// Test fixtures: a harness over the faux provider, with small extensions to exercise it.

import { BACKGROUND_CONTEXT as context } from "@earendil-works/chord/context";
import { type AssistantMessage, type Message, Type } from "@earendil-works/pi-ai";
import { createModels } from "@earendil-works/pi-ai/models";
import { getCurrentTools } from "@earendil-works/pi-ai/utils/transcript";
import {
  fauxAssistantMessage,
  fauxProvider,
  fauxToolCall,
} from "@earendil-works/pi-ai/providers/faux";
import { MemoryStorage } from "@earendil-works/pi-durable";
import { encodeBase64 } from "@std/encoding/base64";
import { fromFileUrl } from "@std/path";
import * as aftercare from "@char/aftercare";
import * as jsxRuntime from "@char/aftercare/jsx-runtime";
import { defineExtension } from "@berry/api";
import { HOST_GLOBAL } from "@berry/api/host.ts";
import { until } from "@berry/util";
import * as api from "@berry/api/web.ts";
import { type Berry, openBerry } from "./berry.ts";
import type { Environments } from "./environment.ts";

export type Dir = { cwd: string };
export type Cd = { type: "cd"; cwd: string };

export const dir = (apply: (state: Dir, event: Cd) => Dir = (_, e) => ({ cwd: e.cwd })) =>
  defineExtension<Dir, Cd>({
    name: "dir",
    description: "a working directory",
    initial: () => ({ cwd: "/" }),
    apply,
    setup(ext) {
      ext.configuration({
        parameters: Type.Object({ cwd: Type.Optional(Type.String()) }),
        values: ({ cwd }) => ({ cwd }),
        events: ({ cwd }) => {
          if (cwd !== undefined && !cwd.startsWith("/")) throw new Error(`not absolute: ${cwd}`);
          return cwd === undefined ? [] : [{ type: "cd", cwd }];
        },
      });
      ext.tool({
        name: "cd",
        description: "change directory",
        parameters: Type.Object({ path: Type.String() }),
        expose: "both",
        async execute({ path }, ctx) {
          await ctx.emit({ type: "cd", cwd: path });
          return `now in ${ctx.state.cwd}`;
        },
      });
      ext.tool({
        name: "say",
        description: "stream text as running output",
        parameters: Type.Object({ text: Type.String() }),
        execute: ({ text }, ctx) => {
          for (const word of text.split(" ")) ctx.output(`${word}\n`);
          return text.length;
        },
      });
      ext.tool({
        name: "shout",
        description: "model-only",
        parameters: Type.Object({}),
        expose: "model",
        execute: () => ({ word: "HEY" }),
        text: ({ word }) => `${word}!`,
      });
      return (conv) => {
        conv.prompt(() => `cwd: ${conv.state.cwd}`);
        conv.tool({
          name: "pwd",
          description: "print the working directory",
          parameters: Type.Object({}),
          execute: (_, ctx) => ctx.state.cwd,
        });
        conv.command({
          name: "go",
          description: "change directory, as the user",
          execute: async (path, ctx) => {
            if (!path.startsWith("/")) throw new Error(`not absolute: ${path}`);
            await ctx.emit({ type: "cd", cwd: path });
            return path;
          },
        });
      };
    },
  });

/** A direct tool that holds its turn open until released. */
export function gated() {
  const gate = { entered: Promise.withResolvers<void>(), release: Promise.withResolvers<string>() };
  const extension = defineExtension({
    name: "gate",
    initial: () => null,
    setup(ext) {
      ext.tool({
        name: "hold",
        description: "wait",
        parameters: Type.Object({}),
        expose: "model",
        execute: () => {
          gate.entered.resolve();
          return gate.release.promise;
        },
      });
    },
  });
  return { gate, extension };
}

/**
 * A model tool, `block`, holding each call until `release` settles or the call is aborted, and a
 * codemode tool, `ready`, that waits until one is held.
 */
export function blocking() {
  const blocker = {
    release: Promise.withResolvers<string>(),
    running: 0,
    /** Each started call's name, to the conversation it ran in. */
    started: new Map<string, string>(),
    cancelled: [] as string[],
  };
  const extension = defineExtension({
    name: "blocking",
    initial: () => null,
    setup(ext) {
      ext.tool({
        name: "block",
        description: "wait for release or cancellation",
        parameters: Type.Object({ name: Type.Optional(Type.String()) }),
        expose: "model",
        execute({ name = "" }, ctx) {
          blocker.started.set(name, ctx.tid);
          blocker.running++;
          return new Promise<string>((resolve, reject) => {
            const abort = () => {
              blocker.cancelled.push(name);
              reject(ctx.signal.reason);
            };
            ctx.signal.addEventListener("abort", abort, { once: true });
            void blocker.release.promise.then((answer) => {
              ctx.signal.removeEventListener("abort", abort);
              resolve(answer);
            });
          }).finally(() => blocker.running--);
        },
      });
      ext.tool({
        name: "ready",
        description: "wait until a block is held",
        parameters: Type.Object({}),
        execute: () => until(() => blocker.running > 0).then(() => "ready"),
      });
    },
  });
  return Object.assign(blocker, { extension });
}

/** A harness with `dir` and `gate` installed and the faux model enabled; `await using` closes it. */
export async function setup(
  environments?: Environments,
  provider?: Parameters<typeof fauxProvider>[0],
) {
  const faux = fauxProvider(provider);
  const models = createModels();
  models.setProvider(faux.provider);
  const berry = await openBerry(new MemoryStorage(), models, undefined, environments);
  await berry.install(dir());
  const { gate, extension } = gated();
  await berry.install(extension);
  const model = { provider: "faux", modelId: faux.getModel().id };
  await berry.enableModels([model]);
  return { faux, berry, model, models, gate, [Symbol.asyncDispose]: () => berry.close() };
}

export const script = (code: string) =>
  fauxAssistantMessage(fauxToolCall("codemode", { code }), { stopReason: "toolUse" });

/**
 * Answer one input with scripted steps, then "done"; resolves with the messages each request saw, once the
 * conversation is idle.
 */
export async function turn(
  { faux, berry }: { faux: ReturnType<typeof fauxProvider>; berry: Berry },
  tid: string,
  steps: readonly AssistantMessage[],
): Promise<(readonly Message[])[]> {
  const seen: (readonly Message[])[] = [];
  faux.setResponses(
    [...steps, fauxAssistantMessage("done")].map(
      (step) => (ctx) => (seen.push(ctx.messages), step),
    ),
  );
  const conversation = (await berry.conversation(tid))!;
  await (await conversation.submit({ type: "input", content: "go" }, context)).wait(context);
  await conversation.waitForIdle(context);
  return seen;
}

export function lastToolResult(messages: readonly Message[]) {
  const result = messages.findLast((m) => m.role === "toolResult");
  if (result?.role !== "toolResult") throw new Error("no tool result");
  return {
    text: result.content.flatMap((block) => (block.type === "text" ? [block.text] : [])).join("\n"),
    isError: result.isError,
    details: result.details,
  };
}

export const sectionsSeen = (messages: readonly Message[]) =>
  messages.flatMap((m) => (m.role === "system" ? [m.sections ?? {}] : []));

export const toolsOffered = (messages: readonly Message[]) =>
  getCurrentTools(messages).map((tool) => tool.name);

/** An extension's frontend as the app loads it: built on its own, over the app's instances of the shared modules. */
export async function builtRenderers(name: string): Promise<api.Renderers> {
  // vite is slow to load, and only these tests need it
  const web = (await import("./web.ts")).extensionWeb();
  const entry = fromFileUrl(new URL(`../extensions/${name}/web.tsx`, import.meta.url));
  const js = await web.serve((await web.build(name, entry)).module)!.text();
  const host = globalThis as Record<string, unknown>;
  host[HOST_GLOBAL] = {
    "@char/aftercare": aftercare,
    "@char/aftercare/jsx-runtime": jsxRuntime,
    "@berry/api/web.ts": api,
  };
  try {
    const encoded = encodeBase64(new TextEncoder().encode(js));
    return (await import(`data:text/javascript;base64,${encoded}`)).default;
  } finally {
    delete host[HOST_GLOBAL];
  }
}