import { type Container, type FederatedPointerEvent, Graphics, Rectangle } from 'pixi.js';
import { Button, crisp, drawFloatingBox, Icon, Label, Spacer, Theme, ui, Widget } from '../ui';
import { keptSize, leastBox, onScreen, sized, type WindowBox } from './floating';
import { TabHeader } from './TabHeader';

/** The corner taken hold of to size the window. */
const GRIP = 14;

export interface FloatWindowHost {
  onDock: () => void;
  onClose: () => void;
  /** Any press inside the window, before what is under the pointer sees it. */
  onPress: () => void;
}

/** A pane that is one size only (#379); null while it takes any. */
export interface SizedPane {
  readonly fixedSize: { w: number; h: number } | null;
}

/**
 * A tab's pane in a window of its own (#371), above the editor. The pane is lent, not owned: the
 * editor puts it in with `setContent` and takes it back before the window goes. The title bar
 * moves the window, the lower right corner sizes it, and neither is remembered.
 */
export class FloatWindow extends Widget {
  private readonly bg = new Graphics();
  private readonly bar = new TabHeader();
  private icon: { svg: string; widget: Icon } | null = null;
  private readonly title = new Label('', { style: 'bodyBold' });
  readonly dockButton: Button;
  readonly closeButton: Button;
  private readonly grip = crisp(new Graphics());
  private content: Widget | null = null;
  private gesture: { kind: 'move' | 'size'; x: number; y: number; box: WindowBox } | null = null;

  constructor(host: FloatWindowHost) {
    super();
    this.dockButton = new Button('Dock', {
      variant: 'ghost',
      tooltip: 'Back into the tab row',
      onClick: () => host.onDock(),
    });
    this.closeButton = new Button('×', { variant: 'ghost', tooltip: 'Close', onClick: () => host.onClose() });
    this.bar.add(this.title);
    this.bar.add(new Spacer(), 1);
    this.bar.add(this.dockButton);
    this.bar.add(this.closeButton);
    this.bar.cursor = 'move';
    this.bar.on('pointerdown', (e: FederatedPointerEvent) => {
      if (e.button === 0 && !onButton(e.target, this.bar)) this.grab('move', e);
    });
    this.grip.eventMode = 'static';
    this.grip.cursor = 'nwse-resize';
    this.grip.hitArea = new Rectangle(0, 0, GRIP, GRIP);
    this.grip.on('pointerdown', (e: FederatedPointerEvent) => {
      if (e.button === 0) this.grab('size', e);
    });
    this.on('globalpointermove', (e: FederatedPointerEvent) => this.drag(e));
    this.onPointerRelease(() => (this.gesture = null));
    // Before anything inside: the window comes up, and Delete or Ctrl+V go to it from now on.
    this.on('pointerdowncapture', () => {
      this.toFront();
      host.onPress();
    });
    this.addChild(this.bg, this.bar, this.grip);
  }

  get isOpen(): boolean {
    return this.parent !== null;
  }

  /** Where the window is and how large, for the check scripts. */
  get box(): WindowBox {
    return { x: this.x, y: this.y, w: this.w, h: this.h };
  }

  /** Where the title bar can be taken hold of: left of the buttons, clear of the name. */
  barPoint(): { x: number; y: number } {
    const at = this.bar.getGlobalPosition();
    const first = this.dockButton.visible ? this.dockButton : this.closeButton;
    return { x: at.x + first.x - Theme.padding * 2, y: at.y + this.bar.h / 2 };
  }

  /** The size of a window around a pane of one size, or null where it can be sized. */
  get fixedSize(): { w: number; h: number } | null {
    const size = (this.content as Partial<SizedPane> | null)?.fixedSize;
    return size ? { w: size.w + 2, h: size.h + this.bar.measure().h + 2 } : null;
  }

  /**
   * After the pane has changed what it is: a pane of one size has the window at that size, with no
   * corner to size it and no Dock (#379) – it cannot go into the tab row.
   */
  refit(): void {
    const fixed = this.fixedSize !== null;
    this.grip.visible = !fixed;
    if (this.dockButton.visible === fixed) {
      this.dockButton.visible = !fixed;
      this.bar.relayout();
    }
    if (this.isOpen) this.place(this.box);
  }

  /** The middle of the sizing corner, for the check scripts. */
  gripPoint(): { x: number; y: number } {
    const at = this.grip.getGlobalPosition();
    return { x: at.x + GRIP / 2, y: at.y + GRIP / 2 };
  }

  get titleText(): string {
    return this.title.text;
  }

  /** The pane to show; the one before is left without a parent for the caller to put back. */
  setContent(content: Widget): void {
    if (this.content?.parent === this) this.removeChild(this.content);
    this.content = content;
    content.visible = true;
    this.addChildAt(content, this.getChildIndex(this.bar));
    this.layout();
    // A pane that needs more than the window has grows the window.
    this.refit();
  }

  /** The name and the icon of the document shown, as its tab had them. */
  setTitle(text: string, svg: string): void {
    if (this.icon?.svg !== svg) {
      if (this.icon) this.icon.widget.destroy();
      this.icon = { svg, widget: new Icon(svg) };
      this.bar.addChildAt(this.icon.widget, this.bar.getChildIndex(this.title));
    }
    if (this.title.text === text) return;
    this.title.setText(text);
    this.bar.relayout();
  }

  open(box: WindowBox): void {
    ui().overlay.addChild(this);
    ui().app.renderer.on('resize', this.keepOnScreen);
    this.place(box);
  }

  /** Takes the window off the screen; the pane in it stays where it is until the caller moves it. */
  close(): void {
    if (!this.isOpen) return;
    ui().app.renderer.off('resize', this.keepOnScreen);
    this.parent!.removeChild(this);
    // A field in the window would keep the keyboard after the window is gone, as in `Popup.close`.
    if (ui().focus.isWithin(this)) ui().focus.blur();
  }

  toFront(): void {
    const overlay = this.parent;
    if (overlay && overlay.getChildIndex(this) < overlay.children.length - 1)
      overlay.setChildIndex(this, overlay.children.length - 1);
  }

  private grab(kind: 'move' | 'size', e: FederatedPointerEvent): void {
    e.stopPropagation();
    this.gesture = { kind, x: e.global.x, y: e.global.y, box: this.box };
  }

  private drag(e: FederatedPointerEvent): void {
    const g = this.gesture;
    if (!g) return;
    const screen = ui().app.screen;
    const dx = e.global.x - g.x;
    const dy = e.global.y - g.y;
    if (g.kind === 'size') this.place(sized(g.box, dx, dy, screen.width, screen.height, this.least()));
    else this.place({ ...g.box, x: g.box.x + dx, y: g.box.y + dy });
  }

  private readonly keepOnScreen = () => this.place(this.box);

  /** The window's least size: the usual one, or more where the pane in it says it needs more. */
  least(): { w: number; h: number } {
    const content = this.content;
    if (!content) return leastBox(0, 0);
    return leastBox(content.minWidth + 2, content.minHeight + this.bar.measure().h + 2);
  }

  private place(box: WindowBox): void {
    const screen = ui().app.screen;
    const fixed = this.fixedSize;
    const fit = fixed
      ? onScreen(keptSize(box, fixed), screen.width, screen.height, fixed)
      : onScreen(box, screen.width, screen.height, this.least());
    this.position.set(fit.x, fit.y);
    this.resize(fit.w, fit.h);
  }

  override layout(): void {
    const line = 1;
    const barH = this.bar.measure().h;
    this.bar.position.set(line, line);
    this.bar.resize(Math.max(0, this.w - line * 2), barH);
    if (this.content) {
      this.content.position.set(line, line + barH);
      // Laid out even at the same size: a pane that comes from the tab row may not have been.
      const w = Math.max(0, this.w - line * 2);
      const h = Math.max(0, this.h - line * 2 - barH);
      if (this.content.w === w && this.content.h === h) this.content.layout();
      this.content.resize(w, h);
    }
    this.grip.position.set(this.w - GRIP - line, this.h - GRIP - line);
  }

  override redraw(): void {
    const c = Theme.colors;
    drawFloatingBox(this.bg, this.w, this.h, c.panel);
    // Three short diagonals in the corner, the usual sign of a handle that sizes a window.
    this.grip.clear();
    for (const at of [4, 8, 12]) this.grip.moveTo(GRIP - at, GRIP).lineTo(GRIP, GRIP - at);
    this.grip.stroke({ width: 1, color: c.textMuted });
  }
}

/** Whether a press landed on one of the title bar's buttons rather than on the bar itself. */
function onButton(target: Container | null, bar: Container): boolean {
  for (let node = target; node && node !== bar; node = node.parent) if (node instanceof Button) return true;
  return false;
}