package handlers

import (
	"encoding/json"
	"fmt"
	"html/template"
	"log"
	"net/http"
	"os"
	"path/filepath"
	"strings"
	"time"

	"app_compartir/internal/auth"
	"app_compartir/internal/config"
	"app_compartir/internal/db"
	"app_compartir/internal/models"
	"app_compartir/internal/storage"
	"github.com/skip2/go-qrcode"
)

type Handlers struct {
	cfg       *config.Config
	db        *db.Database
	auth      *auth.AuthService
	templates map[string]*template.Template
}

func New(cfg *config.Config, database *db.Database, authSvc *auth.AuthService) (*Handlers, error) {
	h := &Handlers{
		cfg:       cfg,
		db:        database,
		auth:      authSvc,
		templates: make(map[string]*template.Template),
	}

	if err := h.parseTemplates(); err != nil {
		return nil, err
	}

	return h, nil
}

func (h *Handlers) parseTemplates() error {
	pages := []string{"index.html", "viewer.html", "login.html", "my_shares.html", "expired.html"}
	basePath := "web/templates/base.html"

	for _, page := range pages {
		pagePath := filepath.Join("web/templates", page)
		tmpl, err := template.ParseFiles(basePath, pagePath)
		if err != nil {
			return fmt.Errorf("error parseando plantilla %s: %w", page, err)
		}
		h.templates[page] = tmpl
	}
	return nil
}

type PageData struct {
	Session       *models.Session
	Share         *models.Share
	Shares        []*models.Share
	FormattedDate string
	IsImage       bool
	IsVideo       bool
	IsAudio       bool
	IsPDF         bool
	IsText        bool
	HasGoogle     bool
	Error         string
}

func (h *Handlers) getBaseURL(r *http.Request) string {
	proto := "http"
	if r.TLS != nil ||
		strings.EqualFold(r.Header.Get("X-Forwarded-Proto"), "https") ||
		strings.EqualFold(r.Header.Get("X-Forwarded-Ssl"), "on") ||
		r.Header.Get("X-Forwarded-Port") == "443" {
		proto = "https"
	}
	host := r.Host
	if host == "" {
		host = r.Header.Get("X-Forwarded-Host")
	}
	if host != "" {
		if strings.HasPrefix(h.cfg.BaseURL, "https://") && strings.Contains(h.cfg.BaseURL, host) {
			proto = "https"
		}
		return fmt.Sprintf("%s://%s", proto, host)
	}
	return h.cfg.BaseURL
}

func (h *Handlers) Index(w http.ResponseWriter, r *http.Request) {
	if r.URL.Path != "/" {
		http.NotFound(w, r)
		return
	}

	session := h.auth.GetOrCreateSession(w, r)
	data := PageData{
		Session: session,
	}

	tmpl := h.templates["index.html"]
	if err := tmpl.ExecuteTemplate(w, "base.html", data); err != nil {
		log.Printf("Error renderizando index.html: %v", err)
		http.Error(w, "Error interno", http.StatusInternalServerError)
	}
}

func (h *Handlers) Upload(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodPost {
		http.Error(w, "Método no permitido", http.StatusMethodNotAllowed)
		return
	}

	// Límite de 500 MB por subida
	r.Body = http.MaxBytesReader(w, r.Body, 500<<20)
	if err := r.ParseMultipartForm(32 << 20); err != nil {
		http.Error(w, "Archivo demasiado grande o formulario inválido", http.StatusBadRequest)
		return
	}

	file, header, err := r.FormFile("file")
	if err != nil {
		http.Error(w, "No se encontró el archivo en la petición", http.StatusBadRequest)
		return
	}
	defer file.Close()

	session := h.auth.GetOrCreateSession(w, r)
	slug := storage.GenerateSlug(7)

	storedPath, written, err := storage.SaveFile(h.cfg.UploadDir, slug, header.Filename, file)
	if err != nil {
		log.Printf("Error guardando archivo en disco: %v", err)
		http.Error(w, "Error guardando archivo en el servidor", http.StatusInternalServerError)
		return
	}

	// Detectar tipo MIME
	mimeType := storage.DetectMimeType(header.Filename, nil)
	now := time.Now()

	var expiresAt *time.Time
	var userID *string
	userDisplay := "Invitado"

	if session.IsGuest {
		// REGLA FUNDAMENTAL: Solo los invitados expiran en 24 horas
		exp := now.Add(24 * time.Hour)
		expiresAt = &exp
	} else if session.User != nil {
		// Las cuentas registradas son PERMANENTES
		expiresAt = nil
		userID = &session.User.ID
		userDisplay = session.User.Name
		if userDisplay == "" {
			userDisplay = session.User.Email
		}
	}

	share := &models.Share{
		ID:             slug,
		UserID:         userID,
		UserDisplay:    userDisplay,
		IsGuest:        session.IsGuest,
		Type:           "file",
		Title:          header.Filename,
		StoredPath:     storedPath,
		FileSize:       written,
		MimeType:       mimeType,
		TextContent:    "",
		ViewsCount:     0,
		DownloadsCount: 0,
		CreatedAt:      now,
		ExpiresAt:      expiresAt,
	}

	if err := h.db.CreateShare(share); err != nil {
		log.Printf("Error registrando share en BD: %v", err)
		_ = os.Remove(filepath.Join(h.cfg.UploadDir, storedPath))
		http.Error(w, "Error registrando archivo en base de datos", http.StatusInternalServerError)
		return
	}

	baseURL := h.getBaseURL(r)
	resp := map[string]interface{}{
		"id":           share.ID,
		"title":        share.Title,
		"file_size":    share.FileSize,
		"mime_type":    share.MimeType,
		"is_guest":     share.IsGuest,
		"viewer_url":   fmt.Sprintf("%s/v/%s", baseURL, share.ID),
		"download_url": fmt.Sprintf("%s/d/%s", baseURL, share.ID),
	}
	if share.IsGuest {
		resp["expires_in"] = "24 horas"
	} else {
		resp["expires_in"] = "Permanente"
	}

	w.Header().Set("Content-Type", "application/json")
	json.NewEncoder(w).Encode(resp)
}

func (h *Handlers) ShareText(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodPost {
		http.Error(w, "Método no permitido", http.StatusMethodNotAllowed)
		return
	}

	var req struct {
		Title string `json:"title"`
		Text  string `json:"text"`
	}
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil || strings.TrimSpace(req.Text) == "" {
		http.Error(w, "Contenido de texto requerido", http.StatusBadRequest)
		return
	}

	session := h.auth.GetOrCreateSession(w, r)
	slug := storage.GenerateSlug(7)
	now := time.Now()

	title := strings.TrimSpace(req.Title)
	if title == "" {
		// Generar título a partir de la primera línea de texto
		lines := strings.Split(req.Text, "\n")
		firstLine := strings.TrimSpace(lines[0])
		if len(firstLine) > 40 {
			firstLine = firstLine[:40] + "..."
		}
		if firstLine != "" {
			title = firstLine
		} else {
			title = "Nota de texto"
		}
	}

	var expiresAt *time.Time
	var userID *string
	userDisplay := "Invitado"

	if session.IsGuest {
		// REGLA: Los invitados expiran a las 24 horas
		exp := now.Add(24 * time.Hour)
		expiresAt = &exp
	} else if session.User != nil {
		// Los registrados son PERMANENTES
		expiresAt = nil
		userID = &session.User.ID
		userDisplay = session.User.Name
		if userDisplay == "" {
			userDisplay = session.User.Email
		}
	}

	share := &models.Share{
		ID:             slug,
		UserID:         userID,
		UserDisplay:    userDisplay,
		IsGuest:        session.IsGuest,
		Type:           "text",
		Title:          title,
		StoredPath:     "",
		FileSize:       int64(len(req.Text)),
		MimeType:       "text/plain; charset=utf-8",
		TextContent:    req.Text,
		ViewsCount:     0,
		DownloadsCount: 0,
		CreatedAt:      now,
		ExpiresAt:      expiresAt,
	}

	if err := h.db.CreateShare(share); err != nil {
		log.Printf("Error registrando share de texto en BD: %v", err)
		http.Error(w, "Error guardando texto en base de datos", http.StatusInternalServerError)
		return
	}

	baseURL := h.getBaseURL(r)
	resp := map[string]interface{}{
		"id":           share.ID,
		"title":        share.Title,
		"file_size":    share.FileSize,
		"mime_type":    share.MimeType,
		"is_guest":     share.IsGuest,
		"viewer_url":   fmt.Sprintf("%s/v/%s", baseURL, share.ID),
		"download_url": fmt.Sprintf("%s/d/%s", baseURL, share.ID),
	}
	if share.IsGuest {
		resp["expires_in"] = "24 horas"
	} else {
		resp["expires_in"] = "Permanente"
	}

	w.Header().Set("Content-Type", "application/json")
	json.NewEncoder(w).Encode(resp)
}

func (h *Handlers) View(w http.ResponseWriter, r *http.Request) {
	id := strings.TrimPrefix(r.URL.Path, "/v/")
	if id == "" {
		http.NotFound(w, r)
		return
	}

	share, err := h.db.GetShare(id)
	if err != nil || share == nil {
		h.renderExpired(w, r)
		return
	}

	// Verificar si ya expiró (en caso de que el worker aún no lo haya borrado)
	if share.IsGuest && share.ExpiresAt != nil && share.ExpiresAt.Before(time.Now()) {
		h.renderExpired(w, r)
		return
	}

	_ = h.db.IncrementViews(id)
	share.ViewsCount++

	session := h.auth.GetOrCreateSession(w, r)
	data := PageData{
		Session:       session,
		Share:         share,
		FormattedDate: share.CreatedAt.Format("02/01/2006 15:04"),
		IsImage:       strings.HasPrefix(share.MimeType, "image/"),
		IsVideo:       strings.HasPrefix(share.MimeType, "video/"),
		IsAudio:       strings.HasPrefix(share.MimeType, "audio/"),
		IsPDF:         share.MimeType == "application/pdf",
		IsText:        strings.HasPrefix(share.MimeType, "text/") || share.Type == "text",
	}

	tmpl := h.templates["viewer.html"]
	if err := tmpl.ExecuteTemplate(w, "base.html", data); err != nil {
		log.Printf("Error renderizando visor: %v", err)
		http.Error(w, "Error interno", http.StatusInternalServerError)
	}
}

func (h *Handlers) renderExpired(w http.ResponseWriter, r *http.Request) {
	session := h.auth.GetOrCreateSession(w, r)
	data := PageData{
		Session: session,
	}
	tmpl := h.templates["expired.html"]
	w.WriteHeader(http.StatusNotFound)
	_ = tmpl.ExecuteTemplate(w, "base.html", data)
}

func (h *Handlers) Download(w http.ResponseWriter, r *http.Request) {
	id := strings.TrimPrefix(r.URL.Path, "/d/")
	if id == "" {
		http.NotFound(w, r)
		return
	}

	share, err := h.db.GetShare(id)
	if err != nil || share == nil {
		h.renderExpired(w, r)
		return
	}

	if share.IsGuest && share.ExpiresAt != nil && share.ExpiresAt.Before(time.Now()) {
		h.renderExpired(w, r)
		return
	}

	_ = h.db.IncrementDownloads(id)

	if share.Type == "text" {
		w.Header().Set("Content-Type", "text/plain; charset=utf-8")
		w.Header().Set("Content-Disposition", fmt.Sprintf("attachment; filename=%q", share.Title+".txt"))
		_, _ = w.Write([]byte(share.TextContent))
		return
	}

	fullPath := filepath.Join(h.cfg.UploadDir, share.StoredPath)
	if _, err := os.Stat(fullPath); os.IsNotExist(err) {
		h.renderExpired(w, r)
		return
	}

	w.Header().Set("Content-Disposition", fmt.Sprintf("attachment; filename=%q", share.Title))
	http.ServeFile(w, r, fullPath)
}

func (h *Handlers) Raw(w http.ResponseWriter, r *http.Request) {
	id := strings.TrimPrefix(r.URL.Path, "/raw/")
	if id == "" {
		http.NotFound(w, r)
		return
	}

	share, err := h.db.GetShare(id)
	if err != nil || share == nil {
		http.NotFound(w, r)
		return
	}

	if share.IsGuest && share.ExpiresAt != nil && share.ExpiresAt.Before(time.Now()) {
		http.NotFound(w, r)
		return
	}

	if share.Type == "text" {
		w.Header().Set("Content-Type", "text/plain; charset=utf-8")
		_, _ = w.Write([]byte(share.TextContent))
		return
	}

	fullPath := filepath.Join(h.cfg.UploadDir, share.StoredPath)
	if _, err := os.Stat(fullPath); os.IsNotExist(err) {
		http.NotFound(w, r)
		return
	}

	w.Header().Set("Content-Type", share.MimeType)
	w.Header().Set("Content-Disposition", "inline")
	http.ServeFile(w, r, fullPath)
}

func (h *Handlers) QR(w http.ResponseWriter, r *http.Request) {
	id := strings.TrimPrefix(r.URL.Path, "/qr/")
	if id == "" {
		http.NotFound(w, r)
		return
	}

	baseURL := h.getBaseURL(r)
	targetURL := fmt.Sprintf("%s/v/%s", baseURL, id)
	pngBytes, err := qrcode.Encode(targetURL, qrcode.Medium, 256)
	if err != nil {
		http.Error(w, "Error generando QR", http.StatusInternalServerError)
		return
	}

	w.Header().Set("Content-Type", "image/png")
	w.Header().Set("Cache-Control", "public, max-age=86400")
	_, _ = w.Write(pngBytes)
}

func (h *Handlers) LoginView(w http.ResponseWriter, r *http.Request) {
	session := h.auth.GetOrCreateSession(w, r)
	if !session.IsGuest && session.User != nil {
		http.Redirect(w, r, "/mis-archivos", http.StatusFound)
		return
	}

	data := PageData{
		Session:   session,
		HasGoogle: h.auth.HasGoogleConfigured(),
	}

	tmpl := h.templates["login.html"]
	_ = tmpl.ExecuteTemplate(w, "base.html", data)
}

func (h *Handlers) WebControlLogin(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodPost {
		http.Redirect(w, r, "/login", http.StatusSeeOther)
		return
	}

	email := strings.TrimSpace(r.FormValue("email"))
	password := strings.TrimSpace(r.FormValue("password"))

	if email == "" || password == "" {
		h.renderLoginError(w, r, "Por favor ingresa usuario y contraseña.")
		return
	}

	user, err := h.auth.LoginWebControl(email, password)
	if err != nil {
		log.Printf("Fallo login WebControl: %v", err)
		h.renderLoginError(w, r, "Credenciales incorrectas o servidor WebControl no disponible.")
		return
	}

	if err := h.auth.AttachUserToSession(w, r, user); err != nil {
		log.Printf("Error adjuntando sesión: %v", err)
		h.renderLoginError(w, r, "Error interno estableciendo sesión.")
		return
	}

	http.Redirect(w, r, "/mis-archivos", http.StatusFound)
}

func (h *Handlers) renderLoginError(w http.ResponseWriter, r *http.Request, msg string) {
	session := h.auth.GetOrCreateSession(w, r)
	data := PageData{
		Session:   session,
		HasGoogle: h.auth.HasGoogleConfigured(),
		Error:     msg,
	}
	tmpl := h.templates["login.html"]
	_ = tmpl.ExecuteTemplate(w, "base.html", data)
}

func (h *Handlers) GoogleLogin(w http.ResponseWriter, r *http.Request) {
	state := h.auth.GenerateToken(16)
	// Guardar state en cookie temporal
	http.SetCookie(w, &http.Cookie{
		Name:     "oauth_state",
		Value:    state,
		Path:     "/",
		Expires:  time.Now().Add(10 * time.Minute),
		HttpOnly: true,
	})

	url, err := h.auth.GetGoogleAuthURL(state)
	if err != nil {
		h.renderLoginError(w, r, err.Error())
		return
	}

	http.Redirect(w, r, url, http.StatusTemporaryRedirect)
}

func (h *Handlers) GoogleCallback(w http.ResponseWriter, r *http.Request) {
	stateCookie, err := r.Cookie("oauth_state")
	if err != nil || stateCookie.Value == "" || stateCookie.Value != r.URL.Query().Get("state") {
		h.renderLoginError(w, r, "Error de verificación CSRF en login con Google.")
		return
	}

	code := r.URL.Query().Get("code")
	if code == "" {
		h.renderLoginError(w, r, "No se recibió código de autenticación de Google.")
		return
	}

	user, err := h.auth.HandleGoogleCallback(r.Context(), code)
	if err != nil {
		log.Printf("Error callback Google: %v", err)
		h.renderLoginError(w, r, "No se pudo completar el inicio de sesión con Google.")
		return
	}

	if err := h.auth.AttachUserToSession(w, r, user); err != nil {
		h.renderLoginError(w, r, "Error interno estableciendo sesión.")
		return
	}

	http.Redirect(w, r, "/mis-archivos", http.StatusFound)
}

func (h *Handlers) Logout(w http.ResponseWriter, r *http.Request) {
	h.auth.Logout(w, r)
	http.Redirect(w, r, "/", http.StatusFound)
}

func (h *Handlers) MyShares(w http.ResponseWriter, r *http.Request) {
	session := h.auth.GetOrCreateSession(w, r)
	if session.IsGuest || session.User == nil {
		http.Redirect(w, r, "/login", http.StatusFound)
		return
	}

	shares, err := h.db.GetUserShares(session.User.ID)
	if err != nil {
		log.Printf("Error obteniendo archivos de usuario: %v", err)
		shares = []*models.Share{}
	}

	data := PageData{
		Session: session,
		Shares:  shares,
	}

	tmpl := h.templates["my_shares.html"]
	_ = tmpl.ExecuteTemplate(w, "base.html", data)
}

func (h *Handlers) DeleteShare(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodDelete {
		http.Error(w, "Método no permitido", http.StatusMethodNotAllowed)
		return
	}

	id := strings.TrimPrefix(r.URL.Path, "/api/shares/")
	if id == "" {
		http.Error(w, "ID requerido", http.StatusBadRequest)
		return
	}

	session := h.auth.GetOrCreateSession(w, r)
	if session.IsGuest || session.User == nil {
		http.Error(w, "No autorizado", http.StatusUnauthorized)
		return
	}

	share, err := h.db.GetShare(id)
	if err != nil || share == nil {
		http.Error(w, "Archivo no encontrado", http.StatusNotFound)
		return
	}

	// Verificar pertenencia
	if share.UserID == nil || *share.UserID != session.User.ID {
		http.Error(w, "No tienes permiso para eliminar este archivo", http.StatusForbidden)
		return
	}

	if share.StoredPath != "" {
		_ = os.Remove(filepath.Join(h.cfg.UploadDir, share.StoredPath))
	}

	if err := h.db.DeleteShare(id, &session.User.ID); err != nil {
		http.Error(w, "Error eliminando de base de datos", http.StatusInternalServerError)
		return
	}

	w.Header().Set("Content-Type", "application/json")
	json.NewEncoder(w).Encode(map[string]bool{"ok": true})
}