/*!
 * Copyright (c) Microsoft Corporation and contributors. All rights reserved.
 * Licensed under the MIT License.
 */

import { stringToBuffer } from "@fluid-internal/client-utils";
import { assert } from "@fluidframework/core-utils/internal";
import { IChannelStorageService } from "@fluidframework/datastore-definitions/internal";
import { ISummaryTree } from "@fluidframework/driver-definitions";
import { IBlob, ITree, type ISnapshotTree } from "@fluidframework/driver-definitions/internal";
import { buildSnapshotTree } from "@fluidframework/driver-utils/internal";
import {
	convertSummaryTreeToITree,
	listBlobsAtTreePath,
} from "@fluidframework/runtime-utils/internal";

/**
 * Mock implementation of IChannelStorageService based on ITree input.
 * @legacy @beta
 */
export class MockStorage implements IChannelStorageService {
	public static createFromSummary(summaryTree: ISummaryTree): MockStorage {
		const tree = convertSummaryTreeToITree(summaryTree);
		return new MockStorage(tree);
	}

	private static readBlobCore(tree: ITree | undefined, paths: string[]): IBlob | undefined {
		if (tree) {
			for (const entry of tree.entries) {
				if (entry.path === paths[0]) {
					if (entry.type === "Blob") {
						// eslint-disable-next-line prefer-rest-params
						assert(paths.length === 1, JSON.stringify({ ...arguments }));
						return entry.value;
					}
					if (entry.type === "Tree") {
						return MockStorage.readBlobCore(entry.value, paths.slice(1));
					}
					return undefined;
				}
			}
			return undefined;
		}
	}

	private readonly snapshotTree: ISnapshotTree | undefined;

	constructor(protected tree?: ITree) {
		if (tree === undefined) {
			return;
		}
		this.snapshotTree = buildSnapshotTree(tree.entries, new Map());
	}

	public async readBlob(path: string): Promise<ArrayBufferLike> {
		const blob = MockStorage.readBlobCore(this.tree, path.split("/"));
		assert(blob !== undefined, `Blob does not exist: ${path}`);
		return stringToBuffer(blob.contents, blob.encoding);
	}

	public async contains(path: string): Promise<boolean> {
		return MockStorage.readBlobCore(this.tree, path.split("/")) !== undefined;
	}

	public async list(path: string): Promise<string[]> {
		return listBlobsAtTreePath(this.tree, path);
	}

	public getSnapshotTree(): ISnapshotTree | undefined {
		return this.snapshotTree;
	}
}