// Rummikub — heuristic AI. No Phaser, no state mutation. `planTurn` inspects an
// (already-current) engine state and returns a plain plan describing what tiles
// to lay down (and the resulting table arrangement) or a decision to draw. The
// scene applies & animates the plan; the engine validates the commit.

import { INITIAL_MELD_MIN } from './RummikubData.js';
import { bestMeldDecomposition } from './RummikubSolver.js';

// Skill 1–5: lower skill is slower, less likely to manipulate the table, and
// adds "noise" (sometimes declines an available meld to draw instead).
const PROFILE = {
  1: { delay: [780, 1250], manipulate: false, declineChance: 0.30 },
  2: { delay: [680, 1100], manipulate: false, declineChance: 0.18 },
  3: { delay: [600, 980],  manipulate: false, declineChance: 0.08 },
  4: { delay: [500, 860],  manipulate: true,  declineChance: 0.03 },
  5: { delay: [430, 740],  manipulate: true,  declineChance: 0.0 },
};

function profile(skill) { return PROFILE[Math.max(1, Math.min(5, skill | 0))] || PROFILE[3]; }

export function thinkDelay(skill) {
  const [lo, hi] = profile(skill).delay;
  return lo + Math.floor(Math.random() * (hi - lo));
}

// Returns { type:'commit', tilesPlayed, newTable, firstMeld } or { type:'draw' }.
export function planTurn(state, seat, skill) {
  const p = profile(skill);
  const player = state.players[seat];
  const rack = player.rack;
  const table = state.table.map((s) => s.slice());

  const plan = bestMeldDecomposition(rack, table, {
    mustReach: player.hasMelded ? 0 : INITIAL_MELD_MIN,
    alreadyMelded: player.hasMelded,
    manipulate: p.manipulate,
  });

  if (!plan || plan.tilesPlayed.length === 0) return { type: 'draw' };

  // Low-skill players sometimes sit on a small play and draw instead — but never
  // decline a chance to go out.
  const goesOut = plan.tilesPlayed.length === rack.length;
  if (!goesOut && Math.random() < p.declineChance) return { type: 'draw' };

  return { type: 'commit', tilesPlayed: plan.tilesPlayed, newTable: plan.newTable, firstMeld: plan.firstMeld };
}