/**
 * @file file-manager.js
 * @description The files THIS machine's file manager (Explorer, Finder,
 * Nautilus/Dolphin) is handing the browser, by their own absolute paths —
 * what a native terminal pastes or types for them. A browser gives a page a
 * pasted or dropped file as bytes and a name only (Chrome: never its path),
 * so the terminal and the prompt box would upload a copy, capped in size.
 * Two sources, each answered only to a loopback browser of a local-mode
 * dashboard; the client uses a path only when its name and size match the
 * file the browser holds, so an SSH tunnel's browser still uploads:
 * - `clipboardFiles` (`POST /api/run/clipboard-files`, a paste): what a Copy
 *   put on the clipboard — Windows `powershell -Sta` +
 *   `Clipboard.GetFileDropList()` (Claude Code reads its images the same
 *   way), macOS JXA over `NSPasteboard` file URLs, Linux `wl-paste`/`xclip`
 *   for `text/uri-list` or `x-special/gnome-copied-files`;
 * - `selectedFiles` (`POST /api/run/selected-files`, a drop): a drag from
 *   a file manager carries the items selected in it, so its selection —
 *   Windows `Shell.Application` (every Explorer window, and the desktop),
 *   macOS Finder's `selection` (macOS asks once to let AgentHub control
 *   Finder). Linux file managers publish no selection: a drop there takes
 *   the `file://` list the browser already hands over, else uploads.
 * Nothing is searched for on disk. Every reader is a fixed argv, nothing from
 * the request; a missing reader or an empty answer is an empty list.
 * @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>
 */

const { execFile } = require("node:child_process");
const fs = require("node:fs");
const path = require("node:path");

const MAX_FILES = 100;
const TIMEOUT_MS = 4000;

let execImpl = (cmd, args, env) =>
  new Promise((resolve) => {
    execFile(
      cmd,
      args,
      { encoding: "utf8", timeout: TIMEOUT_MS, maxBuffer: 1024 * 1024, env, windowsHide: true },
      (err, stdout) => resolve(err ? "" : String(stdout || ""))
    );
  });

/** Test seam: `(cmd, args, env) => Promise<stdout>`. */
function __setExecImpl(fn) {
  execImpl = fn;
}

const WIN_SCRIPT =
  "[Console]::OutputEncoding = [Text.Encoding]::UTF8; Add-Type -AssemblyName System.Windows.Forms; " +
  "[System.Windows.Forms.Clipboard]::GetFileDropList() | ForEach-Object { $_ }";

const MAC_SCRIPT = [
  'ObjC.import("AppKit");',
  "const pb = $.NSPasteboard.generalPasteboard;",
  "const urls = pb.readObjectsForClassesOptions($([$.NSURL]), $({ NSPasteboardURLReadingFileURLsOnlyKey: true }));",
  "const out = [];",
  "if (urls) for (let i = 0; i < urls.count; i++) out.push(urls.objectAtIndex(i).path.js);",
  'out.join("\\n");',
].join("\n");

/** `file://` URIs (and a gnome list's leading `copy`/`cut`) as local paths. */
function uriListPaths(text) {
  const out = [];
  for (const raw of String(text || "").split(/\r?\n/)) {
    const line = raw.trim();
    if (!line || line.startsWith("#") || line === "copy" || line === "cut") continue;
    try {
      const u = new URL(line);
      if (u.protocol !== "file:" || (u.host && u.host !== "localhost")) continue;
      out.push(decodeURIComponent(u.pathname));
    } catch {
      /* not a URI */
    }
  }
  return out;
}

/** The raw paths on the clipboard, per platform; [] when it holds none. */
async function clipboardPaths(platform = process.platform) {
  if (platform === "win32") {
    const out = await execImpl(
      "powershell",
      ["-NoProfile", "-NonInteractive", "-Sta", "-Command", WIN_SCRIPT],
      process.env
    );
    return out
      .split(/\r?\n/)
      .map((l) => l.trim())
      .filter(Boolean);
  }
  if (platform === "darwin") {
    const out = await execImpl("osascript", ["-l", "JavaScript", "-e", MAC_SCRIPT], process.env);
    return out
      .split(/\r?\n/)
      .map((l) => l.trim())
      .filter(Boolean);
  }
  // Linux: the desktop session's variables, which a user service lacks.
  const env = { ...process.env, ...require("./desktop-env").desktopEnv() };
  const tries = [];
  if (env.WAYLAND_DISPLAY) {
    tries.push(["wl-paste", ["--no-newline", "--type", "text/uri-list"]]);
    tries.push(["wl-paste", ["--no-newline", "--type", "x-special/gnome-copied-files"]]);
  }
  if (env.DISPLAY) {
    tries.push(["xclip", ["-selection", "clipboard", "-t", "text/uri-list", "-o"]]);
    tries.push(["xclip", ["-selection", "clipboard", "-t", "x-special/gnome-copied-files", "-o"]]);
  }
  for (const [cmd, args] of tries) {
    const paths = uriListPaths(await execImpl(cmd, args, env));
    if (paths.length) return paths;
  }
  return [];
}

const WIN_SELECTION =
  "[Console]::OutputEncoding = [Text.Encoding]::UTF8; $sh = New-Object -ComObject Shell.Application; " +
  "foreach ($w in @($sh.Windows())) { try { foreach ($i in $w.Document.SelectedItems()) { $i.Path } } catch {} }; " +
  // The desktop is no Explorer window: ShellWindows.FindWindowSW(SWC_DESKTOP).
  "try { $d = $sh.Windows().FindWindowSW(0, $null, 8, [ref]0, 1); foreach ($i in $d.Document.SelectedItems()) { $i.Path } } catch {}";

const MAC_SELECTION = [
  'tell application "Finder"',
  'set out to ""',
  "repeat with a in (selection as alias list)",
  "set out to out & POSIX path of a & linefeed",
  "end repeat",
  "return out",
  "end tell",
];

/** The paths a file manager has selected, per platform; [] when unknown. */
async function selectionPaths(platform = process.platform) {
  let out = "";
  if (platform === "win32") {
    out = await execImpl(
      "powershell",
      ["-NoProfile", "-NonInteractive", "-Sta", "-Command", WIN_SELECTION],
      process.env
    );
  } else if (platform === "darwin") {
    out = await execImpl(
      "osascript",
      MAC_SELECTION.flatMap((l) => ["-e", l]),
      process.env
    );
  }
  return out
    .split(/\r?\n/)
    .map((l) => l.trim())
    .filter(Boolean);
}

/** `[{ path, size, dir }]` for each absolute path that exists here (`size`
 *  null for a folder), at most 100, without repeats. */
function existing(paths) {
  const out = [];
  const seen = new Set();
  for (const p of paths.slice(0, MAX_FILES)) {
    if (!path.isAbsolute(p) && !/^[A-Za-z]:[\\/]/.test(p)) continue;
    if (seen.has(p)) continue;
    seen.add(p);
    try {
      const st = fs.statSync(p);
      if (st.isFile()) out.push({ path: p, size: st.size, dir: false });
      else if (st.isDirectory()) out.push({ path: p, size: null, dir: true });
    } catch {
      /* gone since the copy */
    }
  }
  return out;
}

/** The clipboard's files (a file manager's Copy); [] when it holds none. */
async function clipboardFiles(platform = process.platform) {
  try {
    return existing(await clipboardPaths(platform));
  } catch {
    return [];
  }
}

/** The files selected in the file manager — what a drag from it carries;
 *  [] when none, or on a platform whose file manager publishes none. */
async function selectedFiles(platform = process.platform) {
  try {
    return existing(await selectionPaths(platform));
  } catch {
    return [];
  }
}

module.exports = { clipboardFiles, selectedFiles, uriListPaths, __setExecImpl };