package handlers

import (
	"net/http"
	"strconv"

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

	"veza-backend-api/internal/core/marketplace"
	apperrors "veza-backend-api/internal/errors"
)

// AdminTransferHandler handles admin transfer dashboard endpoints (v0.701).
type AdminTransferHandler struct {
	db      *gorm.DB
	ts      marketplace.TransferService
	logger  *zap.Logger
	feeRate float64
}

// NewAdminTransferHandler creates a new AdminTransferHandler.
func NewAdminTransferHandler(db *gorm.DB, ts marketplace.TransferService, feeRate float64, logger *zap.Logger) *AdminTransferHandler {
	return &AdminTransferHandler{
		db:      db,
		ts:      ts,
		logger:  logger,
		feeRate: feeRate,
	}
}

// GetTransfers returns a paginated list of all platform transfers with optional filters.
// Query params: status, seller_id, from, to, limit (default 50), offset (default 0).
func (h *AdminTransferHandler) GetTransfers(c *gin.Context) {
	query := h.db.Model(&marketplace.SellerTransfer{})

	if status := c.Query("status"); status != "" {
		query = query.Where("status = ?", status)
	}
	if sellerIDStr := c.Query("seller_id"); sellerIDStr != "" {
		sellerID, err := uuid.Parse(sellerIDStr)
		if err != nil {
			RespondWithAppError(c, apperrors.NewValidationError("invalid seller_id"))
			return
		}
		query = query.Where("seller_id = ?", sellerID)
	}
	if from := c.Query("from"); from != "" {
		query = query.Where("created_at >= ?", from)
	}
	if to := c.Query("to"); to != "" {
		query = query.Where("created_at <= ?", to)
	}

	var total int64
	if err := query.Count(&total).Error; err != nil {
		h.logger.Error("GetTransfers count failed", zap.Error(err))
		RespondWithAppError(c, apperrors.NewInternalErrorWrap("Failed to count transfers", err))
		return
	}

	limit := 50
	if l := c.Query("limit"); l != "" {
		if parsed, err := strconv.Atoi(l); err == nil && parsed > 0 && parsed <= 100 {
			limit = parsed
		}
	}
	offset := 0
	if o := c.Query("offset"); o != "" {
		if parsed, err := strconv.Atoi(o); err == nil && parsed >= 0 {
			offset = parsed
		}
	}

	var transfers []marketplace.SellerTransfer
	if err := query.Order("created_at DESC").Limit(limit).Offset(offset).Find(&transfers).Error; err != nil {
		h.logger.Error("GetTransfers find failed", zap.Error(err))
		RespondWithAppError(c, apperrors.NewInternalErrorWrap("Failed to fetch transfers", err))
		return
	}

	RespondSuccess(c, http.StatusOK, gin.H{
		"transfers": transfers,
		"total":     total,
	})
}

// RetryTransfer manually retries a failed transfer.
func (h *AdminTransferHandler) RetryTransfer(c *gin.Context) {
	if h.ts == nil {
		RespondWithAppError(c, apperrors.NewServiceUnavailableError("Stripe Connect is not enabled"))
		return
	}

	idStr := c.Param("id")
	if idStr == "" {
		RespondWithAppError(c, apperrors.NewValidationError("transfer id required"))
		return
	}
	transferID, err := uuid.Parse(idStr)
	if err != nil {
		RespondWithAppError(c, apperrors.NewValidationError("invalid transfer id"))
		return
	}

	var t marketplace.SellerTransfer
	if err := h.db.First(&t, transferID).Error; err != nil {
		if err == gorm.ErrRecordNotFound {
			RespondWithAppError(c, apperrors.NewNotFoundError("transfer"))
			return
		}
		h.logger.Error("RetryTransfer find failed", zap.Error(err), zap.String("transfer_id", idStr))
		RespondWithAppError(c, apperrors.NewInternalErrorWrap("Failed to fetch transfer", err))
		return
	}

	if t.Status != "failed" {
		RespondWithAppError(c, apperrors.NewValidationError("only failed transfers can be retried"))
		return
	}

	stripeTransferID, err := h.ts.CreateTransfer(c.Request.Context(), t.SellerID, t.AmountCents, t.Currency, t.OrderID.String())
	if err != nil {
		// Failure: stay in 'failed' (same-state) but bump retry_count and
		// record the error. For manual admin retry we don't set
		// next_retry_at — ops is driving this, not the worker.
		failExtras := map[string]interface{}{
			"retry_count":   t.RetryCount + 1,
			"error_message": err.Error(),
		}
		if saveErr := t.TransitionStatus(h.db.WithContext(c.Request.Context()), t.Status, failExtras); saveErr != nil {
			h.logger.Error("RetryTransfer save failed", zap.Error(saveErr))
		}
		h.logger.Error("RetryTransfer CreateTransfer failed", zap.Error(err), zap.String("transfer_id", idStr))
		RespondWithAppError(c, apperrors.NewInternalErrorWrap("Transfer failed", err))
		return
	}

	extras := map[string]interface{}{
		"error_message":      "",
		"stripe_transfer_id": stripeTransferID,
	}
	if err := t.TransitionStatus(h.db.WithContext(c.Request.Context()), marketplace.TransferStatusCompleted, extras); err != nil {
		h.logger.Error("RetryTransfer save failed", zap.Error(err))
		RespondWithAppError(c, apperrors.NewInternalErrorWrap("Failed to update transfer", err))
		return
	}

	RespondSuccess(c, http.StatusOK, t)
}