/**
 * Zendy — unified pi extension entry point.
 *
 * Provides:
 *   - Tools (LLM-callable): zendy_ticket_get, zendy_ticket_search,
 *     zendy_helm_get, zendy_kg_search, zendy_source_status
 *   - Slash commands: /zendy-config, /zendy-status
 *   - Session lifecycle: workspace dir + cleanup + orphan sweep
 *   - Custom header on session start
 *
 * No external CLI dependencies (zcli, zendesk-kg) required.
 * All data access is through direct REST APIs.
 */

import type { ExtensionAPI } from "@earendil-works/pi-coding-agent";
import { registerAllTools } from "./tools.js";
import { registerAllCommands } from "./commands.js";
import { mkdirSync, rmSync, readdirSync } from "node:fs";
import { join } from "node:path";

// ── Constants ──────────────────────────────────────────────────────────

const BASE_DIR = "/tmp";
const SESSION_PREFIX = "zendy-session-";
const WIPE_PREFIXES = ["dify-", SESSION_PREFIX];

// ── Session workspace helpers ──────────────────────────────────────────

function parseSessionDir(name: string): { pid: number } | null {
  const m = /^zendy-session-(\d+)-(\d+)$/.exec(name);
  return m ? { pid: parseInt(m[1]!, 10) } : null;
}

function isProcessAlive(pid: number): boolean {
  try {
    process.kill(pid, 0);
    return true;
  } catch (e) {
    return (e as NodeJS.ErrnoException).code === "EPERM";
  }
}

function safeRmrf(path: string): boolean {
  try {
    rmSync(path, { recursive: true, force: true });
    return true;
  } catch {
    return false;
  }
}

function sweepOrphans(base: string, exclude: string): string[] {
  let entries;
  try {
    entries = readdirSync(base, { withFileTypes: true });
  } catch {
    return [];
  }
  const removed: string[] = [];
  for (const e of entries) {
    if (!e.isDirectory()) continue;
    const info = parseSessionDir(e.name);
    if (!info) continue;
    const full = join(base, e.name);
    if (full === exclude) continue;
    if (isProcessAlive(info.pid)) continue;
    if (safeRmrf(full)) removed.push(full);
  }
  return removed;
}

// ── ASCII header ───────────────────────────────────────────────────────

const HEADER = `
███████╗███████╗███╗   ██╗██████╗ ██╗   ██╗
╚══███╔╝██╔════╝████╗  ██║██╔══██╗╚██╗ ██╔╝
  ███╔╝ █████╗  ██╔██╗ ██║██║  ██║ ╚████╔╝
 ███╔╝  ██╔══╝  ██║╚██╗██║██║  ██║  ╚██╔╝
███████╗███████╗██║ ╚████║██████╔╝   ██║
╚══════╝╚══════╝╚═╝  ╚═══╝╚═════╝    ╚═╝
Dify Enterprise Support Harness
`;

// ── Extension entry ────────────────────────────────────────────────────

export default function (pi: ExtensionAPI) {
  // ── Tools & Commands ────────────────────────────────────────────────
  
  registerAllTools(pi);
  registerAllCommands(pi);

  // ── Session lifecycle ───────────────────────────────────────────────

  const ts = Date.now();
  const sessionDir = join(BASE_DIR, `${SESSION_PREFIX}${process.pid}-${ts}`);
  let cleanedUp = false;

  function ensureDir(): void {
    try {
      mkdirSync(sessionDir, { recursive: true, mode: 0o700 });
    } catch {
      // non-fatal
    }
  }

  function cleanupSession(): void {
    if (cleanedUp) return;
    cleanedUp = true;
    safeRmrf(sessionDir);

    // Do not rely on the human remembering manual cleanup: wipe standalone
    // source clones too when pi exits. The current session dir was already
    // removed above; this covers clones created directly under /tmp/dify-*.
    try {
      const entries = readdirSync(BASE_DIR, { withFileTypes: true });
      for (const e of entries) {
        if (!e.isDirectory()) continue;
        if (!WIPE_PREFIXES.some((p) => e.name.startsWith(p))) continue;
        safeRmrf(join(BASE_DIR, e.name));
      }
    } catch {
      // non-fatal
    }
  }

  process.on("exit", cleanupSession);
  process.on("SIGINT", () => { cleanupSession(); process.exit(130); });
  process.on("SIGTERM", () => { cleanupSession(); process.exit(143); });
  process.on("uncaughtException", (err) => {
    cleanupSession();
    console.error(err);
    process.exit(1);
  });

  pi.on("session_start", async (_event, ctx) => {
    ensureDir();
    process.env["ZENDY_SRC_DIR"] = sessionDir;

    // Custom header
    if (ctx.hasUI) {
      ctx.ui.notify(HEADER, "info");
    }

    // Sweep orphan session dirs
    const removed = sweepOrphans(BASE_DIR, sessionDir);
    if (ctx.hasUI && removed.length > 0) {
      ctx.ui.notify(`[zendy] swept ${removed.length} orphan session dir(s)`, "info");
    }
  });

  pi.on("session_shutdown", async () => {
    cleanupSession();
  });
}