/*
 * Copyright (C) 2024 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.screenshot.ui.viewmodel

import android.graphics.Bitmap
import android.graphics.Rect
import android.graphics.drawable.Drawable
import android.util.Log
import android.view.accessibility.AccessibilityManager
import kotlinx.coroutines.flow.MutableStateFlow
import kotlinx.coroutines.flow.StateFlow

class ScreenshotViewModel(private val accessibilityManager: AccessibilityManager) {
    private val _preview = MutableStateFlow<Bitmap?>(null)
    val preview: StateFlow<Bitmap?> = _preview
    private val _scrollingScrim = MutableStateFlow<Bitmap?>(null)
    val scrollingScrim: StateFlow<Bitmap?> = _scrollingScrim
    private val _badge = MutableStateFlow<Drawable?>(null)
    val badge: StateFlow<Drawable?> = _badge
    private val _previewAction = MutableStateFlow<PreviewAction?>(null)
    val previewAction: StateFlow<PreviewAction?> = _previewAction
    private val _actions = MutableStateFlow(emptyList<ActionButtonViewModel>())
    val actions: StateFlow<List<ActionButtonViewModel>> = _actions
    private val _animationState = MutableStateFlow(AnimationState.NOT_STARTED)
    val animationState: StateFlow<AnimationState> = _animationState

    private val _isAnimating = MutableStateFlow(false)
    val isAnimating: StateFlow<Boolean> = _isAnimating
    private val _scrollableRect = MutableStateFlow<Rect?>(null)
    val scrollableRect: StateFlow<Rect?> = _scrollableRect
    val showDismissButton: Boolean
        get() = accessibilityManager.isEnabled

    fun setScreenshotBitmap(bitmap: Bitmap?) {
        _preview.value = bitmap
    }

    fun setScrollingScrimBitmap(bitmap: Bitmap?) {
        _scrollingScrim.value = bitmap
    }

    fun setScreenshotBadge(badge: Drawable?) {
        _badge.value = badge
    }

    fun setPreviewAction(previewAction: PreviewAction) {
        _previewAction.value = previewAction
    }

    fun addAction(
        actionAppearance: ActionButtonAppearance,
        showDuringEntrance: Boolean,
        onClicked: (() -> Unit)
    ): Int {
        val actionList = _actions.value.toMutableList()
        val action =
            ActionButtonViewModel.withNextId(actionAppearance, showDuringEntrance, onClicked)
        actionList.add(action)
        _actions.value = actionList
        return action.id
    }

    fun setActionVisibility(actionId: Int, visible: Boolean) {
        val actionList = _actions.value.toMutableList()
        val index = actionList.indexOfFirst { it.id == actionId }
        if (index >= 0) {
            actionList[index] =
                ActionButtonViewModel(
                    actionList[index].appearance,
                    actionId,
                    visible,
                    actionList[index].showDuringEntrance,
                    actionList[index].onClicked
                )
            _actions.value = actionList
        } else {
            Log.w(TAG, "Attempted to update unknown action id $actionId")
        }
    }

    fun updateActionAppearance(actionId: Int, appearance: ActionButtonAppearance) {
        val actionList = _actions.value.toMutableList()
        val index = actionList.indexOfFirst { it.id == actionId }
        if (index >= 0) {
            actionList[index] =
                ActionButtonViewModel(
                    appearance,
                    actionId,
                    actionList[index].visible,
                    actionList[index].showDuringEntrance,
                    actionList[index].onClicked
                )
            _actions.value = actionList
        } else {
            Log.w(TAG, "Attempted to update unknown action id $actionId")
        }
    }

    fun removeAction(actionId: Int) {
        val actionList = _actions.value.toMutableList()
        if (actionList.removeIf { it.id == actionId }) {
            // Update if something was removed.
            _actions.value = actionList
        } else {
            Log.w(TAG, "Attempted to remove unknown action id $actionId")
        }
    }

    // TODO: this should be handled entirely within the view binder.
    fun setAnimationState(state: AnimationState) {
        _animationState.value = state
    }

    fun setIsAnimating(isAnimating: Boolean) {
        _isAnimating.value = isAnimating
    }

    fun setScrollableRect(rect: Rect?) {
        _scrollableRect.value = rect
    }

    fun reset() {
        _preview.value = null
        _scrollingScrim.value = null
        _badge.value = null
        _previewAction.value = null
        _actions.value = listOf()
        _animationState.value = AnimationState.NOT_STARTED
        _isAnimating.value = false
        _scrollableRect.value = null
    }

    companion object {
        const val TAG = "ScreenshotViewModel"
    }
}

data class PreviewAction(
    val contentDescription: CharSequence,
    val onClick: () -> Unit,
)

enum class AnimationState {
    NOT_STARTED,
    ENTRANCE_STARTED, // The first 200ms of the entrance animation
    ENTRANCE_REVEAL, // The rest of the entrance animation
    ENTRANCE_COMPLETE,
}