import { existsSync, mkdirSync, writeFileSync } from "node:fs";
import { homedir } from "node:os";
import { dirname, resolve } from "node:path";

/**
 * Result of {@link runConfigInit}: stdout/stderr text and a process exit code,
 * mirroring the rest of the CLI dispatcher. Code 0 = wrote a file (or would in
 * --dry-run); 1 = file existed and `force` was false; 2 = bad input.
 */
export interface ConfigInitResult {
  stdout: string;
  stderr: string;
  code: number;
  path: string;
}

export interface ConfigInitOptions {
  /** Target file path. Defaults to `~/.tdmcp/config.env`. A leading `~`, `~/`, or `~\` is expanded to the user's home directory. */
  out?: string;
  /** Overwrite an existing file. Without it, refuses (code 1) if the path exists. */
  force?: boolean;
  /** When true, returns the body that would be written without touching the filesystem. */
  dryRun?: boolean;
  /** Shared TD bridge token to bake into the starter file as an uncommented `TDMCP_BRIDGE_TOKEN=...` line. */
  bridgeToken?: string;
}

/** Expand a leading `~`, `~/`, or `~\\` in a path to the user's home directory. */
function expandHome(p: string): string {
  if (p === "~") return resolve(homedir());
  if (p.startsWith("~/") || p.startsWith("~\\")) return resolve(homedir(), p.slice(2));
  return resolve(p);
}

/**
 * Render the starter `.env`-style file body: every TDMCP_* env var the server
 * reads, with a sane default (or a clearly marked "unset" placeholder for
 * secrets) and a one-line comment per variable. Sourced via `set -a; source
 * config.env; set +a` or pasted into a shell.
 *
 * Kept in lock-step with src/utils/config.ts — any new TDMCP_* env there should
 * also land here (covered by the unit test that asserts the rendered body
 * mentions every config key).
 */
export function renderStarterConfig(opts: { bridgeToken?: string } = {}): string {
  const tokenLine = opts.bridgeToken
    ? `TDMCP_BRIDGE_TOKEN=${JSON.stringify(opts.bridgeToken)}`
    : '# TDMCP_BRIDGE_TOKEN=""';
  return [
    "# tdmcp starter config",
    "# Generated by `tdmcp config init`. Source with:",
    "#   set -a && source ~/.tdmcp/config.env && set +a",
    "# or paste the lines you want into your shell rc.",
    "",
    "# --- Config resolution -----------------------------------------------------",
    "# These two control HOW the rest of the variables are loaded — set them in your",
    "# shell, not in this file (sourcing this file is too late to influence its own",
    "# discovery).",
    "# Absolute path to an alternate tdmcp config file (JSON). When set, this file",
    "# is loaded instead of the default search path (./tdmcp.json, ./.tdmcprc,",
    "# $XDG_CONFIG_HOME/tdmcp/config.json).",
    '# TDMCP_CONFIG_FILE=""',
    "# Active profile name to select from a multi-profile config file. Profiles let",
    "# you keep per-venue/per-show overrides under a single `profiles: {…}` block.",
    '# TDMCP_PROFILE=""',
    "",
    "# --- TouchDesigner bridge --------------------------------------------------",
    "# Host + port the WebServer DAT inside TD listens on.",
    'TDMCP_TD_HOST="127.0.0.1"',
    'TDMCP_TD_PORT="9980"',
    "# Per-request timeout against the TD bridge, in milliseconds.",
    'TDMCP_REQUEST_TIMEOUT_MS="10000"',
    "# Optional shared bearer token. Set the SAME value in TD's environment to enforce auth.",
    tokenLine,
    "",
    "# --- MCP server ------------------------------------------------------------",
    '# Transport: "stdio" (default, for local clients) or "http" (Streamable HTTP, loopback-only).',
    'TDMCP_TRANSPORT="stdio"',
    "# HTTP transport port (only used when TDMCP_TRANSPORT=http).",
    'TDMCP_HTTP_PORT="3939"',
    "# Log verbosity. One of: debug, info, warn, error, silent.",
    'TDMCP_LOG_LEVEL="info"',
    "# Forward TD WebSocket events as MCP logging notifications. on|off.",
    'TDMCP_EVENTS="on"',
    "",
    "# --- Tool exposure ---------------------------------------------------------",
    '# Tool surface: "full" (every tool) or "safe" (hides destructive + raw-code tools).',
    'TDMCP_TOOL_PROFILE="full"',
    "# Raw Python escape-hatch tools (execute_python_script, exec_node_method). on|off.",
    'TDMCP_RAW_PYTHON="on"',
    "",
    "# --- Local LLM copilot (`tdmcp chat`) --------------------------------------",
    "# Base URL of an OpenAI-compatible chat endpoint. Default points at local Ollama.",
    'TDMCP_LLM_BASE_URL="http://127.0.0.1:11434/v1"',
    "# Model id (must be pulled in the backend, e.g. `ollama pull qwen2.5:3b`).",
    'TDMCP_LLM_MODEL="qwen2.5:3b"',
    "# Optional bearer token for paid/cloud LLM APIs (ignored by local Ollama).",
    '# TDMCP_LLM_API_KEY=""',
    '# Default copilot tool tier: "standard", "safe" (read-only), or "creative".',
    'TDMCP_LLM_TIER="standard"',
    "# Max model/tool loop iterations for one local copilot turn (clamped to 1..32).",
    'TDMCP_LLM_MAX_STEPS="8"',
    "# Sampling temperature for the local copilot (clamped to 0..2).",
    'TDMCP_LLM_TEMPERATURE="0.4"',
    "# Loopback port the `tdmcp chat` web UI binds to.",
    'TDMCP_CHAT_PORT="4141"',
    "",
    "# --- Telegram Bot API entry point (`tdmcp telegram`) ----------------------",
    "# Bot token from BotFather. Keep unset unless you run the Telegram adapter.",
    '# TDMCP_TELEGRAM_BOT_TOKEN=""',
    "# Comma-separated chat ids allowed to reach the local copilot.",
    '# TDMCP_TELEGRAM_ALLOWED_CHATS=""',
    "# Optional comma-separated user ids allowed to reach the local copilot.",
    '# TDMCP_TELEGRAM_ALLOWED_USERS=""',
    '# Default Telegram copilot tier: "safe" (default), "standard", or "creative".',
    'TDMCP_TELEGRAM_DEFAULT_TIER="safe"',
    "# Telegram getUpdates long-poll timeout in seconds.",
    'TDMCP_TELEGRAM_POLL_TIMEOUT_SEC="30"',
    "# Expiry for a pending non-safe Telegram prompt awaiting /approve.",
    'TDMCP_TELEGRAM_CONFIRM_TIMEOUT_MS="60000"',
    "",
    "# --- Obsidian vault integration --------------------------------------------",
    "# Absolute path to an Obsidian vault folder; leave unset to disable vault tools.",
    '# TDMCP_VAULT_PATH=""',
    "",
  ].join("\n");
}

/**
 * Write a starter config file (or print it under `--dry-run`). Never throws —
 * filesystem errors are returned as a non-zero exit code. The default target
 * is `~/.tdmcp/config.env`; pass `out` to override. Existing files are
 * refused unless `force` is true (so re-running the command is safe).
 */
export function runConfigInit(opts: ConfigInitOptions = {}): ConfigInitResult {
  const target = expandHome(opts.out ?? "~/.tdmcp/config.env");
  const body = renderStarterConfig({ bridgeToken: opts.bridgeToken });

  if (opts.dryRun) {
    return {
      stdout: body,
      stderr: `# Dry run — would write ${target}\n`,
      code: 0,
      path: target,
    };
  }

  if (existsSync(target) && !opts.force) {
    return {
      stdout: "",
      stderr: `Refusing to overwrite existing file ${target}. Re-run with --force to replace it.\n`,
      code: 1,
      path: target,
    };
  }

  try {
    mkdirSync(dirname(target), { recursive: true });
    writeFileSync(target, body, { mode: 0o600 });
    return {
      stdout: `${target}\n`,
      stderr: `Wrote starter tdmcp config to ${target}.\nSource it with:  set -a && source ${target} && set +a\n`,
      code: 0,
      path: target,
    };
  } catch (err) {
    return {
      stdout: "",
      stderr: `Failed to write ${target}: ${(err as Error).message}\n`,
      code: 2,
      path: target,
    };
  }
}