/* --------------------------------------------------------------------------------------------
 * Copyright (c) Microsoft Corporation. All Rights Reserved.
 * See 'LICENSE' in the project root for license information.
 * ------------------------------------------------------------------------------------------ */

import { createHash } from 'crypto';
import { homedir } from 'os';
import { posix, win32 } from 'path';

function isFullyQualifiedPath(value: string, platform: NodeJS.Platform): boolean {
    const path = platform === 'win32' ? win32 : posix;
    return path.isAbsolute(value) && (platform !== 'win32' || path.parse(value).root.length > 1);
}

export function getVSCodeTestIsolate(
    scriptDirectory: string,
    platform: NodeJS.Platform = process.platform,
    environment: NodeJS.ProcessEnv = process.env,
    homeDirectory: string = homedir()): string {
    const path = platform === 'win32' ? win32 : posix;
    const override = environment.CPPTOOLS_VSCODE_TEST_ROOT;
    let root: string;

    if (override) {
        if (!isFullyQualifiedPath(override, platform)) {
            throw new Error('CPPTOOLS_VSCODE_TEST_ROOT must be a fully qualified absolute path.');
        }
        root = override;
    } else {
        switch (platform) {
            case 'win32': {
                const localAppData = environment.LOCALAPPDATA;
                const cacheDirectory = localAppData && isFullyQualifiedPath(localAppData, platform) ? localAppData : path.resolve(homeDirectory, 'AppData', 'Local');
                root = path.resolve(cacheDirectory, 'Microsoft', 'vscode-cpptools', 'vscode-test');
                break;
            }
            case 'darwin':
                root = path.resolve(homeDirectory, 'Library', 'Caches', 'vscode-cpptools', 'vscode-test');
                break;
            default: {
                const xdgCacheHome = environment.XDG_CACHE_HOME;
                const cacheDirectory = xdgCacheHome && isFullyQualifiedPath(xdgCacheHome, platform) ? xdgCacheHome : path.resolve(homeDirectory, '.cache');
                root = path.resolve(cacheDirectory, 'vscode-cpptools', 'vscode-test');
                break;
            }
        }
    }

    const worktreeHash = createHash('sha256').update(scriptDirectory).digest('hex').substring(0, 6);
    return path.resolve(root, worktreeHash);
}