// ============ magic.js — spell casting system ============
import { SPELLS } from '../core/config.js';
import { clamp } from '../core/util.js';

export function spellUnlocked(state, id) {
  const def = SPELLS[id];
  if (!def) return false;
  if (state.sandbox || def.tier === 0) return true;
  return state.research.unlocked.includes(id);
}

export function canCast(state, id) {
  const def = SPELLS[id];
  if (!spellUnlocked(state, id)) return { ok: false, why: 'Not researched' };
  if ((state.spells.cds[id] || 0) > 0) return { ok: false, why: 'Recharging' };
  if (state.mana < def.mana) return { ok: false, why: 'Not enough mana' };
  return { ok: true };
}

export function castSpell(state, id) {
  const chk = canCast(state, id);
  if (!chk.ok) return chk;
  const def = SPELLS[id];
  state.mana -= def.mana;
  state.spells.cds[id] = def.cd;
  switch (id) {
    case 'sunburst':
      state.spells.active.sunburst = 2;      // brief force-sunny
      state.weather.cur = 'sunny';
      burst(state, '☀️');
      break;
    case 'joy_aura':
      state.spells.active.joy_aura = def.dur;
      burst(state, '😊');
      break;
    case 'healing_light':
      for (const h of state.heroes) if (h.alive) { h.hp = h.maxHp; state.effects.push({ kind: 'heal', x: h.x, y: h.y, t: 0, dur: 0.8 }); }
      burst(state, '💚');
      break;
    case 'fortune_rain':
      state.spells.active.fortune_rain = def.dur;
      burst(state, '💸');
      break;
    case 'swift_build':
      state.spells.active.swift_build = def.dur;
      burst(state, '⚡');
      break;
    case 'monster_bane': {
      for (const mo of [...state.monsters]) mo.hp -= 70;
      for (let i = state.monsters.length - 1; i >= 0; i--) {
        if (state.monsters[i].hp <= 0) { /* deaths handled by battle loop */ }
      }
      burst(state, '💥');
      state.toasts.push({ kind: 'magic', title: 'Monster Bane!', text: 'Arcane fire rains on the invaders.' });
      break;
    }
    case 'warding_sigil':
      state.spells.active.warding_sigil = def.dur;
      burst(state, '🛡️');
      state.toasts.push({ kind: 'magic', title: 'Warding Sigil raised', text: 'Monsters flee; invasions blocked while active.' });
      break;
    case 'transmute': {
      transmuteGold(state);
      burst(state, '🪙');
      break;
    }
  }
  return { ok: true };
}

function transmuteGold(state) {
  state.cash += 900;
  state.finance.current['misc'] = (state.finance.current['misc'] || 0) + 900;
  state.toasts.push({ kind: 'gold', title: 'Transmutation!', text: '+$900 conjured from the arcane ether.' });
}

function burst(state, icon) {
  state.effects.push({ kind: 'spellburst', icon, t: 0, dur: 1.4 });
}

export function tickSpells(state, dt) {
  // cooldowns
  for (const k of Object.keys(state.spells.cds)) {
    if (state.spells.cds[k] > 0) state.spells.cds[k] -= dt;
  }
  // durations
  for (const k of Object.keys(state.spells.active)) {
    state.spells.active[k] -= dt;
    if (state.spells.active[k] <= 0) delete state.spells.active[k];
  }
  // mana regen
  if (state.manaRegen === undefined) state.manaRegen = 0.4;
  state.mana = clamp(state.mana + state.manaRegen * dt, 0, state.manaMax);
}

/** construction discount multiplier from spells */
export function buildDiscount(state) {
  return state.spells.active.swift_build ? 0.5 : 1;
}