// Knowing whether the browser profile is already open, so the server never starts a second copy.
//
// Starting zen.exe with a profile that is already open does not fail: Zen opens another window
// or tab in the running browser. Firefox-family browsers keep a lock on an open profile, which
// is checked here, and every start is recorded on disk so that a server restarted moments later
// does not start the browser again while it is still coming up.

import * as fs from "node:fs";
import * as os from "node:os";
import * as path from "node:path";
import { windowsFolders } from "./config";

// The profile's folder, from the browser's profiles.ini. Null when it cannot be found.
export function profileDir(profile: string, env: NodeJS.ProcessEnv = process.env): string | null {
  // An explicit folder (tests and unusual setups) is the only place looked when it is given.
  const home = env.HOME || env.USERPROFILE || os.homedir();
  const roots = env.SIMPLESEARCH_PROFILES_DIR
    ? [env.SIMPLESEARCH_PROFILES_DIR]
    : [
        path.join(windowsFolders(env, home).appData, "zen"),
        path.join(home, ".zen"),
        path.join(home, "Library", "Application Support", "zen"),
      ];
  for (const root of roots) {
    let ini: string;
    try {
      ini = fs.readFileSync(path.join(root, "profiles.ini"), "utf8");
    } catch {
      continue;
    }
    for (const section of ini.split(/^\[/m)) {
      const get = (key: string) => new RegExp(`^${key}=(.*)$`, "mi").exec(section)?.[1]?.trim();
      if (get("Name") !== profile) continue;
      const p = get("Path");
      if (!p) continue;
      return get("IsRelative") === "0" ? p : path.join(root, ...p.split(/[\\/]/));
    }
  }
  return null;
}

// True when a running browser holds the profile, false when it does not, null when unknown.
export function profileInUse(dir: string, platform: NodeJS.Platform = process.platform): boolean | null {
  if (platform === "win32") {
    // The browser keeps parent.lock open without sharing; anyone else's open fails.
    const lock = path.join(dir, "parent.lock");
    if (!fs.existsSync(lock)) return false;
    try {
      fs.closeSync(fs.openSync(lock, "r+"));
      return false;
    } catch (e) {
      const code = (e as NodeJS.ErrnoException).code;
      return code === "EBUSY" || code === "EPERM" || code === "EACCES" ? true : null;
    }
  }
  // Elsewhere the lock is a symbolic link naming the owner, "address:+pid".
  try {
    const target = fs.readlinkSync(path.join(dir, "lock"));
    const pid = Number(/\+(\d+)$/.exec(target)?.[1]);
    if (!pid) return null;
    try {
      process.kill(pid, 0);
      return true;
    } catch (e) {
      return (e as NodeJS.ErrnoException).code === "EPERM" ? true : false;
    }
  } catch (e) {
    return (e as NodeJS.ErrnoException).code === "ENOENT" ? false : null;
  }
}

// When the browser was last started by any copy of the server, from a small file in the data folder.
export function lastLaunchAt(dataDir: string): number {
  try {
    return Number(JSON.parse(fs.readFileSync(path.join(dataDir, "launch.json"), "utf8")).at) || 0;
  } catch {
    return 0;
  }
}

export function recordLaunch(dataDir: string, at = Date.now()): void {
  try {
    fs.mkdirSync(dataDir, { recursive: true });
    fs.writeFileSync(path.join(dataDir, "launch.json"), JSON.stringify({ at }));
  } catch {
    // Without the record, only this process's own cooldown applies.
  }
}

// Knowing whether the browser profile is already open, so the server never starts a second copy.
//
// Starting zen.exe with a profile that is already open does not fail: Zen opens another window
// or tab in the running browser. Firefox-family browsers keep a lock on an open profile, which
// is checked here, and every start is recorded on disk so that a server restarted moments later
// does not start the browser again while it is still coming up.

import * as fs from "node:fs";
import * as os from "node:os";
import * as path from "node:path";
import { windowsFolders } from "./config";

// The profile's folder, from the browser's profiles.ini. Null when it cannot be found.
export function profileDir(profile: string, env: NodeJS.ProcessEnv = process.env): string | null {
  // An explicit folder (tests and unusual setups) is the only place looked when it is given.
  const home = env.HOME || env.USERPROFILE || os.homedir();
  const roots = env.SIMPLESEARCH_PROFILES_DIR
    ? [env.SIMPLESEARCH_PROFILES_DIR]
    : [
        path.join(windowsFolders(env, home).appData, "zen"),
        path.join(home, ".zen"),
        path.join(home, "Library", "Application Support", "zen"),
      ];
  for (const root of roots) {
    let ini: string;
    try {
      ini = fs.readFileSync(path.join(root, "profiles.ini"), "utf8");
    } catch {
      continue;
    }
    for (const section of ini.split(/^\[/m)) {
      const get = (key: string) => new RegExp(`^${key}=(.*)$`, "mi").exec(section)?.[1]?.trim();
      if (get("Name") !== profile) continue;
      const p = get("Path");
      if (!p) continue;
      return get("IsRelative") === "0" ? p : path.join(root, ...p.split(/[\\/]/));
    }
  }
  return null;
}

// True when a running browser holds the profile, false when it does not, null when unknown.
export function profileInUse(dir: string, platform: NodeJS.Platform = process.platform): boolean | null {
  if (platform === "win32") {
    // The browser keeps parent.lock open without sharing; anyone else's open fails.
    const lock = path.join(dir, "parent.lock");
    if (!fs.existsSync(lock)) return false;
    try {
      fs.closeSync(fs.openSync(lock, "r+"));
      return false;
    } catch (e) {
      const code = (e as NodeJS.ErrnoException).code;
      return code === "EBUSY" || code === "EPERM" || code === "EACCES" ? true : null;
    }
  }
  // Elsewhere the lock is a symbolic link naming the owner, "address:+pid".
  try {
    const target = fs.readlinkSync(path.join(dir, "lock"));
    const pid = Number(/\+(\d+)$/.exec(target)?.[1]);
    if (!pid) return null;
    try {
      process.kill(pid, 0);
      return true;
    } catch (e) {
      return (e as NodeJS.ErrnoException).code === "EPERM" ? true : false;
    }
  } catch (e) {
    return (e as NodeJS.ErrnoException).code === "ENOENT" ? false : null;
  }
}

// When the browser was last started by any copy of the server, from a small file in the data folder.
export function lastLaunchAt(dataDir: string): number {
  try {
    return Number(JSON.parse(fs.readFileSync(path.join(dataDir, "launch.json"), "utf8")).at) || 0;
  } catch {
    return 0;
  }
}

export function recordLaunch(dataDir: string, at = Date.now()): void {
  try {
    fs.mkdirSync(dataDir, { recursive: true });
    fs.writeFileSync(path.join(dataDir, "launch.json"), JSON.stringify({ at }));
  } catch {
    // Without the record, only this process's own cooldown applies.
  }
}