rs-rl/src/melee_combat_system.rs

use specs::prelude::*;
use super::{CombatStats, WantsToMelee, Name, 
            SufferDamage, GameLog, MeleePowerBonus,
            DefenseBonus, Equipped, particle_system::ParticleBuilder,
            Position};

pub struct MeleeCombatSystem {}

impl<'a> System<'a> for MeleeCombatSystem {
    type SystemData = ( Entities<'a>,
                        WriteExpect<'a, GameLog>,
                        WriteStorage<'a, WantsToMelee>,
                        ReadStorage<'a, Name>,
                        ReadStorage<'a, CombatStats>,
                        WriteStorage<'a, SufferDamage>,
                        ReadStorage<'a, MeleePowerBonus>,
                        ReadStorage<'a, DefenseBonus>,
                        ReadStorage<'a, Equipped>,
                        WriteExpect<'a, ParticleBuilder>,
                        ReadStorage<'a, Position>
                      );

    fn run(&mut self, data : Self::SystemData) {
        let (entities, 
            mut log, 
            mut wants_melee, 
            names, 
            combat_stats, 
            mut inflict_damage, 
            melee_power_bonuses, 
            defense_bonuses, 
            equipped,
            mut particle_builder,
            positions) = data;

        for (entity, wants_melee, name, stats) in (&entities, &wants_melee, &names, &combat_stats).join() {
            if stats.hp > 0 {
                let mut offensive_bonus = 0;
                for (_item_entity, power_bonus, equipped_by) in (&entities, &melee_power_bonuses, &equipped).join() {
                    if equipped_by.owner == entity {
                        offensive_bonus += power_bonus.power;
                    }
                }

                let target_stats = combat_stats.get(wants_melee.target).unwrap();
                if target_stats.hp > 0 {
                    let target_name = names.get(wants_melee.target).unwrap();

                    let mut defensive_bonus = 0;
                    for (_item_entity, defense_bonus, equipped_by) in (&entities, &defense_bonuses, &equipped).join() {
                        if equipped_by.owner == wants_melee.target {
                            defensive_bonus += defense_bonus.defense;
                        }
                    }

                    let pos = positions.get(wants_melee.target);
                    if let Some(pos) = pos {
                        particle_builder.request(pos.x, pos.y, rltk::RGB::named(rltk::ORANGE), rltk::RGB::named(rltk::BLACK), rltk::to_cp437('‼'), 200.0);
                    }
                    let damage = i32::max(0, (stats.power + offensive_bonus) - (target_stats.defense + defensive_bonus));

                    if damage == 0 {
                        log.entries.push(format!("{} is unable to hurt {}", &name.name, &target_name.name));
                    } else {
                        log.entries.push(format!("{} hits {}, for {} damage.", &name.name, &target_name.name, damage));
                        SufferDamage::new_damage(&mut inflict_damage, wants_melee.target, damage);
                    }
                }
            }
        }

        wants_melee.clear();
    }
}