package server

import (
	"context"
	"encoding/csv"
	"fmt"
	"strconv"
	"strings"
	"time"

	"github.com/gin-gonic/gin"
	"github.com/google/uuid"
	"go.uber.org/zap"

	"scrabble/backend/internal/payments"
)

// consoleRefund refunds a paid order in full at the operator's request: it records the reversal — a
// refund ledger row and a floor-0 chip revoke (never negative, D27) — and, on the direct rail, moves
// the money back through the provider's refund API first, so one click does the whole job and the
// ledger cannot claim a refund the provider never made. The rails with no refund API of ours (VK
// support, Telegram refundStarPayment, the Robokassa cabinet) still need the operator to move the
// money by hand; this records that. Idempotent either way.
func (s *Server) consoleRefund(c *gin.Context) {
	id, ok := s.consoleUUID(c, "/_gm/users")
	if !ok {
		return
	}
	back := "/_gm/users/" + id.String()
	if s.payments == nil {
		s.renderConsoleMessage(c, "Unavailable", "payments are not enabled", back)
		return
	}
	orderID, err := uuid.Parse(strings.TrimSpace(c.PostForm("order_id")))
	if err != nil {
		s.renderConsoleMessage(c, "Refund failed", "no order to refund", back)
		return
	}
	ctx := c.Request.Context()
	ref, err := s.payments.OrderProviderRef(ctx, orderID)
	if err != nil {
		s.renderConsoleMessage(c, "Refund failed", err.Error(), back)
		return
	}
	out, err := s.refundOrder(ctx, ref)
	if err != nil {
		s.renderConsoleMessage(c, "Refund failed", err.Error(), back)
		return
	}
	if out.AlreadyRefunded {
		s.renderConsoleMessage(c, "Already refunded", "this order was already refunded", back)
		return
	}
	s.publishBannerChange(id)
	msg := fmt.Sprintf("revoked %d chips", out.Revoked)
	if out.Loss > 0 {
		msg += fmt.Sprintf("; %d chips were already spent (recorded as a loss + abuse flag)", out.Loss)
	}
	s.renderConsoleMessage(c, "Refunded", msg, back)
}

// refundOrder reverses a paid order, moving the money back through the rail's own refund API when
// there is one. The provider call comes first and a failure aborts with nothing recorded: the ledger
// must never claim a refund that did not happen. The reversal is then recorded under the provider's
// own refund id, which keeps the ledger reconcilable against the provider's records.
//
// A rail with no refund API of ours records under the operator's key instead, and the operator moves
// the money by hand (VK support, Telegram refundStarPayment, the Robokassa cabinet).
func (s *Server) refundOrder(ctx context.Context, ref payments.OrderRef) (payments.RefundOutcome, error) {
	if ref.Provider != providerYooKassa {
		return s.payments.RefundOrderFull(ctx, ref.OrderID)
	}
	refundID, err := s.refundYooKassa(ctx, ref)
	if err != nil {
		s.log.Error("yookassa refund failed", zap.String("order", ref.OrderID.String()), zap.Error(err))
		return payments.RefundOutcome{}, fmt.Errorf("the provider did not refund the payment, nothing was recorded: %w", err)
	}
	return s.payments.RefundOrderFullAs(ctx, ref.OrderID, providerYooKassa, refundID)
}

// consoleLedgerExport streams the entire append-only ledger as a CSV attachment for tax reporting
// and rail reconciliation. The snapshot column carries the raw purchase/refund JSON.
func (s *Server) consoleLedgerExport(c *gin.Context) {
	rows, err := s.payments.LedgerExport(c.Request.Context())
	if err != nil {
		s.consoleError(c, err)
		return
	}
	c.Header("Content-Type", "text/csv; charset=utf-8")
	c.Header("Content-Disposition", `attachment; filename="ledger.csv"`)
	w := csv.NewWriter(c.Writer)
	_ = w.Write([]string{
		"created_at", "account_id", "kind", "source", "origin", "chips_delta",
		"product_id", "order_id", "provider", "provider_payment_id", "snapshot",
	})
	for _, r := range rows {
		_ = w.Write([]string{
			r.CreatedAt.UTC().Format(time.RFC3339), r.AccountID, r.Kind, r.Source, r.Origin,
			strconv.Itoa(r.ChipsDelta), r.ProductID, r.OrderID, r.Provider, r.ProviderPaymentID, r.Snapshot,
		})
	}
	w.Flush()
}