// TODO: Find a way to avoid code duplication between this and the example code in lib.rs docs.

use std::cmp::PartialEq;
use std::convert::TryInto;
use std::fmt;

use rt_format::{Format, FormatArgument, Specifier};

#[derive(Debug, PartialEq)]
#[allow(dead_code)]
pub enum Variant {
    Int(i32),
    Float(f64),
}

impl FormatArgument for Variant {
    fn supports_format(&self, spec: &Specifier) -> bool {
        match self {
            Self::Int(_) => true,
            Self::Float(_) => match spec.format {
                Format::Display | Format::Debug | Format::LowerExp | Format::UpperExp => true,
                _ => false,
            },
        }
    }

    fn fmt_display(&self, f: &mut fmt::Formatter) -> fmt::Result {
        match self {
            Self::Int(val) => fmt::Display::fmt(&val, f),
            Self::Float(val) => fmt::Display::fmt(&val, f),
        }
    }

    fn fmt_debug(&self, f: &mut fmt::Formatter) -> fmt::Result {
        fmt::Debug::fmt(self, f)
    }

    fn fmt_octal(&self, f: &mut fmt::Formatter) -> fmt::Result {
        match self {
            Self::Int(val) => fmt::Octal::fmt(&val, f),
            _ => Err(fmt::Error),
        }
    }

    fn fmt_lower_hex(&self, f: &mut fmt::Formatter) -> fmt::Result {
        match self {
            Self::Int(val) => fmt::LowerHex::fmt(&val, f),
            _ => Err(fmt::Error),
        }
    }

    fn fmt_upper_hex(&self, f: &mut fmt::Formatter) -> fmt::Result {
        match self {
            Self::Int(val) => fmt::UpperHex::fmt(&val, f),
            _ => Err(fmt::Error),
        }
    }

    fn fmt_binary(&self, f: &mut fmt::Formatter) -> fmt::Result {
        match self {
            Self::Int(val) => fmt::Binary::fmt(&val, f),
            _ => Err(fmt::Error),
        }
    }

    fn fmt_lower_exp(&self, f: &mut fmt::Formatter) -> fmt::Result {
        match self {
            Self::Int(val) => fmt::LowerExp::fmt(&val, f),
            Self::Float(val) => fmt::LowerExp::fmt(&val, f),
        }
    }

    fn fmt_upper_exp(&self, f: &mut fmt::Formatter) -> fmt::Result {
        match self {
            Self::Int(val) => fmt::UpperExp::fmt(&val, f),
            Self::Float(val) => fmt::UpperExp::fmt(&val, f),
        }
    }

    fn to_usize(&self) -> Result<usize, ()> {
        match self {
            Variant::Int(val) => (*val).try_into().map_err(|_| ()),
            Variant::Float(_) => Err(()),
        }
    }
}