// ---------------------------------------------------------------------------
// Shared game constants & helpers (used by both the server sim and the client)
// ---------------------------------------------------------------------------

export const TICK_RATE = 30;               // server simulation ticks per second
export const SNAP_EVERY = 2;               // send a snapshot every N ticks (15 Hz)

export const ARENA_RADIUS = 4200;          // playable circle radius in world px

export const BASE_SPEED = 178;             // px per second
export const BOOST_MULT = 1.95;            // speed multiplier while boosting
export const TURN_RATE = 4.4;              // radians per second
export const BOOST_TURN_RATE = 3.8;        // slightly stiffer steering while boosting

export const START_SCORE = 25;
export const MIN_BOOST_SCORE = 18;         // cannot boost below this score
export const BOOST_DRAIN = 16;             // score per second burned while boosting
export const BOOST_DROP_INTERVAL = 0.26;   // seconds between tail pellets while boosting

export const PELLET_COUNT = 950;           // ambient pellets kept alive in the arena
export const BOT_TARGET_TOTAL = 12;        // arena is kept filled to this many snakes
export const RESPAWN_PROTECT_TICKS = TICK_RATE * 2; // ~2s of spawn protection

// --- derived snake geometry -------------------------------------------------

export function snakeRadius(score: number): number {
  return 5 + Math.sqrt(Math.max(0, score)) * 0.32;
}

export function snakePointCount(score: number): number {
  return Math.min(420, Math.round(14 + Math.sqrt(Math.max(0, score)) * 2.1));
}

export function snakeSpacing(score: number): number {
  return Math.max(5.5, snakeRadius(score) * 0.5);
}

// --- math helpers ------------------------------------------------------------

export function clamp(v: number, lo: number, hi: number): number {
  return v < lo ? lo : v > hi ? hi : v;
}

/** Normalize an angle to (-PI, PI]. */
export function normAngle(a: number): number {
  while (a > Math.PI) a -= Math.PI * 2;
  while (a <= -Math.PI) a += Math.PI * 2;
  return a;
}

export function dist(x1: number, y1: number, x2: number, y2: number): number {
  return Math.hypot(x2 - x1, y2 - y1);
}

// --- palettes ---------------------------------------------------------------

export const SNAKE_COLORS = [
  '#ff5b5b', '#ffb84d', '#ffe14d', '#7dff5b', '#4dffd2', '#4dc9ff',
  '#8a7dff', '#c95bff', '#ff5bd0', '#9dff4d', '#5bff9d', '#ffd24d',
];

export const PELLET_COLORS = [
  '#ff6b6b', '#ffd93d', '#6bff8f', '#4dd2ff',
  '#c586ff', '#ff8fe1', '#8ffcff', '#ffe28f',
];

export const BOT_NAMES = [
  'Noodle', 'Viper', 'Slinky', 'Zigzag', 'Cobra', 'Python', 'Nagini',
  'Basilisk', 'Wiggles', 'Turbo', 'Boa', 'Rattles', 'Medusa',
  'Sidewinder', 'Anaconda', 'DangerNoodle', 'Hiss', 'Monty',
];