'use strict';

const path = require('node:path');
const { spawn, execFileSync } = require('node:child_process');
const { desktopCapturer, screen, BrowserWindow, nativeImage } = require('electron');
const { expandPlaceholders } = require('../core/placeholders');

/**
 * Capture service: full-screen, active-window, and region capture via
 * Electron's desktopCapturer, plus a click-marker annotation at the cursor
 * position and a capture session (start/pause/resume/finish).
 *
 * A session captures continuously, with three triggers layered by what the
 * platform supports:
 *  - click-capture via an OS adapter (xinput on X11, PowerShell on Windows),
 *  - a global hotkey (unreliable on some Wayland compositors),
 *  - interval auto-capture as the always-works fallback.
 *
 * Note: under Wayland/WSLg, screen capture may require portal support; all
 * failures surface as { ok: false, reason } instead of crashing.
 */

const CLICK_DEBOUNCE_MS = 700;

function hasBinary(name) {
  try {
    execFileSync('which', [name], { stdio: 'pipe' });
    return true;
  } catch {
    return false;
  }
}

class CaptureService {
  constructor({ store, settings, getWindow, notify }) {
    this.store = store;
    this.settings = settings;
    this.getWindow = getWindow;
    this.notify = notify;
    this.session = null; // { guideId, paused, count, intervalSec }
    this.intervalTimer = null;
    this.clickWatcher = null;
    this.lastClickCapture = 0;
    this.shooting = false;
  }

  state() {
    return this.session
      ? {
        active: true,
        paused: this.session.paused,
        guideId: this.session.guideId,
        count: this.session.count,
        intervalSec: this.session.intervalSec || 0,
        clickCapture: Boolean(this.clickWatcher),
        clickCaptureAvailable: this.clickCaptureAvailable(),
      }
      : { active: false, clickCaptureAvailable: this.clickCaptureAvailable() };
  }

  clickCaptureAvailable() {
    if (this._clickAvail === undefined) {
      this._clickAvail = process.platform === 'win32' || (process.platform === 'linux' && hasBinary('xinput'));
    }
    return this._clickAvail;
  }

  startSession(guideId, { intervalSec = null } = {}) {
    this.finishSession();
    // Default trigger: clicks when the platform supports it, otherwise an
    // interval so a session always produces steps even if the global hotkey
    // never fires (common under Wayland/WSLg).
    let interval = intervalSec;
    if (interval == null) {
      interval = this.clickCaptureAvailable() ? 0 : (this.settings.get('capture.autoIntervalSec') || 5);
    }
    this.session = { guideId, paused: false, count: 0, intervalSec: interval };
    if (this.settings.get('capture.captureOutsideClicks') !== false) this.startClickWatcher();
    this.applyInterval();
    this.notify('capture:state', this.state());
  }

  setInterval(intervalSec) {
    if (!this.session) return this.state();
    this.session.intervalSec = Math.max(0, Number(intervalSec) || 0);
    this.applyInterval();
    this.notify('capture:state', this.state());
    return this.state();
  }

  applyInterval() {
    if (this.intervalTimer) {
      clearInterval(this.intervalTimer);
      this.intervalTimer = null;
    }
    const sec = this.session && this.session.intervalSec;
    if (sec > 0) {
      this.intervalTimer = setInterval(() => {
        this.sessionCapture('interval').catch(() => {});
      }, sec * 1000);
    }
  }

  togglePause(force) {
    if (!this.session) return;
    this.session.paused = typeof force === 'boolean' ? force : !this.session.paused;
    this.notify('capture:state', this.state());
  }

  finishSession() {
    if (this.intervalTimer) {
      clearInterval(this.intervalTimer);
      this.intervalTimer = null;
    }
    this.stopClickWatcher();
    this.session = null;
  }

  /** One capture inside the active session (hotkey/click/interval/manual). */
  async sessionCapture(trigger = 'hotkey') {
    if (!this.session || this.session.paused) return { ok: false, reason: 'no active capture session' };
    if (this.shooting) return { ok: false, reason: 'capture already in progress' };
    this.shooting = true;
    try {
      const mode = this.settings.get('capture.mode') || 'fullscreen';
      const result = await this.shoot({
        guideId: this.session.guideId,
        mode: mode === 'region' ? 'fullscreen' : mode,
        delayMs: 0,
        refocus: false, // don't steal focus from the app the user is documenting
      });
      if (result.ok) {
        this.session.count += 1;
        this.notify('capture:added', { guideId: this.session.guideId, step: result.step, trigger });
        this.notify('capture:state', this.state());
      }
      return result;
    } finally {
      this.shooting = false;
    }
  }

  hotkeyCapture() {
    return this.sessionCapture('hotkey');
  }

  // ---- click-triggered capture --------------------------------------------

  startClickWatcher() {
    this.stopClickWatcher();
    try {
      if (process.platform === 'linux' && hasBinary('xinput')) {
        // Stream raw button events from the X server; one capture per press.
        this.clickWatcher = spawn('xinput', ['test-xi2', '--root'], { stdio: ['ignore', 'pipe', 'ignore'] });
        let sawPress = false;
        this.clickWatcher.stdout.on('data', (chunk) => {
          const text = chunk.toString();
          if (/RawButtonPress|ButtonPress/.test(text)) sawPress = true;
          if (sawPress) {
            sawPress = false;
            this.onOsClick();
          }
        });
      } else if (process.platform === 'win32') {
        // Poll the left mouse button via GetAsyncKeyState; print one line per click.
        const ps = `
Add-Type -Namespace W -Name U -MemberDefinition '[DllImport("user32.dll")] public static extern short GetAsyncKeyState(int k);'
$down = $false
while ($true) {
  $s = [W.U]::GetAsyncKeyState(0x01) -band 0x8000
  if ($s -and -not $down) { Write-Output CLICK }
  $down = [bool]$s
  Start-Sleep -Milliseconds 40
}`;
        this.clickWatcher = spawn('powershell.exe', ['-NoProfile', '-Command', ps], { stdio: ['ignore', 'pipe', 'ignore'] });
        this.clickWatcher.stdout.on('data', (chunk) => {
          if (chunk.toString().includes('CLICK')) this.onOsClick();
        });
      }
      if (this.clickWatcher) {
        this.clickWatcher.on('error', () => { this.clickWatcher = null; });
        this.clickWatcher.on('exit', () => { this.clickWatcher = null; });
      }
    } catch {
      this.clickWatcher = null;
    }
  }

  stopClickWatcher() {
    if (this.clickWatcher) {
      try { this.clickWatcher.kill(); } catch { /* already gone */ }
      this.clickWatcher = null;
    }
  }

  onOsClick() {
    if (!this.session || this.session.paused) return;
    // Ignore clicks on StepForge itself (pausing, finishing, editing).
    if (BrowserWindow.getFocusedWindow()) return;
    const now = Date.now();
    if (now - this.lastClickCapture < CLICK_DEBOUNCE_MS) return;
    this.lastClickCapture = now;
    this.sessionCapture('click').catch(() => {});
  }

  autoTitle(mode) {
    const tplStr = this.settings.get('editor.autoTitleTemplate') || '[[Mode]] capture [[Time]]';
    const now = new Date();
    const pad = (n) => String(n).padStart(2, '0');
    return expandPlaceholders(tplStr, {
      Mode: { fullscreen: 'Screen', window: 'Window', region: 'Region' }[mode] || 'Screen',
      Time: `${pad(now.getHours())}:${pad(now.getMinutes())}:${pad(now.getSeconds())}`,
      Date: `${now.getFullYear()}-${pad(now.getMonth() + 1)}-${pad(now.getDate())}`,
    });
  }

  /** Grab the screen/window image as { image, display } or throw. */
  async grab(mode) {
    const cursor = screen.getCursorScreenPoint();
    const display = screen.getDisplayNearestPoint(cursor);
    const { width, height } = display.size;
    const scale = display.scaleFactor || 1;
    // Ask for both kinds: some compositors (WSLg/Wayland portals) expose no
    // individual window sources, so window mode falls back to the screen.
    const sources = await desktopCapturer.getSources({
      types: mode === 'window' ? ['window', 'screen'] : ['screen'],
      thumbnailSize: { width: Math.round(width * scale), height: Math.round(height * scale) },
    });
    if (!sources.length) throw new Error('no capture sources available (portal/permissions?)');

    let source = null;
    if (mode === 'window') {
      const win = this.getWindow();
      const ownTitle = win ? win.getTitle() : '';
      const windows = sources.filter((s) => s.id.startsWith('window:'));
      source = windows.find((s) => s.name && s.name !== ownTitle && !/stepforge/i.test(s.name))
        || windows[0]
        || sources.find((s) => s.id.startsWith('screen:'));
    } else {
      const screens = sources.filter((s) => s.id.startsWith('screen:'));
      source = screens.find((s) => String(s.display_id) === String(display.id)) || screens[0] || sources[0];
    }
    if (!source) throw new Error('no capture source matched');
    const image = source.thumbnail;
    if (!image || image.isEmpty()) throw new Error('capture returned an empty image');
    return { image, display, cursor };
  }

  /**
   * Hide the app window while `fn` runs so screenshots show the user's work,
   * not StepForge itself. Restores visibility afterwards.
   */
  async withWindowHidden(fn, { refocus = true } = {}) {
    const win = this.getWindow();
    const wasVisible = win && !win.isDestroyed() && win.isVisible() && !win.isMinimized();
    if (wasVisible) {
      win.hide();
      await new Promise((r) => setTimeout(r, 350)); // let the compositor repaint
    }
    try {
      return await fn();
    } finally {
      if (wasVisible && win && !win.isDestroyed()) {
        if (refocus) {
          win.show();
          win.focus();
        } else {
          win.showInactive();
        }
      }
    }
  }

  /**
   * Take a screenshot and append it to the guide as a new image step.
   * Adds a click-marker annotation at the cursor position when enabled.
   */
  async shoot({ guideId, mode = 'fullscreen', delayMs = null, hideWindow = true, refocus = true }) {
    const delay = delayMs == null ? this.settings.get('capture.delayMs') || 0 : delayMs;
    if (delay > 0) await new Promise((resolve) => setTimeout(resolve, delay));
    let grabbed;
    try {
      grabbed = hideWindow
        ? await this.withWindowHidden(() => this.grab(mode), { refocus })
        : await this.grab(mode);
    } catch (err) {
      return { ok: false, reason: err.message };
    }
    const { image, display, cursor } = grabbed;
    const size = image.getSize();
    const annotations = [];
    if (mode !== 'window' && this.settings.get('capture.clickMarker')) {
      const fx = (cursor.x - display.bounds.x) / display.bounds.width;
      const fy = (cursor.y - display.bounds.y) / display.bounds.height;
      if (fx >= 0 && fx <= 1 && fy >= 0 && fy <= 1) {
        const d = 0.035;
        annotations.push({
          type: 'oval',
          x: fx - d / 2, y: fy - (d * size.width / size.height) / 2,
          w: d, h: d * size.width / size.height,
          style: {
            stroke: this.settings.get('capture.clickMarkerColor') || '#E5484D',
            strokeWidth: 4, fill: 'transparent',
          },
        });
      }
    }

    const step = this.store.addStep(guideId, {
      title: this.autoTitle(mode),
      annotations,
      focusedView: {
        enabled: Boolean(this.settings.get('editor.focusedViewDefaultForNewSteps')),
        zoom: 1, panX: 0.5, panY: 0.5,
      },
    }, image.toPNG(), size);
    return { ok: true, step };
  }

  /**
   * Region capture: shoot the full screen, then let the user drag a
   * rectangle in a fullscreen overlay; the crop becomes the step image.
   */
  async regionCapture(guideId) {
    let grabbed;
    try {
      grabbed = await this.withWindowHidden(() => this.grab('fullscreen'));
    } catch (err) {
      return { ok: false, reason: err.message };
    }
    const { image, display } = grabbed;
    const rect = await this.pickRegion(display, image);
    if (!rect) return { ok: false, reason: 'selection cancelled' };

    const cropped = image.crop(rect);
    const size = cropped.getSize();
    if (!size.width || !size.height) return { ok: false, reason: 'empty selection' };
    const step = this.store.addStep(guideId, { title: this.autoTitle('region') },
      cropped.toPNG(), size);
    return { ok: true, step };
  }

  /** Fullscreen overlay window that resolves with a crop rect (image px). */
  pickRegion(display, image) {
    return new Promise((resolve) => {
      const overlay = new BrowserWindow({
        x: display.bounds.x,
        y: display.bounds.y,
        width: display.bounds.width,
        height: display.bounds.height,
        frame: false,
        transparent: true,
        alwaysOnTop: true,
        fullscreen: true,
        skipTaskbar: true,
        webPreferences: {
          preload: path.join(__dirname, 'region-preload.js'),
          contextIsolation: true,
        },
      });
      let settled = false;
      const finish = (rect) => {
        if (settled) return;
        settled = true;
        if (!overlay.isDestroyed()) overlay.close();
        resolve(rect);
      };
      const { ipcMain } = require('electron');
      const onPick = (event, rect) => {
        if (event.sender !== overlay.webContents) return;
        ipcMain.removeListener('region:picked', onPick);
        if (!rect) return finish(null);
        const imgSize = image.getSize();
        const sx = imgSize.width / display.bounds.width;
        const sy = imgSize.height / display.bounds.height;
        finish({
          x: Math.round(rect.x * sx),
          y: Math.round(rect.y * sy),
          width: Math.round(rect.w * sx),
          height: Math.round(rect.h * sy),
        });
      };
      ipcMain.on('region:picked', onPick);
      overlay.on('closed', () => finish(null));
      overlay.loadFile(path.join(__dirname, 'renderer', 'region.html'));
    });
  }
}

module.exports = CaptureService;