Feature: Paperless AI (#10319)

src-ui/src/app/components/chat/chat/chat.component.ts

@@ -0,0 +1,140 @@
+import { Component, ElementRef, inject, OnInit, ViewChild } from '@angular/core'
+import { FormsModule, ReactiveFormsModule } from '@angular/forms'
+import { NavigationEnd, Router } from '@angular/router'
+import { NgbDropdownModule } from '@ng-bootstrap/ng-bootstrap'
+import { NgxBootstrapIconsModule } from 'ngx-bootstrap-icons'
+import { filter, map } from 'rxjs'
+import { ChatMessage, ChatService } from 'src/app/services/chat.service'
+
+@Component({
+  selector: 'pngx-chat',
+  imports: [
+    FormsModule,
+    ReactiveFormsModule,
+    NgxBootstrapIconsModule,
+    NgbDropdownModule,
+  ],
+  templateUrl: './chat.component.html',
+  styleUrl: './chat.component.scss',
+})
+export class ChatComponent implements OnInit {
+  public messages: ChatMessage[] = []
+  public loading = false
+  public input: string = ''
+  public documentId!: number
+
+  private chatService: ChatService = inject(ChatService)
+  private router: Router = inject(Router)
+
+  @ViewChild('scrollAnchor') scrollAnchor!: ElementRef<HTMLDivElement>
+  @ViewChild('chatInput') chatInput!: ElementRef<HTMLInputElement>
+
+  private typewriterBuffer: string[] = []
+  private typewriterActive = false
+
+  public get placeholder(): string {
+    return this.documentId
+      ? $localize`Ask a question about this document...`
+      : $localize`Ask a question about a document...`
+  }
+
+  ngOnInit(): void {
+    this.updateDocumentId(this.router.url)
+    this.router.events
+      .pipe(
+        filter((event) => event instanceof NavigationEnd),
+        map((event) => (event as NavigationEnd).url)
+      )
+      .subscribe((url) => {
+        this.updateDocumentId(url)
+      })
+  }
+
+  private updateDocumentId(url: string): void {
+    const docIdRe = url.match(/^\/documents\/(\d+)/)
+    this.documentId = docIdRe ? +docIdRe[1] : undefined
+  }
+
+  sendMessage(): void {
+    if (!this.input.trim()) return
+
+    const userMessage: ChatMessage = { role: 'user', content: this.input }
+    this.messages.push(userMessage)
+    this.scrollToBottom()
+
+    const assistantMessage: ChatMessage = {
+      role: 'assistant',
+      content: '',
+      isStreaming: true,
+    }
+    this.messages.push(assistantMessage)
+    this.loading = true
+
+    let lastPartialLength = 0
+
+    this.chatService.streamChat(this.documentId, this.input).subscribe({
+      next: (chunk) => {
+        const delta = chunk.substring(lastPartialLength)
+        lastPartialLength = chunk.length
+        this.enqueueTypewriter(delta, assistantMessage)
+      },
+      error: () => {
+        assistantMessage.content += '\n\n⚠️ Error receiving response.'
+        assistantMessage.isStreaming = false
+        this.loading = false
+      },
+      complete: () => {
+        assistantMessage.isStreaming = false
+        this.loading = false
+        this.scrollToBottom()
+      },
+    })
+
+    this.input = ''
+  }
+
+  enqueueTypewriter(chunk: string, message: ChatMessage): void {
+    if (!chunk) return
+
+    this.typewriterBuffer.push(...chunk.split(''))
+
+    if (!this.typewriterActive) {
+      this.typewriterActive = true
+      this.playTypewriter(message)
+    }
+  }
+
+  playTypewriter(message: ChatMessage): void {
+    if (this.typewriterBuffer.length === 0) {
+      this.typewriterActive = false
+      return
+    }
+
+    const nextChar = this.typewriterBuffer.shift()
+    message.content += nextChar
+    this.scrollToBottom()
+
+    setTimeout(() => this.playTypewriter(message), 10) // 10ms per character
+  }
+
+  private scrollToBottom(): void {
+    setTimeout(() => {
+      this.scrollAnchor?.nativeElement?.scrollIntoView({ behavior: 'smooth' })
+    }, 50)
+  }
+
+  public onOpenChange(open: boolean): void {
+    if (open) {
+      setTimeout(() => {
+        this.chatInput.nativeElement.focus()
+      }, 10)
+    }
+  }
+
+  public searchInputKeyDown(event: KeyboardEvent) {
+    if (event.key === 'Enter') {
+      event.preventDefault()
+      this.sendMessage()
+    }
+  }
+}