import type {
  AdapterContext,
  BrowserActRequest,
  BrowserActResult,
  BrowserNavigateRequest,
  BrowserNavigateResult,
  BrowserProvider,
  BrowserSnapshotNode,
  BrowserSnapshotRequest,
  BrowserSnapshotResult,
  ComputerRef,
  PageBrowserCommand,
  PageBrowserResult,
  SandboxProvider,
} from "@rakazo/adapter-kit";
import { FakeBrowserProvider, type FakeBrowserProviderOptions } from "./fake-browser.js";

const DETACHED_MESSAGE =
  "Page browser is not attached to this computer's Chrome. Use computer_act on the desktop browser instead.";

type LivePayload = Partial<PageBrowserResult>;

export type LivePageBrowserDriver = (
  computer: ComputerRef,
  request: PageBrowserCommand,
  context: AdapterContext,
) => Promise<LivePayload>;

/**
 * Production page-browser adapter for the bot computer.
 *
 * Fake computers (and the fake sandbox) use the in-process DOM session.
 * Real computers drive the live Chrome already on the graphical display via
 * CDP (`rakazo-page-browser`). If that path cannot operate, return
 * `fallback: "computer_act"` — never report success against a detached DOM.
 */
export class ComputerBrowserProvider implements BrowserProvider {
  private readonly fake: FakeBrowserProvider;
  private readonly sandbox?: SandboxProvider;
  private readonly liveDriver?: LivePageBrowserDriver;

  constructor(
    options: FakeBrowserProviderOptions & {
      sandbox?: SandboxProvider;
      /** Test seam for the live CDP helper. */
      liveDriver?: LivePageBrowserDriver;
    } = {},
  ) {
    const { sandbox, liveDriver, ...fakeOptions } = options;
    this.sandbox = sandbox;
    this.liveDriver = liveDriver;
    this.fake = new FakeBrowserProvider(fakeOptions);
  }

  describe() {
    return {
      id: "computer",
      contractVersion: "1",
      adapterVersion: "0.1.0",
      capabilities: {
        page: Boolean(
          this.liveDriver || this.sandbox?.pageBrowser || this.sandbox?.describe().id === "fake",
        ),
        refs: true,
        keyless: true,
      },
    };
  }

  async navigate(
    computer: ComputerRef,
    request: BrowserNavigateRequest,
    context: AdapterContext,
  ): Promise<BrowserNavigateResult> {
    if (this.canUseInProcess(computer)) {
      return this.fake.navigate(computer, request, context);
    }
    const live = await this.runLive(computer, { command: "navigate", url: request.url }, context);
    if (live?.ok !== true || live.fallback === "computer_act") {
      return {
        url: request.url,
        title: "",
        fallback: "computer_act",
        error: live?.error || DETACHED_MESSAGE,
      };
    }
    return {
      url: typeof live.url === "string" ? live.url : request.url,
      title: typeof live.title === "string" ? live.title : "",
    };
  }

  async snapshot(
    computer: ComputerRef,
    request: BrowserSnapshotRequest,
    context: AdapterContext,
  ): Promise<BrowserSnapshotResult> {
    if (this.canUseInProcess(computer)) {
      return this.fake.snapshot(computer, request, context);
    }
    const live = await this.runLive(computer, { command: "snapshot" }, context);
    if (live?.ok !== true || live.fallback === "computer_act") {
      return {
        url: "",
        title: "",
        tree: "",
        elements: [],
        fallback: "computer_act",
        error: live?.error || DETACHED_MESSAGE,
      };
    }
    const elements = Array.isArray(live.elements) ? live.elements : [];
    return {
      url: typeof live.url === "string" ? live.url : "",
      title: typeof live.title === "string" ? live.title : "",
      tree: typeof live.tree === "string" ? live.tree : formatTree(elements),
      elements,
      ...(live.screen ? { screen: live.screen } : {}),
    };
  }

  async act(
    computer: ComputerRef,
    request: BrowserActRequest,
    context: AdapterContext,
  ): Promise<BrowserActResult> {
    if (this.canUseInProcess(computer)) {
      return this.fake.act(computer, request, context);
    }
    const live = await this.runLive(
      computer,
      { command: "act", actions: request.actions },
      context,
    );
    if (live?.ok !== true || live.fallback === "computer_act") {
      return {
        ok: false,
        completed: typeof live?.completed === "number" ? live.completed : 0,
        uncertain: live?.uncertain ?? true,
        url: typeof live?.url === "string" ? live.url : "",
        title: typeof live?.title === "string" ? live.title : "",
        fallback: "computer_act",
        error: live?.error || DETACHED_MESSAGE,
      };
    }
    const elements = Array.isArray(live.elements) ? live.elements : undefined;
    return {
      ok: true,
      completed: typeof live.completed === "number" ? live.completed : request.actions.length,
      url: typeof live.url === "string" ? live.url : "",
      title: typeof live.title === "string" ? live.title : "",
      tree: typeof live.tree === "string" ? live.tree : elements ? formatTree(elements) : undefined,
      elements,
      ...(live.screen ? { screen: live.screen } : {}),
    };
  }

  private canUseInProcess(computer: ComputerRef): boolean {
    return computer.kind === "fake";
  }

  private async runLive(
    computer: ComputerRef,
    request: PageBrowserCommand,
    context: AdapterContext,
  ): Promise<LivePayload> {
    context.signal.throwIfAborted();
    try {
      const result = this.liveDriver
        ? await this.liveDriver(computer, request, context)
        : this.sandbox?.pageBrowser
          ? await this.sandbox.pageBrowser(computer, request, context)
          : {
              ok: false,
              error: DETACHED_MESSAGE,
              fallback: "computer_act" as const,
              uncertain: false,
            };
      if (result?.ok === true) {
        if (typeof result.url !== "string" || typeof result.title !== "string") {
          throw new Error("Incomplete page browser response");
        }
        if (
          request.command === "snapshot" &&
          (typeof result.tree !== "string" || !Array.isArray(result.elements))
        ) {
          throw new Error("Incomplete page snapshot");
        }
        if (
          request.command === "act" &&
          (!Number.isInteger(result.completed) ||
            result.completed !== request.actions.length ||
            result.uncertain)
        ) {
          throw new Error("Unconfirmed page actions");
        }
      }
      return result;
    } catch (error) {
      context.signal.throwIfAborted();
      return {
        uncertain: request.command === "act",
        ok: false,
        error: error instanceof Error ? error.message : String(error),
        fallback: "computer_act",
      };
    }
  }
}

function formatTree(elements: BrowserSnapshotNode[]): string {
  if (elements.length === 0) return "(no interactive elements)";
  return elements
    .map((el) => {
      const value =
        el.value !== undefined && el.value !== "" ? ` value=${JSON.stringify(el.value)}` : "";
      return `- ${el.role} "${el.name}" [${el.ref}]${value}`;
    })
    .join("\n");
}