export async function useRubyVersion(parameters: TaskParameters, platform: Platform): Promise<void> {
    const toolName: string = 'Ruby';
    const installDir: string | null = tool.findLocalTool(toolName, parameters.versionSpec);
    if (!installDir) {
        // Fail and list available versions
        throw new Error([
            task.loc('VersionNotFound', parameters.versionSpec),
            task.loc('ListAvailableVersions'),
            tool.findLocalToolVersions('Ruby')
        ].join(os.EOL));
    }

    const toolPath: string = path.join(installDir, 'bin');
    if (platform !== Platform.Windows) {
        // replace the default
        const dest: string = '/usr/bin/ruby';
        if (fs.existsSync(dest)) {
            task.debug('removing ' + dest);
            fs.unlinkSync(dest);
        }
        fs.symlinkSync(path.join(toolPath, 'ruby'), dest);
    }

    task.setVariable('rubyLocation', toolPath);
    if (parameters.addToPath) {
        tool.prependPath(toolPath);
    }
}

export async function useRubyVersion(parameters: TaskParameters, platform: Platform): Promise<void> {
    const toolName: string = 'Ruby';
    const installDir: string | null = tool.findLocalTool(toolName, parameters.versionSpec);
    if (!installDir) {
        // Fail and list available versions
        throw new Error([
            task.loc('VersionNotFound', parameters.versionSpec),
            task.loc('ListAvailableVersions', task.getVariable('Agent.ToolsDirectory')),
            tool.findLocalToolVersions('Ruby'),
            task.loc('ToolNotFoundMicrosoftHosted', 'Ruby', 'https://aka.ms/hosted-agent-software'),
            task.loc('ToolNotFoundSelfHosted', 'Ruby', 'https://go.microsoft.com/fwlink/?linkid=2005989')
        ].join(os.EOL));
    }

    const toolPath: string = path.join(installDir, 'bin');
    if (platform !== Platform.Windows) {
        // Ruby / Gem heavily use the '#!/usr/bin/ruby' to find ruby, so this task needs to
        // replace that version of ruby so all the correct version of ruby gets selected
        // replace the default
        const dest: string = '/usr/bin/ruby';
        task.execSync('sudo', `ln -sf ${path.join(toolPath, 'ruby')} ${dest}`); // replace any existing
    }

    task.setVariable('rubyLocation', toolPath);
    if (parameters.addToPath) {
        tool.prependPath(toolPath);
    }
}

export async function usePythonVersion(parameters: Readonly<TaskParameters>, platform: Platform): Promise<void> {
    // Python's prelease versions look like `3.7.0b2`.
    // This is the one part of Python versioning that does not look like semantic versioning, which specifies `3.7.0-b2`.
    // If the version spec contains prerelease versions, we need to convert them to the semantic version equivalent
    const semanticVersionSpec = pythonVersionToSemantic(parameters.versionSpec);
    task.debug(`Semantic version spec of ${parameters.versionSpec} is ${semanticVersionSpec}`);

    const installDir: string | null = tool.findLocalTool('Python', semanticVersionSpec, parameters.architecture);
    if (!installDir) {
        // Fail and list available versions
        const x86Versions = tool.findLocalToolVersions('Python', 'x86')
            .map(s => `${s} (x86)`)
            .join(os.EOL);

        const x64Versions = tool.findLocalToolVersions('Python', 'x64')
            .map(s => `${s} (x64)`)
            .join(os.EOL);

        throw new Error([
            task.loc('VersionNotFound', parameters.versionSpec),
            task.loc('ListAvailableVersions'),
            x86Versions,
            x64Versions
        ].join(os.EOL));
    }

    task.setVariable('pythonLocation', installDir);
    if (parameters.addToPath) {
        toolUtil.prependPathSafe(installDir);

        // Make sure Python's "bin" directories are in PATH.
        // Python has "scripts" or "bin" directories where command-line tools that come with packages are installed.
        // This is where pip is, along with anything that pip installs.
        // There is a seperate directory for `pip install --user`.
        //
        // For reference, these directories are as follows:
        //   macOS / Linux:
        //      <sys.prefix>/bin (by default /usr/local/bin, but not on hosted agents -- see the `else`)
        //      (--user) ~/.local/bin
        //   Windows:
        //      <Python installation dir>\Scripts
        //      (--user) %APPDATA%\Python\PythonXY\Scripts
        // See https://docs.python.org/3/library/sysconfig.html
        if (platform === Platform.Windows) {
            // On Windows, these directories do not get added to PATH, so we will add them ourselves.
            const scriptsDir = path.join(installDir, 'Scripts');
            toolUtil.prependPathSafe(scriptsDir);

            // Add --user directory
            // `installDir` from tool cache should look like $AGENT_TOOLSDIRECTORY/Python/<semantic version>/x64/
            // So if `findLocalTool` succeeded above, we must have a conformant `installDir`
            const version = path.basename(path.dirname(installDir));
            const major = semver.major(version);
            const minor = semver.minor(version);

            const userScriptsDir = path.join(process.env['APPDATA'], 'Python', `Python${major}${minor}`, 'Scripts');
            toolUtil.prependPathSafe(userScriptsDir);
        } else {
            // On Linux and macOS, tools cache should be set up so that each Python version has its own "bin" directory.
            // We do this so that the tool cache can just be dropped on an agent with minimal installation (no copying to /usr/local).
            // This allows us side-by-side the same minor version of Python with different patch versions or architectures (since Python uses /usr/local/lib/python3.6, etc.).
            toolUtil.prependPathSafe(path.join(installDir, 'bin'));

            // On Linux and macOS, pip will create the --user directory and add it to PATH as needed.
        }
    }
}