package video

import (
	"fmt"
	"html/template"
	"net/http"
	"net/url"
	"path/filepath"
	"sort"
	"strconv"
	"strings"
	"time"

	"github.com/domagojzecevic/cammonitor/internal/auth"
	"github.com/domagojzecevic/cammonitor/internal/config"
	"github.com/domagojzecevic/cammonitor/internal/footage"
	webtemplates "github.com/domagojzecevic/cammonitor/internal/web/templates"
	"github.com/go-chi/chi/v5"
)

type Handler struct {
	cfg        *config.Config
	idx        *footage.Index
	thumbs     *Cache
	ffmpegPath string
}

type ShellData struct {
	Title       string
	User        *auth.User
	Months      []MonthGroup
	CurrentDate string
	ActiveTab   string
	Content     any
}

type MonthGroup struct {
	Label string
	Days  []string
}

type PageData struct {
	Date        string
	Videos      []VideoItem
	ActiveIndex int
	PrevIndex   int
	NextIndex   int
	Current     VideoItem
}

type VideoItem struct {
	Index         int
	Filename      string
	RelPath       string
	StreamURL     string
	ThumbURL      string
	DurationLabel string
	Active        bool
}

func NewHandler(cfg *config.Config, idx *footage.Index) *Handler {
	return &Handler{
		cfg:        cfg,
		idx:        idx,
		ffmpegPath: defaultFFmpegPath,
		thumbs:     NewCache(defaultCacheEntries, defaultFFmpegPath),
	}
}

func (h *Handler) ServeStream(w http.ResponseWriter, r *http.Request) {
	absPath, ok := h.resolveRequestPath(w, r)
	if !ok {
		return
	}

	if err := Stream(w, r, absPath, h.ffmpegPath); err != nil {
		http.Error(w, "stream video failed", http.StatusBadGateway)
	}
}

func (h *Handler) ServeThumb(w http.ResponseWriter, r *http.Request) {
	absPath, ok := h.resolveRequestPath(w, r)
	if !ok {
		return
	}

	thumb, err := h.thumbs.Thumbnail(absPath)
	if err != nil {
		http.NotFound(w, r)
		return
	}

	w.Header().Set("Cache-Control", "max-age=3600")
	w.Header().Set("Content-Type", "image/jpeg")
	w.WriteHeader(http.StatusOK)
	_, _ = w.Write(thumb)
}

func (h *Handler) ServePage(w http.ResponseWriter, r *http.Request) {
	date := chi.URLParam(r, "date")
	day, ok := h.day(date)
	if !ok {
		http.NotFound(w, r)
		return
	}

	data := h.pageData(date, day.Videos, parseIndex(r.URL.Query().Get("idx"), len(day.Videos)))
	h.render(w, r, ShellData{
		Title:       "CamMonitor " + date + " videos",
		CurrentDate: date,
		ActiveTab:   "videos",
		Content:     data,
	})
}

func (h *Handler) pageData(date string, files []footage.VideoFile, active int) PageData {
	items := make([]VideoItem, 0, len(files))
	for i, file := range files {
		items = append(items, VideoItem{
			Index:         i,
			Filename:      file.Filename,
			RelPath:       filepath.ToSlash(file.RelPath),
			StreamURL:     "/stream/video/" + pathEscape(file.RelPath),
			ThumbURL:      "/thumb/video/" + pathEscape(file.RelPath),
			DurationLabel: formatDuration(file.Duration),
			Active:        i == active,
		})
	}

	page := PageData{
		Date:        date,
		Videos:      items,
		ActiveIndex: active,
	}
	if len(items) > 0 {
		page.PrevIndex = (active - 1 + len(items)) % len(items)
		page.NextIndex = (active + 1) % len(items)
		page.Current = items[active]
	}
	return page
}

func (h *Handler) resolveRequestPath(w http.ResponseWriter, r *http.Request) (string, bool) {
	relPath := chi.URLParam(r, "*")
	if routePattern := chi.RouteContext(r.Context()).RoutePattern(); routePattern != "" {
		prefix := strings.TrimSuffix(routePattern, "*")
		escaped := strings.TrimPrefix(r.URL.EscapedPath(), prefix)
		if unescaped, err := url.PathUnescape(escaped); err == nil && unescaped != "" {
			relPath = unescaped
		}
	}

	absPath, err := h.resolveRelPath(relPath)
	if err != nil {
		http.Error(w, "invalid video path", http.StatusBadRequest)
		return "", false
	}
	return absPath, true
}

func (h *Handler) resolveRelPath(relPath string) (string, error) {
	if h.cfg == nil || h.cfg.FootageRoot == "" {
		return "", fmt.Errorf("missing footage root")
	}
	if relPath == "" {
		return "", fmt.Errorf("missing path")
	}

	clean := filepath.Clean(filepath.FromSlash(relPath))
	if clean == "." || clean == ".." || filepath.IsAbs(clean) || strings.HasPrefix(clean, ".."+string(filepath.Separator)) {
		return "", fmt.Errorf("unsafe path")
	}

	root, err := filepath.Abs(h.cfg.FootageRoot)
	if err != nil {
		return "", err
	}
	target, err := filepath.Abs(filepath.Join(root, clean))
	if err != nil {
		return "", err
	}

	rel, err := filepath.Rel(root, target)
	if err != nil {
		return "", err
	}
	if rel == ".." || strings.HasPrefix(rel, ".."+string(filepath.Separator)) {
		return "", fmt.Errorf("path escapes footage root")
	}
	return target, nil
}

func (h *Handler) render(w http.ResponseWriter, r *http.Request, data ShellData) {
	data.User, _ = auth.UserFromContext(r.Context())
	data.Months = groupDaysByMonth(h.dayList())

	w.Header().Set("Content-Type", "text/html; charset=utf-8")
	if err := videoTemplate.ExecuteTemplate(w, "base", data); err != nil {
		http.Error(w, "render video page failed", http.StatusInternalServerError)
	}
}

func (h *Handler) dayList() []string {
	if h.idx == nil {
		return nil
	}
	return h.idx.DayList()
}

func (h *Handler) day(date string) (*footage.DayEntry, bool) {
	if h.idx == nil {
		return nil, false
	}
	return h.idx.Day(date)
}

func parseIndex(value string, length int) int {
	if length <= 0 {
		return 0
	}
	index, err := strconv.Atoi(value)
	if err != nil || index < 0 || index >= length {
		return 0
	}
	return index
}

func pathEscape(relPath string) string {
	parts := strings.Split(filepath.ToSlash(relPath), "/")
	for i, part := range parts {
		parts[i] = url.PathEscape(part)
	}
	return strings.Join(parts, "/")
}

func groupDaysByMonth(days []string) []MonthGroup {
	groups := make(map[string][]string)
	labels := make([]string, 0)

	for _, day := range days {
		if len(day) != len("20060102") {
			continue
		}

		parsed, err := time.Parse("20060102", day)
		if err != nil {
			continue
		}

		label := parsed.Format("2006-01")
		if _, ok := groups[label]; !ok {
			labels = append(labels, label)
		}
		groups[label] = append(groups[label], day)
	}

	sort.Sort(sort.Reverse(sort.StringSlice(labels)))
	monthGroups := make([]MonthGroup, 0, len(labels))
	for _, label := range labels {
		monthGroups = append(monthGroups, MonthGroup{
			Label: label,
			Days:  groups[label],
		})
	}
	return monthGroups
}

func formatDuration(duration time.Duration) string {
	totalSeconds := int(duration.Round(time.Second) / time.Second)
	if totalSeconds < 0 {
		totalSeconds = 0
	}

	hours := totalSeconds / 3600
	minutes := (totalSeconds % 3600) / 60
	seconds := totalSeconds % 60

	if hours > 0 {
		return fmt.Sprintf("%02d:%02d:%02d", hours, minutes, seconds)
	}
	return fmt.Sprintf("%02d:%02d", minutes, seconds)
}

var videoTemplate = template.Must(template.ParseFS(
	webtemplates.FS,
	webtemplates.Base,
	webtemplates.Videos,
))