Dialog Helper with Kotlin

CustomDialog.kt

/**
 * ex)
 * CustomDialog
 *         .create {
 *              with { mContext }
 *              items {
 *                  CustomDialog.Items().apply {
 *                      message = "This is dialog message"
 *                      positiveTitle = "Positive title"
 *                      negativeTitle = "Negative title"
 *                  }
 *              }
 *              listener({
 *                  // do positive something
 *              },{
 *                  // do negative something
 *              })
 *         }
 */
 
class CustomDialog private constructor(
        private val mContext: Context,
        private val items: Items,
        private val positive: ()-> Unit,
        private val negative: (()-> Unit)? = null){

    private constructor(builder: Builder): this(builder.context, builder.items, builder.positive, builder.negative)

    private fun show() = AlertDialog.Builder(mContext).apply {
                with(items){
                    setMessage(message)

                    setPositiveButton(positiveTitle, { _, _ ->
                        positive()

                    })

                    negative?.let{
                        setNegativeButton(negativeTitle, { dialog, _ ->
                            dialog.dismiss()
                            negative?.invoke()
                        })
                    }
                }
            }.create().show()

    companion object {
        fun create(init: Builder.() -> Unit) = Builder(init).build().show()
    }

    class Builder private constructor(){
        lateinit var context: Context

        lateinit var items: Items

        lateinit var positive: ()-> Unit

        var negative: (()-> Unit)?= null

        constructor(init: Builder.()-> Unit): this(){
            init()
        }

        fun with(init: Builder.() -> Context) = apply { context = init() }

        fun items(init: Builder.() -> Items) = apply { items = init() }

        fun listener(pos: () -> Unit, neg: (()-> Unit)? = null) = apply {
            positive = pos
            neg?.let { negative = neg }
        }

        fun build() = CustomDialogE(this)
    }

    class Items {
        lateinit var message: String

        lateinit var positiveTitle: String

        lateinit var negativeTitle: String
    }
}