export type ButtonRect = [x: number, y: number, w: number, h: number];

export interface ButtonNavigationConfig<T extends string> {
  up?: T | "last";
  down?: T | "last";
  left?: T;
  right?: T;
  horizontalMode?: "navigate" | "preview";
}

export class ButtonNavigation<T extends string> {
  private selectedButton: T;
  private nextButton?: T;
  private buttons: Record<T, ButtonRect>;
  private navigation: Record<T, ButtonNavigationConfig<T>>;
  private onButtonClick?: (buttonName: T) => void;
  private keydownHandler: (event: KeyboardEvent) => void;

  constructor(config: {
    buttons: Record<T, ButtonRect>;
    initialButton: T;
    navigation: Record<T, ButtonNavigationConfig<T>>;
    onButtonClick?: (buttonName: T) => void;
  }) {
    this.buttons = config.buttons;
    this.selectedButton = config.initialButton;
    this.navigation = config.navigation;
    this.onButtonClick = config.onButtonClick;

    // TODO: this should be handled by the nds itself i think, and dispatched
    this.keydownHandler = this.handleKeyPress.bind(this);
    window.addEventListener("keydown", this.keydownHandler);
  }

  public getSelectedButton(): T {
    return this.selectedButton;
  }

  public getSelectorPosition(): ButtonRect {
    return this.buttons[this.selectedButton];
  }

  public handleTouch(x: number, y: number): void {
    for (const [buttonName, config] of Object.entries(this.buttons) as [
      T,
      ButtonRect,
    ][]) {
      const [sx, sy, sw, sh] = config;
      if (x >= sx && x <= sx + sw && y >= sy && y <= sy + sh) {
        if (this.selectedButton === buttonName) {
          this.onButtonClick?.(buttonName);
        } else {
          if (
            (this.navigation[buttonName].down === "last" &&
              this.navigation[this.selectedButton]!.up === buttonName) ||
            (this.navigation[buttonName].up === "last" &&
              this.navigation[this.selectedButton]!.down === buttonName)
          ) {
            this.nextButton = this.selectedButton;
          }

          this.selectedButton = buttonName;
        }
        break;
      }
    }
  }

  private handleKeyPress(event: KeyboardEvent): void {
    const currentButton = this.selectedButton;
    const currentNav = this.navigation[currentButton];

    if (!currentNav) return;

    switch (event.key) {
      case "ArrowUp":
        if (!currentNav.up) return;

        if (currentNav.up === "last") {
          if (this.nextButton) {
            this.selectedButton = this.nextButton;
          } else {
            this.selectedButton = (currentNav.left ?? currentNav.right) as T;
          }
        } else {
          if (this.navigation[currentNav.up].down === "last") {
            this.nextButton = this.selectedButton;
          }
          this.selectedButton = currentNav.up;
        }

        break;

      case "ArrowDown":
        if (!currentNav.down) return;

        if (currentNav.down === "last") {
          if (this.nextButton) {
            this.selectedButton = this.nextButton;
          } else {
            this.selectedButton = (currentNav.left ?? currentNav.right) as T;
          }
        } else {
          if (this.navigation[currentNav.down].up === "last") {
            this.nextButton = this.selectedButton;
          }
          this.selectedButton = currentNav.down;
        }
        break;

      case "ArrowLeft":
        if (!currentNav.left) return;

        if (currentNav.horizontalMode === "preview") {
          this.nextButton = currentNav.left;
        } else {
          this.selectedButton = currentNav.left;
        }
        break;

      case "ArrowRight":
        if (!currentNav.right) return;

        if (currentNav.horizontalMode === "preview") {
          this.nextButton = currentNav.right;
        } else {
          this.selectedButton = currentNav.right;
        }
        break;

      case "Enter":
      case " ":
        this.onButtonClick?.(this.selectedButton);
        break;

      default:
        return;
    }

    event.preventDefault();
  }

  public destroy(): void {
    window.removeEventListener("keydown", this.keydownHandler);
  }
}