⚡ Introduce a new high-performing standalone chat API (#1200)

Closes #1154

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit

- **New Features**
	- Added authentication functionality for user sessions in chat API.
- Introduced chat-related API endpoints for starting, previewing, and
continuing chat sessions, and streaming messages.
- Implemented WhatsApp API webhook handling for receiving and processing
messages.
- Added environment variable `NEXT_PUBLIC_CHAT_API_URL` for chat API URL
configuration.

- **Bug Fixes**
	- Adjusted file upload logic to correctly determine the API host.
	- Fixed message streaming URL in chat integration with OpenAI.

- **Documentation**
- Updated guides for creating blocks, local installation, self-hosting,
and deployment to use `bun` instead of `pnpm`.

- **Refactor**
	- Refactored chat API functionalities to use modular architecture.
- Simplified client log saving and session update functionalities by
using external functions.
	- Transitioned package management and workflow commands to use `bun`.

- **Chores**
- Switched to `bun` for package management in Dockerfiles and GitHub
workflows.
	- Added new Dockerfile for chat API service setup with Bun framework.
	- Updated `.prettierignore` and documentation with new commands.

- **Style**
	- No visible changes to end-users.

- **Tests**
	- No visible changes to end-users.

- **Revert**
	- No reverts in this release.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

packages/bot-engine/apiHandlers/continueChat.ts

@@ -0,0 +1,102 @@
+import { TRPCError } from '@trpc/server'
+import { isDefined, isNotDefined } from '@typebot.io/lib/utils'
+import { getSession } from '../queries/getSession'
+import { continueBotFlow } from '../continueBotFlow'
+import { filterPotentiallySensitiveLogs } from '../logs/filterPotentiallySensitiveLogs'
+import { parseDynamicTheme } from '../parseDynamicTheme'
+import { saveStateToDatabase } from '../saveStateToDatabase'
+import { computeCurrentProgress } from '../computeCurrentProgress'
+
+type Props = {
+  origin: string | undefined
+  message?: string
+  sessionId: string
+}
+export const continueChat = async ({ origin, sessionId, message }: Props) => {
+  const session = await getSession(sessionId)
+
+  if (!session) {
+    throw new TRPCError({
+      code: 'NOT_FOUND',
+      message: 'Session not found.',
+    })
+  }
+
+  const isSessionExpired =
+    session &&
+    isDefined(session.state.expiryTimeout) &&
+    session.updatedAt.getTime() + session.state.expiryTimeout < Date.now()
+
+  if (isSessionExpired)
+    throw new TRPCError({
+      code: 'NOT_FOUND',
+      message: 'Session expired. You need to start a new session.',
+    })
+
+  let corsOrigin
+
+  if (
+    session?.state.allowedOrigins &&
+    session.state.allowedOrigins.length > 0
+  ) {
+    if (origin && session.state.allowedOrigins.includes(origin))
+      corsOrigin = origin
+    else corsOrigin = session.state.allowedOrigins[0]
+  }
+
+  const {
+    messages,
+    input,
+    clientSideActions,
+    newSessionState,
+    logs,
+    lastMessageNewFormat,
+    visitedEdges,
+  } = await continueBotFlow(message, {
+    version: 2,
+    state: session.state,
+    startTime: Date.now(),
+  })
+
+  if (newSessionState)
+    await saveStateToDatabase({
+      session: {
+        id: session.id,
+        state: newSessionState,
+      },
+      input,
+      logs,
+      clientSideActions,
+      visitedEdges,
+      hasCustomEmbedBubble: messages.some(
+        (message) => message.type === 'custom-embed'
+      ),
+    })
+
+  const isPreview = isNotDefined(session.state.typebotsQueue[0].resultId)
+
+  const isEnded =
+    newSessionState.progressMetadata &&
+    !input?.id &&
+    (clientSideActions?.filter((c) => c.expectsDedicatedReply).length ?? 0) ===
+      0
+
+  return {
+    messages,
+    input,
+    clientSideActions,
+    dynamicTheme: parseDynamicTheme(newSessionState),
+    logs: isPreview ? logs : logs?.filter(filterPotentiallySensitiveLogs),
+    lastMessageNewFormat,
+    corsOrigin,
+    progress: newSessionState.progressMetadata
+      ? isEnded
+        ? 100
+        : computeCurrentProgress({
+            typebotsQueue: newSessionState.typebotsQueue,
+            progressMetadata: newSessionState.progressMetadata,
+            currentInputBlockId: input?.id,
+          })
+      : undefined,
+  }
+}