package heleket

import (
	"bytes"
	"context"
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"strconv"
	"time"
)

const apiBase = "https://api.heleket.com"

type Client struct {
	merchantID string
	apiKey     string
	http       *http.Client
}

type InvoiceRequest struct {
	Amount       string `json:"amount"`
	Currency     string `json:"currency"`
	OrderID      string `json:"order_id"`
	URLReturn    string `json:"url_return,omitempty"`
	URLSuccess   string `json:"url_success,omitempty"`
	URLCallback  string `json:"url_callback,omitempty"`
	PayerEmail   string `json:"payer_email,omitempty"`
	Lifetime     int    `json:"lifetime,omitempty"`
	AdditionalData string `json:"additional_data,omitempty"`
}

type Invoice struct {
	UUID          string `json:"uuid"`
	OrderID       string `json:"order_id"`
	Amount        string `json:"amount"`
	PaymentStatus string `json:"payment_status"`
	URL           string `json:"url"`
	ExpiredAt     int64  `json:"expired_at"`
	IsFinal       bool   `json:"is_final"`
}

type apiResponse struct {
	State  int             `json:"state"`
	Result json.RawMessage `json:"result"`
	Errors json.RawMessage `json:"errors"`
}

func NewClient(merchantID, apiKey string) *Client {
	return &Client{
		merchantID: merchantID,
		apiKey:     apiKey,
		http:       &http.Client{Timeout: 30 * time.Second},
	}
}

func (c *Client) Enabled() bool {
	return c.merchantID != "" && c.apiKey != ""
}

func OrderExternalID(orderID int) string {
	return fmt.Sprintf("shop-order-%d", orderID)
}

func ParseOrderExternalID(orderID string) (int, bool) {
	const prefix = "shop-order-"
	if len(orderID) <= len(prefix) || orderID[:len(prefix)] != prefix {
		return 0, false
	}
	id, err := strconv.Atoi(orderID[len(prefix):])
	return id, err == nil && id > 0
}

func FormatAmount(amount float64) string {
	return strconv.FormatFloat(amount, 'f', 2, 64)
}

func (c *Client) CreateInvoice(ctx context.Context, req InvoiceRequest) (Invoice, error) {
	body, err := encodeBody(req)
	if err != nil {
		return Invoice{}, err
	}

	httpReq, err := http.NewRequestWithContext(ctx, http.MethodPost, apiBase+"/v1/payment", bytes.NewReader(body))
	if err != nil {
		return Invoice{}, err
	}
	httpReq.Header.Set("Content-Type", "application/json")
	httpReq.Header.Set("merchant", c.merchantID)
	httpReq.Header.Set("sign", SignBody(body, c.apiKey))

	resp, err := c.http.Do(httpReq)
	if err != nil {
		return Invoice{}, err
	}
	defer resp.Body.Close()

	respBody, err := io.ReadAll(resp.Body)
	if err != nil {
		return Invoice{}, err
	}
	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
		return Invoice{}, fmt.Errorf("heleket http %d: %s", resp.StatusCode, string(respBody))
	}

	var wrapped apiResponse
	if err := json.Unmarshal(respBody, &wrapped); err != nil {
		return Invoice{}, err
	}
	if wrapped.State != 0 {
		return Invoice{}, fmt.Errorf("heleket api state %d: %s", wrapped.State, string(wrapped.Errors))
	}

	var invoice Invoice
	if err := json.Unmarshal(wrapped.Result, &invoice); err != nil {
		return Invoice{}, err
	}
	return invoice, nil
}

// MapPaymentStatus maps Heleket payment_status to shop order status.
func MapPaymentStatus(paymentStatus string) string {
	switch paymentStatus {
	case "paid", "paid_over":
		return "paid"
	case "cancel", "fail", "system_fail":
		return "cancelled"
	case "refund_paid":
		return "refunded"
	default:
		return "unpaid"
	}
}

func IsPaid(paymentStatus string) bool {
	return paymentStatus == "paid" || paymentStatus == "paid_over"
}