Reddit MCP Server

import { config } from "./config.js"; import { RedditPost, RedditComment, RedditSubreddit, RedditUser, RedditSearchResult, ApiCallResult, } from "../types/index.js"; import fs from 'fs/promises'; import path from 'path'; /** * Reddit API Service * Handles all API calls to Reddit with proper error handling and rate limiting * Supports both Client Credentials and Authorization Code OAuth flows */ export class RedditAPIService { private clientId: string; private clientSecret: string; private userAgent: string; private timeout: number; private redirectUri: string; private oauthScopes: string[]; private accessToken: string | null = null; private tokenExpiry: number = 0; private refreshToken: string | null = null; private readonly tokenStoragePath: string; private rateLimitRemaining: number = 60; private rateLimitReset: number = 0; constructor() { this.clientId = config.redditClientId; this.clientSecret = config.redditClientSecret; this.userAgent = config.redditUserAgent; this.timeout = config.timeoutSeconds * 1000; this.redirectUri = config.redditRedirectUri; this.oauthScopes = config.redditOAuthScopes; this.tokenStoragePath = path.join(process.cwd(), 'reddit_tokens.json'); // Load existing tokens on startup this.loadTokensFromStorage(); } /** * Save tokens to persistent storage */ private async saveTokensToStorage(): Promise<void> { try { const tokenData = { accessToken: this.accessToken, refreshToken: this.refreshToken, tokenExpiry: this.tokenExpiry, savedAt: new Date().toISOString() }; await fs.writeFile(this.tokenStoragePath, JSON.stringify(tokenData, null, 2)); } catch (error) { console.error('Failed to save tokens to storage:', error); } } /** * Load tokens from persistent storage */ private async loadTokensFromStorage(): Promise<void> { try { const data = await fs.readFile(this.tokenStoragePath, 'utf-8'); const tokenData = JSON.parse(data); // Only load if tokens are still valid if (tokenData.accessToken && tokenData.tokenExpiry && Date.now() < tokenData.tokenExpiry) { this.accessToken = tokenData.accessToken; this.refreshToken = tokenData.refreshToken; this.tokenExpiry = tokenData.tokenExpiry; // Tokens loaded successfully } else { // Stored tokens expired, will need re-authentication } } catch (error) { // File doesn't exist or invalid format, that's okay // No stored tokens found, will use client credentials } } /** * Get OAuth authorization URL for user to authorize the app */ public getAuthorizationUrl(state?: string): string { const params = new URLSearchParams({ client_id: this.clientId, response_type: 'code', state: state || 'mcp_reddit_auth', redirect_uri: this.redirectUri, duration: 'permanent', scope: this.oauthScopes.join(' ') }); return `https://www.reddit.com/api/v1/authorize?${params.toString()}`; } /** * Exchange authorization code for access token */ public async exchangeCodeForToken(authorizationCode: string): Promise<boolean> { try { const response = await fetch("https://www.reddit.com/api/v1/access_token", { method: "POST", headers: { "Authorization": `Basic ${Buffer.from(`${this.clientId}:${this.clientSecret}`).toString("base64")}`, "Content-Type": "application/x-www-form-urlencoded", "User-Agent": this.userAgent, }, body: new URLSearchParams({ grant_type: 'authorization_code', code: authorizationCode, redirect_uri: this.redirectUri }), signal: AbortSignal.timeout(this.timeout), }); if (!response.ok) { const errorText = await response.text(); throw new Error(`OAuth code exchange failed: ${response.status} ${errorText}`); } const data = await response.json(); this.accessToken = data.access_token; this.refreshToken = data.refresh_token; this.tokenExpiry = Date.now() + (data.expires_in * 1000); // Save tokens to persistent storage await this.saveTokensToStorage(); // OAuth authorization successful // Token expires in: ${data.expires_in} seconds // Scopes granted: ${data.scope} return true; } catch (error) { // OAuth code exchange failed: ${error instanceof Error ? error.message : 'Unknown error'} return false; } } /** * Get OAuth access token for Reddit API * Tries Authorization Code flow first, falls back to Client Credentials */ private async getAccessToken(): Promise<string> { // Check if we have a valid token if (this.accessToken && Date.now() < this.tokenExpiry) { return this.accessToken; } // Try to refresh token if available if (this.refreshToken) { const refreshed = await this.refreshAccessToken(); if (refreshed) { return this.accessToken!; } } // Fall back to client credentials flow return this.getClientCredentialsToken(); } /** * Refresh access token using refresh token */ private async refreshAccessToken(): Promise<boolean> { try { const response = await fetch("https://www.reddit.com/api/v1/access_token", { method: "POST", headers: { "Authorization": `Basic ${Buffer.from(`${this.clientId}:${this.clientSecret}`).toString("base64")}`, "Content-Type": "application/x-www-form-urlencoded", "User-Agent": this.userAgent, }, body: new URLSearchParams({ grant_type: 'refresh_token', refresh_token: this.refreshToken! }), signal: AbortSignal.timeout(this.timeout), }); if (!response.ok) { return false; } const data = await response.json(); this.accessToken = data.access_token; this.tokenExpiry = Date.now() + (data.expires_in * 1000); // Save refreshed tokens to storage await this.saveTokensToStorage(); return true; } catch (error) { return false; } } /** * Get access token using client credentials flow (fallback) */ private async getClientCredentialsToken(): Promise<string> { try { const response = await fetch("https://www.reddit.com/api/v1/access_token", { method: "POST", headers: { "Authorization": `Basic ${Buffer.from(`${this.clientId}:${this.clientSecret}`).toString("base64")}`, "Content-Type": "application/x-www-form-urlencoded", "User-Agent": this.userAgent, }, body: "grant_type=client_credentials", signal: AbortSignal.timeout(this.timeout), }); if (!response.ok) { throw new Error(`OAuth failed: ${response.status} ${response.statusText}`); } const data = await response.json(); this.accessToken = data.access_token; this.tokenExpiry = Date.now() + (data.expires_in * 1000); // Using Client Credentials flow (limited scope) return this.accessToken!; } catch (error) { throw new Error(`Failed to get access token: ${error instanceof Error ? error.message : "Unknown error"}`); } } /** * Check if we have a valid OAuth token with proper scopes */ public hasValidOAuthToken(): boolean { return this.accessToken !== null && Date.now() < this.tokenExpiry; } /** * Get current OAuth scopes */ public getCurrentScopes(): string[] { return this.oauthScopes; } /** * Make a GET request to Reddit API */ private async makeRequest<T>( endpoint: string, params: Record<string, any> = {}, ): Promise<ApiCallResult> { try { const accessToken = await this.getAccessToken(); // Build URL with parameters const url = new URL(`https://oauth.reddit.com${endpoint}`); Object.entries(params).forEach(([key, value]) => { if (value !== undefined && value !== null) { url.searchParams.append(key, value.toString()); } }); // Make the request const response = await fetch(url.toString(), { method: "GET", headers: { "Authorization": `Bearer ${accessToken}`, "User-Agent": this.userAgent, }, signal: AbortSignal.timeout(this.timeout), }); // Handle rate limiting const remaining = response.headers.get('x-ratelimit-remaining'); const reset = response.headers.get('x-ratelimit-reset'); if (remaining) { this.rateLimitRemaining = parseInt(remaining); } if (reset) { this.rateLimitReset = parseInt(reset); } // Check if we're approaching rate limit if (this.rateLimitRemaining < 5) { // Rate limit warning: ${this.rateLimitRemaining} requests remaining } if (!response.ok) { const errorText = await response.text(); // Handle rate limit exceeded if (response.status === 429) { const waitTime = this.rateLimitReset > 0 ? this.rateLimitReset : 60; return { success: false, error: `Rate limit exceeded. Please wait ${waitTime} seconds before trying again.`, endpoint, timestamp: Date.now(), }; } return { success: false, error: `Reddit API Error ${response.status}: ${errorText}`, endpoint, timestamp: Date.now(), }; } const data = await response.json(); return { success: true, data, endpoint, timestamp: Date.now(), }; } catch (error) { return { success: false, error: error instanceof Error ? error.message : "Unknown error", endpoint, timestamp: Date.now(), }; } } /** * Get posts from a subreddit */ async getSubredditPosts( subreddit: string, sort: "hot" | "new" | "top" | "rising" | "controversial" = "hot", limit: number = 25, time?: "hour" | "day" | "week" | "month" | "year" | "all", ): Promise<ApiCallResult> { const params: Record<string, any> = { limit }; if (time && (sort === "top" || sort === "controversial")) { params.t = time; } return this.makeRequest<{ data: { children: Array<{ data: RedditPost }> } }>( `/r/${subreddit}/${sort}.json`, params, ); } /** * Search Reddit posts and comments */ async searchReddit( query: string, subreddit?: string, sort: "relevance" | "hot" | "top" | "new" | "comments" = "relevance", time: "hour" | "day" | "week" | "month" | "year" | "all" = "all", limit: number = 25, ): Promise<ApiCallResult> { const params: Record<string, any> = { q: query, sort, t: time, limit }; if (subreddit) { params.restrict_sr = "on"; params.subreddit = subreddit; } return this.makeRequest<{ data: { children: Array<{ data: RedditPost }> } }>( "/search.json", params, ); } /** * Get user profile information */ async getUserProfile(username: string): Promise<ApiCallResult> { return this.makeRequest<{ data: RedditUser }>( `/user/${username}/about.json`, ); } /** * Get subreddit information */ async getSubredditInfo(subreddit: string): Promise<ApiCallResult> { return this.makeRequest<{ data: RedditSubreddit }>( `/r/${subreddit}/about.json`, ); } /** * Get comments for a specific post */ async getPostComments( postId: string, limit: number = 25, sort: "best" | "top" | "new" | "controversial" | "old" | "qa" = "best", ): Promise<ApiCallResult> { const params: Record<string, any> = { limit, sort }; return this.makeRequest<Array<{ data: { children: Array<{ data: RedditComment }> } }>>( `/comments/${postId}.json`, params, ); } /** * Get trending subreddits */ async getTrendingSubreddits(limit: number = 25): Promise<ApiCallResult> { return this.makeRequest<{ data: { children: Array<{ data: RedditSubreddit }> } }>( "/subreddits/popular.json", { limit }, ); } /** * Get crossposts for a specific post */ async getCrossPosts(postId: string, limit: number = 25): Promise<ApiCallResult> { return this.makeRequest<{ data: { children: Array<{ data: RedditPost }> } }>( `/duplicates/${postId}.json`, { limit }, ); } // ======================================== // 🎯 ACTION METHODS (OAuth Required) // ======================================== /** * Submit a new post to a subreddit */ async submitPost( subreddit: string, title: string, content: string, kind: "self" | "link" = "self", nsfw: boolean = false, spoiler: boolean = false ): Promise<ApiCallResult> { const params: Record<string, any> = { sr: subreddit, title, kind, nsfw: nsfw ? "on" : "off", spoiler: spoiler ? "on" : "off" }; if (kind === "self") { params.text = content; } else { params.url = content; } return this.makePostRequest("/api/submit", params); } /** * Submit a comment on a post */ async submitComment( postId: string, text: string, parentId?: string ): Promise<ApiCallResult> { const params: Record<string, any> = { thing_id: parentId || postId, text }; return this.makePostRequest("/api/comment", params); } /** * Vote on a post or comment */ async vote( postId: string, direction: "1" | "0" | "-1" ): Promise<ApiCallResult> { const params = { id: postId, dir: direction }; return this.makePostRequest("/api/vote", params); } /** * Save or unsave a post */ async savePost( postId: string, action: "save" | "unsave" ): Promise<ApiCallResult> { const params = { id: postId }; const endpoint = action === "save" ? "/api/save" : "/api/unsave"; return this.makePostRequest(endpoint, params); } /** * Send a private message */ async sendMessage( to: string, subject: string, text: string ): Promise<ApiCallResult> { const params = { to, subject, text }; return this.makePostRequest("/api/compose", params); } /** * Subscribe or unsubscribe from a subreddit */ async subscribeSubreddit( subreddit: string, action: "follow" | "unfollow" ): Promise<ApiCallResult> { // Convert follow/unfollow to sub/unsub for Reddit API const redditAction = action === "follow" ? "sub" : "unsub"; const params = { sr_name: subreddit, // Use sr_name instead of sr action: redditAction }; return this.makePostRequest("/api/subscribe", params); } /** * Make a POST request to Reddit API */ private async makePostRequest<T>( endpoint: string, params: Record<string, any> = {}, ): Promise<ApiCallResult> { try { const accessToken = await this.getAccessToken(); // Build URL const url = new URL(`https://oauth.reddit.com${endpoint}`); // Make the POST request const response = await fetch(url.toString(), { method: "POST", headers: { Authorization: `Bearer ${accessToken}`, "User-Agent": this.userAgent, "Content-Type": "application/x-www-form-urlencoded", }, body: new URLSearchParams(params), signal: AbortSignal.timeout(this.timeout), }); if (!response.ok) { const errorText = await response.text(); return { success: false, error: `Reddit API Error ${response.status}: ${errorText}`, endpoint, timestamp: Date.now(), }; } const data = await response.json(); return { success: true, data, endpoint, timestamp: Date.now(), }; } catch (error) { return { success: false, error: error instanceof Error ? error.message : "Unknown error", endpoint, timestamp: Date.now(), }; } } // Check if OAuth tokens are valid hasValidTokens(): boolean { return !!(this.accessToken && this.tokenExpiry && Date.now() < this.tokenExpiry); } // Set OAuth tokens manually (for environment variables) setTokens(accessToken: string, refreshToken?: string, expiresIn?: number): void { this.accessToken = accessToken; if (refreshToken) { this.refreshToken = refreshToken; } if (expiresIn) { this.tokenExpiry = Date.now() + (expiresIn * 1000); } // Save to storage this.saveTokensToStorage(); } } // Export singleton instance export const redditAPI = new RedditAPIService();