// Master of Vega — human-readable descriptions for `tech.effects` values.
// Headless, no Phaser: kept separate from VegaTurnReport.js so any other
// screen (a future tech-tree view, say) can reuse the same wording without
// pulling in turn-report-specific code.
//
// Every formatter is hand-matched to how the effect is actually consumed
// elsewhere in the engine (VegaCombat.js/VegaLogic.js/VegaShips.js) — not a
// generic key/value dump. A few effects (cloaked, scanRange, singularity)
// are currently inert stats with no downstream mechanic wired up yet; their
// wording stays modest/flavor rather than promising a numeric benefit that
// doesn't exist in the sim.

const pct = (mult) => `${Math.round(Math.abs(mult - 1) * 100)}%`;

function describeWeapon(w) {
  const perRound = w.shots > 1 ? `, ${w.shots} shots per round` : '';
  const pierce = w.shieldPierce
    ? `, pierces ${w.shieldPierce} point${w.shieldPierce === 1 ? '' : 's'} of enemy shields` : '';
  const cracker = w.planetCracker ? ' — powerful enough to crack a planet apart' : '';
  return `New ${w.kind} weapon available: ${w.name}, ${w.min}-${w.max} damage per shot${perRound}${pierce}${cracker}.`;
}

function hostilityWorlds(rules, tier) {
  const names = rules.planetTypes
    .filter((t) => t.colonizable && t.hostility === tier)
    .map((t) => t.name);
  return names.length ? `${names.join('/')}-class` : `hostility ${tier}`;
}

const FORMATTERS = {
  armor: (rules, v) => `Hull armor upgraded to ${v.name} plating — hull hit points ×${v.hpMult} (+${pct(v.hpMult)}).`,
  cloaked: () => 'Ships are fitted with a stealth field, cloaking them from enemy sensors.',
  colonizeHostility: (rules, v) => `Colonists can now settle ${hostilityWorlds(rules, v)} worlds.`,
  counterEspionage: (rules, v) => `+${v} counter-espionage — makes it harder for enemy agents to steal your technology.`,
  engine: (rules, v) => `Engines upgraded to ${v.name} Drive (speed ${v.speed}).`,
  espionage: (rules, v) => `+${v} espionage — improves your odds of stealing enemy technology.`,
  factoryCostMult: (rules, v) => `Factories cost ${pct(v)} less to build.`,
  fuelRange: (rules, v) => `Fuel range extended to ${v} parsecs — fleets can be ordered further from friendly colonies and starbases.`,
  groundAttack: (rules, v) => `+${v} ground attack — improves the odds of a successful invasion.`,
  groundDefense: (rules, v) => `+${v} ground defense — colonies field more defenders when invaded.`,
  initiative: (rules, v) => `+${v} initiative — fleets choose their engagement range before slower opponents each combat round.`,
  maxPopBonus: (rules, v) => `+${v} maximum population per colony.`,
  planetaryShield: (rules, v) => (
    `+${v} planetary shield — cuts population lost to bombardment by about ${Math.round((1 - 1 / (1 + v * 0.15)) * 100)}%.`
  ),
  redirectInFlight: () => 'Fleets already in transit can be redirected to a new destination.',
  refitCostMult: (rules, v) => `Auto-refit costs reduced by ${pct(v)}.`,
  repairPerRound: (rules, v) => `Ships self-repair ${Math.round(v * 100)}% of max hull every combat round.`,
  researchMult: (rules, v) => `Research output increased by ${pct(v)} empire-wide.`,
  scanRange: (rules, v) => `+${v} scanner range for detecting distant fleets and systems.`,
  shield: (rules, v) => `Deflector shields absorb ${v} point${v === 1 ? '' : 's'} of damage from every incoming hit, on ships and planetary defenses alike.`,
  singularity: () => "A breakthrough in exotic physics — the foundation for the galaxy's ultimate weapon.",
  targeting: (rules, v) => `Combat accuracy increased by ${Math.round(v * 6)}% (better targeting computers).`,
  wasteMult: (rules, v) => `Industrial waste reduced by ${pct(v)}.`,
  weapon: (rules, v) => describeWeapon(v),
};

/** Turns a tech's `effects` object into an array of full sentences, one per effect. */
export function describeTechEffects(rules, effects) {
  return Object.entries(effects ?? {})
    .map(([key, value]) => FORMATTERS[key]?.(rules, value))
    .filter(Boolean);
}