import { Graphics } from 'pixi.js';
import { Button, crisp, hairline, HStack, Menu, Theme } from '../ui';
import { DocumentTab } from './DocumentTab';
import { TabButton } from './TabButton';
import { tabRowLayout } from './tabRow';

/** Fixed, so that the count of hidden tabs cannot feed back into how much room the row has. */
const OVERFLOW_WIDTH = 28;
/** The bar Graphics is the first child, so a tab's index among the children is two past its place. */
const TABS_AT = 2;

export interface TabPlace<T extends string> {
  tab: T;
  x: number;
  right: number;
  /** Top edge and height, so a check can tell the tab from a label of the same text elsewhere. */
  y: number;
  h: number;
  /** Whether the name is drawn bold – the tab showing must not be (#176). */
  bold: boolean;
  /** Whether an icon stands in front of the name; the fixed tabs have one too, bar Plugins (#176). */
  icon: boolean;
  /** A document's kind as shown before its name, and where its × is. */
  kind?: string;
  close?: { x: number; y: number };
}

/** A document's tab: the icon of its kind before the name, and an × that calls `onClose`. */
export interface DocumentSpec {
  /** The kind as a word, for the check scripts; the tab shows `icon`. */
  kind: string;
  icon: string;
  onClose: () => void;
  /** A right-click on the tab (#371). */
  onMenu?: (globalX: number, globalY: number) => void;
}

/**
 * The row of tab buttons. What does not fit goes behind a `»` button that opens the rest as a
 * menu, so the row survives any window width and any number of tabs.
 */
export class TabStrip<T extends string> extends HStack {
  private readonly order: T[] = [];
  private readonly buttons = new Map<T, Button>();
  /** A document's icon, which the `»` menu shows in front of its name too. */
  private readonly icons = new Map<T, string>();
  private readonly overflow: Button;
  /** The bar the cards sit on, drawn behind every tab. */
  private readonly bar = crisp(new Graphics());
  private hiddenTabs: T[] = [];
  private active: T | null;

  constructor(
    tabs: readonly { tab: T; label: string; icon?: string }[],
    private readonly onPick: (tab: T) => void,
  ) {
    super({ gap: 2, padding: 4, align: 'center' });
    this.active = tabs[0]!.tab;
    this.overflow = new Button('»', {
      variant: 'ghost',
      width: OVERFLOW_WIDTH,
      tooltip: 'More tabs',
      onClick: () => this.openMenu(),
    });
    this.addChild(this.bar);
    this.add(this.overflow);
    for (const { tab, label, icon } of tabs) this.place(tab, label, this.order.length, undefined, icon);
    this.buttons.get(this.active)!.setToggled(true);
  }

  /** Puts a tab at `at` in the row (default: last, in front of the `»` button). */
  addTab(tab: T, label: string, at = this.order.length, document?: DocumentSpec): void {
    this.place(tab, label, at, document);
    this.relayout();
  }

  /** Takes a tab out of the row again. Unknown tabs are ignored. */
  removeTab(tab: T): void {
    const button = this.buttons.get(tab);
    if (!button) return;
    this.order.splice(this.order.indexOf(tab), 1);
    this.buttons.delete(tab);
    this.icons.delete(tab);
    this.hiddenTabs = this.hiddenTabs.filter((hidden) => hidden !== tab);
    button.destroy({ children: true });
    this.relayout();
  }

  /** A renamed document; the row measures again, since the name decides the width. */
  setLabel(tab: T, label: string): void {
    const button = this.buttons.get(tab);
    if (!button || button.text === label) return;
    button.setText(label);
    this.relayout();
  }

  has(tab: T): boolean {
    return this.buttons.has(tab);
  }

  /** Every tab in row order, hidden ones included. */
  get tabs(): readonly T[] {
    return this.order;
  }

  private place(tab: T, label: string, at: number, document?: DocumentSpec, icon?: string): void {
    const button = document
      ? new DocumentTab(
          label,
          document.kind,
          document.icon,
          () => this.onPick(tab),
          document.onClose,
          document.onMenu,
        )
      : new TabButton(label, { icon, onClick: () => this.onPick(tab) });
    this.order.splice(at, 0, tab);
    this.buttons.set(tab, button);
    const shown = document?.icon ?? icon;
    if (shown) this.icons.set(tab, shown);
    this.addChildAt(button, at + TABS_AT);
    this.setChildIndex(this.overflow, this.children.length - 1);
    button.setToggled(tab === this.active);
  }

  setActive(tab: T | null): void {
    this.active = tab;
    for (const [key, button] of this.buttons) button.setToggled(key === tab);
    // Not `resize`: the strip keeps its size while a different tab has to come into view.
    this.relayout();
  }

  /** Global x-extent of the tab buttons currently in the row, in order. */
  places(): TabPlace<T>[] {
    const out: TabPlace<T>[] = [];
    for (const tab of this.order) {
      const button = this.buttons.get(tab)!;
      if (!button.visible) continue;
      const at = button.toGlobal({ x: 0, y: 0 });
      const place: TabPlace<T> = {
        tab,
        x: at.x,
        right: at.x + button.w,
        y: at.y,
        h: button.h,
        bold: button.labelBold,
        icon: button.hasIcon,
      };
      if (button instanceof DocumentTab) {
        place.kind = button.kindLabel;
        place.close = button.closePoint();
      }
      out.push(place);
    }
    return out;
  }

  hidden(): T[] {
    return [...this.hiddenTabs];
  }

  override layout(): void {
    this.applyOverflow();
    super.layout();
    // The cards reach down to the bar: the stack's padding below them is theirs, not free space.
    for (const item of this.items) {
      if (!(item instanceof TabButton)) continue;
      item.position.set(item.x, this.padding);
      item.resize(item.w, Math.max(0, this.h - this.padding));
    }
  }

  override redraw(): void {
    const c = Theme.colors;
    this.bar.clear();
    this.bar.rect(0, 0, this.w, this.h).fill(c.tabBar);
    // The line the cards stand on; the one showing covers its own stretch of it.
    this.bar.rect(0, this.h - hairline(), this.w, hairline()).fill(c.border);
  }

  private applyOverflow(): void {
    const tabs = this.order.map((tab) => ({ key: tab, width: this.buttons.get(tab)!.measure().w }));
    const { hidden } = tabRowLayout({
      tabs,
      available: this.w - this.padding * 2,
      gap: this.gap,
      overflowWidth: OVERFLOW_WIDTH,
      active: this.active,
    });
    this.hiddenTabs = hidden;
    const away = new Set(hidden);
    for (const [tab, button] of this.buttons) button.visible = !away.has(tab);
    this.overflow.visible = hidden.length > 0;
  }

  private openMenu(): void {
    const items = this.hiddenTabs.map((tab) => {
      const button = this.buttons.get(tab)!;
      return { label: button.text, icon: this.icons.get(tab), onSelect: () => this.onPick(tab) };
    });
    new Menu(items).openBelow(this.overflow);
  }
}