/*
 * Copyright 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 androidx.compose.material3

import androidx.compose.material.ripple.LocalRippleTheme
import androidx.compose.material.ripple.RippleAlpha
import androidx.compose.material.ripple.RippleTheme
import androidx.compose.material3.tokens.State
import androidx.compose.runtime.Composable
import androidx.compose.runtime.CompositionLocalProvider
import androidx.compose.runtime.Immutable
import androidx.compose.runtime.ReadOnlyComposable
import androidx.compose.runtime.remember

// TODO: Create a sample androidx.compose.material3.samples.MaterialThemeSample
// TODO(b/197880751) Update to link M3 Material Theming page (i.e. a <a href="https://material
//  .io/design/material-theming/overview.html" class="external" target="_blank">Material
//  Theming</a> M3 equivalent).
/**
 * Material Theming refers to the customization of your Material Design app to better reflect your
 * product’s brand.
 *
 * Material components such as [Button] and [Checkbox] use values provided here when retrieving
 * default values.
 *
 * All values may be set by providing this component with the [colorScheme][ColorScheme],
 * [typography][Typography] attributes. Use this to configure the overall
 * theme of elements within this MaterialTheme.
 *
 * Any values that are not set will inherit the current value from the theme, falling back to the
 * defaults if there is no parent MaterialTheme. This allows using a MaterialTheme at the top
 * of your application, and then separate MaterialTheme(s) for different screens / parts of your
 * UI, overriding only the parts of the theme definition that need to change.
 *
 * @param colorScheme A complete definition of the Material Color theme for this hierarchy
 * @param typography A set of text styles to be used as this hierarchy's typography system
 */

@Composable
fun MaterialTheme(
    colorScheme: ColorScheme = MaterialTheme.colorScheme,
    typography: Typography = MaterialTheme.typography,
    content: @Composable () -> Unit
) {
    val rememberedColorScheme = remember {
        // Explicitly creating a new object here so we don't mutate the initial [colorScheme]
        // provided, and overwrite the values set in it.
        colorScheme.copy()
    }.apply {
        updateColorSchemeFrom(colorScheme)
    }
    CompositionLocalProvider(
        LocalColorScheme provides rememberedColorScheme,
        LocalTypography provides typography,
        LocalRippleTheme provides MaterialRippleTheme,
    ) {
        ProvideTextStyle(value = typography.bodyLarge, content = content)
    }
}

/**
 * Contains functions to access the current theme values provided at the call site's position in
 * the hierarchy.
 */
object MaterialTheme {
    /**
     * Retrieves the current [ColorScheme] at the call site's position in the hierarchy.
     */
    val colorScheme: ColorScheme
        @Composable
        @ReadOnlyComposable
        get() = LocalColorScheme.current

    /**
     * Retrieves the current [Typography] at the call site's position in the hierarchy.
     */
    val typography: Typography
        @Composable
        @ReadOnlyComposable
        get() = LocalTypography.current
}

@Immutable
private object MaterialRippleTheme : RippleTheme {
    @Composable
    override fun defaultColor() = LocalContentColor.current

    @Composable
    override fun rippleAlpha() = DefaultRippleAlpha
}

private val DefaultRippleAlpha = RippleAlpha(
    pressedAlpha = State.PressedStateLayerOpacity,
    focusedAlpha = State.FocusStateLayerOpacity,
    draggedAlpha = State.DraggedStateLayerOpacity,
    hoveredAlpha = State.HoverStateLayerOpacity
)