import { homedir } from "os";
import { join } from "path";

/**
 * The shared storage selection (`ATOMIC_STORAGE` JSON) the launching Atomic process hands its broker: its
 * `--storage`/`--storage-file` or its own `ATOMIC_STORAGE`. It outranks the agent directory's settings.
 */
export const BROKER_STORAGE_ENV = "ATOMIC_STORAGE";

function getHomeDir(): string {
  if (process.platform === "win32") {
    if (process.env.USERPROFILE) return process.env.USERPROFILE;
    if (process.env.HOMEDRIVE && process.env.HOMEPATH) return `${process.env.HOMEDRIVE}${process.env.HOMEPATH}`;
    if (process.env.HOME) return process.env.HOME;
    return homedir();
  }
  return process.env.HOME || process.env.USERPROFILE || homedir();
}

function expandTildePath(path: string): string {
  if (path === "~") return getHomeDir();
  if (path.startsWith("~/") || (process.platform === "win32" && path.startsWith("~\\"))) {
    return join(getHomeDir(), path.slice(2));
  }
  return path;
}

function getAgentDir(): string {
  const atomicAgentDir = process.env.ATOMIC_CODING_AGENT_DIR;
  if (atomicAgentDir) return expandTildePath(atomicAgentDir);
  const piAgentDir = process.env.PI_CODING_AGENT_DIR;
  if (piAgentDir) return expandTildePath(piAgentDir);
  return join(getHomeDir(), ".atomic", "agent");
}

function sanitizePipeSegment(value: string): string {
  return value
    .replace(/[^a-zA-Z0-9]+/g, "-")
    .replace(/^-+|-+$/g, "")
    .toLowerCase() || "default";
}

export function getIntercomDirPath(agentDir: string = getAgentDir()): string {
  return join(agentDir, "intercom");
}

export function getBrokerPidPath(agentDir: string = getAgentDir()): string {
  return join(getIntercomDirPath(agentDir), "broker.pid");
}

export function getBrokerSpawnLockPath(agentDir: string = getAgentDir()): string {
  return join(getIntercomDirPath(agentDir), "broker.spawn.lock");
}

export function getBrokerSocketReplacementLockPath(agentDir: string = getAgentDir()): string {
  return join(getIntercomDirPath(agentDir), "broker.sock.replace.lock");
}

/** Durable accepted-operation authority shared by replacement broker processes. */
export function getBrokerDeliveredMessagesPath(agentDir: string = getAgentDir()): string {
  return join(getIntercomDirPath(agentDir), "delivered-messages.sqlite");
}

/** Owner-only HMAC key paired with durable accepted-operation authority. */
export function getBrokerDeliveredMessagesKeyPath(agentDir: string = getAgentDir()): string {
  return join(getIntercomDirPath(agentDir), "delivered-messages.key");
}

/**
 * Startup/diagnostic log for the detached broker process. The parent opens this file
 * and hands the descriptor to the child as stderr, so a broker that dies before it can
 * accept connections leaves a readable reason behind for whichever process inspects it.
 */
export function getBrokerLogPath(agentDir: string = getAgentDir()): string {
  return join(getIntercomDirPath(agentDir), "broker.log");
}

export function getBrokerWatchdogLogPath(agentDir: string = getAgentDir()): string {
  return join(getIntercomDirPath(agentDir), "broker-watchdog.log");
}

export function getBrokerSocketPath(
  platform: NodeJS.Platform = process.platform,
  agentDir: string = getAgentDir(),
): string {
  if (platform === "win32") {
    return `\\\\.\\pipe\\pi-intercom-${sanitizePipeSegment(agentDir)}`;
  }

  return join(getIntercomDirPath(agentDir), "broker.sock");
}