elseware/drops/src/rare_drop_table.rs

use std::collections::HashMap;
use rand::Rng;
use serde::{Serialize, Deserialize};
use entity::item::weapon::{Weapon, WeaponType};
use entity::item::armor::{Armor, ArmorType};
use entity::item::shield::{Shield, ShieldType};
use entity::item::unit::{Unit, UnitType};
use entity::item::tool::{Tool, ToolType};
use entity::item::mag::{Mag, MagType};
use entity::character::SectionID;
use maps::monster::MonsterType;
use maps::room::{Difficulty, Episode};
use maps::area::MapArea;
use crate::{ItemDropType, load_data_file};
use crate::generic_weapon::AttributeTable;
use crate::generic_armor::GenericArmorTable;
use crate::generic_shield::GenericShieldTable;

type ItemParseFn = Box<dyn Fn(&String) -> Option<RareDropItem>>;

#[derive(Debug, Copy, Clone)]
pub enum RareDropItem {
    Weapon(WeaponType),
    Armor(ArmorType),
    Shield(ShieldType),
    Unit(UnitType),
    Tool(ToolType),
    Mag(MagType)
}

impl RareDropItem {
    pub fn from_string(name: String) -> RareDropItem {
        let parse_funcs: [ItemParseFn; 6] = [
            Box::new(|i| Some(RareDropItem::Weapon(str::parse::<WeaponType>(i).ok()?))),
            Box::new(|i| Some(RareDropItem::Armor(str::parse::<ArmorType>(i).ok()?))),
            Box::new(|i| Some(RareDropItem::Shield(str::parse::<ShieldType>(i).ok()?))),
            Box::new(|i| Some(RareDropItem::Unit(str::parse::<UnitType>(i).ok()?))),
            Box::new(|i| Some(RareDropItem::Tool(str::parse::<ToolType>(i).ok()?))),
            Box::new(|i| Some(RareDropItem::Mag(str::parse::<MagType>(i).ok()?))),
        ];

        for parse in parse_funcs.iter() {
           if let Some (k) = parse(&name) {
                return k
           }
        }

        panic!()
    }
}


pub struct RareDropRate {
    pub rate: f32,
    pub item: RareDropItem
}



#[derive(Debug, Serialize, Deserialize)]
pub struct RareDropConfigEntity {
    pub rate: f32,
    pub item: String,
}


pub struct RareDropTable {
    rates: HashMap<MonsterType, Vec<RareDropRate>>,
    attribute_table: AttributeTable,
    armor_stats: GenericArmorTable,
    shield_stats: GenericShieldTable,
}

fn load_default_monster_rates(episode: Episode, difficulty: Difficulty, section_id: SectionID) -> HashMap<MonsterType, Vec<RareDropRate>> {
    let cfg: HashMap<String, Vec<RareDropConfigEntity>> = load_data_file(episode, difficulty, section_id, "rare_rate.toml");

    cfg.into_iter()
        .map(|(monster, drops)| {
            let monster = monster.parse().unwrap();
            let drops = drops.into_iter().map(|drop| {
                RareDropRate {
                    rate: drop.rate,
                    item: RareDropItem::from_string(drop.item),
                }
            }).collect();
            (monster, drops)
        }).collect()
}

impl RareDropTable {
    pub fn new(episode: Episode, difficulty: Difficulty, section_id: SectionID) -> RareDropTable {
        RareDropTable {
            rates: load_default_monster_rates(episode, difficulty, section_id),
            attribute_table: AttributeTable::new(episode, difficulty, section_id),
            armor_stats: GenericArmorTable::new(episode, difficulty, section_id),
            shield_stats: GenericShieldTable::new(episode, difficulty, section_id),
        }
    }

    pub fn builder() -> RareDropTableBuilder {
        RareDropTableBuilder {
            rates: None,
            attribute_table: None,
            armor_stats: None,
            shield_stats: None,
        }
    }

    pub fn apply_item_stats<R: Rng>(&self, map_area: &MapArea, item: RareDropItem, rng: &mut R) -> ItemDropType {
        match item {
            RareDropItem::Weapon(weapon) => {
                ItemDropType::Weapon(Weapon {
                    weapon,
                    special: None,
                    grind: 0,
                    attrs: self.attribute_table.generate_rare_attributes(map_area, rng),
                    tekked: false,
                })

            },
            RareDropItem::Armor(armor) => {
                ItemDropType::Armor(Armor {
                    armor,
                    dfp: self.armor_stats.dfp_modifier(&armor, rng) as u8,
                    evp: self.armor_stats.evp_modifier(&armor, rng) as u8,
                    slots: self.armor_stats.slots(map_area, rng) as u8,
                })
            },
            RareDropItem::Shield(shield) => {
                ItemDropType::Shield(Shield {
                    shield,
                    dfp: self.shield_stats.dfp_modifier(&shield, rng) as u8,
                    evp: self.shield_stats.evp_modifier(&shield, rng) as u8,
                })
            },
            RareDropItem::Unit(unit) => {
                ItemDropType::Unit(Unit {
                    unit,
                    modifier: None,
                })
            },
            RareDropItem::Tool(tool) => {
                ItemDropType::Tool(Tool {
                    tool,
                })
            },
            RareDropItem::Mag(_mag) => {
                ItemDropType::Mag(Mag::baby_mag(rng.gen_range(0, 18)))
            }
        }
    }

    pub fn get_drop<R: Rng>(&self, map_area: &MapArea, monster: &MonsterType, rng: &mut R) -> Option<ItemDropType> {
        self.rates.get(monster)
            .and_then(|drop_rates| {
                drop_rates.iter()
                    .filter_map(|drop_rate| {
                        let rand: f32 = rng.gen();
                        if rand < drop_rate.rate {
                            Some(self.apply_item_stats(map_area, drop_rate.item, rng))
                        }
                        else {
                            None
                        }
                    }).next()
            })
    }
}


pub struct RareDropTableBuilder {
    rates: Option<HashMap<MonsterType, Vec<RareDropRate>>>,
    attribute_table: Option<AttributeTable>,
    armor_stats: Option<GenericArmorTable>,
    shield_stats: Option<GenericShieldTable>,
}


// TODO: add the rest of these later I just need these ones right now
impl RareDropTableBuilder {
    pub fn rates(mut self, rates: HashMap<MonsterType, Vec<RareDropRate>>) -> RareDropTableBuilder {
        self.rates = Some(rates);
        self
    }

    #[must_use]
    pub fn rate(mut self, monster_type: MonsterType, drop_rate: RareDropRate) -> RareDropTableBuilder {
        match &mut self.rates {
            Some(rates) => {
                rates.entry(monster_type)
                    .or_insert(Vec::new())
                    .push(drop_rate);
            },
            None => {
                let mut rates = HashMap::default();
                rates.insert(monster_type, vec![drop_rate]);
                self.rates = Some(rates);
            }
        }
        self
    }

    pub fn build(self, episode: Episode, difficulty: Difficulty, section_id: SectionID) -> RareDropTable {
        RareDropTable {
            rates: self.rates.unwrap_or_else(|| load_default_monster_rates(episode, difficulty, section_id)),
            attribute_table: self.attribute_table.unwrap_or_else(|| AttributeTable::new(episode, difficulty, section_id)),
            armor_stats: self.armor_stats.unwrap_or_else(|| GenericArmorTable::new(episode, difficulty, section_id)),
            shield_stats: self.shield_stats.unwrap_or_else(|| GenericShieldTable::new(episode, difficulty, section_id)),
        }
    }
}