package storage

import (
	"context"
	"fmt"
	"net/http"
	"time"

	"luxick/chronological/internal/models"

	"github.com/emersion/go-ical"
	"github.com/emersion/go-webdav/caldav"
)

// CalDAVStore handles fetching events from a CalDAV server.
type CalDAVStore struct {
	url      string
	username string
	password string
	client   *caldav.Client
}

// NewCalDAVStore creates a new CalDAV store with the given credentials.
func NewCalDAVStore(url, username, password string) *CalDAVStore {
	return &CalDAVStore{
		url:      url,
		username: username,
		password: password,
	}
}

// Connect establishes a connection to the CalDAV server.
func (s *CalDAVStore) Connect(ctx context.Context) error {
	httpClient := &http.Client{
		Transport: &basicAuthTransport{
			username: s.username,
			password: s.password,
		},
	}

	client, err := caldav.NewClient(httpClient, s.url)
	if err != nil {
		return fmt.Errorf("failed to create caldav client: %w", err)
	}

	s.client = client
	return nil
}

// LoadEvents fetches events from the CalDAV server for a date range.
func (s *CalDAVStore) LoadEvents(ctx context.Context, start, end time.Time) ([]*models.Event, error) {
	if s.client == nil {
		return nil, fmt.Errorf("caldav client not connected")
	}

	principal, err := s.client.FindCurrentUserPrincipal(ctx)
	if err != nil {
		return nil, fmt.Errorf("failed to find user principal: %w", err)
	}

	homeSet, err := s.client.FindCalendarHomeSet(ctx, principal)
	if err != nil {
		return nil, fmt.Errorf("failed to find calendar home set: %w", err)
	}

	calendars, err := s.client.FindCalendars(ctx, homeSet)
	if err != nil {
		return nil, fmt.Errorf("failed to find calendars: %w", err)
	}

	var allEvents []*models.Event

	for _, cal := range calendars {
		query := &caldav.CalendarQuery{
			CompRequest: caldav.CalendarCompRequest{
				Name: "VCALENDAR",
				Comps: []caldav.CalendarCompRequest{{
					Name: "VEVENT",
					Props: []string{
						"SUMMARY",
						"DESCRIPTION",
						"DTSTART",
						"DTEND",
						"LOCATION",
						"UID",
					},
				}},
			},
			CompFilter: caldav.CompFilter{
				Name: "VCALENDAR",
				Comps: []caldav.CompFilter{{
					Name:  "VEVENT",
					Start: start,
					End:   end,
				}},
			},
		}

		objects, err := s.client.QueryCalendar(ctx, cal.Path, query)
		if err != nil {
			continue // Skip calendars that fail
		}

		events, err := parseCalDAVObjects(objects)
		if err != nil {
			continue
		}

		allEvents = append(allEvents, events...)
	}

	return allEvents, nil
}

// LoadEventsForMonth fetches events for a specific month.
func (s *CalDAVStore) LoadEventsForMonth(ctx context.Context, year int, month time.Month) ([]*models.Event, error) {
	start := time.Date(year, month, 1, 0, 0, 0, 0, time.Local)
	end := start.AddDate(0, 1, 0)
	return s.LoadEvents(ctx, start, end)
}

func parseCalDAVObjects(objects []caldav.CalendarObject) ([]*models.Event, error) {
	var events []*models.Event

	for _, obj := range objects {
		cal := obj.Data
		if cal == nil {
			continue
		}

		for _, child := range cal.Children {
			if child.Name != ical.CompEvent {
				continue
			}

			event := ical.Event{Component: child}

			uid, _ := event.Props.Text(ical.PropUID)
			summary, _ := event.Props.Text(ical.PropSummary)
			description, _ := event.Props.Text(ical.PropDescription)
			location, _ := event.Props.Text(ical.PropLocation)

			dtstart, err := event.Props.DateTime(ical.PropDateTimeStart, time.Local)
			if err != nil {
				continue
			}

			dtend, err := event.Props.DateTime(ical.PropDateTimeEnd, time.Local)
			if err != nil {
				dtend = dtstart.Add(time.Hour)
			}

			// Check if all-day event
			prop := event.Props.Get(ical.PropDateTimeStart)
			allDay := false
			if prop != nil {
				valueParam := prop.Params.Get(ical.ParamValue)
				allDay = valueParam == "DATE"
			}

			events = append(events, &models.Event{
				ID:          uid,
				Title:       summary,
				Description: description,
				Start:       dtstart,
				End:         dtend,
				AllDay:      allDay,
				Location:    location,
				Source:      models.SourceCalDAV,
			})
		}
	}

	return events, nil
}

// basicAuthTransport adds basic auth to HTTP requests.
type basicAuthTransport struct {
	username string
	password string
}

func (t *basicAuthTransport) RoundTrip(req *http.Request) (*http.Response, error) {
	req.SetBasicAuth(t.username, t.password)
	return http.DefaultTransport.RoundTrip(req)
}