// What the host and the human commands read before they touch the bus:
// the system config (through scripts/mosaic-config.mjs, as `mosaic business`
// does), the business file, and the boot message for the broker process.
// Everything here reads and refuses; nothing writes.

import { spawnSync } from "node:child_process";
import { existsSync } from "node:fs";
import { dirname, join, resolve } from "node:path";
import { fileURLToPath } from "node:url";
import { BusinessError, configDir, loadBusiness, loadProject, projectFilePath, resolveInstance, systemVars } from "../../business/src/index.mjs";
import { busBusiness } from "../../bus/src/business.mjs";
import { BusError } from "../../bus/src/broker.mjs";
import { CliError } from "./errors.mjs";

export const REPO = resolve(dirname(fileURLToPath(import.meta.url)), "..", "..", "..");

// The broker's socket. One broker per data root: the bus store takes
// `<dataRoot>/bus/writer.lock` (packages/bus/src/store.mjs).
export const socketPath = (dataRoot) => join(dataRoot, "bus", "broker.sock");

export function loadSystem({ env = process.env } = {}) {
  const proc = spawnSync(process.execPath, [join(REPO, "scripts", "mosaic-config.mjs"), "validate"], {
    encoding: "utf8",
    maxBuffer: 1024 * 1024,
    env,
  });
  if (proc.status !== 0) throw new CliError(`system config problem (mosaic-config exit ${proc.status}): ${proc.stderr.trim()}`, 3);
  try {
    return JSON.parse(proc.stdout);
  } catch {
    throw new CliError("system config: mosaic-config printed something that isn't JSON", 3);
  }
}

export function rolesDir(env = process.env) {
  return resolve(env.MOSAIC_ROLES_DIR || join(REPO, "roles"));
}

// A business-package or adapter refusal is a config problem: exit 3.
function business(fn) {
  try {
    return fn();
  } catch (error) {
    if (error instanceof BusinessError) throw new CliError(error.message, 3);
    if (error instanceof BusError) throw new CliError(`business adapter refused: ${error.code}`, 3);
    throw error;
  }
}

// config.trackers[<business>] (lead decision 70): plain data from the
// tracker.* variables. tracker.project is a project-layer variable, so the
// entry comes from the one declared project whose file sets it. No
// tracker.baseUrl, or no project naming a tracker project, means no entry
// and no task verbs; two projects naming one each refuse, since the boot
// shape holds one tracker project per business.
function trackerFor(system, b, warn) {
  const first = Object.keys(b.roles)[0];
  const base = resolveInstance({ system, business: b, instance: first }).vars;
  if (base["tracker.baseUrl"] === undefined) return null;
  const named = [];
  for (const [id, entry] of Object.entries(b.projects)) {
    if (!existsSync(projectFilePath(entry.root))) continue;
    const project = loadProject(entry.root);
    if (project.id !== id) throw new CliError(`project file ${project.file} has id ${project.id}, but business ${b.id} declares it as ${id}`, 3);
    const vars = resolveInstance({ system, business: b, project, instance: first }).vars;
    if (vars["tracker.project"] !== undefined) named.push({ id, vars });
  }
  if (named.length > 1) {
    throw new CliError(`business ${b.id}: projects ${named.map((n) => n.id).join(", ")} each set tracker.project; the broker takes one tracker project per business`, 3);
  }
  if (named.length === 0) {
    warn(`business ${b.id} sets tracker.baseUrl, but no project file sets tracker.project; the broker gets no task verbs`);
    return null;
  }
  const v = named[0].vars;
  return {
    baseUrl: v["tracker.baseUrl"],
    project: v["tracker.project"],
    pollSeconds: v["tracker.pollSeconds"],
    reconcileMinutes: v["tracker.reconcileMinutes"],
  };
}

// The `{op: 'boot'}` config for packages/bus/src/process.mjs, for one
// business. The host holds a reader capability for the notifier and binds
// launches later through bindLaunch, so `launches` starts empty.
export function bootConfig({ system, businessId, env = process.env, warn = () => {} }) {
  return business(() => {
    const vars = systemVars(system);
    const b = loadBusiness(businessId, { dir: configDir(env), rolesDir: rolesDir(env) });
    const resolved = {};
    for (const instance of Object.keys(b.roles)) resolved[instance] = resolveInstance({ system: vars, business: b, instance });
    const config = {
      dataRoot: system.dataRoot,
      businesses: { [b.id]: busBusiness(b, resolved) },
      launches: [],
      readers: [b.id],
    };
    const tracker = trackerFor(vars, b, warn);
    if (tracker) config.trackers = { [b.id]: tracker };
    return config;
  });
}