// Shared helpers for the dungeon venue submodules (layout / zones / props /
// hazards). Pure, no THREE, no wall-clock, no Math.random — seeded Rng only,
// all motion analytic f(t, seed) so seek === playback.
//
// A submodule owns ONE portion of the image and the 3D space its objects live
// in. The facade (../dungeon.js) owns the single walk clock and the path;
// every submodule reads (t, plan, pathAt) and never integrates.

import { Rng } from '../../engine/rng.js';

/** Independent seeded stream that never perturbs sibling streams. */
export function forkDungeon(seed, label) {
    return new Rng(hashSeed(seed) ^ 0x9e3779b9).fork(String(label));
}

function hashSeed(seed) {
    return (seed >>> 0) || 1;
}

/** Analytic wrap: position of a base offset walking at rate dz after time t. */
export function streamWrap(s0, t, dz, span) {
    const s = s0 + t * dz;
    return s0 + ((((s - s0) % span) + span) % span);
}

/** Smoothstep 0..1. */
export function smooth01(x) {
    const t = Math.max(0, Math.min(1, x));
    return t * t * (3 - 2 * t);
}

/**
 * Crew-style visibility fade: how many of a population with `count` members
 * show at a continuous level in [0, ~1.1]. Never toggles — pure f(level,index).
 * Same pattern as ride.js crew fade (DESIGN §4: furniture never hard-toggles
 * on interpolated state).
 */
export function fadeFor(level, index, count, soft = 0.12) {
    const showIndex = index / Math.max(1, count);
    return Math.max(0, Math.min(1, (level - showIndex) / soft));
}

/** Segment kinds the layout planner may emit. */
export const SEGMENT_KINDS = [
    'hall',
    'room',
    'forest',
    'wallwalk',
];

/** Zone names the zone planner may emit (one per section). */
export const ZONE_NAMES = ['hall', 'room', 'forest', 'wallwalk'];

/** Prop types in the prop library (primitives only, no glTF). */
export const PROP_TYPES = ['rubble', 'furniture', 'trees', 'rampart', 'torch', 'banner', 'stalagmite'];

/** Hazard types (visual only — the walk sidesteps them). */
export const HAZARD_TYPES = ['gate', 'gap', 'patrol'];