package handler

import (
	"bytes"
	"fmt"
	"html/template"
	"net/http"
	"net/url"
	"path/filepath"
	"runtime"
	"strconv"
	"strings"

	"github.com/gabriel-vasile/mimetype"
	"github.com/go-chi/chi/v5"

	"vidarchive/internal/config"
	"vidarchive/internal/models"
	"vidarchive/internal/service"
	"vidarchive/internal/worker"
)

type Handler struct {
	cfg         *config.Config
	templates   *template.Template
	presetSvc   *service.PresetService
	downloadSvc *service.DownloadService
	librarySvc  *service.LibraryService
	settingsSvc *service.SettingsService
	workerPool  *worker.Pool
}

func New(cfg *config.Config, presetSvc *service.PresetService, downloadSvc *service.DownloadService, librarySvc *service.LibraryService, settingsSvc *service.SettingsService, workerPool *worker.Pool) (*Handler, error) {
	presetSvcGlobal = presetSvc
	tmpl, err := loadTemplates()
	if err != nil {
		return nil, fmt.Errorf("load templates: %w", err)
	}

	return &Handler{
		cfg:         cfg,
		templates:   tmpl,
		presetSvc:   presetSvc,
		downloadSvc: downloadSvc,
		librarySvc:  librarySvc,
		settingsSvc: settingsSvc,
		workerPool:  workerPool,
	}, nil
}

func loadTemplates() (*template.Template, error) {
	tmpl := template.New("").Funcs(template.FuncMap{
		"formatDuration": formatDuration,
		"formatFileSize": formatFileSize,
		"splitPath":      func(p string) []string { return strings.Split(strings.Trim(p, "/"), "/") },
		"baseName":       filepath.Base,
		"ext":            filepath.Ext,
		"mimeType":       mimeTypeFromFile,
		"presetFlags":    func(p *models.Preset) string { return presetSvcGlobal.EffectiveFlags(p, "", "") },
		"urlEncode":      template.URLQueryEscaper,
		"urlEncodePath": func(p string) string {
			parts := strings.Split(strings.Trim(p, "/"), "/")
			for i, part := range parts {
				parts[i] = url.PathEscape(part)
			}
			return strings.Join(parts, "/")
		},
		"sub": func(a, b int) int { return a - b },
		// isLongText reports whether text spans more than ~2 lines, so the detail
		// view can make long descriptions collapsible. Uses rune count (not bytes)
		// so CJK text isn't flagged early.
		"isLongText": func(s string) bool {
			return strings.Count(s, "\n") >= 2 || len([]rune(s)) > 180
		},
	})

	if repoRoot == "" {
		return nil, fmt.Errorf("failed to determine template path")
	}
	return tmpl.ParseGlob(filepath.Join(repoRoot, "web", "templates", "*.html"))
}

var (
	presetSvcGlobal *service.PresetService
	repoRoot        string
)

func init() {
	_, file, _, ok := runtime.Caller(0)
	if ok {
		repoRoot = filepath.Join(filepath.Dir(file), "..", "..")
	}
}

func formatDuration(seconds int) string {
	if seconds <= 0 {
		return "--:--"
	}
	m := seconds / 60
	s := seconds % 60
	h := m / 60
	m = m % 60
	if h > 0 {
		return fmt.Sprintf("%d:%02d:%02d", h, m, s)
	}
	return fmt.Sprintf("%d:%02d", m, s)
}

func formatFileSize(bytes int64) string {
	const unit = 1024
	if bytes < unit {
		return fmt.Sprintf("%d B", bytes)
	}
	div, exp := int64(unit), 0
	for n := bytes / unit; n >= unit; n /= unit {
		div *= unit
		exp++
	}
	return fmt.Sprintf("%.1f %cB", float64(bytes)/float64(div), "KMGTPE"[exp])
}

func mimeTypeFromFile(path string) string {
	mtype, err := mimetype.DetectFile(path)
	if err != nil || mtype == nil {
		return "application/octet-stream"
	}
	return mtype.String()
}

type PageData struct {
	Title       string
	ActiveTab   string
	Data        interface{}
	BaseURL     string
	AutoRefresh bool
	RefreshSec  int
	Theme       string
}

const cookieMaxAge = 365 * 24 * 60 * 60

func getCookie(r *http.Request, name, defaultVal string) string {
	cookie, err := r.Cookie(name)
	if err != nil {
		return defaultVal
	}
	return cookie.Value
}

func setCookie(w http.ResponseWriter, name, value string) {
	http.SetCookie(w, &http.Cookie{
		Name:     name,
		Value:    value,
		Path:     "/",
		MaxAge:   cookieMaxAge,
		HttpOnly: true,
		SameSite: http.SameSiteLaxMode,
	})
}

func (h *Handler) renderWithRequest(w http.ResponseWriter, r *http.Request, contentTmpl string, data PageData) {
	data.BaseURL = h.cfg.BaseURL
	if data.Theme == "" {
		data.Theme = getCookie(r, "theme", "auto")
	}
	w.Header().Set("Content-Type", "text/html; charset=utf-8")

	var contentBuf bytes.Buffer
	if err := h.templates.ExecuteTemplate(&contentBuf, contentTmpl, data); err != nil {
		http.Error(w, fmt.Sprintf("render content: %v", err), http.StatusInternalServerError)
		return
	}

	layoutData := struct {
		PageData
		Content template.HTML
	}{
		PageData: data,
		Content:  template.HTML(contentBuf.String()),
	}

	if err := h.templates.ExecuteTemplate(w, "layout", layoutData); err != nil {
		http.Error(w, fmt.Sprintf("render layout: %v", err), http.StatusInternalServerError)
	}
}

func (h *Handler) Library(w http.ResponseWriter, r *http.Request) {
	path := r.URL.Query().Get("path")
	sortBy := r.URL.Query().Get("sort")
	filter := r.URL.Query().Get("filter")

	if sortBy == "" {
		sortBy = getCookie(r, "library_sort", "date")
	} else {
		setCookie(w, "library_sort", sortBy)
	}

	items, folders, err := h.librarySvc.GetAll(path, sortBy, filter)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	settings, _ := h.settingsSvc.GetAll()

	h.renderWithRequest(w, r, "library", PageData{
		Title:       "Library",
		ActiveTab:   "library",
		AutoRefresh: settings.AutoRefreshLibrary,
		RefreshSec:  settings.RefreshInterval,
		Data: struct {
			Items   []*models.LibraryItem
			Folders []string
			Path    string
			SortBy  string
			Filter  string
		}{
			Items:   items,
			Folders: folders,
			Path:    path,
			SortBy:  sortBy,
			Filter:  filter,
		},
	})
}

func normalizeRelPath(r *http.Request) string {
	relPath := chi.URLParam(r, "*")
	relPath = strings.ReplaceAll(relPath, "+", " ")
	relPath = strings.Trim(relPath, "/")
	relPath, _ = url.PathUnescape(relPath)
	return relPath
}

func (h *Handler) LibraryItem(w http.ResponseWriter, r *http.Request) {
	relPath := normalizeRelPath(r)
	if r.Method == "POST" && strings.HasSuffix(relPath, "/delete") {
		relPath = strings.TrimSuffix(relPath, "/delete")
		h.deleteMedia(relPath, w, r)
		return
	}
	h.libraryDetail(relPath, w, r)
}

func (h *Handler) libraryDetail(relPath string, w http.ResponseWriter, r *http.Request) {

	ctx := r.Context()
	item, err := h.librarySvc.GetByRelPath(ctx, relPath)
	if err != nil {
		http.Error(w, "Not found", http.StatusNotFound)
		return
	}

	selectedFilename := r.URL.Query().Get("file")
	if selectedFilename == "" && len(item.MediaFiles) > 0 {
		selectedFilename = item.MediaFiles[0].Filename
	}

	meta, _ := h.librarySvc.GetMetadata(ctx, relPath, selectedFilename)
	subtitles, _ := h.librarySvc.GetSubtitles(ctx, relPath)

	h.renderWithRequest(w, r, "library_detail", PageData{
		Title:     item.Name,
		ActiveTab: "library",
		Data: struct {
			Item             *models.LibraryItem
			SelectedFilename string
			Metadata         *service.MediaMetadata
			Subtitles        []models.SubtitleTrack
		}{
			Item:             item,
			SelectedFilename: selectedFilename,
			Metadata:         meta,
			Subtitles:        subtitles,
		},
	})
}

func (h *Handler) ServeMediaItem(w http.ResponseWriter, r *http.Request) {
	relPath := normalizeRelPath(r)
	if strings.HasSuffix(relPath, "/thumbnail") {
		h.serveThumbnail(strings.TrimSuffix(relPath, "/thumbnail"), w, r)
		return
	}
	if strings.HasSuffix(relPath, "/subtitles") {
		h.serveSubtitles(strings.TrimSuffix(relPath, "/subtitles"), w, r)
		return
	}
	h.serveMedia(relPath, w, r)
}

func (h *Handler) serveMedia(relPath string, w http.ResponseWriter, r *http.Request) {

	filename := r.URL.Query().Get("file")
	if filename == "" {
		http.Error(w, "Missing file", http.StatusBadRequest)
		return
	}

	mediaPath, err := h.librarySvc.GetMediaFile(r.Context(), relPath, filename)
	if err != nil {
		http.Error(w, "Not found", http.StatusNotFound)
		return
	}

	http.ServeFile(w, r, mediaPath)
}

func (h *Handler) serveThumbnail(relPath string, w http.ResponseWriter, r *http.Request) {
	ctx := r.Context()
	filename := r.URL.Query().Get("file")

	if thumb, ok := h.librarySvc.ThumbnailForFile(ctx, relPath, filename); ok {
		http.ServeFile(w, r, thumb)
		return
	}

	// Fall back to an icon, matched to the requested file's type (or the item's
	// primary file when no specific file was requested).
	icon := "video-icon.svg"
	if item, err := h.librarySvc.GetByRelPath(ctx, relPath); err == nil {
		if isAudioFile(item, filename) {
			icon = "audio-icon.svg"
		}
	}
	http.ServeFile(w, r, filepath.Join(repoRoot, "web", "static", "icons", icon))
}

// isAudioFile reports whether the named file (or, if unnamed, the first media
// file) of an item is audio.
func isAudioFile(item *models.LibraryItem, filename string) bool {
	if filename != "" {
		for _, mf := range item.MediaFiles {
			if mf.Filename == filename {
				return mf.IsAudio
			}
		}
		return false
	}
	return len(item.MediaFiles) > 0 && item.MediaFiles[0].IsAudio
}

func (h *Handler) serveSubtitles(relPath string, w http.ResponseWriter, r *http.Request) {

	lang := r.URL.Query().Get("lang")
	if lang == "" {
		http.Error(w, "Missing language", http.StatusBadRequest)
		return
	}

	if strings.Contains(lang, "/") || strings.Contains(lang, "..") || strings.Contains(lang, "\\") {
		http.Error(w, "Invalid language", http.StatusBadRequest)
		return
	}

	subtitlePath := h.librarySvc.GetSubtitlePath(relPath, lang)

	w.Header().Set("Content-Type", "text/vtt")
	http.ServeFile(w, r, subtitlePath)
}

func (h *Handler) deleteMedia(relPath string, w http.ResponseWriter, r *http.Request) {

	if err := h.librarySvc.Delete(relPath); err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	http.Redirect(w, r, "/library", http.StatusSeeOther)
}

func (h *Handler) Downloads(w http.ResponseWriter, r *http.Request) {
	status := r.URL.Query().Get("status")
	sortBy := r.URL.Query().Get("sort")

	if sortBy == "" {
		sortBy = getCookie(r, "queue_sort", "date")
	} else {
		setCookie(w, "queue_sort", sortBy)
	}

	downloads, err := h.downloadSvc.GetAll(status, sortBy)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	settings, _ := h.settingsSvc.GetAll()

	h.renderWithRequest(w, r, "queue", PageData{
		Title:       "Queue",
		ActiveTab:   "queue",
		AutoRefresh: settings.AutoRefreshDownloads,
		RefreshSec:  settings.RefreshInterval,
		Data: struct {
			Items  []*models.Download
			Status string
			SortBy string
		}{
			Items:  downloads,
			Status: status,
			SortBy: sortBy,
		},
	})
}

func (h *Handler) DownloadDetail(w http.ResponseWriter, r *http.Request) {
	idStr := chi.URLParam(r, "id")
	id, err := strconv.ParseInt(idStr, 10, 64)
	if err != nil {
		http.Error(w, "Invalid ID", http.StatusBadRequest)
		return
	}

	download, err := h.downloadSvc.GetByID(id)
	if err != nil {
		http.Error(w, "Not found", http.StatusNotFound)
		return
	}

	h.renderWithRequest(w, r, "queue_detail", PageData{
		Title:     "Queue Details",
		ActiveTab: "queue",
		Data:      download,
	})
}

func (h *Handler) CreateDownload(w http.ResponseWriter, r *http.Request) {
	if err := r.ParseForm(); err != nil {
		http.Error(w, err.Error(), http.StatusBadRequest)
		return
	}

	url := r.FormValue("url")
	if url == "" {
		http.Error(w, "URL is required", http.StatusBadRequest)
		return
	}

	var presetID *int64
	if pid := r.FormValue("preset_id"); pid != "" {
		id, err := strconv.ParseInt(pid, 10, 64)
		if err == nil {
			presetID = &id
		}
	}

	formatOverride := r.FormValue("format_override")
	customFlags := r.FormValue("custom_flags")
	outputDir := r.FormValue("output_dir")

	download, err := h.downloadSvc.Create(url, presetID, formatOverride, customFlags, outputDir)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	h.workerPool.Submit(download)

	http.Redirect(w, r, "/queue", http.StatusSeeOther)
}

func (h *Handler) ListFormats(w http.ResponseWriter, r *http.Request) {
	url := r.URL.Query().Get("url")
	if url == "" {
		http.Error(w, "URL is required", http.StatusBadRequest)
		return
	}

	formats, err := h.downloadSvc.ListFormats(url)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	h.renderWithRequest(w, r, "formats", PageData{
		Title:     "Available Formats",
		ActiveTab: "download",
		Data: struct {
			URL     string
			Formats []*models.FormatInfo
		}{
			URL:     url,
			Formats: formats,
		},
	})
}

func (h *Handler) DeleteDownload(w http.ResponseWriter, r *http.Request) {
	idStr := chi.URLParam(r, "id")
	id, err := strconv.ParseInt(idStr, 10, 64)
	if err != nil {
		http.Error(w, "Invalid ID", http.StatusBadRequest)
		return
	}

	if err := h.downloadSvc.Delete(id); err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	http.Redirect(w, r, "/queue", http.StatusSeeOther)
}

func (h *Handler) ClearAllDownloads(w http.ResponseWriter, r *http.Request) {
	if err := h.downloadSvc.DeleteAll(); err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	http.Redirect(w, r, "/queue", http.StatusSeeOther)
}

func (h *Handler) Settings(w http.ResponseWriter, r *http.Request) {
	presets, err := h.presetSvc.GetAll()
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	settings, err := h.settingsSvc.GetAll()
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	h.renderWithRequest(w, r, "settings", PageData{
		Title:     "Settings",
		ActiveTab: "settings",
		Data: struct {
			Presets  []*models.Preset
			Settings *models.Settings
		}{
			Presets:  presets,
			Settings: settings,
		},
	})
}

func (h *Handler) CreatePreset(w http.ResponseWriter, r *http.Request) {
	if err := r.ParseForm(); err != nil {
		http.Error(w, err.Error(), http.StatusBadRequest)
		return
	}

	preset := &models.Preset{
		Name:         r.FormValue("name"),
		Description:  r.FormValue("description"),
		FormatMode:   r.FormValue("format_mode"),
		Format:       r.FormValue("format"),
		Quality:      r.FormValue("quality"),
		CustomFormat: r.FormValue("custom_format"),
		AudioFormat:  r.FormValue("audio_format"),
		SubLangs:     r.FormValue("sub_langs"),
		CustomFlags:  r.FormValue("custom_flags"),
	}

	preset.IsDefault = r.FormValue("is_default") == "1"
	preset.ExtractAudio = r.FormValue("extract_audio") == "1"
	preset.EmbedSubs = r.FormValue("embed_subs") == "1"
	preset.EmbedThumbnail = r.FormValue("embed_thumbnail") == "1"
	preset.EmbedMetadata = r.FormValue("embed_metadata") == "1"
	preset.WriteInfoJSON = r.FormValue("write_info_json") == "1"

	if err := h.presetSvc.Create(preset); err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	http.Redirect(w, r, "/settings", http.StatusSeeOther)
}

func (h *Handler) UpdatePreset(w http.ResponseWriter, r *http.Request) {
	idStr := chi.URLParam(r, "id")
	id, err := strconv.ParseInt(idStr, 10, 64)
	if err != nil {
		http.Error(w, "Invalid ID", http.StatusBadRequest)
		return
	}

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

	preset, err := h.presetSvc.GetByID(id)
	if err != nil {
		http.Error(w, "Not found", http.StatusNotFound)
		return
	}

	preset.Name = r.FormValue("name")
	preset.Description = r.FormValue("description")
	preset.FormatMode = r.FormValue("format_mode")
	preset.Format = r.FormValue("format")
	preset.Quality = r.FormValue("quality")
	preset.CustomFormat = r.FormValue("custom_format")
	preset.AudioFormat = r.FormValue("audio_format")
	preset.SubLangs = r.FormValue("sub_langs")
	preset.CustomFlags = r.FormValue("custom_flags")
	preset.IsDefault = r.FormValue("is_default") == "1"
	preset.ExtractAudio = r.FormValue("extract_audio") == "1"
	preset.EmbedSubs = r.FormValue("embed_subs") == "1"
	preset.EmbedThumbnail = r.FormValue("embed_thumbnail") == "1"
	preset.EmbedMetadata = r.FormValue("embed_metadata") == "1"
	preset.WriteInfoJSON = r.FormValue("write_info_json") == "1"

	if err := h.presetSvc.Update(preset); err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	http.Redirect(w, r, "/settings", http.StatusSeeOther)
}

func (h *Handler) DeletePreset(w http.ResponseWriter, r *http.Request) {
	idStr := chi.URLParam(r, "id")
	id, err := strconv.ParseInt(idStr, 10, 64)
	if err != nil {
		http.Error(w, "Invalid ID", http.StatusBadRequest)
		return
	}

	if err := h.presetSvc.Delete(id); err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	http.Redirect(w, r, "/settings", http.StatusSeeOther)
}

func (h *Handler) UpdateSettings(w http.ResponseWriter, r *http.Request) {
	if err := r.ParseForm(); err != nil {
		http.Error(w, err.Error(), http.StatusBadRequest)
		return
	}

	if interval := r.FormValue("refresh_interval"); interval != "" {
		h.settingsSvc.SetRefreshInterval(interval)
	}

	h.settingsSvc.SetAutoRefreshLibrary(r.FormValue("auto_refresh_library") == "1")
	h.settingsSvc.SetAutoRefreshDownloads(r.FormValue("auto_refresh_downloads") == "1")
	h.settingsSvc.SetCookies(r.FormValue("cookies"))

	http.Redirect(w, r, "/settings", http.StatusSeeOther)
}

func (h *Handler) DownloadForm(w http.ResponseWriter, r *http.Request) {
	presets, err := h.presetSvc.GetAll()
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	defaultPreset, _ := h.presetSvc.GetDefault()

	url := r.URL.Query().Get("url")
	var formats []*models.FormatInfo
	if r.URL.Query().Get("list_formats") == "1" && url != "" {
		formats, _ = h.downloadSvc.ListFormats(url)
	}

	h.renderWithRequest(w, r, "download_form", PageData{
		Title:     "Download",
		ActiveTab: "download",
		Data: struct {
			Presets        []*models.Preset
			DefaultPreset  *models.Preset
			URL            string
			FormatOverride string
			CustomFlags    string
			OutputDir      string
			Formats        []*models.FormatInfo
			ShowFormats    bool
		}{
			Presets:        presets,
			DefaultPreset:  defaultPreset,
			URL:            url,
			FormatOverride: r.URL.Query().Get("format_override"),
			CustomFlags:    r.URL.Query().Get("custom_flags"),
			OutputDir:      r.URL.Query().Get("output_dir"),
			Formats:        formats,
			ShowFormats:    r.URL.Query().Get("list_formats") == "1",
		},
	})
}

func (h *Handler) GetPresetFlags(w http.ResponseWriter, r *http.Request) {
	idStr := r.URL.Query().Get("id")
	id, err := strconv.ParseInt(idStr, 10, 64)
	if err != nil {
		http.Error(w, "Invalid ID", http.StatusBadRequest)
		return
	}

	preset, err := h.presetSvc.GetByID(id)
	if err != nil {
		http.Error(w, "Not found", http.StatusNotFound)
		return
	}

	flags := h.presetSvc.EffectiveFlags(preset, "", "")
	w.Header().Set("Content-Type", "text/plain")
	w.Write([]byte(flags))
}

func (h *Handler) Theme(w http.ResponseWriter, r *http.Request) {
	if err := r.ParseForm(); err != nil {
		http.Error(w, err.Error(), http.StatusBadRequest)
		return
	}

	theme := r.FormValue("theme")
	if theme == "" {
		theme = "auto"
	}

	setCookie(w, "theme", theme)

	referer := r.Header.Get("Referer")
	if referer == "" {
		referer = "/"
	}
	http.Redirect(w, r, referer, http.StatusSeeOther)
}