#!/usr/bin/env node
/**
 * `mesh` — the mesh's tools from a workstation, for a person (novox/hq design 25 §7).
 *
 * Three verbs and nothing else. What tools are there, call one, and serve the same two to an agent
 * over MCP. Deliberately thin: everything that could be a decision is one the mesh already made, and a
 * client that grew opinions would be a second place the mesh's behaviour is defined.
 *
 *     mesh tools                        what this credential may call
 *     mesh call <module>.<tool> [json]  call one, arguments as JSON on the command line or on stdin
 *     mesh mcp                          the same, as an MCP server over stdio
 *
 * The credential comes from MESH_CREDENTIAL, or --credential. It is the JSON `operator issue` printed.
 */
import { readFile } from "node:fs/promises";

import { callTool, connectAs, credentialFrom, toolsOn, whyItFailed, type Tool } from "./client.js";
import { serveMcp } from "./mcp.js";

const usage = `mesh tools
mesh call <module>.<tool> [json]
mesh mcp

  --credential <file>   the JSON \`operator issue\` printed; default $MESH_CREDENTIAL`;

async function main(argv: string[]): Promise<number> {
  const args = [...argv];
  let credentialPath = process.env.MESH_CREDENTIAL ?? "";
  for (let i = 0; i < args.length; i++) {
    if (args[i] === "--credential") {
      credentialPath = args[i + 1] ?? "";
      args.splice(i, 2);
      i--;
    }
  }
  const verb = args.shift();
  if (!verb || verb === "help" || verb === "--help") {
    console.log(usage);
    return verb ? 0 : 1;
  }
  if (!credentialPath) {
    console.error(
      "no credential: set MESH_CREDENTIAL or pass --credential <file>. It is the JSON " +
        "`operator issue` printed, saved verbatim.",
    );
    return 1;
  }

  const held = await credentialFrom(credentialPath);
  const bus = await connectAs(held);
  try {
    switch (verb) {
      case "tools":
        return await listing(bus, held.person);
      case "call":
        return await calling(bus, args);
      case "mcp":
        // Serves until stdin closes, which is how an MCP host ends a session.
        await serveMcp(bus, held.person ?? held.user ?? "somebody");
        return 0;
      default:
        console.error(`mesh has no "${verb}".\n\n${usage}`);
        return 1;
    }
  } finally {
    await bus.close();
  }
}

async function listing(bus: Awaited<ReturnType<typeof connectAs>>, who?: string): Promise<number> {
  let tools: Tool[];
  try {
    tools = await toolsOn(bus);
  } catch (e) {
    console.error(whyItFailed("mesh-catalog.catalog_tools", e));
    return 1;
  }
  if (tools.length === 0) {
    console.log("the catalogue lists no tools; nothing on this mesh serves any");
    return 0;
  }
  // **What the catalogue has, not what this credential may call.** The two differ and the difference
  // is the point: a person seeing only their own tools cannot tell "not installed" from "not yours",
  // and those need different people to fix them.
  for (const t of tools) {
    const name = `${t.module}.${t.name}`;
    console.log(t.description ? `${name.padEnd(36)} ${t.description}` : name);
  }
  if (who) {
    console.log(`\nthis is what the mesh has. What ${who} may call was fixed when the credential was issued.`);
  }
  return 0;
}

async function calling(
  bus: Awaited<ReturnType<typeof connectAs>>,
  args: string[],
): Promise<number> {
  const key = args.shift();
  if (!key) {
    console.error("mesh call <module>.<tool> [json]");
    return 1;
  }
  const raw = args.length > 0 ? args.join(" ") : await maybeStdin();
  let parsed: unknown = {};
  if (raw.trim() !== "") {
    try {
      parsed = JSON.parse(raw);
    } catch (e) {
      console.error(`the arguments are not JSON: ${(e as Error).message}`);
      return 1;
    }
  }
  try {
    const answer = await callTool(bus, key, parsed);
    console.log(JSON.stringify(answer, null, 2));
    return 0;
  } catch (e) {
    console.error(whyItFailed(key, e));
    return 1;
  }
}

/** Arguments on stdin, for a call whose JSON is too long or too quoted to type. Empty when stdin is a
 *  terminal, so `mesh call x.y` with no arguments does not hang waiting for something nobody is
 *  typing. */
async function maybeStdin(): Promise<string> {
  if (process.stdin.isTTY) return "";
  const chunks: Buffer[] = [];
  for await (const chunk of process.stdin) chunks.push(chunk as Buffer);
  return Buffer.concat(chunks).toString("utf8");
}

// Only when run, so a test can import the pieces.
if (process.argv[1] && import.meta.url === new URL(`file://${process.argv[1]}`).href) {
  main(process.argv.slice(2))
    .then((code) => process.exit(code))
    .catch((e) => {
      console.error(e instanceof Error ? e.message : String(e));
      process.exit(1);
    });
}

export { main, usage };
export const _readFile = readFile;