import QtQuick 2.15
import QtQml 2.15

Behavior {
    id: root

    property QtObject fadeTarget: targetProperty.object
    property string fadeProperty: "opacity"
    property var fadeProperties: [fadeProperty]
    property var exitValue: 0
    property var enterValue: 0
    property int fadeDuration: 300
    property string easingType: "Quad"
    property bool delayWhile: false
    onDelayWhileChanged: {
        if (!delayWhile)
            sequentialAnimation.finished();
    }

    readonly property Component shaderEffectSourceWrapperComponent: Item {
        id: ses
        property alias shaderEffectSource: shaderEffectSource
        property alias sourceItem: shaderEffectSource.sourceItem
        parent: sourceItem.parent
        x: sourceItem.x
        y: sourceItem.y
        ShaderEffectSource {
            id: shaderEffectSource
            transformOrigin: sourceItem.transformOrigin
            hideSource: true
            live: false
            width: sourceItem.width
            height: sourceItem.height
        }
    }

    readonly property Component defaultExitAnimation: NumberAnimation {
        properties: root.fadeProperties.join(',')
        duration: root.fadeDuration
        to: root.exitValue
        easing.type: root.easingType === "Linear" ? Easing.Linear : Easing["In"+root.easingType]
    }
    property Component exitAnimation: defaultExitAnimation

    readonly property Component defaultEnterAnimation: NumberAnimation {
        properties: root.fadeProperties.join(',')
        duration: root.fadeDuration
        from: root.enterValue
        to: root.fadeTarget[root.fadeProperties[0]]
        easing.type: root.easingType === "Linear" ? Easing.Linear : Easing["Out"+root.easingType]
    }
    property Component enterAnimation: defaultEnterAnimation

    SequentialAnimation {
        id: sequentialAnimation
        ScriptAction {
            script: {
                const exitItem = shaderEffectSourceWrapperComponent.createObject(null, { sourceItem: root.fadeTarget });
                const exitShaderEffectSource = exitItem.shaderEffectSource;
                if (exitAnimation === root.defaultExitAnimation)
                    root.fadeProperties.forEach(p => exitShaderEffectSource[p] = root.fadeTarget[p]);
                exitShaderEffectSource.width = root.fadeTarget.width;
                exitShaderEffectSource.height = root.fadeTarget.height;
                const exitAnimationInstance = exitAnimation.createObject(root, { target: exitItem.shaderEffectSource });
                exitAnimationInstance.finished.connect(() => {
                                                           sequentialAnimation.finished.disconnect(exitAnimationInstance.start);
                                                           exitAnimationInstance.target = null;
                                                           exitItem.destroy();
                                                           exitAnimationInstance.destroy();
                                                       });
                sequentialAnimation.finished.connect(exitAnimationInstance.start);
            }
        }
        PauseAnimation {
            duration: 5 // figure out how to wait on a signal in an animation (for ShaderEffectSource update)
        }
        PropertyAction {}
        ScriptAction {
            script: {
                const enterItem = shaderEffectSourceWrapperComponent.createObject(null, { sourceItem: root.fadeTarget });
                const enterShaderEffectSource = enterItem.shaderEffectSource;
                if (enterAnimation === root.defaultEnterAnimation)
                    root.fadeProperties.forEach(p => enterShaderEffectSource[p] = root.enterValue);
                enterShaderEffectSource.live = true;
                const enterAnimationInstance = enterAnimation.createObject(root, { target: enterItem.shaderEffectSource });
                enterAnimationInstance.finished.connect(() => {
                                                            sequentialAnimation.finished.disconnect(enterAnimationInstance.start);
                                                            enterAnimationInstance.target = null;
                                                            enterItem.destroy();
                                                            enterAnimationInstance.destroy();
                                                        })
                sequentialAnimation.finished.connect(enterAnimationInstance.start);
                if (!root.delayWhile)
                    sequentialAnimation.finished();
            }
        }
    }
}