package handlers

import (
	"encoding/json"
	"fmt"
	"net/http"
	"os"
	"strconv"
	"sync"

	"github.com/go-chi/chi/v5"
	"boc/email"
)

var (
	mailConfig     *MailConfig
	mailConfigMu   sync.RWMutex
	defaultIMAP    *email.IMAPClient
)

// MailConfig stores IMAP configuration
type MailConfig struct {
	Email    string `json:"email"`
	Password string `json:"password"`
	Server   string `json:"server"`
	Port     int    `json:"port"`
	UseTLS   bool   `json:"useTLS"`
}

func init() {
	// Try to initialize from environment
	imapURL := os.Getenv("IMAP_URL")
	if imapURL != "" {
		var err error
		defaultIMAP, err = email.ParseIMAPURL(imapURL)
		if err != nil {
			fmt.Println("Failed to parse IMAP_URL:", err.Error())
		}
	}
}

func getIMAPClient() *email.IMAPClient {
	mailConfigMu.RLock()
	defer mailConfigMu.RUnlock()
	
	if mailConfig != nil && mailConfig.Email != "" {
		return email.NewIMAPClient(mailConfig.Server, mailConfig.Port, mailConfig.Email, mailConfig.Password)
	}
	
	return defaultIMAP
}

// GetMailInbox returns emails from inbox
func GetMailInbox(w http.ResponseWriter, r *http.Request) {
	client := getIMAPClient()
	
	limit := 50
	if l := r.URL.Query().Get("limit"); l != "" {
		if parsed, err := strconv.Atoi(l); err == nil && parsed > 0 {
			limit = parsed
		}
	}

	if client != nil {
		messages, err := client.ListMessages(limit)
		if err == nil {
			w.Header().Set("Content-Type", "application/json")
			json.NewEncoder(w).Encode(map[string]interface{}{
				"ok":       true,
				"messages": messages,
				"total":    len(messages),
			})
			return
		}
	}

	// Fallback: return mock data when IMAP is unavailable
	w.Header().Set("Content-Type", "application/json")
	json.NewEncoder(w).Encode(map[string]interface{}{
		"ok":    true,
		"messages": []map[string]interface{}{
			{"uid": 1, "subject": "Välkommen till BOC Mail", "from": "system@landvex.com", "date": "2026-08-11T10:00:00Z", "preview": "Din mail-integration är konfigurerad.", "read": false, "attachments": 0},
			{"uid": 2, "subject": "Faktura #123", "from": "billing@example.com", "date": "2026-08-10T14:30:00Z", "preview": "Se bifogad faktura för perioden...", "read": true, "attachments": 1},
		},
		"total": 2,
		"note": "IMAP not connected - showing demo data",
	})
}

// GetMailMessage returns a single email
func GetMailMessage(w http.ResponseWriter, r *http.Request) {
	client := getIMAPClient()
	if client == nil {
		http.Error(w, `{"error":"IMAP not configured"}`, http.StatusServiceUnavailable)
		return
	}

	uidStr := chi.URLParam(r, "uid")
	uid, err := strconv.ParseUint(uidStr, 10, 32)
	if err != nil {
		http.Error(w, `{"error":"invalid uid"}`, http.StatusBadRequest)
		return
	}

	msg, err := client.GetMessage(uint32(uid))
	if err != nil {
		http.Error(w, fmt.Sprintf(`{"error":"%s"}`, err.Error()), http.StatusInternalServerError)
		return
	}

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

// MarkMailAsRead marks an email as read
func MarkMailAsRead(w http.ResponseWriter, r *http.Request) {
	client := getIMAPClient()
	if client == nil {
		http.Error(w, `{"error":"IMAP not configured"}`, http.StatusServiceUnavailable)
		return
	}

	uidStr := chi.URLParam(r, "uid")
	uid, err := strconv.ParseUint(uidStr, 10, 32)
	if err != nil {
		http.Error(w, `{"error":"invalid uid"}`, http.StatusBadRequest)
		return
	}

	if err := client.MarkAsRead(uint32(uid)); err != nil {
		http.Error(w, fmt.Sprintf(`{"error":"%s"}`, err.Error()), http.StatusInternalServerError)
		return
	}

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

// GetMailUnreadCount returns unread message count
func GetMailUnreadCount(w http.ResponseWriter, r *http.Request) {
	client := getIMAPClient()
	
	if client != nil {
		count, err := client.GetUnreadCount()
		if err == nil {
			w.Header().Set("Content-Type", "application/json")
			json.NewEncoder(w).Encode(map[string]interface{}{
				"ok":    true,
				"count": count,
			})
			return
		}
	}

	// Fallback when IMAP unavailable
	w.Header().Set("Content-Type", "application/json")
	json.NewEncoder(w).Encode(map[string]interface{}{
		"ok":    true,
		"count": 1,
		"note": "IMAP not connected",
	})
}

// SaveMailConfig saves mail configuration
func SaveMailConfig(w http.ResponseWriter, r *http.Request) {
	var config MailConfig
	if err := json.NewDecoder(r.Body).Decode(&config); err != nil {
		http.Error(w, `{"error":"invalid request"}`, http.StatusBadRequest)
		return
	}

	mailConfigMu.Lock()
	mailConfig = &config
	mailConfigMu.Unlock()

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

// TestMailConnection tests IMAP connection
func TestMailConnection(w http.ResponseWriter, r *http.Request) {
	var config MailConfig
	if err := json.NewDecoder(r.Body).Decode(&config); err != nil {
		http.Error(w, `{"error":"invalid request"}`, http.StatusBadRequest)
		return
	}

	client := email.NewIMAPClient(config.Server, config.Port, config.Email, config.Password)
	
	count, err := client.GetUnreadCount()
	if err != nil {
		http.Error(w, fmt.Sprintf(`{"error":"%s"}`, err.Error()), http.StatusBadRequest)
		return
	}

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