import {
  AfterViewChecked,
  ChangeDetectorRef,
  Component,
  ElementRef,
  EventEmitter,
  OnDestroy,
  OnInit,
  Output,
  ViewChild,
} from '@angular/core';
import { CommonModule } from '@angular/common';
import { FormsModule } from '@angular/forms';
import { Subscription } from 'rxjs';
import {
  AssistantMessage,
  AssistantService,
  AssistantSuggestion,
  Conversation,
} from '../../services/assistant.service';

/**
 * 全局 AI 助手浮窗
 *
 * - 收起态：右下 56px FAB
 * - 展开态：聊天 / 历史列表二选一视图，可新建会话
 */
@Component({
  selector: 'app-assistant',
  standalone: true,
  imports: [CommonModule, FormsModule],
  templateUrl: './app-assistant.component.html',
  styleUrls: ['./app-assistant.component.css'],
})
export class AppAssistantComponent implements OnInit, OnDestroy, AfterViewChecked {
  @Output() suggestionPick = new EventEmitter<AssistantSuggestion>();
  @Output() expandedChange = new EventEmitter<boolean>();

  @ViewChild('msgList') msgList!: ElementRef<HTMLElement>;
  @ViewChild('inputEl') inputEl!: ElementRef<HTMLTextAreaElement>;

  messages: AssistantMessage[] = [];
  conversations: Conversation[] = [];
  activeId: string | null = null;
  expanded = false;
  loading = false;
  view: 'chat' | 'history' = 'chat';
  draft = '';
  /** 内联模式（首屏对话页）激活中：完全隐藏浮窗 + FAB */
  inlineActive = false;

  private subs = new Subscription();
  private shouldScroll = false;

  constructor(public svc: AssistantService, private cdr: ChangeDetectorRef) {}

  ngOnInit(): void {
    // fetch 路径下回调可能跳出 zone，所有订阅都显式 detectChanges 兜底
    this.subs.add(this.svc.activeMessages$.subscribe((list) => {
      this.messages = list;
      this.shouldScroll = true;
      this.cdr.detectChanges();
    }));
    this.subs.add(this.svc.conversations$.subscribe((list) => {
      this.conversations = list;
      this.cdr.detectChanges();
    }));
    this.subs.add(this.svc.activeId$.subscribe((id) => {
      this.activeId = id;
      this.cdr.detectChanges();
    }));
    this.subs.add(this.svc.expanded$.subscribe((v) => {
      this.expanded = v;
      this.expandedChange.emit(v);
      if (v && this.view === 'chat') {
        this.shouldScroll = true;
        setTimeout(() => this.inputEl?.nativeElement?.focus(), 60);
      }
      this.cdr.detectChanges();
    }));
    this.subs.add(this.svc.view$.subscribe((v) => {
      this.view = v;
      if (v === 'chat') this.shouldScroll = true;
      this.cdr.detectChanges();
    }));
    this.subs.add(this.svc.loading$.subscribe((v) => {
      this.loading = v;
      this.cdr.detectChanges();
    }));
    this.subs.add(this.svc.inlineActive$.subscribe((v) => {
      this.inlineActive = v;
      this.cdr.detectChanges();
    }));
  }

  ngOnDestroy(): void {
    this.subs.unsubscribe();
  }

  ngAfterViewChecked(): void {
    if (this.shouldScroll && this.view === 'chat' && this.msgList) {
      const el = this.msgList.nativeElement;
      el.scrollTop = el.scrollHeight;
      this.shouldScroll = false;
    }
  }

  // ============== UI 操作 ==============

  toggle(): void { this.svc.toggle(); }
  close(): void { this.svc.close(); }

  toggleHistory(): void {
    if (this.view === 'history') this.svc.showChat();
    else this.svc.showHistory();
  }

  newChat(): void {
    this.svc.newConversation();
    setTimeout(() => this.inputEl?.nativeElement?.focus(), 60);
  }

  pickConv(id: string): void {
    this.svc.switchTo(id);
  }

  deleteConv(id: string, ev: MouseEvent): void {
    ev.stopPropagation();
    if (confirm('删除这条会话？')) {
      this.svc.deleteConversation(id);
    }
  }

  submit(): void {
    const text = this.draft.trim();
    if (!text || this.loading) return;
    this.svc.send(text);
    this.draft = '';
  }

  onInputKey(ev: KeyboardEvent): void {
    if (ev.key === 'Enter' && !ev.shiftKey && !ev.altKey) {
      ev.preventDefault();
      this.submit();
    }
  }

  pickSuggestion(s: AssistantSuggestion): void {
    this.suggestionPick.emit(s);
  }

  // ============== 工具 ==============

  trackByMsg = (_: number, m: AssistantMessage) => m.id;
  trackBySuggest = (_: number, s: AssistantSuggestion) => s.tab + s.label;
  trackByConv = (_: number, c: Conversation) => c.id;

  formatTime(ts: number): string {
    if (!ts) return '';
    const d = new Date(ts);
    const now = new Date();
    const isToday = d.toDateString() === now.toDateString();
    const yest = new Date(now.getTime() - 86400000);
    const isYest = d.toDateString() === yest.toDateString();
    const hh = `${d.getHours()}`.padStart(2, '0');
    const mm = `${d.getMinutes()}`.padStart(2, '0');
    if (isToday) return `今天 ${hh}:${mm}`;
    if (isYest) return `昨天 ${hh}:${mm}`;
    return `${d.getMonth() + 1}/${d.getDate()} ${hh}:${mm}`;
  }

  convPreview(c: Conversation): string {
    const lastMsg = [...c.messages].reverse().find((m) => !m.pending && m.content);
    if (!lastMsg) return '（空对话）';
    const txt = lastMsg.content.replace(/\s+/g, ' ').trim();
    return txt.length > 40 ? txt.slice(0, 40) + '…' : txt;
  }
}