import {
  ChangeDetectionStrategy,
  Component,
  ElementRef,
  computed,
  input,
  output,
  viewChild,
} from '@angular/core';

/**
 * 底部输入坞（Demo `.dock`）
 *
 * Demo 形态：圆角卡片 + 自适应高度 textarea + 工具行（附件 / 目标 / 发送）。
 * 与桌面 `composer` 的区别：桌面版工具行在上、输入在下；移动端输入在上、
 * 工具行在下（拇指可达区）。事件语义与桌面一致（draftChange / send / attach）。
 *
 * 安全区：坞底由页面负责加 `--mob-safe-bottom`。
 */
@Component({
  selector: 'app-m-dock',
  changeDetection: ChangeDetectionStrategy.OnPush,
  template: `
    <div class="m-dock">
      <textarea
        rows="1"
        [value]="draft()"
        [placeholder]="placeholder()"
        [attr.aria-label]="placeholder()"
        [disabled]="disabled()"
        (input)="onInput($event)"
        (keydown.enter)="onEnter($event)"
      ></textarea>
      <div class="m-dock-tools">
        <button type="button" class="m-tool" aria-label="添加附件" [disabled]="disabled() || uploading()" (click)="pickFile()">
          <i class="fa-solid fa-paperclip" aria-hidden="true"></i>
        </button>
        <input #fileRef type="file" multiple hidden (change)="onFile($event)" />

        @if (target()) {
          <span class="m-target">
            <i class="fa-solid fa-robot" aria-hidden="true"></i>
            {{ target() }}
          </span>
        }

        <button
          type="button"
          class="m-send"
          [class.ready]="hasContent()"
          [disabled]="disabled() || !hasContent()"
          [attr.aria-label]="sending() ? '发送中' : '发送'"
          (click)="submit()"
        >
          <i [class]="sending() ? 'fa-solid fa-spinner fa-spin' : 'fa-solid fa-arrow-up'" aria-hidden="true"></i>
        </button>
      </div>
      @if (uploading()) {
        <div class="m-dock-progress" role="progressbar" [attr.aria-valuenow]="pct()" aria-valuemin="0" aria-valuemax="100">
          <i [style.width.%]="pct()"></i>
        </div>
      }
    </div>
  `,
  styles: [
    `
      :host {
        display: block;
      }
      .m-dock {
        margin: 0 var(--sp-4);
        padding: var(--sp-3) var(--sp-4);
        border: 1px solid var(--edge);
        border-radius: var(--r-lg);
        background: var(--surface);
        box-shadow: var(--shadow-pop);
        box-sizing: border-box;
      }
      textarea {
        display: block;
        width: 100%;
        min-height: 44px;
        max-height: 120px;
        padding: var(--sp-2) 0;
        border: 0;
        outline: 0;
        resize: none;
        background: transparent;
        color: var(--ink);
        font: inherit;
        font-size: var(--fs-17);
        line-height: 1.5;
      }
      .m-dock-tools {
        display: flex;
        align-items: center;
        gap: var(--sp-3);
        color: var(--muted);
      }
      .m-tool {
        display: grid;
        place-items: center;
        width: 36px;
        height: 36px;
        border: 0;
        border-radius: var(--r-tag);
        background: none;
        color: var(--muted);
        font-size: var(--fs-17);
        cursor: pointer;
      }
      .m-target {
        display: inline-flex;
        align-items: center;
        gap: var(--sp-1);
        min-width: 0;
        overflow: hidden;
        text-overflow: ellipsis;
        white-space: nowrap;
        color: var(--muted);
        font-size: var(--fs-13);
      }
      .m-send {
        margin-left: auto;
        display: grid;
        place-items: center;
        flex: none;
        width: 36px;
        height: 36px;
        border: 0;
        border-radius: var(--r-tag);
        background: var(--primary-subtle);
        color: var(--muted);
        font-size: var(--fs-15);
        cursor: pointer;
        transition:
          background var(--motion-fast) var(--ease-standard),
          color var(--motion-fast) var(--ease-standard);
      }
      .m-send.ready {
        background: var(--primary);
        color: var(--primary-content);
      }
      .m-send:disabled {
        cursor: not-allowed;
      }
      .m-dock-progress {
        height: 3px;
        margin-top: var(--sp-2);
        border-radius: var(--r-tag);
        background: var(--surface-active);
        overflow: hidden;
      }
      .m-dock-progress i {
        display: block;
        height: 100%;
        background: var(--primary);
        transition: width var(--motion-detail) var(--ease-standard);
      }
    `,
  ],
})
export class MDockComponent {
  readonly draft = input('');
  readonly placeholder = input('发消息…');
  /** 右侧显示的目标（数字生命名称）；空则不显示 */
  readonly target = input('');
  readonly disabled = input(false);
  readonly sending = input(false);
  readonly uploading = input(false);
  readonly pct = input(0);

  readonly draftChange = output<string>();
  readonly send = output<string>();
  readonly attach = output<FileList>();

  /** 是否已有待发附件（由页面传入；纯附件也可发送） */
  readonly hasAttachments = input(false);

  protected readonly fileRef = viewChild.required<ElementRef<HTMLInputElement>>('fileRef');

  /** 文本非空 **或** 有待发附件即可发送 */
  protected readonly hasContent = computed(
    () => (this.draft() ?? '').trim().length > 0 || this.hasAttachments(),
  );

  protected onInput(e: Event): void {
    const el = e.target as HTMLTextAreaElement;
    this.draftChange.emit(el.value);
    el.style.height = 'auto';
    el.style.height = `${Math.min(el.scrollHeight, 120)}px`;
  }

  /** 回车发送，Shift+Enter 换行 */
  protected onEnter(e: Event): void {
    const ke = e as KeyboardEvent;
    if (ke.shiftKey) return;
    ke.preventDefault();
    this.submit();
  }

  protected submit(): void {
    if (this.disabled() || this.sending() || !this.hasContent()) return;
    this.send.emit(this.draft().trim());
  }

  /** 打开系统文件选择器 */
  protected pickFile(): void {
    this.fileRef().nativeElement.click();
  }

  protected onFile(e: Event): void {
    const input = e.target as HTMLInputElement;
    if (input.files && input.files.length > 0) this.attach.emit(input.files);
    input.value = '';
  }
}