//Calendar implementation for the HTWK Leipzig timetable. Evaluation and display of the individual dates in iCal format.
//Copyright (C) 2024 HTWKalender support@htwkalender.de

//This program is free software: you can redistribute it and/or modify
//it under the terms of the GNU Affero General Public License as published by
//the Free Software Foundation, either version 3 of the License, or
//(at your option) any later version.

//This program is distributed in the hope that it will be useful,
//but WITHOUT ANY WARRANTY; without even the implied warranty of
//MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
//GNU Affero General Public License for more details.

//You should have received a copy of the GNU Affero General Public License
//along with this program.  If not, see <https://www.gnu.org/licenses/>.

package feed

import (
	"database/sql"
	"github.com/pocketbase/dbx"
	"github.com/pocketbase/pocketbase/daos"
	"htwkalender/model"
	database "htwkalender/service/db"
	"htwkalender/service/functions"
	localTime "htwkalender/service/functions/time"
	"log/slog"
	"strings"
)

func ClearFeeds(db *daos.Dao, months int, clock localTime.Clock) {
	feeds, err := database.GetAllFeeds(db)
	if err != nil {
		slog.Error("CleanFeeds: failed to get all feeds", err)
		return
	}
	for _, feed := range feeds {
		// if retrieved time is older than a half year delete feed
		now := clock.Now()
		feedRetrievedTime := feed.Retrieved.Time()
		timeShift := now.AddDate(0, -months, 0)

		if feedRetrievedTime.Before(timeShift) {
			// delete feed
			var sqlResult sql.Result
			sqlResult, err = db.DB().Delete("feeds", dbx.NewExp("id = {:id}", dbx.Params{"id": feed.GetId()})).Execute()
			if err != nil {
				slog.Error("CleanFeeds: delete feed "+feed.GetId()+" failed", err)
				slog.Error("SQL Result: ", sqlResult)
			} else {
				slog.Info("CleanFeeds: delete feed " + feed.GetId() + " successful")
			}
		}
	}
}

func CombineEventsInFeed(events model.Events) model.Events {
	// Combine events with the same Prof, Name, Start and End time into one event
	// if the note is empty then there is no room displayed in the new note
	// room listing isn't displayed if there is only one event.

	combinedEvents := make(model.Events, 0)
	combinedEvents = append(combinedEvents, events[0])

	for index1 := 1; index1 < len(events); index1++ {
		for index2 := 0; index2 < len(combinedEvents); index2++ {

			if events[index1].Name == combinedEvents[index2].Name &&
				events[index1].Start == combinedEvents[index2].Start &&
				events[index1].End == combinedEvents[index2].End &&
				events[index1].Course == combinedEvents[index2].Course {

				// if no notes are present skip
				if !functions.OnlyWhitespace(events[index1].Notes) {
					// if combinedEvents notes are empty, add the new notes
					if functions.OnlyWhitespace(combinedEvents[index2].Notes) {
						combinedEvents[index2].Notes = descriptionString(events[index1])
					} else {
						addNotesIfAlreadyRoomsAdded(events, combinedEvents, index2, index1)
					}
				}

				combineRooms(events, index1, combinedEvents, index2)
				combineProfs(events, index1, combinedEvents, index2)

				// remove the event from the events list
				events = append(events[:index1], events[index1+1:]...)

				break

			} else {
				// if the event is not in the combinedEvents list, add it
				if index2 == len(combinedEvents)-1 {
					combinedEvents = append(combinedEvents, events[index1])
					events = append(events[:index1], events[index1+1:]...)
					break
				}
			}
		}
	}
	return combinedEvents
}

func addNotesIfAlreadyRoomsAdded(events model.Events, combinedEvents model.Events, index2 int, index1 int) {
	// check if combinedEvents[index2].Rooms string contains comma "," &#44
	if !strings.Contains(combinedEvents[index2].Rooms, ",") {
		combinedEvents[index2].Notes = descriptionString(combinedEvents[index2]) + "\n" + descriptionString(events[index1])
	} else {
		combinedEvents[index2].Notes += "\n" + descriptionString(events[index1])
	}
}

func combineProfs(events model.Events, index1 int, combinedEvents model.Events, index2 int) {
	// combine the profs
	if events[index1].Prof != "" {
		if combinedEvents[index2].Prof == "" {
			combinedEvents[index2].Prof = events[index1].Prof
		} else {
			if !strings.Contains(combinedEvents[index2].Prof, events[index1].Prof) {
				combinedEvents[index2].Prof += ", " + events[index1].Prof
			}
		}
	}
}

func descriptionString(event model.Event) string {
	return event.Rooms + " - " + event.Notes + " (" + event.Prof + ")"
}

func combineRooms(events model.Events, index1 int, combinedEvents model.Events, index2 int) {
	// combine the rooms
	if events[index1].Rooms != "" {
		if combinedEvents[index2].Rooms == "" {
			combinedEvents[index2].Rooms = events[index1].Rooms
		} else {
			if !strings.Contains(combinedEvents[index2].Rooms, events[index1].Rooms) {
				combinedEvents[index2].Rooms += ", " + events[index1].Rooms
			}
		}
	}
}