lootalot/lootalot_db/src/models/player/wealth.rs

use crate::schema::players;

/// Unpack a floating value of gold pieces to integer
/// values of copper, silver, gold and platinum pieces
///
/// # Note
///
/// The conversion is slightly different than standard rules :
/// ``` 1pp = 100gp = 1000sp = 10000 cp ```
///
fn unpack_gold_value(gold: f64) -> (i32, i32, i32, i32) {
    let rest = (gold.fract() * 100.0).round() as i32;
    let gold = gold.trunc() as i32;
    let pp = gold / 100;
    let gp = gold % 100;
    let sp = rest / 10;
    let cp = rest % 10;
    (cp, sp, gp, pp)
}

/// State of a player's wealth
///
/// Values are held as individual pieces counts.
/// Allows conversion from and to a floating amount of gold pieces.
#[derive(Queryable, AsChangeset, Serialize, Deserialize, PartialEq, Copy, Clone, Debug)]
#[table_name = "players"]
pub struct Wealth {
    pub cp: i32,
    pub sp: i32,
    pub gp: i32,
    pub pp: i32,
}

impl Wealth {
    /// Unpack individual pieces counts from gold value
    ///
    /// # Examples
    /// ```
    /// # use lootalot_db::models::Wealth;
    /// let wealth = Wealth::from_gp(403.21);
    /// assert_eq!(wealth.as_tuple(), (1, 2, 3, 4));
    /// ```
    pub fn from_gp(gp: f64) -> Self {
        let (cp, sp, gp, pp) = unpack_gold_value(gp);
        Self { cp, sp, gp, pp }
    }
    /// Convert total value to a floating value in gold pieces
    ///
    /// # Examples
    /// ```
    /// # use lootalot_db::models::Wealth;
    /// let wealth = Wealth{ pp: 4, gp: 5, sp: 8, cp: 4};
    /// assert_eq!(wealth.to_gp(), 405.84);
    /// ```
    pub fn to_gp(&self) -> f64 {
        let i = self.pp * 100 + self.gp;
        let f = (self.sp * 10 + self.cp) as f64 / 100.0;
        i as f64 + f
    }
    /// Pack the counts inside a tuple, from lower to higher coin value.
    pub fn as_tuple(&self) -> (i32, i32, i32, i32) {
        (self.cp, self.sp, self.gp, self.pp)
    }
}


impl std::ops::Sub for Wealth {
    type Output = Self;
    /// What needs to be added to 'other' so that
    /// the result equals 'self'
    fn sub(self, other: Self) -> Self {
        Wealth {
            cp: self.cp - other.cp,
            sp: self.sp - other.sp,
            gp: self.gp - other.gp,
            pp: self.pp - other.pp,
        }
    }
}

impl std::ops::Add for Wealth {
    type Output = Self;

    fn add(self, other: Self) -> Self {
        Wealth {
            cp: self.cp + other.cp,
            sp: self.sp + other.sp,
            gp: self.gp + other.gp,
            pp: self.pp + other.pp
        }
    }
}

#[cfg(test)]
mod tests {

    #[test]
    fn test_unpack_gold_values() {
        use super::unpack_gold_value;
        let test_values = [
            (0.01, (1, 0, 0, 0)),
            (0.1, (0, 1, 0, 0)),
            (1.0, (0, 0, 1, 0)),
            (1.23, (3, 2, 1, 0)),
            (1.03, (3, 0, 1, 0)),
            (100.23, (3, 2, 0, 1)),
            (-100.23, (-3, -2, -0, -1)),
            (10189.23, (3, 2, 89, 101)),
            (141805.9, (0, 9, 5, 1418)),
            (123141805.9, (0, 9, 5, 1231418)),
            (-8090.20, (0, -2, -90, -80)),
        ];

        for (tested, expected) in test_values.into_iter() {
            assert_eq!(unpack_gold_value(*tested), *expected);
        }
    }

    #[test]
    fn test_negative_wealth() {
        use super::Wealth;

        assert_eq!(
            Wealth{ cp: 3, sp: 2, gp: 1, pp: 0 } + Wealth{ cp: -8, pp: 0, sp: 0, gp: 0 },
            Wealth::from_gp(1.23 - 0.08)
        )

    }
    #[test]
    fn test_negative_wealth_inverse() {
        use super::Wealth;

        assert_eq!(
            (Wealth{ cp: 3, sp: 2, gp: 1, pp: 0 } + Wealth{ cp: -8, pp: 0, sp: 0, gp: 0 }).to_gp(),
            1.23 - 0.08
        )

    }
    #[test]
    fn test_diff_adding() {
        use super::Wealth;

        /// Let say we add 0.08 gp
        /// 1.23 + 0.08 gold is 1.31, diff is cp: -2, sp: +1
        let old = Wealth::from_gp(1.23);
        let new = Wealth::from_gp(1.31);
        let diff = new - old;
        assert_eq!(diff.as_tuple(), (-2, 1, 0, 0));
        assert_eq!(diff.to_gp(), 0.08);
        assert_eq!(new - diff, old);

    }
    #[test]
    fn test_diff_subbing() {
        use super::Wealth;

        /// Let say we sub 0.08 gp
        /// 1.31 - 0.08 gold is 1.23, diff is cp: +2, sp: -1
        let old = Wealth::from_gp(1.31);
        let new = Wealth::from_gp(1.23);
        let diff = new - old;
        assert_eq!(diff.as_tuple(), (2, -1, 0, 0));
        assert_eq!(diff.to_gp(), -0.08);
        assert_eq!(new - diff, old);
    }

}