BaseAdapter.kt

EasyAdapter.kt

class EasyAdapter<T : Any> private constructor(
    private val layoutResId: Int,
    areContentsTheSame: (T, T) -> Boolean = { old, new -> old == new },
    areItemsTheSame: (T, T) -> Boolean = { old, new -> old == new },
    private val onBind: (View, T) -> Unit,
    private val onViewCreated: (View, position: () -> Pair<Int, T>) -> Unit,
) : ListAdapter<T, RecyclerView.ViewHolder>(
    GenericDiffCallback(
        areContentsTheSame,
        areItemsTheSame,
    )
) {


    companion object {

        fun <T : Any> create(
            @LayoutRes layoutResId: Int,
        ): Builder<T> {
            return Builder(layoutResId)
        }

    }


    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): RecyclerView.ViewHolder {

        val itemView = LayoutInflater.from(parent.context).inflate(layoutResId, parent, false)

        return ViewHolder(itemView)
    }

    override fun onBindViewHolder(holder: RecyclerView.ViewHolder, position: Int) {
        val item = getItem(position)
        onBind(holder.itemView, item)
    }

    inner class ViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView) {

        init {
            try {
                onViewCreated(itemView, ::item)
            } catch (e: Exception) {
                Timber.e(e.stackTraceToString())
            }
        }

        fun item(): Pair<Int, T> {
            val absoluteAdapterPosition = absoluteAdapterPosition
            return Pair(absoluteAdapterPosition, getItem(absoluteAdapterPosition))
        }

    }

    private class GenericDiffCallback<T : Any>(
        private val areContentsSame: (T, T) -> Boolean,
        private val areItemsSame: (T, T) -> Boolean,
    ) : DiffUtil.ItemCallback<T>() {
        override fun areContentsTheSame(oldItem: T, newItem: T): Boolean {
            return areContentsSame(oldItem, newItem)
        }

        override fun areItemsTheSame(oldItem: T, newItem: T): Boolean {
            return areItemsSame(oldItem, newItem)
        }
    }

    class Builder<T : Any>(
        private val layoutResId: Int,
    ) {
        private var areContentsTheSame: (T, T) -> Boolean = { old, new -> old == new }
        private var areItemsTheSame: (T, T) -> Boolean = { old, new -> old == new }
        private var onBind: (View, T) -> Unit = { _, _ -> }
        private var onViewCreated: (View, position: () -> Pair<Int, T>) -> Unit = { _, _ -> }

        fun setAreContentsTheSame(areContentsTheSame: (T, T) -> Boolean): Builder<T> {
            this.areContentsTheSame = areContentsTheSame
            return this
        }

        fun setAreItemsTheSame(areItemsTheSame: (T, T) -> Boolean): Builder<T> {
            this.areItemsTheSame = areItemsTheSame
            return this
        }

        fun setOnBind(onBind: (View, T) -> Unit): Builder<T> {
            this.onBind = onBind
            return this
        }

        fun setOnViewCreated(onViewCreated: (View, position: () -> Pair<Int, T>) -> Unit): Builder<T> {
            this.onViewCreated = onViewCreated
            return this
        }

        fun build(): EasyAdapter<T> {
            return EasyAdapter(
                layoutResId = layoutResId,
                areContentsTheSame = areContentsTheSame,
                areItemsTheSame = areItemsTheSame,
                onBind = onBind,
                onViewCreated = onViewCreated,
            )
        }
    }

}