/*
 * Copyright (C) 2021 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.android.systemui.util

import android.content.pm.ActivityInfo
import android.content.res.Resources
import android.graphics.Rect
import android.graphics.drawable.Drawable
import android.graphics.drawable.DrawableWrapper
import android.graphics.drawable.InsetDrawable

/**
 * [DrawableWrapper] to use in the progress of brightness slider.
 *
 * This drawable is used to change the bounds of the enclosed drawable depending on the level to
 * simulate a sliding progress, instead of using clipping or scaling. That way, the shape of the
 * edges is maintained.
 *
 * Meant to be used with a rounded ends background, it will also prevent deformation when the slider
 * is meant to be smaller than the rounded corner. The background should have rounded corners that
 * are half of the height.
 *
 * This class also assumes that a "thumb" icon exists within the end's edge of the progress
 * drawable, and the slider's width, when interacted on, if offset by half the size of the thumb
 * icon which puts the icon directly underneath the user's finger.
 */
class BrightnessProgressDrawable @JvmOverloads constructor(drawable: Drawable? = null) :
    InsetDrawable(drawable, 0) {

    companion object {
        private const val MAX_LEVEL = 10000 // Taken from Drawable
    }

    override fun onLayoutDirectionChanged(layoutDirection: Int): Boolean {
        onLevelChange(level)
        return super.onLayoutDirectionChanged(layoutDirection)
    }

    override fun onBoundsChange(bounds: Rect) {
        super.onBoundsChange(bounds)
        onLevelChange(level)
    }

    override fun onLevelChange(level: Int): Boolean {
        val db = drawable?.bounds!!

        // The thumb offset shifts the sun icon directly under the user's thumb
        val thumbOffset = bounds.height() / 2
        val width = bounds.width() * level / MAX_LEVEL + thumbOffset

        // On 0, the width is bounds.height (a circle), and on MAX_LEVEL, the width is bounds.width
        drawable?.setBounds(
            bounds.left,
            db.top,
            width.coerceAtMost(bounds.width()).coerceAtLeast(bounds.height()),
            db.bottom
        )
        return super.onLevelChange(level)
    }

    override fun getConstantState(): ConstantState {
        // This should not be null as it was created with a state in the constructor.
        return RoundedCornerState(super.getConstantState()!!)
    }

    override fun getChangingConfigurations(): Int {
        return super.getChangingConfigurations() or ActivityInfo.CONFIG_DENSITY
    }

    override fun canApplyTheme(): Boolean {
        return (drawable?.canApplyTheme() ?: false) || super.canApplyTheme()
    }

    private class RoundedCornerState(private val wrappedState: ConstantState) : ConstantState() {
        override fun newDrawable(): Drawable {
            return newDrawable(null, null)
        }

        override fun newDrawable(res: Resources?, theme: Resources.Theme?): Drawable {
            val wrapper = wrappedState.newDrawable(res, theme) as DrawableWrapper
            return BrightnessProgressDrawable(wrapper.drawable)
        }

        override fun getChangingConfigurations(): Int {
            return wrappedState.changingConfigurations
        }

        override fun canApplyTheme(): Boolean {
            return true
        }
    }
}