package handlers

import (
	"encoding/json"
	"errors"

	"Yimaru-Backend/internal/domain"
	"Yimaru-Backend/internal/services/chapa"

	"github.com/gofiber/fiber/v2"
)

// HandleChapaWebhook godoc
// @Summary Handle Chapa webhook
// @Description Processes payment notifications from Chapa (charge.success, etc.)
// @Tags payments
// @Accept json
// @Produce json
// @Success 200 {object} domain.Response
// @Failure 400 {object} domain.ErrorResponse
// @Router /api/v1/payments/webhook [post]
func (h *Handler) HandleChapaWebhook(c *fiber.Ctx) error {
	body := c.Body()
	signature := c.Get("x-chapa-signature")
	if signature == "" {
		signature = c.Get("chapa-signature")
	}

	if err := h.chapaSvc.VerifyWebhookSignature(body, signature); err != nil {
		h.logger.Error("Invalid Chapa webhook signature", "error", err)
		return c.Status(fiber.StatusUnauthorized).JSON(domain.ErrorResponse{
			Message: "Invalid webhook signature",
		})
	}

	var payload domain.ChapaWebhookPayload
	if err := json.Unmarshal(body, &payload); err != nil {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{
			Message: "Invalid webhook payload",
			Error:   err.Error(),
		})
	}

	if err := h.chapaSvc.ProcessPaymentWebhook(c.Context(), payload); err != nil {
		if errors.Is(err, chapa.ErrPaymentAlreadyPaid) {
			return c.JSON(domain.Response{Message: "Webhook already processed"})
		}
		h.logger.Error("Failed to process Chapa webhook", "error", err, "tx_ref", payload.TxRef)
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{
			Message: "Failed to process webhook",
			Error:   err.Error(),
		})
	}

	return c.JSON(domain.Response{
		Message: "Webhook processed successfully",
	})
}

// HandleChapaCallback godoc
// @Summary Chapa payment callback
// @Description Verifies payment after Chapa redirects to callback_url
// @Tags payments
// @Produce json
// @Param trx_ref query string false "Transaction reference"
// @Param ref_id query string false "Chapa reference ID"
// @Param status query string false "Payment status"
// @Success 200 {object} domain.Response
// @Router /api/v1/payments/chapa/callback [get]
func (h *Handler) HandleChapaCallback(c *fiber.Ctx) error {
	query := domain.ChapaCallbackQuery{
		TrxRef: c.Query("trx_ref"),
		RefID:  c.Query("ref_id"),
		Status: c.Query("status"),
	}
	if query.TrxRef == "" {
		query.TrxRef = c.Query("tx_ref")
	}

	if query.TrxRef == "" {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{
			Message: "trx_ref is required",
		})
	}

	if err := h.chapaSvc.ProcessCallback(c.Context(), query); err != nil {
		if errors.Is(err, chapa.ErrPaymentAlreadyPaid) {
			return c.JSON(domain.Response{Message: "Payment already processed"})
		}
		h.logger.Error("Failed to process Chapa callback", "error", err, "trx_ref", query.TrxRef)
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{
			Message: "Failed to process callback",
			Error:   err.Error(),
		})
	}

	return c.JSON(domain.Response{
		Message: "Callback processed successfully",
	})
}

// HandleChapaSuccessPage godoc
// @Summary Chapa payment success page
// @Description Displays the Yimaru Academy success page after Chapa redirects the learner to return_url
// @Tags payments
// @Produce html
// @Param trx_ref query string false "Chapa transaction reference (tx_ref)"
// @Param tx_ref query string false "Chapa transaction reference"
// @Param ref_id query string false "Chapa reference ID"
// @Param status query string false "Payment status from Chapa redirect"
// @Success 200 {string} string "HTML success page"
// @Router /api/v1/payments/chapa/success [get]
// @Router /payment/success [get]
func (h *Handler) HandleChapaSuccessPage(c *fiber.Ctx) error {
	txRef := firstNonEmpty(
		c.Query("trx_ref"),
		c.Query("tx_ref"),
	)

	page := defaultPaymentSuccessPage()

	if txRef != "" {
		payment, err := h.chapaSvc.VerifyPayment(c.Context(), txRef)
		if err != nil {
			h.logger.Warn("Failed to verify Chapa success redirect", "error", err, "tx_ref", txRef)
			page.Body = "Thank you for your payment. We are confirming it with Chapa and will activate your subscription shortly."
			page.Helper = "You can safely return to Yimaru Academy. If activation takes longer than expected, refresh the app in a moment."
			page.Reference = txRef
		} else {
			page.Reference = txRef
			page.PlanName = derefString(payment.PlanName)
			if payment.Status == string(domain.PaymentStatusSuccess) {
				page.StatusLabel = "Subscription active"
				page.Body = "Your Yimaru Academy subscription is active. You now have access to your learning content."
			} else {
				page.Body = "Thank you for your payment. We received your success redirect and are finalizing subscription activation."
				page.StatusLabel = "Processing confirmation"
			}
		}
	} else {
		page.Helper = "Return to Yimaru Academy and refresh your subscription status if you do not see access immediately."
	}

	html, err := renderPaymentSuccessPage(page)
	if err != nil {
		return c.Status(fiber.StatusInternalServerError).SendString("Failed to render success page")
	}
	c.Type("html", "utf-8")
	return c.SendString(html)
}

// GetChapaPaymentMethods godoc
// @Summary Get Chapa payment methods
// @Description Returns payment methods available on Chapa checkout
// @Tags payments
// @Produce json
// @Success 200 {object} domain.Response
// @Router /api/v1/payments/methods [get]
func (h *Handler) GetChapaPaymentMethods(c *fiber.Ctx) error {
	return c.JSON(domain.Response{
		Message: "Payment methods retrieved successfully",
		Data:    h.chapaSvc.GetPaymentMethods(),
	})
}