package middleware

import (
	"crypto/rand"
	"encoding/hex"

	"github.com/gin-gonic/gin"
)

// TracingMiddleware adds trace ID to requests for better observability
func TracingMiddleware() gin.HandlerFunc {
	return func(c *gin.Context) {
		// Check if trace ID is already provided in headers
		traceID := c.GetHeader("X-Trace-ID")

		// Generate new trace ID if not provided
		if traceID == "" {
			traceID = generateTraceID()
		}

		// Set trace ID in context and response header
		c.Set("trace_id", traceID)
		c.Header("X-Trace-ID", traceID)

		c.Next()
	}
}

// generateTraceID generates a random trace ID
func generateTraceID() string {
	bytes := make([]byte, 16)
	if _, err := rand.Read(bytes); err != nil {
		// Fallback to a simple timestamp-based ID if random generation fails
		return "trace-" + hex.EncodeToString([]byte("fallback"))
	}
	return hex.EncodeToString(bytes)
}