cljrs-eval 0.1.7

use bigdecimal::BigDecimal;
use cljrs_value::{Value, ValueError, ValueResult};
use num_bigint::BigInt;
use num_traits::{Signed, ToPrimitive};
use std::ops::{Div, Mul};

pub fn bigdec_to_i64(d: &BigDecimal) -> ValueResult<i64> {
    let (num, exp) = d.as_bigint_and_exponent();
    let res = if exp >= 0 {
        let pow = BigInt::from(10).pow(exp as u32);
        num.div(pow)
    } else {
        let scale = BigInt::from(10).pow((-exp) as u32);
        num.mul(scale)
    };
    res.to_i64()
        .ok_or_else(|| ValueError::Other("BigDecimal too large for i64".into()))
}

pub fn numeric_as_i64(v: &Value) -> ValueResult<i64> {
    match v {
        Value::Long(n) => Ok(*n),
        Value::Double(f) => {
            if f64::is_infinite(*f) || f64::is_nan(*f) {
                Err(ValueError::Other(
                    "cannot convert non-number to i64".to_string(),
                ))
            } else {
                Ok(*f as i64)
            }
        }
        Value::Char(c) => Ok(*c as i64),
        Value::BigInt(n) => n
            .get()
            .to_i64()
            .ok_or_else(|| ValueError::Other("BigInt too large for i64".into())),
        Value::Ratio(r) => {
            let trunc = if r.get().is_negative() {
                // Use ceiling to truncate towards zero.
                r.get().ceil()
            } else {
                r.get().floor()
            };
            trunc
                .to_i64()
                .ok_or_else(|| ValueError::Other("cannot convert ratio".into()))
        }
        Value::BigDecimal(d) => bigdec_to_i64(d.get()),
        Value::Bool(b) => Ok(*b as i64),
        Value::Str(s) => match s.get().parse::<BigDecimal>() {
            Ok(d) => bigdec_to_i64(&d),
            Err(_) => Err(ValueError::Other(
                "failed to parse string as number".to_string(),
            )),
        },
        _ => Err(ValueError::WrongType {
            expected: "integer",
            got: v.type_name().to_string(),
        }),
    }
}