import Phaser from '../vendor/phaser.js';

/**
 * Converts a config color (number or CSS string like '#1b2540')
 * into the integer format Phaser expects.
 */
export function toColor(value, fallback = 0xffffff) {
  if (typeof value === 'number' && Number.isFinite(value)) {
    return value >>> 0;
  }
  if (typeof value === 'string' && value.length > 0) {
    const color = Phaser.Display.Color.ValueToColor(value.trim());
    if (color) return color.color;
  }
  return fallback;
}

/**
 * Converts a color (number or CSS string) to a '#rrggbb' CSS string.
 *
 * Phaser v4 (4.2.1 Giedi) quirk: Text styles are written straight to the
 * canvas — `fillStyle = style.color` — so a numeric color (e.g. 0xeaf6ff)
 * is an *invalid* fillStyle and the text silently renders black. Canvas-
 * backed text (add.text / TextStyle) must therefore always get CSS strings;
 * keep toColor for Graphics/shape APIs that want numbers.
 */
export function toCss(value, fallback = '#ffffff') {
  const n = toColor(value, toColor(fallback));
  return '#' + (n >>> 0).toString(16).padStart(6, '0');
}

/**
 * Rotate a color's HUE (degrees; + is clockwise on the hue wheel) and
 * rescale its saturation and lightness (1 = unchanged). Returns a 0xRRGGBB
 * number (ready for setTint()).
 *
 * Used by the nebula FRONT gas layer: the accent tint is the system's base
 * color rotated a little and lifted — two gas species of one nebula
 * (see data/game.json → nebula.front.accent). Pure math (no Phaser), so it
 * is testable in bare Node; grays stay grays (s=0 ⇒ hue is irrelevant),
 * and black/white are preserved.
 */
export function shiftHue(color, { hueShift = 0, satScale = 1, lightScale = 1 } = {}) {
  const n = toColor(color, 0xffffff) >>> 0;
  const r = ((n >> 16) & 255) / 255;
  const g = ((n >> 8) & 255) / 255;
  const b = (n & 255) / 255;
  const max = Math.max(r, g, b);
  const min = Math.min(r, g, b);
  const d = max - min;
  const l = (max + min) / 2;
  let h = 0;
  const s = d === 0 ? 0 : d / (1 - Math.abs(2 * l - 1));
  if (d !== 0) {
    if (max === r) h = ((g - b) / d) % 6;
    else if (max === g) h = (b - r) / d + 2;
    else h = (r - g) / d + 4;
    h *= 60;
    if (h < 0) h += 360;
  }
  h = (h + hueShift) % 360;
  const s2 = Math.min(1, Math.max(0, s * satScale));
  const l2 = Math.min(1, Math.max(0, l * lightScale));
  const c = (1 - Math.abs(2 * l2 - 1)) * s2;
  const hp = h / 60;
  const x = c * (1 - Math.abs((hp % 2) - 1));
  const [r2, g2, b2] =
    hp < 1 ? [c, x, 0] : hp < 2 ? [x, c, 0] : hp < 3 ? [0, c, x] :
    hp < 4 ? [0, x, c] : hp < 5 ? [x, 0, c] : [c, 0, x];
  const m = l2 - c / 2;
  const to255 = (v) => Math.min(255, Math.max(0, Math.round((v + m) * 255)));
  return ((to255(r2) << 16) | (to255(g2) << 8) | to255(b2)) >>> 0;
}