// Package handlers contains HTTP handlers for all routes.
package handlers

import (
	"context"
	"html/template"
	"net/http"
	"strconv"
	"time"

	"github.com/luxick/chronological/internal/models"
	"github.com/luxick/chronological/internal/storage"
)

// Handlers holds all HTTP handlers and their dependencies.
type Handlers struct {
	templates   *template.Template
	icsStore    *storage.ICSStore
	photoStore  *storage.PhotoStore
	caldavStore *storage.CalDAVStore
}

// New creates a new Handlers instance.
func New(tmpl *template.Template, ics *storage.ICSStore, photos *storage.PhotoStore, caldav *storage.CalDAVStore) *Handlers {
	return &Handlers{
		templates:   tmpl,
		icsStore:    ics,
		photoStore:  photos,
		caldavStore: caldav,
	}
}

// HandleIndex serves the main timeline page.
func (h *Handlers) HandleIndex(w http.ResponseWriter, r *http.Request) {
	now := time.Now()
	data := h.buildPageData(now.Year(), now.Month())
	h.render(w, "index.html", data)
}

// HandleCalendar serves the calendar grid partial for HTMX.
func (h *Handlers) HandleCalendar(w http.ResponseWriter, r *http.Request) {
	year, month, err := parseYearMonth(r)
	if err != nil {
		http.Error(w, "Invalid date", http.StatusBadRequest)
		return
	}

	data := h.buildCalendarData(year, month)
	h.render(w, "calendar.html", data)
}

// HandleTimeline serves the timeline partial for HTMX.
func (h *Handlers) HandleTimeline(w http.ResponseWriter, r *http.Request) {
	year, month, err := parseYearMonth(r)
	if err != nil {
		http.Error(w, "Invalid date", http.StatusBadRequest)
		return
	}

	data := h.buildTimelineData(year, month)
	h.render(w, "timeline.html", data)
}

// HandleDay serves the day detail view.
func (h *Handlers) HandleDay(w http.ResponseWriter, r *http.Request) {
	year, month, err := parseYearMonth(r)
	if err != nil {
		http.Error(w, "Invalid date", http.StatusBadRequest)
		return
	}

	dayStr := r.PathValue("day")
	day, err := strconv.Atoi(dayStr)
	if err != nil || day < 1 || day > 31 {
		http.Error(w, "Invalid day", http.StatusBadRequest)
		return
	}

	date := time.Date(year, month, day, 0, 0, 0, 0, time.Local)
	data := h.buildDayData(date)
	h.render(w, "day.html", data)
}

// HandleGetDiary serves a diary entry for a specific date.
func (h *Handlers) HandleGetDiary(w http.ResponseWriter, r *http.Request) {
	date, err := parseDate(r.PathValue("date"))
	if err != nil {
		http.Error(w, "Invalid date", http.StatusBadRequest)
		return
	}

	entry, err := h.icsStore.LoadDiaryEntry(date)
	if err != nil {
		http.Error(w, "Failed to load diary", http.StatusInternalServerError)
		return
	}

	data := map[string]any{
		"Date":  date,
		"Entry": entry,
	}
	h.render(w, "diary_form.html", data)
}

// HandleSaveDiary saves or updates a diary entry.
func (h *Handlers) HandleSaveDiary(w http.ResponseWriter, r *http.Request) {
	date, err := parseDate(r.PathValue("date"))
	if err != nil {
		http.Error(w, "Invalid date", http.StatusBadRequest)
		return
	}

	if err := r.ParseForm(); err != nil {
		http.Error(w, "Failed to parse form", http.StatusBadRequest)
		return
	}

	text := r.FormValue("text")
	entry := &models.DiaryEntry{
		Date: date,
		Text: text,
	}

	if err := h.icsStore.SaveDiaryEntry(entry); err != nil {
		http.Error(w, "Failed to save diary", http.StatusInternalServerError)
		return
	}

	// Return updated day content
	data := h.buildDayData(date)
	h.render(w, "day_content.html", data)
}

// HandleDeleteDiary deletes a diary entry.
func (h *Handlers) HandleDeleteDiary(w http.ResponseWriter, r *http.Request) {
	date, err := parseDate(r.PathValue("date"))
	if err != nil {
		http.Error(w, "Invalid date", http.StatusBadRequest)
		return
	}

	if err := h.icsStore.DeleteDiaryEntry(date); err != nil {
		http.Error(w, "Failed to delete diary", http.StatusInternalServerError)
		return
	}

	// Return updated day content
	data := h.buildDayData(date)
	h.render(w, "day_content.html", data)
}

func (h *Handlers) render(w http.ResponseWriter, name string, data any) {
	w.Header().Set("Content-Type", "text/html; charset=utf-8")
	if err := h.templates.ExecuteTemplate(w, name, data); err != nil {
		http.Error(w, "Template error", http.StatusInternalServerError)
	}
}

func (h *Handlers) buildPageData(year int, month time.Month) map[string]any {
	return map[string]any{
		"Year":     year,
		"Month":    month,
		"Calendar": h.buildCalendarData(year, month),
		"Timeline": h.buildTimelineData(year, month),
	}
}

func (h *Handlers) buildCalendarData(year int, month time.Month) map[string]any {
	// Load content indicators for each day
	events, _ := h.icsStore.LoadEventsForMonth(year, month)
	diaries, _ := h.icsStore.LoadDiaryEntries()
	photos, _ := h.photoStore.LoadPhotosForMonth(year, month)

	// Load CalDAV events if available
	if h.caldavStore != nil {
		ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
		defer cancel()
		caldavEvents, err := h.caldavStore.LoadEventsForMonth(ctx, year, month)
		if err == nil {
			events = append(events, caldavEvents...)
		}
	}

	// Build day content map
	days := make(map[int]*models.DayContent)
	daysInMonth := time.Date(year, month+1, 0, 0, 0, 0, 0, time.Local).Day()

	for day := 1; day <= daysInMonth; day++ {
		date := time.Date(year, month, day, 0, 0, 0, 0, time.Local)
		content := &models.DayContent{Date: date}

		// Add events for this day
		for _, event := range events {
			if event.IsOnDate(date) {
				content.Events = append(content.Events, event)
			}
		}

		// Add diary entry for this day
		for _, diary := range diaries {
			if diary.Date.Truncate(24 * time.Hour).Equal(date.Truncate(24 * time.Hour)) {
				content.Diary = diary
				break
			}
		}

		// Add photos for this day
		for _, photo := range photos {
			if photo.Date.Truncate(24 * time.Hour).Equal(date.Truncate(24 * time.Hour)) {
				content.Photos = append(content.Photos, photo)
			}
		}

		days[day] = content
	}

	// Calculate first day offset (0 = Sunday)
	firstDay := time.Date(year, month, 1, 0, 0, 0, 0, time.Local)
	firstDayWeekday := int(firstDay.Weekday())

	// Previous/next month
	prevMonth := time.Date(year, month-1, 1, 0, 0, 0, 0, time.Local)
	nextMonth := time.Date(year, month+1, 1, 0, 0, 0, 0, time.Local)

	return map[string]any{
		"Year":            year,
		"Month":           month,
		"MonthName":       month.String(),
		"DaysInMonth":     daysInMonth,
		"FirstDayWeekday": firstDayWeekday,
		"Days":            days,
		"PrevYear":        prevMonth.Year(),
		"PrevMonth":       int(prevMonth.Month()),
		"NextYear":        nextMonth.Year(),
		"NextMonth":       int(nextMonth.Month()),
	}
}

func (h *Handlers) buildTimelineData(year int, month time.Month) map[string]any {
	events, _ := h.icsStore.LoadEventsForMonth(year, month)
	diaries, _ := h.icsStore.LoadDiaryEntries()
	photos, _ := h.photoStore.LoadPhotosForMonth(year, month)

	// Load CalDAV events if available
	if h.caldavStore != nil {
		ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
		defer cancel()
		caldavEvents, err := h.caldavStore.LoadEventsForMonth(ctx, year, month)
		if err == nil {
			events = append(events, caldavEvents...)
		}
	}

	// Build entries grouped by day
	daysInMonth := time.Date(year, month+1, 0, 0, 0, 0, 0, time.Local).Day()
	var daysWithContent []*models.DayContent

	for day := 1; day <= daysInMonth; day++ {
		date := time.Date(year, month, day, 0, 0, 0, 0, time.Local)
		content := &models.DayContent{Date: date}

		for _, event := range events {
			if event.IsOnDate(date) {
				content.Events = append(content.Events, event)
			}
		}

		for _, diary := range diaries {
			if diary.Date.Truncate(24 * time.Hour).Equal(date.Truncate(24 * time.Hour)) {
				content.Diary = diary
				break
			}
		}

		for _, photo := range photos {
			if photo.Date.Truncate(24 * time.Hour).Equal(date.Truncate(24 * time.Hour)) {
				content.Photos = append(content.Photos, photo)
			}
		}

		if content.HasContent() {
			daysWithContent = append(daysWithContent, content)
		}
	}

	// Previous/next month
	prevMonth := time.Date(year, month-1, 1, 0, 0, 0, 0, time.Local)
	nextMonth := time.Date(year, month+1, 1, 0, 0, 0, 0, time.Local)

	return map[string]any{
		"Year":      year,
		"Month":     month,
		"MonthName": month.String(),
		"Days":      daysWithContent,
		"PrevYear":  prevMonth.Year(),
		"PrevMonth": int(prevMonth.Month()),
		"NextYear":  nextMonth.Year(),
		"NextMonth": int(nextMonth.Month()),
	}
}

func (h *Handlers) buildDayData(date time.Time) map[string]any {
	content := &models.DayContent{Date: date}

	events, _ := h.icsStore.LoadEventsForMonth(date.Year(), date.Month())
	for _, event := range events {
		if event.IsOnDate(date) {
			content.Events = append(content.Events, event)
		}
	}

	// Load CalDAV events if available
	if h.caldavStore != nil {
		ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
		defer cancel()
		caldavEvents, err := h.caldavStore.LoadEventsForMonth(ctx, date.Year(), date.Month())
		if err == nil {
			for _, event := range caldavEvents {
				if event.IsOnDate(date) {
					content.Events = append(content.Events, event)
				}
			}
		}
	}

	entry, _ := h.icsStore.LoadDiaryEntry(date)
	content.Diary = entry

	photos, _ := h.photoStore.LoadPhotosForDate(date)
	content.Photos = photos

	return map[string]any{
		"Date":    date,
		"Content": content,
	}
}

func parseYearMonth(r *http.Request) (int, time.Month, error) {
	yearStr := r.PathValue("year")
	monthStr := r.PathValue("month")

	year, err := strconv.Atoi(yearStr)
	if err != nil {
		return 0, 0, err
	}

	monthInt, err := strconv.Atoi(monthStr)
	if err != nil || monthInt < 1 || monthInt > 12 {
		return 0, 0, err
	}

	return year, time.Month(monthInt), nil
}

func parseDate(dateStr string) (time.Time, error) {
	return time.Parse("2006-01-02", dateStr)
}