package handler

import (
	"strconv"
	"strings"

	"github.com/gin-gonic/gin"

	"apskel-pos-be/internal/constants"
	"apskel-pos-be/internal/contract"
	"apskel-pos-be/internal/service"
	"apskel-pos-be/internal/util"
)

// The header exchanges and transfers require (docs/prd-point-coin.md F4, F5), and the
// X- form the rest of the API uses, which is accepted too.
const (
	idempotencyKeyHeader       = "Idempotency-Key"
	legacyIdempotencyKeyHeader = "X-Idempotency-Key"
)

// CustomerWalletHandler serves what the customer app does with its own wallet. Bodies
// hold the PIN, so they are never logged.
type CustomerWalletHandler struct {
	wallets service.CustomerWalletService
}

func NewCustomerWalletHandler(wallets service.CustomerWalletService) *CustomerWalletHandler {
	return &CustomerWalletHandler{wallets: wallets}
}

// PreviewExchange is GET /customer/wallet/exchange/preview?coins=.
func (h *CustomerWalletHandler) PreviewExchange(c *gin.Context) {
	customerID, ok := customerIDFromGin(c, "CustomerWalletHandler::PreviewExchange")
	if !ok {
		return
	}
	var coins int64
	if raw := c.Query("coins"); raw != "" {
		var err error
		coins, err = strconv.ParseInt(raw, 10, 64)
		if err != nil {
			util.HandleResponse(c.Writer, c.Request, contract.BuildErrorResponse([]*contract.ResponseError{
				contract.NewResponseError(constants.MalformedFieldErrorCode, constants.RequestEntity, "coins must be a whole number"),
			}), "CustomerWalletHandler::PreviewExchange")
			return
		}
	}
	util.HandleResponse(c.Writer, c.Request, h.wallets.PreviewExchange(c.Request.Context(), customerID, coins), "CustomerWalletHandler::PreviewExchange")
}

// Exchange is POST /customer/wallet/exchange.
func (h *CustomerWalletHandler) Exchange(c *gin.Context) {
	customerID, ok := customerIDFromGin(c, "CustomerWalletHandler::Exchange")
	if !ok {
		return
	}
	var req contract.ExchangeCoinsRequest
	if !bindPinRequest(c, &req, "CustomerWalletHandler::Exchange") {
		return
	}
	util.HandleResponse(c.Writer, c.Request, h.wallets.Exchange(c.Request.Context(), customerID, &req, idempotencyKey(c), pinRequestInfo(c)), "CustomerWalletHandler::Exchange")
}

func idempotencyKey(c *gin.Context) string {
	if key := strings.TrimSpace(c.GetHeader(idempotencyKeyHeader)); key != "" {
		return key
	}
	return strings.TrimSpace(c.GetHeader(legacyIdempotencyKeyHeader))
}