// Copyright (C) The Arvados Authors. All rights reserved.
//
// SPDX-License-Identifier: AGPL-3.0

import { CollectionPanelFilesState, CollectionPanelFile, CollectionPanelDirectory, mapCollectionFileToCollectionPanelFile, mergeCollectionPanelFilesStates } from './collection-panel-files-state';
import { CollectionPanelFilesAction, collectionPanelFilesAction } from "./collection-panel-files-actions";
import { createTree, mapTreeValues, getNode, setNode, getNodeAncestorsIds, getNodeDescendantsIds, setNodeValueWith, mapTree } from "~/models/tree";
import { CollectionFileType } from "~/models/collection-file";

export const collectionPanelFilesReducer = (state: CollectionPanelFilesState = createTree(), action: CollectionPanelFilesAction) => {
    // Low-level tree handling setNode() func does in-place data modifications
    // for performance reasons, so we pass a copy of 'state' to avoid side effects.
    return collectionPanelFilesAction.match(action, {
        SET_COLLECTION_FILES: files =>
            mergeCollectionPanelFilesStates({...state}, mapTree(mapCollectionFileToCollectionPanelFile)(files)),

        TOGGLE_COLLECTION_FILE_COLLAPSE: data =>
            toggleCollapse(data.id)({...state}),

        TOGGLE_COLLECTION_FILE_SELECTION: data => [{...state}]
            .map(toggleSelected(data.id))
            .map(toggleAncestors(data.id))
            .map(toggleDescendants(data.id))[0],

        SELECT_ALL_COLLECTION_FILES: () =>
            mapTreeValues(v => ({ ...v, selected: true }))({...state}),

        UNSELECT_ALL_COLLECTION_FILES: () =>
            mapTreeValues(v => ({ ...v, selected: false }))({...state}),

        default: () => state
    }) as CollectionPanelFilesState;
};

const toggleCollapse = (id: string) => (tree: CollectionPanelFilesState) =>
    setNodeValueWith((v: CollectionPanelDirectory | CollectionPanelFile) =>
        v.type === CollectionFileType.DIRECTORY
            ? { ...v, collapsed: !v.collapsed }
            : v)(id)(tree);


const toggleSelected = (id: string) => (tree: CollectionPanelFilesState) =>
    setNodeValueWith((v: CollectionPanelDirectory | CollectionPanelFile) => ({ ...v, selected: !v.selected }))(id)(tree);


const toggleDescendants = (id: string) => (tree: CollectionPanelFilesState) => {
    const node = getNode(id)(tree);
    if (node && node.value.type === CollectionFileType.DIRECTORY) {
        return getNodeDescendantsIds(id)(tree)
            .reduce((newTree, id) =>
                setNodeValueWith(v => ({ ...v, selected: node.value.selected }))(id)(newTree), tree);
    }
    return tree;
};

const toggleAncestors = (id: string) => (tree: CollectionPanelFilesState) => {
    const ancestors = getNodeAncestorsIds(id)(tree).reverse();
    return ancestors.reduce((newTree, parent) => parent ? toggleParentNode(parent)(newTree) : newTree, tree);
};

const toggleParentNode = (id: string) => (tree: CollectionPanelFilesState) => {
    const node = getNode(id)(tree);
    if (node) {
        const parentNode = getNode(node.id)(tree);
        if (parentNode) {
            const selected = parentNode.children
                .map(id => getNode(id)(tree))
                .every(node => node !== undefined && node.value.selected);
            return setNodeValueWith(v => ({ ...v, selected }))(parentNode.id)(tree);
        }
        return setNode(node)(tree);
    }
    return tree;
};