/** Interactive stdio ACP client used to connect a terminal session to an OpenClaw ACP server. */
import { spawn, type ChildProcess } from "node:child_process";
import { once } from "node:events";
import fs from "node:fs";
import path from "node:path";
import * as readline from "node:readline";
import { Readable, Writable } from "node:stream";
import { fileURLToPath } from "node:url";
import {
  ClientSideConnection,
  PROTOCOL_VERSION,
  ndJsonStream,
  type RequestPermissionRequest,
  type SessionNotification,
} from "@agentclientprotocol/sdk";
import { normalizeOptionalString } from "@openclaw/normalization-core/string-coerce";
import { ensureOpenClawCliOnPath } from "../infra/path-env.js";
import { killProcessTree, signalProcessTree } from "../process/kill-tree.js";
import {
  buildAcpClientStripKeys,
  resolveAcpClientSpawnEnv,
  resolveAcpClientSpawnInvocation,
  resolvePermissionRequest,
  shouldStripProviderAuthEnvVarsForAcpServer,
} from "./client-helpers.js";

type AcpClientOptions = {
  cwd?: string;
  serverCommand?: string;
  serverArgs?: string[];
  serverVerbose?: boolean;
  verbose?: boolean;
};

type AcpClientHandle = {
  client: ClientSideConnection;
  agent: ChildProcess;
  sessionId: string;
};

const ACP_SERVER_KILL_GRACE_MS = 1000;
const ACP_SERVER_FORCE_KILL_TIMEOUT_MS = 1000;

function hasChildExited(child: ChildProcess): boolean {
  return child.exitCode !== null || child.signalCode !== null;
}

async function waitForChildExit(child: ChildProcess, timeoutMs: number): Promise<boolean> {
  if (!hasChildExited(child)) {
    await once(child, "exit", { signal: AbortSignal.timeout(timeoutMs) }).catch(() => {});
  }
  return hasChildExited(child);
}

async function terminateAcpServer(child: ChildProcess): Promise<void> {
  if (hasChildExited(child)) {
    return;
  }

  if (child.pid) {
    // This child is not detached, so Unix cleanup must stay on its direct PID.
    // Windows still reaps descendants; both paths escalate if SIGTERM is ignored.
    killProcessTree(child.pid, {
      detached: false,
      graceMs: ACP_SERVER_KILL_GRACE_MS,
    });
  } else {
    child.kill("SIGTERM");
  }

  if (await waitForChildExit(child, ACP_SERVER_KILL_GRACE_MS + ACP_SERVER_FORCE_KILL_TIMEOUT_MS)) {
    return;
  }

  if (child.pid) {
    signalProcessTree(child.pid, "SIGKILL", { detached: false });
  } else {
    child.kill("SIGKILL");
  }
  await waitForChildExit(child, ACP_SERVER_FORCE_KILL_TIMEOUT_MS);
}

function toArgs(value: string[] | string | undefined): string[] {
  if (!value) {
    return [];
  }
  return Array.isArray(value) ? value : [value];
}

function buildServerArgs(opts: AcpClientOptions): string[] {
  const args = ["acp", ...toArgs(opts.serverArgs)];
  if (opts.serverVerbose && !args.includes("--verbose") && !args.includes("-v")) {
    args.push("--verbose");
  }
  return args;
}

function resolveSelfEntryPath(): string | null {
  // Prefer a path relative to the built module location (dist/acp/client.js -> dist/entry.js).
  try {
    const here = fileURLToPath(import.meta.url);
    const candidate = path.resolve(path.dirname(here), "..", "entry.js");
    if (fs.existsSync(candidate)) {
      return candidate;
    }
  } catch {
    // ignore
  }

  const argv1 = normalizeOptionalString(process.argv[1]);
  if (argv1) {
    return path.isAbsolute(argv1) ? argv1 : path.resolve(process.cwd(), argv1);
  }
  return null;
}

function printSessionUpdate(notification: SessionNotification): void {
  const update = notification.update;
  switch (update.sessionUpdate) {
    case "agent_message_chunk": {
      if (update.content?.type === "text") {
        process.stdout.write(update.content.text);
      }
      return;
    }
    case "tool_call": {
      console.log(`\n[tool] ${update.title} (${update.status})`);
      return;
    }
    case "tool_call_update": {
      if (update.status) {
        console.log(`[tool update] ${update.toolCallId}: ${update.status}`);
      }
      return;
    }
    case "available_commands_update": {
      const names = update.availableCommands?.map((cmd) => `/${cmd.name}`).join(" ");
      if (names) {
        console.log(`\n[commands] ${names}`);
      }
    }
    default:
  }
}

async function createAcpClient(opts: AcpClientOptions = {}): Promise<AcpClientHandle> {
  const cwd = opts.cwd ?? process.cwd();
  const verbose = Boolean(opts.verbose);
  const log = verbose ? (msg: string) => console.error(`[acp-client] ${msg}`) : () => {};

  ensureOpenClawCliOnPath();
  const serverArgs = buildServerArgs(opts);

  const entryPath = resolveSelfEntryPath();
  const defaultServerCommand = entryPath ? process.execPath : "openclaw";
  const defaultServerArgs = entryPath ? [entryPath, ...serverArgs] : serverArgs;
  const serverCommand = opts.serverCommand ?? defaultServerCommand;
  const effectiveArgs = opts.serverCommand || !entryPath ? serverArgs : defaultServerArgs;
  const { getActiveSkillEnvKeys } = await import("../skills/runtime/env-overrides.runtime.js");
  const stripProviderAuthEnvVars = shouldStripProviderAuthEnvVarsForAcpServer({
    serverCommand,
    serverArgs: effectiveArgs,
    defaultServerCommand,
    defaultServerArgs,
  });
  const stripKeys = buildAcpClientStripKeys({
    stripProviderAuthEnvVars,
    activeSkillEnvKeys: getActiveSkillEnvKeys(),
  });
  const spawnEnv = resolveAcpClientSpawnEnv(process.env, { stripKeys });
  const spawnInvocation = resolveAcpClientSpawnInvocation(
    { serverCommand, serverArgs: effectiveArgs },
    {
      platform: process.platform,
      env: spawnEnv,
      execPath: process.execPath,
    },
  );

  log(`spawning: ${spawnInvocation.command} ${spawnInvocation.args.join(" ")}`);

  const agent = spawn(spawnInvocation.command, spawnInvocation.args, {
    stdio: ["pipe", "pipe", "inherit"],
    cwd,
    env: spawnEnv,
    shell: spawnInvocation.shell,
    windowsHide: spawnInvocation.windowsHide,
  });

  agent.on("error", (err) => {
    log(`agent error: ${String(err)}`);
  });

  try {
    if (!agent.stdin || !agent.stdout) {
      throw new Error("Failed to create ACP stdio pipes");
    }

    const input = Writable.toWeb(agent.stdin);
    const output = Readable.toWeb(agent.stdout) as unknown as ReadableStream<Uint8Array>;
    const stream = ndJsonStream(input, output);

    const client = new ClientSideConnection(
      () => ({
        sessionUpdate: async (params: SessionNotification) => {
          printSessionUpdate(params);
        },
        requestPermission: async (params: RequestPermissionRequest) => {
          return resolvePermissionRequest(params, { cwd });
        },
      }),
      stream,
    );

    log("initializing");
    await client.initialize({
      protocolVersion: PROTOCOL_VERSION,
      clientCapabilities: {
        fs: { readTextFile: true, writeTextFile: true },
        terminal: true,
      },
      clientInfo: { name: "openclaw-acp-client", version: "1.0.0" },
    });

    log("creating session");
    const session = await client.newSession({
      cwd,
      mcpServers: [],
    });

    return {
      client,
      agent,
      sessionId: session.sessionId,
    };
  } catch (error) {
    await terminateAcpServer(agent);
    throw error;
  }
}

/** Starts the terminal prompt loop for a local ACP client session. */
export async function runAcpClientInteractive(opts: AcpClientOptions = {}): Promise<void> {
  const { client, agent, sessionId } = await createAcpClient(opts);

  const rl = readline.createInterface({
    input: process.stdin,
    output: process.stdout,
  });

  console.log("OpenClaw ACP client");
  console.log(`Session: ${sessionId}`);
  console.log('Type a prompt, or "exit" to quit.\n');

  let quitting = false; // Only client-owned shutdown makes a signal stop successful.
  const quit = async () => {
    if (quitting || hasChildExited(agent)) {
      return;
    }
    quitting = true;
    await terminateAcpServer(agent);
    rl.close();
    process.exit(0);
  };
  rl.once("close", () => {
    void quit();
  });
  const prompt = () => {
    if (quitting) {
      return;
    }
    rl.question("> ", (input) => {
      void (async () => {
        const text = input.trim();
        if (!text) {
          prompt();
          return;
        }
        if (text === "exit" || text === "quit") {
          await quit();
          return;
        }

        try {
          const response = await client.prompt({
            sessionId,
            prompt: [{ type: "text", text }],
          });
          console.log(`\n[${response.stopReason}]\n`);
        } catch (err) {
          console.error(`\n[error] ${String(err)}\n`);
        }

        prompt();
      })();
    });
  };

  prompt();

  agent.on("exit", (code, signal) => {
    console.log(`\nAgent exited with ${signal ? `signal ${signal}` : `code ${code}`}`);
    rl.close();
    process.exit(code ?? (quitting ? 0 : 1));
  });
}