import {
  BufferDrawing,
  BufferSize,
  CharBuffer,
  Color,
  PaletteMap,
} from "./base.ts";
import { UI_CONFIG_DEFAULTS, UIConfig, UIPalette } from "./config.ts";
import { cmp } from "./deps.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));
    }
  }
}

async function getPaletteMapping(
  palette: UIPalette,
  display: Display,
): Promise<PaletteMap> {
  // get the colors supported by display
  const app_colors = palette.map((c): Color[] => Array.isArray(c) ? c : [c]);
  const all_colors = app_colors.reduce((acc, val) => acc.concat(val), []);
  const display_colors = await display.setupPalette(all_colors);

  // rank all supported colors by proximity to each app color
  let ranked: {
    color: Color;
    idx: number;
    penalty: number;
    matches: { color: Color; idx: number; distance: number }[];
  }[] = [];
  app_colors.forEach((colors, idx) => {
    colors.forEach((color, alt) => {
      ranked.push({
        color,
        idx,
        penalty: alt + 1,
        matches: display_colors.map((display_color, didx) => {
          return {
            color: display_color,
            idx: didx,
            distance: colorDistance(color, display_color),
          };
        }).sort(cmp({ key: (info) => info.distance })),
      });
    });
  });

  // TODO negatively score colors too much near previously chosen ones

  // find the best color mapping for each source color
  const result = palette.map(() => -1);
  while (ranked.length > 0) {
    ranked.sort(
      cmp({ key: (info) => info.matches[0].distance * info.penalty }),
    );

    const best = ranked[0];
    const app_idx = best.idx;
    const display_idx = best.matches[0].idx;
    result[app_idx] = display_idx;

    for (const color of ranked) {
      color.matches = color.matches.filter((match) =>
        match.idx !== display_idx
      );
    }
    ranked = ranked.filter((color) =>
      color.idx !== app_idx && color.matches.length > 0
    );
  }
  return result;
}

function colorDistance(e1: Color, e2: Color): number {
  /*return (e2.r - e1.r) * (e2.r - e1.r) +
    (e2.g - e1.g) * (e2.g - e1.g) +
    (e2.b - e1.b) * (e2.b - e1.b);*/
  const c = (x: number) => Math.round(x * 255);
  const rmean = (c(e1.r) + c(e2.r)) / 2;
  const r = c(e1.r) - c(e2.r);
  const g = c(e1.g) - c(e2.g);
  const b = c(e1.b) - c(e2.b);
  return Math.sqrt(
    (((512 + rmean) * r * r) >> 8) + 4 * g * g + (((767 - rmean) * b * b) >> 8),
  );
}