package handlers

import (
	"encoding/base64"
	"encoding/json"
	"fmt"
	"net/http"
	"strings"
	"time"

	"github.com/google/uuid"
	"github.com/gorilla/mux"

	"github.com/orohi/vpn-panel/internal/db"
	"github.com/orohi/vpn-panel/internal/models"
)

func isBrowserRequest(r *http.Request) bool {
	if r.URL.Query().Get("format") == "raw" || r.URL.Query().Get("format") == "base64" {
		return false
	}
	if r.URL.Query().Get("format") == "html" {
		return true
	}
	ua := strings.ToLower(r.UserAgent())
	browsers := []string{"mozilla", "chrome", "safari", "firefox", "edge", "opera"}
	for _, b := range browsers {
		if strings.Contains(ua, b) {
			// Exclude common VPN clients that include mozilla in UA sometimes
			clients := []string{"clash", "v2ray", "sing-box", "singbox", "shadowrocket", "stash", "quantumult", "surge", "hiddify", "nekobox", "streisand"}
			for _, c := range clients {
				if strings.Contains(ua, c) {
					return false
				}
			}
			return true
		}
	}
	return false
}

func writeSubHeaders(w http.ResponseWriter, username string, used, total int64, expireUnix int64) {
	w.Header().Set("Profile-Title", "base64:"+base64.StdEncoding.EncodeToString([]byte(username)))
	w.Header().Set("profile-update-interval", "12")
	w.Header().Set("subscription-userinfo", fmt.Sprintf(
		"upload=0; download=%d; total=%d; expire=%d",
		used, total, expireUnix,
	))
	w.Header().Set("announce", "base64:"+base64.StdEncoding.EncodeToString([]byte("VPN Panel")))
}

func (s *Server) subscriptionGet(w http.ResponseWriter, r *http.Request) {
	token := mux.Vars(r)["token"]
	c, err := db.GetClientBySubToken(s.DB, token)
	if err != nil || c == nil {
		http.Error(w, "not found", http.StatusNotFound)
		return
	}
	info, err := db.BuildSubscriptionInfo(s.DB, c)
	if err != nil {
		http.Error(w, "error", http.StatusInternalServerError)
		return
	}

	expireUnix := int64(0)
	if c.ExpireAt != nil {
		expireUnix = c.ExpireAt.Unix()
	}
	writeSubHeaders(w, c.Username, c.TrafficUsedBytes, c.TrafficLimitBytes, expireUnix)

	format := r.URL.Query().Get("format")
	if format == "json" || strings.Contains(r.Header.Get("Accept"), "application/json") {
		w.Header().Set("Content-Type", "application/json")
		_ = json.NewEncoder(w).Encode(info)
		return
	}

	if isBrowserRequest(r) {
		if !c.IsActive() {
			s.render(w, "subscription.html", pageData{
				"Title":   c.Username,
				"Info":    info,
				"SubURL":  publicSubURL(r, token),
				"Expired": true,
			})
			return
		}
		s.render(w, "subscription.html", pageData{
			"Title":  c.Username,
			"Info":   info,
			"SubURL": publicSubURL(r, token),
			"Now":    time.Now(),
		})
		return
	}

	if !c.IsActive() {
		http.Error(w, "subscription inactive", http.StatusForbidden)
		return
	}

	body := strings.Join(info.Links, "\n")
	if body != "" {
		body += "\n"
	}
	if format == "plain" {
		w.Header().Set("Content-Type", "text/plain; charset=utf-8")
		_, _ = w.Write([]byte(body))
		return
	}
	// Default for VPN apps: base64 (common subscription format)
	w.Header().Set("Content-Type", "text/plain; charset=utf-8")
	_, _ = w.Write([]byte(base64.StdEncoding.EncodeToString([]byte(body))))
}

func (s *Server) subscriptionInfoGet(w http.ResponseWriter, r *http.Request) {
	token := mux.Vars(r)["token"]
	c, err := db.GetClientBySubToken(s.DB, token)
	if err != nil || c == nil {
		http.Error(w, "not found", http.StatusNotFound)
		return
	}
	info, err := db.BuildSubscriptionInfo(s.DB, c)
	if err != nil {
		http.Error(w, "error", http.StatusInternalServerError)
		return
	}
	w.Header().Set("Content-Type", "application/json")
	_ = json.NewEncoder(w).Encode(map[string]any{
		"ok":       true,
		"username": c.Username,
		"status":   c.Status,
		"active":   c.IsActive(),
		"uuid":     c.UUID,
		"expire":   info.ExpireUnix,
		"traffic": map[string]any{
			"used":  c.TrafficUsedBytes,
			"limit": c.TrafficLimitBytes,
		},
		"hosts":    info.Hosts,
		"inbounds": groupHostsByInbound(info.Hosts),
		"sub_url":  publicSubURL(r, token),
	})
}

func groupHostsByInbound(hosts []models.SubHost) []map[string]any {
	type agg struct {
		Tag, Protocol, Network, Security string
		Port                             int
		Servers                          []map[string]any
	}
	order := []uuid.UUID{}
	byID := map[uuid.UUID]*agg{}
	for _, h := range hosts {
		a, ok := byID[h.InboundID]
		if !ok {
			a = &agg{
				Tag: h.Tag, Protocol: h.ProtocolName, Network: h.Network,
				Security: h.Security, Port: h.Port,
			}
			byID[h.InboundID] = a
			order = append(order, h.InboundID)
		}
		server := map[string]any{
			"node":      h.NodeName,
			"address":   h.Address,
			"online":    h.NodeOnline,
			"available": h.Available,
			"link":      h.Link,
			"title":     h.Title(),
		}
		if h.Address != "" || h.NodeName != "" {
			a.Servers = append(a.Servers, server)
		}
	}
	var out []map[string]any
	for _, id := range order {
		a := byID[id]
		out = append(out, map[string]any{
			"id":       id.String(),
			"tag":      a.Tag,
			"protocol": a.Protocol,
			"port":     a.Port,
			"network":  a.Network,
			"security": a.Security,
			"servers":  a.Servers,
		})
	}
	return out
}

func publicSubURL(r *http.Request, token string) string {
	scheme := "https"
	if r.TLS == nil {
		if xf := r.Header.Get("X-Forwarded-Proto"); xf != "" {
			scheme = xf
		} else {
			scheme = "http"
		}
	}
	return scheme + "://" + r.Host + "/sub/" + token
}