const fetch = require('node-fetch');
const { getEnv } = require('@nexusai/shared');

const BASE_URL = getEnv('MEMORY_SERVICE_URL', 'http://localhost:3002');

//function to get session by external id, returns null if not found, throws error for other issues
async function getSessionByExternalId(externalId) {
    const res = await fetch(`${BASE_URL}/sessions/by-external/${externalId}`);

    if (res.status === 404) return null; // Not found or bad request
    if (!res.ok) throw new Error(`Memory service error: ${res.status} ${res.statusText}`);  // Other errors

    return res.json();
}

// create a new session with an external ID, returns the created session
async function createSession(externalId) {
    const res = await fetch(`${BASE_URL}/sessions`, {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({ externalId })
    });
    if (!res.ok) throw new Error(`Failed to create sessions: ${res.status} ${res.statusText}`);
    return res.json();
}

async function getRecentEpisodes(sessionId, limit = 10) {
    const res = await fetch(`${BASE_URL}/sessions/${sessionId}/episodes?limit=${limit}`);
    if (!res.ok) throw new Error(`Failed to fetch episodes: ${res.status} ${res.statusText}`);
    return res.json();
}

async function createEpisode(sessionId, userMessage, aiResponse, tokenCount) {
    const res = await fetch(`${BASE_URL}/episodes`, {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({ sessionId, userMessage, aiResponse, tokenCount })
    });
    if (!res.ok) throw new Error(`Failed to create episode: ${res.status} ${res.statusText}`);
    return res.json();
}

async function getEpisodeById(episodeId) {
    const res = await fetch(`${BASE_URL}/episodes/${episodeId}`);
    if (res.status === 404) return null;
    if (!res.ok) throw new Error(`Failed to fetch episode: ${res.status}`);
    return res.json();
}

module.exports = {
    getSessionByExternalId,
    createSession,
    getRecentEpisodes,
    createEpisode,
    getEpisodeById
}