// ═══ elements.js ═══
// ============================================================
//  ELEMENTS.JS — Elemental damage, debuffs, DoT
// ============================================================

// Apply elemental hit effects to an enemy
function applyElementalEffects(enemy, elements, rawDamage) {
  let totalDamage = rawDamage;
  const results = { damage: 0, critted: false, effects: [] };

  for (const el of elements) {
    if (!el) continue;
    const res = enemy.resistances?.[el] ?? 1.0;
    const weak = enemy.weaknesses?.[el] ?? 1.0;
    const mult = res * weak;

    switch (el) {
      case 'fire':
        applyDoT(enemy, 'burn', 'fire', 1, 30, 180, '#ff6b35');
        results.effects.push('burn');
        break;
      case 'ice':
        applySlow(enemy, 0.5, 120);
        results.effects.push('slow');
        break;
      case 'lightning':
        chainLightningProc(enemy, totalDamage * 0.5, 100);
        results.effects.push('chain');
        break;
      case 'poison':
        applyDoT(enemy, 'poison', 'poison', 1, 20, 240, '#7fff4f');
        results.effects.push('poison');
        break;
      case 'void':
        enemy.armor = Math.max(0, (enemy.armor || 0) - 1);
        results.effects.push('shred');
        break;
      case 'arcane':
        enemy.amplified = (enemy.amplified || 0) + 0.25;
        results.effects.push('amplify');
        break;
    }

    totalDamage *= mult;
  }

  results.damage = totalDamage;
  return results;
}

function applyDoT(enemy, type, element, dmg, interval, duration, color) {
  if (!enemy.dots) enemy.dots = [];
  // Refresh or add
  const existing = enemy.dots.find(d => d.type === type);
  if (existing) {
    existing.remaining = Math.max(existing.remaining, duration);
    existing.dmg = Math.max(existing.dmg, dmg);
    existing.element = element;
  } else {
    enemy.dots.push({ type, element, dmg, interval, remaining: duration, tick: 0, color });
  }
}

function applySlow(enemy, factor, duration) {
  if (!enemy.slow || enemy.slow.factor > factor) {
    enemy.slow = { factor, remaining: duration };
  } else {
    enemy.slow.remaining = Math.max(enemy.slow.remaining, duration);
  }
}

function applyFreeze(enemy, duration) {
  // Diminishing returns: each successive freeze is shorter
  // 60-frame immunity window after thawing
  if (enemy._freezeImmune > 0) return;
  if (enemy.immuneToFreeze) return;
  const diminish = enemy._freezeCount ? Math.pow(0.75, enemy._freezeCount) : 1.0;
  const actual = Math.max(30, Math.round(duration * diminish));
  enemy.frozen = actual;
  enemy._freezeCount = (enemy._freezeCount || 0) + 1;
  if (!enemy.slow) enemy.slow = { factor: 0, remaining: actual };
  enemy.slow.factor = 0;
  enemy.slow.remaining = actual;
}

// Chain lightning proc — bounces to nearby enemies
function chainLightningProc(sourceEnemy, damage, range) {
  if (!G || !G.enemies) return;
  const rangeSq = range * range;
  let seen = 0;
  let target = null;
  for (const e of G.enemies) {
    if (!e.alive || e.id === sourceEnemy.id) continue;
    if (distSq(e.x, e.y, sourceEnemy.x, sourceEnemy.y) >= rangeSq) continue;
    seen++;
    if (Math.random() < 1 / seen) target = e;
  }
  if (!target) return;
  dealDamage(target, damage, ['lightning'], false);
  // Spark visual
  spawnChainArc(sourceEnemy.x, sourceEnemy.y, target.x, target.y, '#ffe033');
}

// Core damage dealer — handles armor, resist, amplify, crits
function dealDamage(enemy, rawDamage, elements = ['physical'], canCrit = false, critChance = 0, armorShred = 0) {
  if (!enemy.alive) return 0;

  // Armor shred
  if (armorShred > 0) {
    enemy.armor = Math.max(0, (enemy.armor || 0) - armorShred);
  }

  // Base damage after armor
  let dmg = Math.max(1, rawDamage - (enemy.armor || 0));

  // Elemental multipliers
  let elemMult = 1;
  for (const el of elements) {
    if (!el || el === 'physical') continue;
    const res = enemy.resistances?.[el] ?? 1.0;
    const weak = enemy.weaknesses?.[el] ?? 1.0;
    elemMult *= res * weak;
  }
  dmg *= elemMult;

  // Amplify debuff
  if (enemy.amplified) dmg *= (1 + enemy.amplified);

  // Crit
  let critted = false;
  if (canCrit && Math.random() < critChance) {
    dmg *= 2;
    critted = true;
  }

  dmg = Math.round(dmg);

  // ── Special enemy modifiers ───────────────────────────────
  // Commander aura: -30% incoming damage
  if (enemy.commanderAuraDR > 0) {
    dmg = Math.max(1, Math.round(dmg * (1 - enemy.commanderAuraDR)));
  }

  // Juggernaut damage cap (12 per hit; lightning doubles cap)
  if (enemy.defId === 'juggernaut') {
    const baseCap = ENEMY_DEFS.find(d => d.id === 'juggernaut')?.damageCapPerHit ?? 12;
    const cap = elements.includes('lightning') ? baseCap * 2 : baseCap;
    dmg = Math.min(dmg, cap);
  }

  // Void Herald shield: absorbs 60% damage when 3+ weapons hit in same frame
  if (enemy.defId === 'voidherald') {
    enemy._voidHitsThisFrame = (enemy._voidHitsThisFrame || 0) + 1;
    if (enemy._voidHitsThisFrame >= 3) {
      dmg = Math.max(1, Math.round(dmg * 0.4));
    }
  }

  // Echo split: on burst hit >30 raw damage, queue a split (once per echo)
  if (enemy.defId === 'echo' && !enemy._echoSplit && rawDamage > 30) {
    enemy._echoSplit = true;
    G._pendingEchoSpawns = G._pendingEchoSpawns || [];
    G._pendingEchoSpawns.push({ x: enemy.x, y: enemy.y, copyHp: Math.round(enemy.maxHp * 0.4) });
  }

  enemy.hp -= dmg;
  enemy.hitFlash = 6;

  // Show damage number for crits / elemental
  const showNumber = critted || (elements.some(e => e && e !== 'physical'));
  if (showNumber && dmg > 0) {
    const color = critted ? '#ffffff' : (ELEMENTS[elements[0]]?.color || '#fff');
    const label = critted ? `${dmg}!` : `${dmg}`;
    spawnFloater(enemy.x, enemy.y - enemy.radius - 4, label, color, critted ? 1.4 : 1.0);
  }

  // Apply elemental side effects
  for (const el of elements) {
    if (!el || el === 'physical') continue;
    applyElementalEffect(enemy, el);
  }

  return dmg;
}

function applyElementalEffect(enemy, el) {
  switch (el) {
    case 'fire':
      applyDoT(enemy, 'burn', 'fire', 1, 30, 180, '#ff6b35');
      break;
    case 'ice':
      applySlow(enemy, 0.5, 120);
      break;
    case 'poison':
      applyDoT(enemy, 'poison', 'poison', 1, 20, 240, '#7fff4f');
      break;
    case 'void':
      enemy.armor = Math.max(0, (enemy.armor || 0) - 1);
      if (enemy.defId === 'siegebreaker') {
        enemy.regenPausedUntil = G.frame + 180; // pause regen 3 seconds
      }
      break;
    case 'arcane':
      enemy.amplified = Math.min(1.5, (enemy.amplified || 0) + 0.1);
      break;
    case 'lightning':
      // chain handled separately in weapon logic
      break;
  }
}

// Tick DoTs and debuffs on an enemy each frame
function tickEnemyStatus(enemy) {
  // DoTs
  if (enemy.dots) {
    for (const dot of enemy.dots) {
      dot.tick++;
      if (dot.tick >= dot.interval) {
        dot.tick = 0;
        const res = enemy.resistances?.[dot.element] ?? 1.0;
        const weak = enemy.weaknesses?.[dot.element] ?? 1.0;
        const dmg = Math.max(0, Math.round(dot.dmg * res * weak));
        if (dmg > 0) {
          enemy.hp -= dmg;
          enemy.hitFlash = 3;
          // Small particle tick
          spawnParticle(enemy.x + (Math.random()-0.5)*8, enemy.y + (Math.random()-0.5)*8,
            dot.color, 0, 0, 0.6, 3, 0.05);
        }
      }
      dot.remaining--;
    }
    let write = 0;
    for (let i = 0; i < enemy.dots.length; i++) {
      const dot = enemy.dots[i];
      if (dot.remaining > 0) enemy.dots[write++] = dot;
    }
    enemy.dots.length = write;
  }

  // Slow / freeze decay
  if (enemy.frozen > 0) {
    enemy.frozen--;
    if (enemy.frozen === 0) {
      if (enemy.slow) enemy.slow = null;
      enemy._freezeImmune = 60; // 1 second immunity after thaw
    }
  }
  if (enemy._freezeImmune > 0) enemy._freezeImmune--;
  if (enemy.slow) {
    enemy.slow.remaining--;
    if (enemy.slow.remaining <= 0) enemy.slow = null;
  }

  // Hit flash decay
  if (enemy.hitFlash > 0) enemy.hitFlash--;

  // Amplify decay
  if (enemy.amplified) {
    enemy.amplified *= 0.995;
    if (enemy.amplified < 0.01) enemy.amplified = 0;
  }

  // Siege Breaker HP regen: +5 HP/sec; void damage pauses for 3s
  if (enemy.defId === 'siegebreaker' && enemy.hp > 0) {
    if (!enemy.regenPausedUntil || G.frame >= enemy.regenPausedUntil) {
      enemy._regenAcc = (enemy._regenAcc || 0) + 5 / 60;
      if (enemy._regenAcc >= 1) {
        const regen = Math.floor(enemy._regenAcc);
        enemy.hp = Math.min(enemy.maxHp, enemy.hp + regen);
        enemy._regenAcc -= regen;
      }
    }
  }
}