import { BufferDrawing, BufferSize, CharBuffer, PaletteMap } from "./base.ts";
import { getPaletteMapping } from "./colors.ts";
import { UI_CONFIG_DEFAULTS, UIConfig } from "./config.ts";
import { Display } from "./display.ts";

/**
 * Common abstraction for a textual UI
 */
export class TextUI {
  private config: UIConfig;
  private buffer = new CharBuffer({ w: 1, h: 1 });
  private palettemap: PaletteMap = [];
  private quitting = false;

  constructor(private display: Display, config: Partial<UIConfig>) {
    this.config = { ...UI_CONFIG_DEFAULTS, ...config };
  }

  get drawing(): BufferDrawing {
    return new BufferDrawing(this.buffer, this.palettemap);
  }

  /**
   * Initializes the UI and display
   *
   * If config.loopInterval is defined, the UI loop is
   * started but not awaited.
   */
  async init(): Promise<void> {
    var size = await this.display.getSize();
    this.buffer = new CharBuffer(size);

    await this.display.init();
    this.palettemap = await getPaletteMapping(
      this.config.palette,
      this.display,
    );
    if (this.config.hideCursor) {
      await this.display.setCursorVisibility(false);
    }
    await this.clear();

    if (this.config.loopInterval) {
      this.loop(this.config.loopInterval); // purposefully not awaited
    }
  }

  /**
   * Quit the UI (this will exit the executable)
   */
  async quit(): Promise<void> {
    this.quitting = true;
    await this.clear();
    await this.display.setCursorVisibility(true);
    await this.display.uninit();
    if (typeof Deno != "undefined") {
      Deno.exit();
    }
  }

  /**
   * Get the current display size
   */
  getSize(): BufferSize {
    return this.buffer.getSize();
  }

  /**
   * Flush the internal buffer to the display
   */
  async flush(): Promise<void> {
    await this.buffer.forEachDirty((at, char) =>
      this.display.setChar(at, char)
    );
    await this.display.flush();
  }

  /**
   * Clear the whole screen
   */
  async clear(bg = 0): Promise<void> {
    const { w, h } = this.getSize();
    const drawing = this.drawing.color(bg, bg);
    for (let y = 0; y < h; y++) {
      drawing.text(Array(w).fill(" ").join(""), { x: 0, y });
    }
    await this.flush();
  }

  /**
   * Resize the buffer to match the display
   */
  async resize(size: BufferSize): Promise<void> {
    this.buffer = new CharBuffer(size);
    await this.clear();
    this.config.onResize(size);
  }

  /**
   * Start the event loop, waiting for input
   */
  async loop(refresh = 100): Promise<void> {
    while (!this.quitting) {
      // handle events
      for (const event of await this.display.getEvents()) {
        const { key, click, size } = event;

        if (key) {
          if (!this.config.ignoreCtrlC && key == "ctrl+c") {
            await this.quit();
          } else {
            this.config.onKeyStroke(key);
          }
        }

        if (size) {
          await this.resize(size);
        }

        if (click) {
          this.config.onMouseClick(click);
        }
      }

      // flush
      await this.flush();

      // wait
      await new Promise((resolve) => setTimeout(resolve, refresh));
    }
  }
}