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import http from 'node:http';
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import { readAllChunks, tryParse } from '../../src/util.js';
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export class MockServer {
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    /** @type {string} */
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    host;
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    /** @type {number} */
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    port;
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    /** @type {import('http').Server} */
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    server;
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    /**
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     * Creates an instance of MockServer.
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     * @param {object} [param] Options object.
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     * @param {string} [param.host] The hostname or IP address to bind the server to.
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     * @param {number} [param.port] The port number to listen on.
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     */
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    constructor({ host, port } = {}) {
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        this.host = host ?? '127.0.0.1';
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        this.port = port ?? 3000;
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    }
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    /**
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     * Handles Chat Completions requests.
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     * @param {object} jsonBody The parsed JSON body from the request.
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     * @returns {object} Mock response object.
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     */
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    handleChatCompletions(jsonBody) {
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        const messages = jsonBody?.messages;
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        const lastMessage = messages?.[messages.length - 1];
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        const mockResponse = {
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            choices: [
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                {
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                    finish_reason: 'stop',
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                    index: 0,
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                    message: {
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                        role: 'assistant',
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                        reasoning_content: `${jsonBody?.model}\n${messages?.length}\n${jsonBody?.max_tokens}`,
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                        content: String(lastMessage?.content ?? 'No prompt messages.'),
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                    },
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                },
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            ],
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            created: 0,
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            model: jsonBody?.model,
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        };
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        return mockResponse;
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    }
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    /**
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     * Starts the mock server.
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     * @returns {Promise<void>}
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     */
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    async start() {
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        return new Promise((resolve, reject) => {
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            this.server = http.createServer(async (req, res) => {
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                try {
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                    const body = await readAllChunks(req);
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                    const jsonBody = tryParse(body.toString());
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                    if (req.method === 'POST' && req.url === '/v1/chat/completions') {
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                        const mockResponse = this.handleChatCompletions(jsonBody);
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                        res.writeHead(200, { 'Content-Type': 'application/json' });
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                        res.end(JSON.stringify(mockResponse));
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                    } else {
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                        res.writeHead(404);
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                        res.end();
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                    }
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                } catch (error) {
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                    res.writeHead(500);
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                    res.end();
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                }
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            });
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            this.server.on('error', (err) => {
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                reject(err);
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            });
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            this.server.listen(this.port, this.host, () => {
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                resolve();
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            });
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        });
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    }
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    /**
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     * Stops the mock server.
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     * @returns {Promise<void>}
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     */
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    async stop() {
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        return new Promise((resolve, reject) => {
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            if (!this.server) {
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                return reject(new Error('Server is not running.'));
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            }
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            this.server.closeAllConnections();
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            this.server.close(( /** @type {NodeJS.ErrnoException|undefined} */ err) => {
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                if (err && (err?.code !== 'ERR_SERVER_NOT_RUNNING')) {
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                    return reject(err);
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                }
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                resolve();
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            });
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        });
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    }
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}