package httphandler

import (
	"encoding/json"
	"fmt"
	"html/template"
	"log"
	"net/http"
	"net/url"
	"strings"

	"golang.project/gocasts/ipg-example/service"
)

type Handler struct {
	service       service.PaymentService
	templatesPath string
	staticPath    string
}

func NewHandler(service service.PaymentService) *Handler {
	return &Handler{
		service:       service,
		templatesPath: "./delivery/html/",
		staticPath:    "./delivery/static/",
	}
}

func (h *Handler) RegisterRoutes() *http.ServeMux {
	mux := http.NewServeMux()

	mux.HandleFunc("/", h.homeHandler)
	mux.HandleFunc("/api/init-payment", h.requestPaymentHandler)
	mux.HandleFunc("/api/callback", h.callbackHandler)
	mux.HandleFunc("/result", h.resultHandler)

	//mux.HandleFunc("/api/verify-payment", h.verifyPaymentHandler)

	mux.Handle("/static/", http.StripPrefix("/static/",
		http.FileServer(http.Dir(h.staticPath))))

	return mux
}

func (h *Handler) StartServer(addr string) {
	mux := h.RegisterRoutes()
	log.Printf("Server running on http://localhost%s", addr)
	log.Fatal(http.ListenAndServe(addr, mux))
}

// Params
type PaymentRequest struct {
	Amount int64  `json:"amount"`
	Phone  string `json:"phone"`
}

type PaymentResponse struct {
	Success    bool   `json:"success"`
	Token      string `json:"token,omitempty"`
	PaymentURL string `json:"payment_url,omitempty"`
	Message    string `json:"message"`
}

type VerifyResponse struct {
	Success       bool   `json:"success"`
	Status        string `json:"status"`
	TransactionID string `json:"transaction_id,omitempty"`
	Message       string `json:"message"`
}

type BankCallbackResponse struct {
	Success       bool   `json:"success"`
	Status        string `json:"status"`
	TransactionID string `json:"transaction_id,omitempty"`
	Message       string `json:"message"`
}

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

	tmpl, err := template.ParseFiles(h.templatesPath + "payment.html")
	if err != nil {
		log.Printf("Template error: %v", err)
		http.Error(w, "Template parsing error", http.StatusInternalServerError)
		return
	}

	if err := tmpl.Execute(w, nil); err != nil {
		log.Printf("Template execute error: %v", err)
	}
}

func (h *Handler) requestPaymentHandler(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodPost {
		http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
		return
	}

	w.Header().Set("Content-Type", "application/json")

	var req PaymentRequest
	decoder := json.NewDecoder(r.Body)
	if err := decoder.Decode(&req); err != nil {
		json.NewEncoder(w).Encode(PaymentResponse{
			Success: false,
			Message: "خطا در پارس کردن داده‌ها",
		})
		return
	}

	if req.Amount < 1000 {
		json.NewEncoder(w).Encode(PaymentResponse{
			Success: false,
			Message: "حداقل مبلغ ۱۰۰۰ تومان",
		})
		return
	}

	if req.Phone == "" {
		json.NewEncoder(w).Encode(PaymentResponse{
			Success: false,
			Message: "شماره تلفن الزامی است",
		})
		return
	}

	token, paymentURL, err := h.service.InitPayment(r.Context(), req.Amount, req.Phone)
	if err != nil {
		json.NewEncoder(w).Encode(PaymentResponse{
			Success: false,
			Message: "خطا در ایجاد پرداخت: " + err.Error(),
		})
		return
	}

	json.NewEncoder(w).Encode(PaymentResponse{
		Success:    true,
		Token:      token,
		PaymentURL: paymentURL,
		Message:    "پرداخت ایجاد شد",
	})
}

func (h *Handler) callbackHandler(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodPost {
		http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
		return
	}

	var state, status, refNum, resNum, traceNo, amount string

	contentType := r.Header.Get("Content-Type")

	if strings.Contains(contentType, "application/json") {
		var data map[string]interface{}
		decoder := json.NewDecoder(r.Body)
		if err := decoder.Decode(&data); err != nil {
			log.Printf("Failed to parse JSON: %v", err)
			h.redirectToResult(w, r, "", "NOK", "failed", "", "")
			return
		}

		if v, ok := data["State"].(string); ok {
			state = v
		}
		if v, ok := data["Status"]; ok {
			status = fmt.Sprintf("%v", v)
		}
		if v, ok := data["RefNum"].(string); ok {
			refNum = v
		}
		if v, ok := data["ResNum"].(string); ok {
			resNum = v
		}
		if v, ok := data["TraceNo"].(string); ok {
			traceNo = v
		}
		if v, ok := data["Amount"]; ok {
			amount = fmt.Sprintf("%v", v)
		}
	} else {
		err := r.ParseForm()
		if err != nil {
			log.Printf("Failed to parse form: %v", err)
			h.redirectToResult(w, r, "", "NOK", "failed", "", "")
			return
		}

		state = r.FormValue("State")
		status = r.FormValue("Status")
		refNum = r.FormValue("RefNum")
		resNum = r.FormValue("ResNum")
		traceNo = r.FormValue("TraceNo")
		amount = r.FormValue("Amount")
	}

	log.Printf("Bank Callback Received:")
	log.Printf("   State: %s", state)
	log.Printf("   Status: %s", status)
	log.Printf("   RefNum: %s", refNum)
	log.Printf("   ResNum: %s", resNum)
	log.Printf("   TraceNo: %s", traceNo)
	log.Printf("   Amount: %s", amount)

	isSuccess := (state == "OK" || status == "0")

	if !isSuccess {
		// payment failed
		h.redirectToResult(w, r, "", state, "failed", refNum, amount)
		return
	}

	// verify transaction
	transactionID, err := h.service.VerifyPayment(r.Context(), resNum, refNum, traceNo, amount)
	if err != nil {
		log.Printf("❌ Verify failed: %v", err)
		h.redirectToResult(w, r, "", state, "verify_failed", refNum, amount)
		return
	}

	log.Printf("Payment verified successfully. TransactionID: %s", transactionID)

	h.redirectToResult(w, r, transactionID, state, "success", refNum, amount)
}

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

	if r.Method == http.MethodPost {
		if err := r.ParseForm(); err != nil {
			http.Error(w, "خطا در پارس کردن داده‌ها", http.StatusBadRequest)
			return
		}
	}

	state := r.FormValue("state")
	status := r.FormValue("status")
	refNum := r.FormValue("refNum")
	amount := r.FormValue("amount")
	transactionID := r.FormValue("transactionId")

	isSuccess := (state == "OK" || status == "success")

	data := map[string]interface{}{
		"State":         state,
		"Status":        status,
		"IsSuccess":     isSuccess,
		"RefNum":        refNum,
		"Amount":        amount,
		"TransactionID": transactionID,
	}

	tmpl, err := template.ParseFiles(h.templatesPath + "result.html")
	if err != nil {
		log.Printf("Template error: %v", err)
		http.Error(w, "Template parsing error", http.StatusInternalServerError)
		return
	}

	if err := tmpl.Execute(w, data); err != nil {
		log.Printf("Template execute error: %v", err)
	}
}

func (h *Handler) redirectToResult(w http.ResponseWriter, r *http.Request, transactionID, state, status, refNum, amount string) {
	query := fmt.Sprintf("state=%s&status=%s", state, status)

	if transactionID != "" {
		query += "&transactionId=" + url.QueryEscape(transactionID)
	}
	if refNum != "" {
		query += "&refNum=" + url.QueryEscape(refNum)
	}
	if amount != "" {
		query += "&amount=" + url.QueryEscape(amount)
	}

	redirectURL := "/result?" + query
	http.Redirect(w, r, redirectURL, http.StatusFound)
}

/*func (h *Handler) verifyPaymentHandler(w http.ResponseWriter, r *http.Request) {
	w.Header().Set("Content-Type", "application/json")

	token := r.URL.Query().Get("token")
	status := r.URL.Query().Get("status")

	if token == "" || status == "" {
		json.NewEncoder(w).Encode(VerifyResponse{
			Success: false,
			Status:  "failed",
			Message: "پارامترهای نامعتبر",
		})
		return
	}

	transactionID, err := h.service.VerifyPayment(r.Context(), token, status, "", "")
	if err != nil || status != "OK" {
		json.NewEncoder(w).Encode(VerifyResponse{
			Success: false,
			Status:  "failed",
			Message: "پرداخت ناموفق",
		})
		return
	}

	json.NewEncoder(w).Encode(VerifyResponse{
		Success:       true,
		Status:        "success",
		TransactionID: transactionID,
		Message:       "پرداخت موفق",
	})
}*/