tw2/examples/agent/a2ui_agent/samples/client/lit/shell/app.ts

/*
 Copyright 2025 Google LLC

 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
 You may obtain a copy of the License at

      https://www.apache.org/licenses/LICENSE-2.0

 Unless required by applicable law or agreed to in writing, software
 distributed under the License is distributed on an "AS IS" BASIS,
 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 See the License for the specific language governing permissions and
 limitations under the License.
 */

import { SignalWatcher } from "@lit-labs/signals";
import { provide } from "@lit/context";
import {
  LitElement,
  html,
  css,
  nothing,
  HTMLTemplateResult,
  unsafeCSS,
} from "lit";
import { customElement, state } from "lit/decorators.js";
import { theme as uiTheme } from "./theme/default-theme.js";
import { A2UIClient } from "./client.js";
import {
  SnackbarAction,
  SnackbarMessage,
  SnackbarUUID,
  SnackType,
} from "./types/types.js";
import { type Snackbar } from "./ui/snackbar.js";
import { repeat } from "lit/directives/repeat.js";
import { v0_8 } from "@a2ui/lit";
import * as UI from "@a2ui/lit/ui";

// App elements.
import "./ui/ui.js";

// Configurations
import { AppConfig } from "./configs/types.js";
import { config as restaurantConfig } from "./configs/restaurant.js";
import { config as contactsConfig } from "./configs/contacts.js";
import { styleMap } from "lit/directives/style-map.js";

const configs: Record<string, AppConfig> = {
  restaurant: restaurantConfig,
  contacts: contactsConfig,
};

@customElement("a2ui-shell")
export class A2UILayoutEditor extends SignalWatcher(LitElement) {
  @provide({ context: UI.Context.themeContext })
  accessor theme: v0_8.Types.Theme = uiTheme;

  @state()
  accessor #requesting = false;

  @state()
  accessor #error: string | null = null;

  @state()
  accessor #lastMessages: v0_8.Types.ServerToClientMessage[] = [];

  @state()
  accessor config: AppConfig = configs.restaurant;

  @state()
  accessor #loadingTextIndex = 0;
  #loadingInterval: number | undefined;

  static styles = [
    unsafeCSS(v0_8.Styles.structuralStyles),
    css`
      * {
        box-sizing: border-box;
      }

      :host {
        display: block;
        max-width: 640px;
        margin: 0 auto;
        min-height: 100%;
        color: light-dark(var(--n-10), var(--n-90));
        font-family: var(--font-family);
      }

      #hero-img {
        width: 100%;
        max-width: 400px;
        aspect-ratio: 1280/720;
        height: auto;
        margin-bottom: var(--bb-grid-size-6);
        display: block;
        margin: 0 auto;
        background: var(--background-image-light) center center / contain
          no-repeat;
      }

      #surfaces {
        width: 100%;
        max-width: 100svw;
        padding: var(--bb-grid-size-3);
        animation: fadeIn 1s cubic-bezier(0, 0, 0.3, 1) 0.3s backwards;
      }

      form {
        display: flex;
        flex-direction: column;
        flex: 1;
        gap: 16px;
        align-items: center;
        padding: 16px 0;
        animation: fadeIn 1s cubic-bezier(0, 0, 0.3, 1) 1s backwards;

        & h1 {
          color: light-dark(var(--p-40), var(--n-90));
        }

        & > div {
          display: flex;
          flex: 1;
          gap: 16px;
          align-items: center;
          width: 100%;

          & > input {
            display: block;
            flex: 1;
            border-radius: 32px;
            padding: 16px 24px;
            border: 1px solid var(--p-60);
            background: light-dark(var(--n-100), var(--n-10));
            font-size: 16px;
          }

          & > button {
            display: flex;
            align-items: center;
            background: var(--p-40);
            color: var(--n-100);
            border: none;
            padding: 8px 16px;
            border-radius: 32px;
            opacity: 0.5;

            &:not([disabled]) {
              cursor: pointer;
              opacity: 1;
            }
          }
        }
      }

      .rotate {
        animation: rotate 1s linear infinite;
      }

      .pending {
        width: 100%;
        min-height: 200px;
        display: flex;
        flex-direction: column;
        align-items: center;
        justify-content: center;
        animation: fadeIn 1s cubic-bezier(0, 0, 0.3, 1) 0.3s backwards;
        gap: 16px;
      }

      .spinner {
        width: 48px;
        height: 48px;
        border: 4px solid rgba(255, 255, 255, 0.1);
        border-left-color: var(--p-60);
        border-radius: 50%;
        animation: spin 1s linear infinite;
      }

      .theme-toggle {
        padding: 0;
        margin: 0;
        border: none;
        display: flex;
        align-items: center;
        justify-content: center;
        position: fixed;
        top: var(--bb-grid-size-3);
        right: var(--bb-grid-size-4);
        background: light-dark(var(--n-100), var(--n-0));
        border-radius: 50%;
        color: var(--p-30);
        cursor: pointer;
        width: 48px;
        height: 48px;
        font-size: 32px;

        & .g-icon {
          pointer-events: none;

          &::before {
            content: "dark_mode";
          }
        }
      }

      @container style(--color-scheme: dark) {
        .theme-toggle .g-icon::before {
          content: "light_mode";
          color: var(--n-90);
        }

        #hero-img {
          background-image: var(--background-image-dark);
        }
      }

      @keyframes spin {
        to {
          transform: rotate(360deg);
        }
      }

      @keyframes pulse {
        0% {
          opacity: 0.6;
        }
        50% {
          opacity: 1;
        }
        100% {
          opacity: 0.6;
        }
      }

      .error {
        color: var(--e-40);
        background-color: var(--e-95);
        border: 1px solid var(--e-80);
        padding: 16px;
        border-radius: 8px;
      }

      @keyframes fadeIn {
        from {
          opacity: 0;
        }

        to {
          opacity: 1;
        }
      }

      @keyframes rotate {
        from {
          rotate: 0deg;
        }

        to {
          rotate: 360deg;
        }
      }
    `,
  ];

  #processor = v0_8.Data.createSignalA2uiMessageProcessor();
  #a2uiClient = new A2UIClient();
  #snackbar: Snackbar | undefined = undefined;
  #pendingSnackbarMessages: Array<{
    message: SnackbarMessage;
    replaceAll: boolean;
  }> = [];

  #maybeRenderError() {
    if (!this.#error) return nothing;

    return html`<div class="error">${this.#error}</div>`;
  }

  connectedCallback() {
    super.connectedCallback();

    // Load config from URL
    const urlParams = new URLSearchParams(window.location.search);
    const appKey = urlParams.get("app") || "restaurant";
    this.config = configs[appKey] || configs.restaurant;

    // Apply the theme directly, which will use the Lit context.
    if (this.config.theme) {
      this.theme = this.config.theme;
    }

    window.document.title = this.config.title;
    window.document.documentElement.style.setProperty(
      "--background",
      this.config.background
    );

    // Initialize client with configured URL
    this.#a2uiClient = new A2UIClient(this.config.serverUrl);
  }

  render() {
    return [
      this.#renderThemeToggle(),
      this.#maybeRenderForm(),
      this.#maybeRenderData(),
      this.#maybeRenderError(),
    ];
  }

  #renderThemeToggle() {
    return html` <div>
      <button
        @click=${(evt: Event) => {
        if (!(evt.target instanceof HTMLButtonElement)) return;
        const { colorScheme } = window.getComputedStyle(evt.target);
        if (colorScheme === "dark") {
          document.body.classList.add("light");
          document.body.classList.remove("dark");
        } else {
          document.body.classList.add("dark");
          document.body.classList.remove("light");
        }
      }}
        class="theme-toggle"
      >
        <span class="g-icon filled-heavy"></span>
      </button>
    </div>`;
  }

  #maybeRenderForm() {
    if (this.#requesting) return nothing;
    if (this.#lastMessages.length > 0) return nothing;

    return html` <form
      @submit=${async (evt: Event) => {
        evt.preventDefault();
        if (!(evt.target instanceof HTMLFormElement)) {
          return;
        }
        const data = new FormData(evt.target);
        const body = data.get("body") ?? null;
        if (!body) {
          return;
        }
        const message = body as v0_8.Types.A2UIClientEventMessage;
        await this.#sendAndProcessMessage(message);
      }}
    >
      ${this.config.heroImage
        ? html`<div
            style=${styleMap({
          "--background-image-light": `url(${this.config.heroImage})`,
          "--background-image-dark": `url(${this.config.heroImageDark ?? this.config.heroImage
            })`,
        })}
            id="hero-img"
          ></div>`
        : nothing}
      <h1 class="app-title">${this.config.title}</h1>
      <div>
        <input
          required
          value="${this.config.placeholder}"
          autocomplete="off"
          id="body"
          name="body"
          type="text"
          ?disabled=${this.#requesting}
        />
        <button type="submit" ?disabled=${this.#requesting}>
          <span class="g-icon filled-heavy">send</span>
        </button>
      </div>
    </form>`;
  }

  #startLoadingAnimation() {
    if (
      Array.isArray(this.config.loadingText) &&
      this.config.loadingText.length > 1
    ) {
      this.#loadingTextIndex = 0;
      this.#loadingInterval = window.setInterval(() => {
        this.#loadingTextIndex =
          (this.#loadingTextIndex + 1) %
          (this.config.loadingText as string[]).length;
      }, 2000);
    }
  }

  #stopLoadingAnimation() {
    if (this.#loadingInterval) {
      clearInterval(this.#loadingInterval);
      this.#loadingInterval = undefined;
    }
  }

  async #sendMessage(
    message: v0_8.Types.A2UIClientEventMessage
  ): Promise<v0_8.Types.ServerToClientMessage[]> {
    try {
      this.#requesting = true;
      this.#startLoadingAnimation();
      const response = this.#a2uiClient.send(message);
      await response;
      this.#requesting = false;
      this.#stopLoadingAnimation();

      return response;
    } catch (err) {
      this.snackbar(err as string, SnackType.ERROR);
    } finally {
      this.#requesting = false;
      this.#stopLoadingAnimation();
    }

    return [];
  }

  #maybeRenderData() {
    if (this.#requesting) {
      let text = "Awaiting an answer...";
      if (this.config.loadingText) {
        if (Array.isArray(this.config.loadingText)) {
          text = this.config.loadingText[this.#loadingTextIndex];
        } else {
          text = this.config.loadingText;
        }
      }

      return html` <div class="pending">
        <div class="spinner"></div>
        <div class="loading-text">${text}</div>
      </div>`;
    }

    const surfaces = this.#processor.getSurfaces();
    if (surfaces.size === 0) {
      return nothing;
    }

    return html`<section id="surfaces">
      ${repeat(
      this.#processor.getSurfaces(),
      ([surfaceId]) => surfaceId,
      ([surfaceId, surface]) => {
        return html`<a2ui-surface
              @a2uiaction=${async (
          evt: v0_8.Events.StateEvent<"a2ui.action">
        ) => {
            const [target] = evt.composedPath();
            if (!(target instanceof HTMLElement)) {
              return;
            }

            const context: v0_8.Types.A2UIClientEventMessage["userAction"]["context"] =
              {};
            if (evt.detail.action.context) {
              const srcContext = evt.detail.action.context;
              for (const item of srcContext) {
                if (item.value.literalBoolean) {
                  context[item.key] = item.value.literalBoolean;
                } else if (item.value.literalNumber) {
                  context[item.key] = item.value.literalNumber;
                } else if (item.value.literalString) {
                  context[item.key] = item.value.literalString;
                } else if (item.value.path) {
                  const path = this.#processor.resolvePath(
                    item.value.path,
                    evt.detail.dataContextPath
                  );
                  const value = this.#processor.getData(
                    evt.detail.sourceComponent,
                    path,
                    surfaceId
                  );
                  context[item.key] = value;
                }
              }
            }

            const message: v0_8.Types.A2UIClientEventMessage = {
              userAction: {
                name: evt.detail.action.name,
                surfaceId,
                sourceComponentId: target.id,
                timestamp: new Date().toISOString(),
                context,
              },
            };

            await this.#sendAndProcessMessage(message);
          }}
              .surfaceId=${surfaceId}
              .surface=${surface}
              .processor=${this.#processor}
            ></a2-uisurface>`;
      }
    )}
    </section>`;
  }

  async #sendAndProcessMessage(request) {
    const messages = await this.#sendMessage(request);

    console.log(messages);

    this.#lastMessages = messages;
    this.#processor.clearSurfaces();
    this.#processor.processMessages(messages);
  }

  snackbar(
    message: string | HTMLTemplateResult,
    type: SnackType,
    actions: SnackbarAction[] = [],
    persistent = false,
    id = globalThis.crypto.randomUUID(),
    replaceAll = false
  ) {
    if (!this.#snackbar) {
      this.#pendingSnackbarMessages.push({
        message: {
          id,
          message,
          type,
          persistent,
          actions,
        },
        replaceAll,
      });
      return;
    }

    return this.#snackbar.show(
      {
        id,
        message,
        type,
        persistent,
        actions,
      },
      replaceAll
    );
  }

  unsnackbar(id?: SnackbarUUID) {
    if (!this.#snackbar) {
      return;
    }

    this.#snackbar.hide(id);
  }
}