import { assert, assertEquals, assertStringIncludes } from "@std/assert";
import { existsSync } from "node:fs";
import type { Channel, ChannelMessage, Environment } from "@berry/api";
import { localEnvironment } from "@berry/api/environment.ts";
import { testExtension } from "@berry/api/testing.ts";
import { tempDir, until } from "@berry/util";
import { dirname, join } from "node:path";
import terminal from "./mod.ts";
import { Ghostty } from "./ghostty.ts";
import { OUTPUT, SNAPSHOT } from "./protocol.ts";

const WASM = new URL("./ghostty-vt.wasm", import.meta.url);
const ready = existsSync(WASM) && Deno.build.os === "linux";

/** This machine, with a plain shell rather than whatever logs in here. */
function plainShell(): Environment {
  const local = localEnvironment(Deno.cwd());
  return new Proxy(local, {
    get(target, property) {
      if (property === "variables") return { ...target.variables, SHELL: "/bin/sh", ENV: "" };
      const value = Reflect.get(target, property, target);
      return typeof value === "function" ? value.bind(target) : value;
    },
  });
}

/** A viewer: everything the channel has said, and a way to wait for what it will. */
function viewer(channel: Channel) {
  const said: ChannelMessage[] = [];
  let heard = () => {};
  void (async () => {
    for await (const message of channel.messages) {
      said.push(message);
      heard();
    }
  })();
  const output = () =>
    new TextDecoder().decode(
      new Uint8Array(
        said.flatMap((m) => m instanceof Uint8Array && m[0] === OUTPUT ? [...m.subarray(1)] : []),
      ),
    );
  return {
    said,
    output,
    async until(done: () => boolean) {
      while (!done()) await new Promise<void>((resolve) => heard = resolve);
    },
    type: (text: string) => channel.send(new TextEncoder().encode(text)),
    close: () => channel.close(),
  };
}

const isSnapshot = (m: ChannelMessage) => m instanceof Uint8Array && m[0] === SNAPSHOT;

Deno.test({
  name: "a shell starts when asked, and its screen outlives its viewers until it exits",
  ignore: !ready,
  async fn() {
    const tested = testExtension(terminal, { env: plainShell() });
    try {
      const first = viewer(tested.connect("session"));
      await first.until(() => first.said.length > 0);
      assertEquals(first.said, [{ t: "none" }]);
      tested.connect("session").send({ t: "start", cols: 40, rows: 10 });
      await first.until(() => first.said.some(isSnapshot));
      first.type("echo marked $((6 * 7))\r");
      await first.until(() => first.output().includes("marked 42"));
      first.close();

      // whoever comes later sees the screen so far, scrollback and all
      const later = viewer(tested.connect("session"));
      await later.until(() => later.said.some(isSnapshot));
      const snapshot = later.said.find(isSnapshot) as Uint8Array;
      const ghostty = await Ghostty.load(await Deno.readFile(WASM));
      assertStringIncludes(ghostty.restore(snapshot.subarray(1)).text(), "marked 42");

      later.type("exit 3\r");
      await later.until(() => later.said.some((m) => (m as { t?: string }).t === "exit"));
      assertEquals(later.said.at(-1), { t: "exit", code: 3 });

      // nothing starts again on its own: the last screen stays, with how it ended
      const after = viewer(tested.connect("session"));
      await after.until(() => after.said.length >= 2);
      assert(isSnapshot(after.said[0]));
      assertEquals(after.said[1], { t: "exit", code: 3 });
    } finally {
      await tested.dispose();
    }
  },
});

Deno.test({
  name: "a resize reaches the shell and every viewer, and one start is one shell",
  ignore: !ready,
  async fn() {
    const tested = testExtension(terminal, { env: plainShell() });
    try {
      const one = viewer(tested.connect("session"));
      const two = viewer(tested.connect("session"));
      tested.connect("session").send({ t: "start", cols: 40, rows: 10 });
      tested.connect("session").send({ t: "start", cols: 40, rows: 10 });
      await one.until(() => one.said.some(isSnapshot));
      tested.connect("session").send({ t: "resize", cols: 60, rows: 20 });
      await two.until(() => two.said.some((m) => (m as { t?: string }).t === "size"));
      one.type("stty size\r");
      await one.until(() => one.output().includes("20 60"));
      assertEquals(one.said.filter(isSnapshot).length, 1);
    } finally {
      await tested.dispose();
    }
  },
});

Deno.test({
  name: "a shell's last output precedes its exit and a replacement shell",
  ignore: !existsSync(WASM),
  async fn() {
    const env = localEnvironment(Deno.cwd());
    let output!: ReadableStreamDefaultController<Uint8Array>;
    let starts = 0;
    env.pty = () =>
      Promise.resolve({
        readable: new ReadableStream({
          start(controller) {
            if (++starts === 1) output = controller;
            else controller.close();
          },
        }),
        writable: new WritableStream(),
        exited: Promise.resolve(0),
        kill() {},
        resize() {},
      });
    const tested = testExtension(terminal, { env });
    let ended = false;
    try {
      const channel = tested.connect("session");
      const view = viewer(channel);
      channel.send({ t: "start", cols: 80, rows: 24 });
      await until(() => view.said.some(isSnapshot));
      // output completion, not the former grace timer, must gate replacement
      await new Promise((resolve) => setTimeout(resolve, 350));
      assertEquals(view.said.some((m) => (m as { t?: string }).t === "exit"), false);
      output.enqueue(new TextEncoder().encode("farewell"));
      output.close();
      ended = true;
      await until(() => view.said.some((m) => (m as { t?: string }).t === "exit"));
      assertStringIncludes(view.output(), "farewell");
      assertEquals(view.said.at(-1), { t: "exit", code: 0 });
      channel.send({ t: "start", cols: 80, rows: 24 });
      await until(() => starts === 2);
    } finally {
      if (output && !ended) output.close();
      await tested.dispose();
    }
  },
});

Deno.test({
  name: "disposing a terminal drains output after hangup before freeing its screen",
  ignore: !existsSync(WASM),
  async fn() {
    const env = localEnvironment(Deno.cwd());
    let output!: ReadableStreamDefaultController<Uint8Array>;
    const exited = Promise.withResolvers<number | null>();
    env.pty = () =>
      Promise.resolve({
        readable: new ReadableStream({ start: (controller) => void (output = controller) }),
        writable: new WritableStream(),
        exited: exited.promise,
        kill() {
          output.enqueue(new TextEncoder().encode("farewell"));
          exited.resolve(null);
        },
        resize() {},
      });
    const tested = testExtension(terminal, { env });
    let disposing: Promise<void> | undefined;
    try {
      const channel = tested.connect("session");
      const view = viewer(channel);
      channel.send({ t: "start", cols: 80, rows: 24 });
      await until(() => view.said.some(isSnapshot));
      let disposed = false;
      disposing = tested.dispose().then(() => {
        disposed = true;
      });
      await until(() => view.output().includes("farewell"));
      assertEquals(disposed, false);
    } finally {
      disposing ??= tested.dispose();
      output?.close();
      await disposing;
    }
  },
});

Deno.test({
  name: "Windows terminals launch an interactive PowerShell on the target, preferring PS7 to PS5",
  ignore: !existsSync(WASM),
  async fn() {
    await using root = await tempDir();
    const binaries = [
      "bin dir/pwsh.EXE",
      "program files/PowerShell/7/pwsh.exe",
      "legacy/powershell.EXE",
      "windows/System32/WindowsPowerShell/v1.0/powershell.exe",
    ].map((path) => join(root.path, path));
    for (const path of binaries) {
      await Deno.mkdir(dirname(path), { recursive: true });
      await Deno.writeTextFile(path, "");
    }
    const invocations: (readonly string[])[] = [];
    const env = localEnvironment(root.path);
    Object.defineProperties(env, {
      platform: { value: "win32" },
      variables: {
        value: {
          pAtH: `"${dirname(binaries[0])}";${dirname(binaries[2])}`,
          PaThExT: ".EXE",
          ProgramFiles: join(root.path, "program files"),
          SystemRoot: join(root.path, "windows"),
          SHELL: "/not/a/windows/shell",
        },
      },
    });
    env.pty = (argv) => {
      invocations.push(argv);
      return Promise.resolve({
        readable: new ReadableStream({ start: (controller) => controller.close() }),
        writable: new WritableStream(),
        exited: Promise.resolve(0),
        kill() {},
        resize() {},
      });
    };
    const tested = testExtension(terminal, { env });
    try {
      const channel = tested.connect("session");
      const view = viewer(channel);
      await until(() => view.said.length > 0);
      for (const binary of binaries) {
        view.said.length = 0;
        channel.send({ t: "start", cols: 80, rows: 24 });
        await until(() => view.said.some((m) => (m as { t?: string }).t === "exit"));
        assertEquals(invocations.at(-1), [binary, "-NoLogo"]);
        await Deno.remove(binary);
      }
      channel.send({ t: "start", cols: 80, rows: 24 });
      await until(() => view.said.some((m) => (m as { t?: string }).t === "error"));
      assertEquals(invocations.length, 4);
    } finally {
      await tested.dispose();
    }
  },
});