elseware/drops/src/generic_shield.rs

use std::collections::HashMap;
use serde::{Serialize, Deserialize};
use rand::Rng;
use rand::distributions::{WeightedIndex, Distribution};

use entity::item::shield::{ShieldType, Shield};
use entity::character::SectionID;
use maps::room::{Difficulty, Episode};
use maps::area::MapArea;
use crate::{ItemDropType, load_data_file};
use stats::items::{shield_stats, ShieldStats};


#[derive(Debug, Serialize, Deserialize)]
struct ShieldRankRates {
    rank0: u32,
    rank1: u32,
    rank2: u32,
    rank3: u32,
    rank4: u32,
}

#[derive(Debug, Serialize, Deserialize)]
pub struct GenericShieldTable {
    rank_rates: ShieldRankRates,
    shield_set: u32,
    #[serde(skip)]
    shield_stats: HashMap<ShieldType, ShieldStats>,
}

impl GenericShieldTable {
    pub fn new(episode: Episode, difficulty: Difficulty, section_id: SectionID) -> GenericShieldTable {
        let mut gst: GenericShieldTable = load_data_file(episode, difficulty, section_id, "shield_rate.toml");
        gst.shield_stats = shield_stats();
        gst
    }

    fn shield_type<R: Rng>(&self, area_map: &MapArea, rng: &mut R) -> ShieldType {
        let rank_weights = WeightedIndex::new([self.rank_rates.rank0, self.rank_rates.rank1, self.rank_rates.rank2,
                                               self.rank_rates.rank3, self.rank_rates.rank4]).unwrap();
        let rank = rank_weights.sample(rng) as i32;
        let shield_level = std::cmp::max(0i32, self.shield_set as i32 - 3i32 + rank + area_map.drop_area_value().unwrap_or(0) as i32);
        match shield_level {
            0x00 => ShieldType::Barrier,
            0x01 => ShieldType::Shield,
            0x02 => ShieldType::CoreShield,
            0x03 => ShieldType::GigaShield,
            0x04 => ShieldType::SoulBarrier,
            0x05 => ShieldType::HardShield,
            0x06 => ShieldType::BraveBarrier,
            0x07 => ShieldType::SolidShield,
            0x08 => ShieldType::FlameBarrier,
            0x09 => ShieldType::PlasmaBarrier,
            0x0A => ShieldType::FreezeBarrier,
            0x0B => ShieldType::PsychicBarrier,
            0x0C => ShieldType::GeneralShield,
            0x0D => ShieldType::ProtectBarrier,
            0x0E => ShieldType::GloriousShield,
            0x0F => ShieldType::ImperialBarrier,
            0x10 => ShieldType::GuardianShield,
            0x11 => ShieldType::DivinityBarrier,
            0x12 => ShieldType::UltimateShield,
            0x13 => ShieldType::SpiritualShield,
            0x14 => ShieldType::CelestialShield,
            _ => panic!(),
        }
    }

    pub fn dfp_modifier<R: Rng>(&self, shield_type: &ShieldType, rng: &mut R) -> u32 {
        let stats = self.shield_stats.get(shield_type).unwrap();
        rng.gen_range(0, stats.dfp_modifier)
    }

    pub fn evp_modifier<R: Rng>(&self, shield_type: &ShieldType, rng: &mut R) -> u32 {
        let stats = self.shield_stats.get(shield_type).unwrap();
        rng.gen_range(0, stats.evp_modifier)
    }

    pub fn get_drop<R: Rng>(&self, area_map: &MapArea, rng: &mut R) -> Option<ItemDropType> {
        let shield_type = self.shield_type(area_map, rng);
        let dfp_modifier = self.dfp_modifier(&shield_type, rng);
        let evp_modifier = self.dfp_modifier(&shield_type, rng);


        Some(ItemDropType::Shield(Shield {
            shield: shield_type,
            dfp: dfp_modifier as u8,
            evp: evp_modifier as u8,
        }))
    }
}


#[cfg(test)]
mod test {
    use super::*;
    use rand::{SeedableRng};
    #[test]
    fn test_shield_generation() {
        let mut rng = rand_chacha::ChaCha20Rng::from_seed([23;32]);

        let gst = GenericShieldTable::new(Episode::One, Difficulty::Ultimate, SectionID::Skyly);

        assert!(gst.get_drop(&MapArea::Forest1, &mut rng) == Some(ItemDropType::Shield(Shield {
            shield: ShieldType::FreezeBarrier,
            dfp: 4,
            evp: 1,
        })));
        assert!(gst.get_drop(&MapArea::Caves3, &mut rng) == Some(ItemDropType::Shield(Shield {
            shield: ShieldType::PsychicBarrier,
            dfp: 3,
            evp: 2,
        })));
        assert!(gst.get_drop(&MapArea::Mines2, &mut rng) == Some(ItemDropType::Shield(Shield {
            shield: ShieldType::ImperialBarrier,
            dfp: 0,
            evp: 4,
        })));
        assert!(gst.get_drop(&MapArea::DarkFalz, &mut rng) == Some(ItemDropType::Shield(Shield {
            shield: ShieldType::DivinityBarrier,
            dfp: 1,
            evp: 0,
        })));
    }
}