combat: rewrite in Zig; add basic damage types and weapon archetypes

Signed-off-by: NotAShelf <raf@notashelf.dev>
Change-Id: Ic8055a1cf6bdad1aca13673ea171b4b46a6a6964

libs/combat/attack.zig

@@ -0,0 +1,185 @@
+const c = @import("c.zig");
+const event = @import("event.zig");
+const effects = @import("effects.zig");
+
+fn rng(min: c_int, max: c_int) c_int {
+    return c.rng_int(min, max);
+}
+
+fn applyResistance(damage: c_int, resistance: c_int) c_int {
+    if (resistance >= 100) return 0;
+    const factor = 100 - resistance;
+    var result = @divTrunc(damage * factor, 100);
+    if (result < 1) result = 1;
+    return result;
+}
+
+fn rollProc(
+    target_effects: [*c]c.StatusEffect,
+    target_count: [*c]c_int,
+    dmg_class: c.DamageClass,
+    status_chance: c_int,
+) c.StatusEffectType {
+    if (status_chance <= 0 or rng(0, 99) >= status_chance)
+        return c.EFFECT_NONE;
+
+    const eff_type = effects.procForClass(dmg_class);
+    if (eff_type == c.EFFECT_NONE)
+        return c.EFFECT_NONE;
+
+    const params = effects.paramsFor(eff_type);
+    effects.apply(target_effects, target_count, eff_type, params.duration, params.intensity);
+    return eff_type;
+}
+
+pub fn playerAttack(p: [*c]c.Player, e: [*c]c.Enemy) void {
+    if (p == null or e == null) return;
+    if (e[0].alive == 0) return;
+
+    event.reset();
+
+    if (e[0].dodge > 0 and rng(0, 99) < e[0].dodge) {
+        event.last.is_player_damage = 0;
+        event.last.was_dodged = 1;
+        event.last.message = "Enemy dodged!";
+        return;
+    }
+
+    // Read weapon stats or unarmed defaults
+    var dmg_class: c.DamageClass = c.DMG_IMPACT;
+    var crit_chance: c_int = c.UNARMED_CRIT_CHANCE;
+    var crit_mult: c_int = c.UNARMED_CRIT_MULT;
+    var status_chance: c_int = c.UNARMED_STATUS_CHANCE;
+
+    if (p[0].has_weapon != 0) {
+        dmg_class = p[0].equipped_weapon.dmg_class;
+        crit_chance = p[0].equipped_weapon.crit_chance;
+        crit_mult = p[0].equipped_weapon.crit_multiplier;
+        status_chance = p[0].equipped_weapon.status_chance;
+    }
+
+    var base_attack = p[0].attack;
+    if (effects.has(&p[0].effects, p[0].effect_count, c.EFFECT_WEAKEN))
+        base_attack -= c.WEAKEN_ATTACK_REDUCTION;
+    if (base_attack < 1) base_attack = 1;
+
+    const variance = rng(80, 120);
+    var damage = @divTrunc(base_attack * variance, 100);
+    if (damage < 1) damage = 1;
+
+    if (rng(0, 99) < crit_chance) {
+        damage = @divTrunc(damage * crit_mult, 100);
+        event.last.is_critical = 1;
+    }
+
+    const res_index: usize = @intCast(dmg_class);
+    if (res_index < c.NUM_DMG_CLASSES) {
+        damage = applyResistance(damage, e[0].resistance[res_index]);
+    }
+
+    if (damage == 0) {
+        event.last.damage = 0;
+        event.last.is_player_damage = 0;
+        event.last.message = "No effect!";
+        return;
+    }
+
+    if (e[0].block > 0 and rng(0, 99) < 30) {
+        var blocked = e[0].block;
+        if (blocked > damage) blocked = damage;
+        damage -= blocked;
+        if (damage < 1) damage = 1;
+        event.last.was_blocked = 1;
+        event.last.block_amount = blocked;
+    }
+
+    e[0].hp -= damage;
+    event.last.damage = damage;
+    event.last.is_player_damage = 0;
+
+    const applied = rollProc(&e[0].effects, &e[0].effect_count, dmg_class, status_chance);
+    event.last.applied_effect = applied;
+
+    if (e[0].hp <= 0) {
+        e[0].hp = 0;
+        e[0].alive = 0;
+        event.last.message = "Enemy killed!";
+    } else if (applied != c.EFFECT_NONE) {
+        event.last.message = switch (applied) {
+            c.EFFECT_BLEED => "Hit! Bleeding!",
+            c.EFFECT_STUN => "Hit! Stunned!",
+            c.EFFECT_WEAKEN => "Hit! Weakened!",
+            c.EFFECT_BURN => "Hit! Burning!",
+            c.EFFECT_POISON => "Hit! Poisoned!",
+            else => "You hit",
+        };
+    } else if (event.last.is_critical != 0) {
+        event.last.message = "Critical hit!";
+    } else {
+        event.last.message = "You hit";
+    }
+}
+
+pub fn enemyAttack(e: [*c]c.Enemy, p: [*c]c.Player) void {
+    if (e == null or p == null) return;
+    if (e[0].alive == 0) return;
+
+    event.reset();
+    event.last.is_player_damage = 1;
+
+    if (p[0].dodge > 0 and rng(0, 99) < p[0].dodge) {
+        event.last.was_dodged = 1;
+        event.last.message = "You dodged!";
+        return;
+    }
+
+    var base_damage = e[0].attack;
+    if (effects.has(&e[0].effects, e[0].effect_count, c.EFFECT_WEAKEN))
+        base_damage -= c.WEAKEN_ATTACK_REDUCTION;
+    base_damage -= p[0].defense;
+    if (base_damage < 1) base_damage = 1;
+
+    const variance = rng(80, 120);
+    var damage = @divTrunc(base_damage * variance, 100);
+    if (damage < 1) damage = 1;
+
+    if (rng(0, 99) < c.ENEMY_CRIT_CHANCE) {
+        damage = @divTrunc(damage * c.ENEMY_CRIT_MULT, 100);
+        event.last.is_critical = 1;
+    }
+
+    if (p[0].block > 0 and rng(0, 99) < 30) {
+        var blocked = p[0].block;
+        if (blocked > damage) blocked = damage;
+        damage -= blocked;
+        if (damage < 1) damage = 1;
+        event.last.was_blocked = 1;
+        event.last.block_amount = blocked;
+    }
+
+    p[0].hp -= damage;
+    event.last.damage = damage;
+
+    const applied = rollProc(&p[0].effects, &p[0].effect_count, e[0].dmg_class, e[0].status_chance);
+    event.last.applied_effect = applied;
+
+    if (p[0].hp <= 0) {
+        p[0].hp = 0;
+        event.last.message = "You died!";
+    } else if (applied != c.EFFECT_NONE) {
+        event.last.message = switch (applied) {
+            c.EFFECT_POISON => "Hit! Poisoned!",
+            c.EFFECT_BLEED => "Hit! Bleeding!",
+            c.EFFECT_STUN => "Hit! Stunned!",
+            c.EFFECT_BURN => "Hit! Burning!",
+            c.EFFECT_WEAKEN => "Hit! Weakened!",
+            else => "Hit",
+        };
+    } else if (event.last.was_blocked != 0) {
+        event.last.message = "Blocked some damage";
+    } else if (event.last.is_critical != 0) {
+        event.last.message = "Critical!";
+    } else {
+        event.last.message = "Hit";
+    }
+}