cli-logger.js

"use strict";
/**
 * @license
 * Copyright Google LLC All Rights Reserved.
 *
 * Use of this source code is governed by an MIT-style license that can be
 * found in the LICENSE file at https://angular.dev/license
 */
Object.defineProperty(exports, "__esModule", { value: true });
exports.createConsoleLogger = createConsoleLogger;
const rxjs_1 = require("rxjs");
const src_1 = require("../src");
/**
 * A Logger that sends information to STDOUT and STDERR.
 */
function createConsoleLogger(verbose = false, stdout = process.stdout, stderr = process.stderr, colors) {
    const logger = new src_1.logging.IndentLogger('cling');
    logger.pipe((0, rxjs_1.filter)((entry) => entry.level !== 'debug' || verbose)).subscribe((entry) => {
        const color = colors && colors[entry.level];
        let output = stdout;
        switch (entry.level) {
            case 'warn':
            case 'fatal':
            case 'error':
                output = stderr;
                break;
        }
        // If we do console.log(message) or process.stdout.write(message + '\n'), the process might
        // stop before the whole message is written and the stream is flushed. This happens when
        // streams are asynchronous.
        //
        // NodeJS IO streams are different depending on platform and usage. In POSIX environment,
        // for example, they're asynchronous when writing to a pipe, but synchronous when writing
        // to a TTY. In windows, it's the other way around. You can verify which is which with
        // stream.isTTY and platform, but this is not good enough.
        // In the async case, one should wait for the callback before sending more data or
        // continuing the process. In our case it would be rather hard to do (but not impossible).
        //
        // Instead we take the easy way out and simply chunk the message and call the write
        // function while the buffer drain itself asynchronously. With a smaller chunk size than
        // the buffer, we are mostly certain that it works. In this case, the chunk has been picked
        // as half a page size (4096/2 = 2048), minus some bytes for the color formatting.
        // On POSIX it seems the buffer is 2 pages (8192), but just to be sure (could be different
        // by platform).
        //
        // For more details, see https://nodejs.org/api/process.html#process_a_note_on_process_i_o
        const chunkSize = 2000; // Small chunk.
        let message = entry.message;
        while (message) {
            const chunk = message.slice(0, chunkSize);
            message = message.slice(chunkSize);
            output.write(color ? color(chunk) : chunk);
        }
        output.write('\n');
    });
    return logger;
}