MarkAsNew()
		// auto mapping for event fields to record fields
		err := app.Dao().Save(&event)
		if err != nil {
			return nil, err
		} else {
			savedRecords = append(savedRecords, event)
		}
	}

	return savedRecords, nil
}

func findEventByDayWeekStartEndNameCourse(event model.Event, course string, app *pocketbase.PocketBase) (*model.Event, error) {
	err := app.Dao().DB().Select("*").From("events").Where(
		dbx.NewExp("Day = {:day} AND Week = {:week} AND Start = {:start} AND End = {:end} AND Name = {:name} AND course = {:course} AND Prof = {:prof} AND Rooms = {:rooms} AND EventType = {:eventType}",
			dbx.Params{"day": event.Day, "week": event.Week, "start": event.Start, "end": event.End, "name": event.Name, "course": course, "prof": event.Prof, "rooms": event.Rooms, "eventType": event.EventType}),
	).One(&event)
	return &event, err
}

func buildIcalQueryForModules(modules []model.FeedCollection) dbx.Expression {

	// build where conditions for each module

	//first check if modules is empty
	if len(modules) == 0 {
		return dbx.HashExp{}
	}

	//second check if modules has only one element
	if len(modules) == 1 {
		return dbx.And(
			dbx.HashExp{"Name": modules[0].Name},
			dbx.HashExp{"course": modules[0].Course},
		)
	}

	//third check if modules has more than one element
	var wheres []dbx.Expression

	for _, module := range modules {
		where := dbx.And(
			dbx.HashExp{"Name": module.Name},
			dbx.HashExp{"course": module.Course},
		)
		wheres = append(wheres, where)
	}

	// Use dbx.And or dbx.Or to combine the where conditions as needed
	where := dbx.Or(wheres...)

	return where

}

// GetPlanForModules returns all events for the given modules with the given course
// used for the ical feed
func GetPlanForModules(app *pocketbase.PocketBase, modules []model.FeedCollection) model.Events {

	var events model.Events

	// iterate over modules in 100 batch sizes
	for i := 0; i < len(modules); i += 100 {
		var moduleBatch []model.FeedCollection

		if i+100 > len(modules) {
			moduleBatch = modules[i:]
		} else {
			moduleBatch = modules[i : i+100]
		}

		var selectedModulesQuery = buildIcalQueryForModules(moduleBatch)
		// get all events from event records in the events collection
		err := app.Dao().DB().Select("*").From("events").Where(selectedModulesQuery).All(&events)
		if err != nil {
			print("Error while getting events from database: ", err)
			return nil
		}
	}

	return events
}

func GetAllModulesForCourse(app *pocketbase.PocketBase, course string, semester string) (model.Events, error) {
	var events model.Events

	// get all events from event records in the events collection
	err := app.Dao().DB().Select("*").From("events").Where(dbx.NewExp("course = {:course} AND semester = {:semester}", dbx.Params{"course": course, "semester": semester})).GroupBy("Name").Distinct(true).All(&events)
	if err != nil {
		print("Error while getting events from database: ", err)
		return nil, err
	}

	return events, nil
}

func GetAllModulesDistinctByNameAndCourse(app *pocketbase.PocketBase) (model.Events, error) {
	var events model.Events

	err := app.Dao().DB().Select("*").From("events").GroupBy("Name", "course").Distinct(true).All(&events)
	if err != nil {
		print("Error while getting events from database: ", err)
		return nil, err
	}

	return events, nil
}

func DeleteAllEventsForCourse(app *pocketbase.PocketBase, course string, semester string) error {
	_, err := app.Dao().DB().Delete("events", dbx.NewExp("course = {:course} AND semester = {:semester}", dbx.Params{"course": course, "semester": semester})).Execute()

	if err != nil {
		print("Error while deleting events from database: ", err)
		return err
	}

	return nil
}

func FindAllEventsByModule(app *pocketbase.PocketBase, moduleName string) (model.Events, error) {
	var events model.Events

	err := app.Dao().DB().Select("*").From("events").Where(dbx.NewExp("Name = {:moduleName}", dbx.Params{"moduleName": moduleName})).All(&events)
	if err != nil {
		print("Error while getting events from database: ", err)
		return nil, err
	}

	return events, nil
}