// SPDX-FileCopyrightText: 2023 suyu Emulator Project
// SPDX-License-Identifier: GPL-2.0-or-later

package org.suyu.suyu_emu.layout

import android.content.Context
import androidx.recyclerview.widget.GridLayoutManager
import androidx.recyclerview.widget.RecyclerView
import androidx.recyclerview.widget.RecyclerView.Recycler
import org.suyu.suyu_emu.R

/**
 *  Cut down version of the solution provided here
 *  https://stackoverflow.com/questions/26666143/recyclerview-gridlayoutmanager-how-to-auto-detect-span-count
 */
class AutofitGridLayoutManager(
    context: Context,
    columnWidth: Int
) : GridLayoutManager(context, 1) {
    private var columnWidth = 0
    private var isColumnWidthChanged = true
    private var lastWidth = 0
    private var lastHeight = 0

    init {
        setColumnWidth(checkedColumnWidth(context, columnWidth))
    }

    private fun checkedColumnWidth(context: Context, columnWidth: Int): Int {
        var newColumnWidth = columnWidth
        if (newColumnWidth <= 0) {
            newColumnWidth = context.resources.getDimensionPixelSize(R.dimen.spacing_xtralarge)
        }
        return newColumnWidth
    }

    private fun setColumnWidth(newColumnWidth: Int) {
        if (newColumnWidth > 0 && newColumnWidth != columnWidth) {
            columnWidth = newColumnWidth
            isColumnWidthChanged = true
        }
    }

    override fun onLayoutChildren(recycler: Recycler, state: RecyclerView.State) {
        val width = width
        val height = height
        if (columnWidth > 0 && width > 0 && height > 0 &&
            (isColumnWidthChanged || lastWidth != width || lastHeight != height)
        ) {
            val totalSpace: Int = if (orientation == VERTICAL) {
                width - paddingRight - paddingLeft
            } else {
                height - paddingTop - paddingBottom
            }
            val spanCount = 1.coerceAtLeast(totalSpace / columnWidth)
            setSpanCount(spanCount)
            isColumnWidthChanged = false
        }
        lastWidth = width
        lastHeight = height
        super.onLayoutChildren(recycler, state)
    }
}
