package middleware

import (
	"crypto/rand"
	"fmt"

	"git.trcreatives.at/trcreatives/go-kite"
)

type RequestIDConfig struct {
	Header    string
	Generator func() string
}

func RequestID() kite.Middleware {
	return RequestIDWithConfig(RequestIDConfig{})
}

func RequestIDWithConfig(cfg RequestIDConfig) kite.Middleware {
	if cfg.Header == "" {
		cfg.Header = "X-Request-ID"
	}

	if cfg.Generator == nil {
		cfg.Generator = func() string {
			b := make([]byte, 16)
			rand.Read(b)
			return fmt.Sprintf("%08x-%04x-%04x-%04x-%012x",
				b[0:4], b[4:6], b[6:8], b[8:10], b[10:16])
		}
	}

	return func(h kite.Handler) kite.Handler {
		return func(ctx *kite.Context) error {
			id := ctx.GetHeader(cfg.Header)
			if id == "" {
				id = cfg.Generator()
			}

			ctx.SetHeader(cfg.Header, id)
			ctx.SetValue(cfg.Header, id)

			return h(ctx)
		}
	}
}