package api

import (
	"context"
	"encoding/json"
	"io"
	"net/http"
	"unicode/utf8"

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

	"veza-backend-api/internal/core/marketplace"
	"veza-backend-api/internal/handlers"
	"veza-backend-api/internal/response"
	"veza-backend-api/internal/services"
	"veza-backend-api/internal/services/hyperswitch"
	"veza-backend-api/internal/workers"
)

// setupWebhookRoutes configure les routes pour les webhooks
func (r *APIRouter) setupWebhookRoutes(router *gin.RouterGroup) {
	webhookService := services.NewWebhookService(r.db.GormDB, r.logger, r.config.JWTSecret)

	webhookWorker := workers.NewWebhookWorker(
		r.db.GormDB,
		webhookService,
		r.logger,
		100,
		5,
		3,
	)

	go webhookWorker.Start(context.Background())

	webhookHandler := handlers.NewWebhookHandler(webhookService, webhookWorker, r.logger)

	webhooks := router.Group("/webhooks")
	{
		// Hyperswitch payment webhook - PUBLIC (no auth), called by Hyperswitch
		webhooks.POST("/hyperswitch", r.hyperswitchWebhookHandler())

		if r.config.AuthMiddleware != nil {
			protected := webhooks.Group("")
			protected.Use(r.config.AuthMiddleware.RequireAuth())
			r.applyCSRFProtection(protected)
			protected.POST("", webhookHandler.RegisterWebhook())
			protected.GET("", webhookHandler.ListWebhooks())
			protected.DELETE("/:id", webhookHandler.DeleteWebhook())
			protected.GET("/stats", webhookHandler.GetWebhookStats())
			protected.POST("/:id/test", webhookHandler.TestWebhook())
			protected.POST("/:id/regenerate-key", webhookHandler.RegenerateAPIKey())
		}
	}
}

// hyperswitchWebhookHandler handles POST /webhooks/hyperswitch from Hyperswitch.
//
// v1.0.7 item E: every delivery is persisted to hyperswitch_webhook_log,
// including deliveries that fail signature verification or processing
// — the log is the forensic audit trail for both legitimate activity
// and attack probes. A 64KB body cap protects the table from log-spam
// DoS (rejected with 413 before any INSERT).
func (r *APIRouter) hyperswitchWebhookHandler() gin.HandlerFunc {
	marketService := r.getMarketplaceService()
	webhookSecret := r.config.HyperswitchWebhookSecret
	return func(c *gin.Context) {
		// v1.0.7 item E: cap the body read at MaxWebhookPayloadBytes+1
		// so we can detect oversize without loading arbitrary megabytes
		// into memory. An attacker posting 10MB gets 413 back; the log
		// table never sees the row.
		limited := io.LimitReader(c.Request.Body, hyperswitch.MaxWebhookPayloadBytes+1)
		body, err := io.ReadAll(limited)
		if err != nil {
			r.logger.Error("Hyperswitch webhook: failed to read body", zap.Error(err))
			response.InternalServerError(c, "Failed to read webhook body")
			return
		}
		if len(body) > hyperswitch.MaxWebhookPayloadBytes {
			r.logger.Warn("Hyperswitch webhook: payload exceeds size cap, rejecting",
				zap.Int("size_bytes", len(body)),
				zap.Int("max_bytes", hyperswitch.MaxWebhookPayloadBytes))
			c.AbortWithStatusJSON(http.StatusRequestEntityTooLarge, gin.H{
				"error": "payload too large",
				"limit": hyperswitch.MaxWebhookPayloadBytes,
			})
			return
		}

		// Payload as TEXT: Hyperswitch sends JSON, but a probe/attack
		// might send anything. Reject invalid UTF-8 outright — the
		// attack-forensics value is in headers + ip + timing, not the
		// binary body.
		payload := string(body)
		if !utf8.ValidString(payload) {
			r.logger.Warn("Hyperswitch webhook: payload contains invalid UTF-8, replacing with empty for log")
			payload = ""
		}

		// Collect forensics context regardless of outcome.
		requestID := c.GetHeader("X-Request-Id")
		if requestID == "" {
			requestID = c.GetHeader("X-Request-ID")
		}
		sigHeader := c.GetHeader("x-webhook-signature-512")
		logRow := &hyperswitch.WebhookLog{
			Payload:         payload,
			SignatureHeader: sigHeader,
			SourceIP:        c.ClientIP(),
			UserAgent:       c.GetHeader("User-Agent"),
			RequestID:       requestID, // filled with UUID by LogWebhook if empty
		}

		// Signature verification. Regardless of outcome, the row lands
		// with signature_valid set accordingly.
		if webhookSecret == "" {
			r.logger.Error("Hyperswitch webhook: HYPERSWITCH_WEBHOOK_SECRET not configured, rejecting webhook")
			logRow.SignatureValid = false
			logRow.ProcessingResult = "error: webhook secret not configured"
			r.persistWebhookLog(c.Request.Context(), logRow)
			response.InternalServerError(c, "Webhook secret not configured")
			return
		}
		if err := hyperswitch.VerifyWebhookSignature(body, sigHeader, webhookSecret); err != nil {
			r.logger.Warn("Hyperswitch webhook: signature verification failed",
				zap.String("source_ip", logRow.SourceIP),
				zap.Error(err))
			logRow.SignatureValid = false
			logRow.ProcessingResult = "signature_invalid"
			r.persistWebhookLog(c.Request.Context(), logRow)
			response.Unauthorized(c, "Invalid webhook signature")
			return
		}
		logRow.SignatureValid = true

		// v1.0.6: dispatch refund events to ProcessRefundWebhook. Payment
		// events keep flowing through ProcessPaymentWebhook unchanged.
		var peek marketplace.HyperswitchWebhookPayload
		if err := json.Unmarshal(body, &peek); err != nil {
			r.logger.Warn("Hyperswitch webhook: payload not JSON — dispatching as payment",
				zap.Error(err))
		}
		var procErr error
		if peek.IsRefundEvent() {
			procErr = marketService.ProcessRefundWebhook(c.Request.Context(), body)
		} else {
			procErr = marketService.ProcessPaymentWebhook(c.Request.Context(), body)
		}
		if procErr != nil {
			r.logger.Error("Hyperswitch webhook: processing failed",
				zap.Bool("is_refund_event", peek.IsRefundEvent()),
				zap.Error(procErr))
			logRow.ProcessingResult = "error: " + procErr.Error()
			r.persistWebhookLog(c.Request.Context(), logRow)
			response.InternalServerError(c, "Webhook processing failed")
			return
		}
		logRow.ProcessingResult = "ok"
		r.persistWebhookLog(c.Request.Context(), logRow)
		response.Success(c, gin.H{"received": true})
	}
}

// persistWebhookLog writes the audit row. Any DB failure is logged and
// swallowed — the endpoint's primary contract is to ack Hyperswitch,
// not to persist audit perfectly. A persistent storage failure is
// operationally visible via this log line.
func (r *APIRouter) persistWebhookLog(ctx context.Context, row *hyperswitch.WebhookLog) {
	if r.db == nil || r.db.GormDB == nil {
		return
	}
	if err := hyperswitch.LogWebhook(ctx, r.db.GormDB, row); err != nil {
		r.logger.Error("Hyperswitch webhook: failed to persist audit log row",
			zap.String("request_id", row.RequestID),
			zap.Bool("signature_valid", row.SignatureValid),
			zap.Error(err))
	}
}

// getMarketplaceService returns the marketplace service with Hyperswitch wiring.
// Used by webhook handler; mirrors setupMarketplaceRoutes service creation.
func (r *APIRouter) getMarketplaceService() marketplace.MarketplaceService {
	if r.config.MarketplaceServiceOverride != nil {
		return r.config.MarketplaceServiceOverride.(marketplace.MarketplaceService)
	}
	uploadDir := r.config.UploadDir
	if uploadDir == "" {
		uploadDir = "uploads/tracks"
	}
	storageService := services.NewTrackStorageService(uploadDir, false, r.logger)
	opts := []marketplace.ServiceOption{}
	if r.config.HyperswitchEnabled && r.config.HyperswitchAPIKey != "" && r.config.HyperswitchURL != "" {
		hsClient := hyperswitch.NewClient(r.config.HyperswitchURL, r.config.HyperswitchAPIKey)
		hsProvider := hyperswitch.NewProvider(hsClient)
		opts = append(opts,
			marketplace.WithPaymentProvider(hsProvider),
			marketplace.WithHyperswitchConfig(true, r.config.CheckoutSuccessURL),
		)
	}
	if r.config.StripeConnectEnabled && r.config.StripeConnectSecretKey != "" {
		scs := services.NewStripeConnectService(r.db.GormDB, r.config.StripeConnectSecretKey, r.logger)
		opts = append(opts, marketplace.WithTransferService(scs, r.config.PlatformFeeRate))
	}
	// v1.0.9 item G Phase 2: subscription webhook dispatcher. The
	// processor reads/writes subscription_invoices + user_subscriptions
	// directly via GORM; injecting it here makes ProcessPaymentWebhook
	// route subscription events instead of swallowing them as "order not
	// found".
	subscriptionProcessor := hyperswitch.NewSubscriptionWebhookProcessor(r.db.GormDB, r.logger)
	opts = append(opts, marketplace.WithSubscriptionWebhookHandler(subscriptionProcessor))
	return marketplace.NewService(r.db.GormDB, r.logger, storageService, opts...)
}