// claude-code's tools (novox/hq design 36, ADR 0183). Served by the node's tool runtime, which runs as
// the operator account; this bundle is given its state directory and two files the mesh renders into it
// (ADR 0192), and the runtime's own words — the operator's account and home among them.
//
// Every time the runtime collects these tools, the managed directory is rendered: written only when its
// content changed, through the account's escalation, because /etc is root's. The credentials file under
// the home is written only when the licence manager hands this node a token (`claude_code_apply`); this
// module calls nothing, the manager starts every exchange (ADR 0183's dated note).

import { chmodSync, existsSync, readFileSync, writeFileSync } from "node:fs";
import { createHash } from "node:crypto";
import { spawnSync } from "node:child_process";
import { join } from "node:path";
import { registerModuleTools, type ToolDefinition } from "@novox/mesh-sdk/tools";

import { MANAGED_DIR, render, type Binding, type Facts, type Settings } from "../render.js";
import { generateKeyPair, open, seal, type SealedBox } from "../seal.js";
import { decideApply, grantOf, holdsLogin, readCredentials, withGrant, writeCredentials, type Grant } from "../grant.js";
import { readIdentity } from "../identity.js";

interface Paths {
  state: string;
  facts: string;
  settings: string;
  home: string;
  account: string;
}

function pathsFrom(env: NodeJS.ProcessEnv): Paths | null {
  const state = env.MESH_CLAUDE_CODE_STATE;
  const facts = env.MESH_CLAUDE_CODE_FACTS;
  const settings = env.MESH_CLAUDE_CODE_SETTINGS;
  const home = env.MESH_OPERATOR_HOME;
  if (!state || !facts || !settings || !home) return null;
  return { state, facts, settings, home, account: env.MESH_OPERATOR_ACCOUNT ?? "" };
}

const readJson = <T>(p: string, fallback: T): T => {
  try {
    return JSON.parse(readFileSync(p, "utf8")) as T;
  } catch {
    return fallback;
  }
};

const credentialsPath = (p: Paths) => join(p.home, ".claude", ".credentials.json");
const identityPath = (p: Paths) => join(p.home, ".claude.json");
const bindingPath = (p: Paths) => join(p.state, "binding.json");
const apiKeyPath = (p: Paths) => join(p.state, "api-key");
const helperPath = (p: Paths) => join(p.state, "api-key-helper");
const keyPath = (p: Paths) => join(p.state, "key.pem");
const pubPath = (p: Paths) => join(p.state, "key.pub.pem");
const fingerprint = (s: string) => "sha256:" + createHash("sha256").update(s).digest("hex").slice(0, 16);

function keypair(p: Paths): { publicKey: string; privateKey: string } {
  if (!existsSync(keyPath(p))) {
    const k = generateKeyPair();
    writeFileSync(keyPath(p), k.privateKey, { mode: 0o600 });
    writeFileSync(pubPath(p), k.publicKey, { mode: 0o644 });
  }
  return { privateKey: readFileSync(keyPath(p), "utf8"), publicKey: readFileSync(pubPath(p), "utf8") };
}

/** Write one managed file as root when its content changed. Returns what happened, in words. */
function writeManaged(name: string, content: string, asRoot: boolean): string {
  const path = join(MANAGED_DIR, name);
  let current: string | null = null;
  try {
    current = readFileSync(path, "utf8");
  } catch {
    /* absent */
  }
  if (current === content) return `${name}: unchanged`;
  const cmd = asRoot ? ["install", "-D", "-m", "0644", "/dev/stdin", path] : ["sudo", "-n", "install", "-D", "-m", "0644", "/dev/stdin", path];
  const r = spawnSync(cmd[0], cmd.slice(1), { input: content, encoding: "utf8" });
  if (r.status !== 0) {
    throw new Error(
      `${name}: could not be written to ${MANAGED_DIR} (${(r.stderr || r.error?.message || "").trim()}). ` +
        `The module writes there through the operator account's passwordless sudo; this machine does not give it.`,
    );
  }
  return `${name}: written`;
}

function renderNow(p: Paths): string[] {
  const facts = readJson<Facts | null>(p.facts, null);
  if (!facts?.console) throw new Error(`the mesh has not rendered ${p.facts} yet; nothing to write`);
  const settings = readJson<Settings>(p.settings, {});
  const binding = readJson<Binding | null>(bindingPath(p), null);
  const files = render(facts, settings, binding, helperPath(p));
  const asRoot = process.getuid?.() === 0;
  return Object.entries(files).map(([name, content]) => writeManaged(name, content, asRoot));
}

interface Handed {
  licence: string;
  kind: "subscription" | "api-key";
  source: "rotation" | "switch";
  sealed: SealedBox;
}

function apply(p: Paths, args: Record<string, unknown>): Record<string, unknown> {
  const handed = args as unknown as Handed;
  if (!handed?.licence || !handed.sealed || (handed.kind !== "subscription" && handed.kind !== "api-key")) {
    return { applied: false, reason: "a hand-over names a licence, its kind and a sealed token" };
  }
  const plain = open(handed.sealed, keypair(p).privateKey);
  const previous = readJson<Binding | null>(bindingPath(p), null);
  const source = previous?.licence === handed.licence ? (handed.source ?? "rotation") : "switch";
  if (handed.kind === "api-key") {
    writeFileSync(apiKeyPath(p), plain.trim() + "\n", { mode: 0o600 });
    writeFileSync(helperPath(p), `#!/bin/sh\nexec cat '${apiKeyPath(p)}'\n`, { mode: 0o700 });
    chmodSync(helperPath(p), 0o700);
  } else {
    const grant = JSON.parse(plain) as Grant;
    const local = readCredentials(credentialsPath(p));
    const d = decideApply(grantOf(local), grant, source);
    if (!d.apply) {
      writeFileSync(bindingPath(p), JSON.stringify({ licence: handed.licence, kind: handed.kind }) + "\n", { mode: 0o600 });
      return { applied: false, licence: handed.licence, reason: d.reason };
    }
    writeCredentials(credentialsPath(p), withGrant(local, grant));
  }
  writeFileSync(bindingPath(p), JSON.stringify({ licence: handed.licence, kind: handed.kind }) + "\n", { mode: 0o600 });
  // An API-key binding adds the key-helper to the managed settings; a subscription takes it away.
  const rendered = renderNow(p);
  return { applied: true, licence: handed.licence, kind: handed.kind, source, rendered };
}

function status(p: Paths): Record<string, unknown> {
  const binding = readJson<Binding | null>(bindingPath(p), null);
  const creds = readCredentials(credentialsPath(p));
  const grant = grantOf(creds);
  const managed = ["managed-mcp.json", "managed-settings.json", "CLAUDE.md"].map((f) => {
    try {
      return { file: join(MANAGED_DIR, f), fingerprint: fingerprint(readFileSync(join(MANAGED_DIR, f), "utf8")) };
    } catch {
      return { file: join(MANAGED_DIR, f), fingerprint: null };
    }
  });
  return {
    node: readJson<Facts | null>(p.facts, null)?.node ?? null,
    licence: binding,
    token: grant
      ? { fingerprint: fingerprint(grant.accessToken), expiresAt: new Date(grant.expiresAt).toISOString(), refreshTokenOnDisk: holdsLogin(creds) }
      : null,
    managed,
    publicKey: existsSync(pubPath(p)) ? fingerprint(readFileSync(pubPath(p), "utf8")) : null,
  };
}

function pendingLogin(p: Paths, args: Record<string, unknown>): Record<string, unknown> {
  const managerKey = typeof args.public_key === "string" ? args.public_key : "";
  if (!managerKey) return { waiting: false, reason: "the caller names the public key to seal a login to" };
  const creds = readCredentials(credentialsPath(p));
  if (!holdsLogin(creds)) return { waiting: false };
  const identity = readIdentity(identityPath(p));
  return { waiting: true, identity, sealed: seal(JSON.stringify(creds!.claudeAiOauth), managerKey) };
}

export function getClaudeCodeTools(p: Paths): ToolDefinition[] {
  return [
    {
      name: "claude_code_status",
      description:
        "This machine's agent as the mesh configured it: the node, the licence it holds and when its token expires, " +
        "and the managed files it rendered. Fingerprints only — never a token.",
      input: {},
      run: async () => status(p),
    },
    {
      name: "claude_code_render",
      description: "Write the agent's managed directory now from the mesh's facts and this module's settings; says which files changed.",
      input: {},
      run: async () => ({ rendered: renderNow(p) }),
    },
    {
      name: "claude_code_public_key",
      description: "The public half of this node's key, which the licence manager seals a token to.",
      input: {},
      run: async () => ({ public_key: keypair(p).publicKey }),
    },
    {
      name: "claude_code_apply",
      description:
        "The licence manager's hand-over: a token sealed to this node's key, with its licence and kind. Applied by the " +
        "lineage rule; the answer says applied or refused and why, never the token.",
      input: {
        licence: { type: "string", description: "the licence's name" },
        kind: { type: "string", description: "subscription or api-key" },
        source: { type: "string", description: "rotation or switch" },
        sealed: { type: "object", description: "the sealed box" },
      },
      run: async (args) => apply(p, args),
    },
    {
      name: "claude_code_pending_login",
      description:
        "A login a person made on this machine, waiting to be adopted: the grant sealed to the key the caller gives, and " +
        "the account it belongs to. Nothing when no login is waiting.",
      input: { public_key: { type: "string", description: "the caller's public key, PEM" } },
      run: async (args) => pendingLogin(p, args),
    },
  ];
}

registerModuleTools("claude-code", (env) => {
  const p = pathsFrom(env);
  if (!p) return [];
  try {
    keypair(p);
    for (const line of renderNow(p)) if (!line.endsWith("unchanged")) console.log(`[claude-code] ${line}`);
  } catch (err) {
    // Said, and the tools still served: claude_code_status and claude_code_render say what is wrong.
    console.log(`[claude-code] ${err instanceof Error ? err.message : String(err)}`);
  }
  return getClaudeCodeTools(p);
});