Added Slack account linking and implemented private Slack channels creation for mentorship pairs

[mafernandag]

This PR introduces a complete Slack integration to enable seamless communication between the Mentorship App and existing Slack workspaces. It supports OAuth linking, admin channel management, and bi-directional message syncing for mentorship pairs. Closes #41.

⚠️ IMPORTANT: This feature has not yet been fully end-to-end tested locally. Verifying the "Private Channel" creation and message bridging requires two distinct Slack accounts (Mentor & Mentee) linked within the same workspace. This code is ready to be deployed to a staging environment where multi-user testing can be performed.

Key Features:

Authentication & Linking:

• OAuth Flow: New endpoints to allow users to link their Slack accounts to their App profiles.
• Token Storage: Securely stores Slack user IDs and access tokens in Firestore.

Admin Capabilities:

• Backend Support for Channel Management: Added API endpoints and client functions to support future admin channel management features. (UI pending)

Mentorship Chat Sync (Two-Way Bridging):

• Private Channels: Automatically creates a private Slack channel (e.g., #mentor-) for each mentorship match.
• Auto-Invite: Automatically invites both the Mentor and Mentee (if linked) to this shared private channel.
• Real-time Sync:
  • App → Slack: Messages sent in the App are posted to the private Slack channel.
  • Slack → App: Replies in the Slack channel are captured via Event Subscriptions and synced back to the App chat interface.

Infrastructure:

• New Google Cloud Functions (slackEvents, slackBridgeMessages) to handle webhooks and API calls.
• Robust error handling for missing scopes or unlinked users.

[github-actions]

Visit the preview URL for this PR (updated for commit 59054ff):

https://mentor-match-backend--pr-56-txwh4zla.web.app

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[Copilot]

Pull request overview

This PR introduces comprehensive Slack integration to enable two-way communication between the Mentorship App and Slack workspaces. The implementation supports OAuth account linking, automatic private channel creation for mentorship pairs, and bidirectional message synchronization.

Key Changes:

• OAuth flow for linking user Slack accounts with user tokens stored in Firestore
• Automatic creation of private Slack channels for each mentorship pair with auto-invite functionality
• Real-time message bridging using Socket.io for app-to-Slack and Slack-to-app synchronization
• Admin API endpoints for manual channel management (UI pending)
• Google Cloud Functions for handling Slack webhooks and message forwarding

Reviewed changes

Copilot reviewed 14 out of 17 changed files in this pull request and generated 21 comments.

Show a summary per file

File	Description
functions/slack.js	Core Slack integration logic including event handling, signature verification, channel creation, and message forwarding
functions/index.js	OAuth callback endpoints and admin channel management routes integrated into Express API
functions/package.json	Upgraded firebase-functions to v7.0.0 for enhanced functionality
src/components/dashboard/SlackPage.jsx	UI component for Slack account linking with connection status display
src/components/SlackOAuthPage.jsx	OAuth callback handler with popup window support and user refresh
src/components/dashboard/SideMenu.jsx	Added Slack menu item with inline SVG icon
src/components/chat/Chat.jsx	Socket.io integration for real-time Slack message sync and dual-send functionality
src/hooks/useUser.jsx	Cross-window message listener for OAuth popup completion events
src/api/slackBridge.js	Client-side API functions for posting messages and creating channels
src/api/firebaseConfig.js	Enhanced test environment compatibility with conditional initialization
package.json	Added dependencies: @slack/web-api, socket.io, socket.io-client, body-parser
App.jsx	Added OAuth success route
.gitignore	Added Slack server directory and local env files

Files not reviewed (2)

• mentor-match-app/functions/package-lock.json: Language not supported
• mentor-match-app/package-lock.json: Language not supported