//
// Generic TreeDataProvider over the node model. Subclasses only implement
// roots(); everything else — lazy children, TreeItem mapping — happens here.
//

const log = require("../util/log.js");
const { message } = require("./nodes.js");

class NodeProvider {
    constructor(store) {
        this.store = store;
        this._roots = null;
    }

    /** Subclasses return an array of nodes (or a Promise of one). */
    roots() {
        return [];
    }

    /** Drops memoised roots so the next getChildren rebuilds from the store. */
    invalidate() {
        this._roots = null;
    }

    async getChildren(element) {
        try {
            if (!element) {
                if (!this._roots) {
                    this._roots = await this.roots();
                    // A section may hoist a repository's children to the top
                    // level; those nodes must not keep a parent Nova cannot see.
                    for (const root of this._roots) root.parent = null;
                }
                return this._roots;
            }

            if (element.children) return element.children;

            if (element.load) {
                const children = await element.load();
                element.children = children || [];
                for (const child of element.children) child.parent = element;
                return element.children;
            }

            return [];
        } catch (error) {
            log.error("tree build failed", String(error && error.stack ? error.stack : error));
            return [message(`⚠ ${error.message || error}`)];
        }
    }

    getParent(element) {
        return element ? element.parent : null;
    }

    getTreeItem(element) {
        const collapsible =
            element.children || element.load
                ? element.expanded
                    ? TreeItemCollapsibleState.Expanded
                    : TreeItemCollapsibleState.Collapsed
                : TreeItemCollapsibleState.None;

        const item = new TreeItem(element.name, collapsible);
        item.identifier = element.identifier;
        item.contextValue = element.contextValue;

        if (element.descriptiveText) item.descriptiveText = element.descriptiveText;
        if (element.tooltip) item.tooltip = element.tooltip;
        if (element.image) item.image = element.image;
        if (element.path) item.path = element.path;
        if (element.command) item.command = element.command;

        return item;
    }
}

exports.NodeProvider = NodeProvider;