package middleware

import (
	"github.com/gin-gonic/gin"
	"github.com/google/uuid"

	"github.com/dhao2001/mygo/internal/logging"
)

// RequestID returns a Gin middleware that ensures every request has a
// request ID. If the client sends X-Request-ID, it is reused; otherwise a
// new UUID v4 is generated. The ID is injected into both the Go
// context.Context (for slog) and the Gin context (for handler access).
func RequestID() gin.HandlerFunc {
	return func(c *gin.Context) {
		reqID := c.GetHeader("X-Request-ID")
		if reqID == "" {
			reqID = uuid.NewString()
		}

		// Inject into Go context for slog.*Context calls.
		c.Request = c.Request.WithContext(logging.WithRequestID(c.Request.Context(), reqID))

		// Also set in Gin context for direct access.
		c.Set("req_id", reqID)
		c.Header("X-Request-ID", reqID)

		c.Next()
	}
}