use serde::de::Error;
use serde::Serialize;
use serde::{Deserialize, Deserializer, Serializer};
use std::str::FromStr;

#[derive(Clone, Debug, Eq, PartialEq, Hash, Ord, PartialOrd)]
pub struct Date {
    pub year: u16,
    pub month: u8,
    pub day: u8,
}

impl Date {
    #[cfg(test)]
    pub fn new(year: u16, month: u8, day: u8) -> Self {
        Date { year, month, day }
    }
}

#[derive(Clone, PartialEq, Eq, Debug)]
pub enum DateParseError {
    InvalidNumber,
    MonthOutOfRange,
    DayOutOfRange,
    WrongFormat,
}

impl FromStr for Date {
    type Err = DateParseError;

    fn from_str(input: &str) -> Result<Date, DateParseError> {
        let mut parts = input.splitn(3, "-");

        let year = parts
            .next()
            .ok_or(DateParseError::WrongFormat)?
            .parse::<u16>()
            .map_err(|_| DateParseError::InvalidNumber)?;

        let month = parts
            .next()
            .ok_or(DateParseError::WrongFormat)?
            .parse::<u8>()
            .map_err(|_| DateParseError::InvalidNumber)?;

        let day = parts
            .next()
            .ok_or(DateParseError::WrongFormat)?
            .parse::<u8>()
            .map_err(|_| DateParseError::InvalidNumber)?;

        if month > 12 {
            return Err(DateParseError::DayOutOfRange);
        }

        if day > 31 {
            return Err(DateParseError::MonthOutOfRange);
        }

        Ok(Date { year, month, day })
    }
}

impl Serialize for Date {
    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
    where
        S: Serializer,
    {
        serializer.serialize_str(&format!(
            "{:04}-{:02}-{:02}",
            self.year, self.month, self.day
        ))
    }
}

impl<'de> Deserialize<'de> for Date {
    fn deserialize<D>(deserializer: D) -> Result<Date, D::Error>
    where
        D: Deserializer<'de>,
    {
        let data = String::deserialize(deserializer)?;

        match Date::from_str(&data) {
            Ok(date) => Ok(date),
            Err(_) => Err(D::Error::custom(
                "Expected a String in this format: YYYY-MM-DD.",
            )),
        }
    }
}

#[cfg(test)]
mod test {
    use super::*;

    #[test]
    fn order() {
        // Other Test not needed, since the Ord is derived.
        assert!(Date::new(2019, 10, 10) > Date::new(2018, 10, 10));
        assert!(Date::new(2018, 11, 10) > Date::new(2018, 10, 10));
        assert!(Date::new(2018, 10, 11) > Date::new(2018, 10, 10));
    }

    #[test]
    fn from_str() {
        assert_eq!(Ok(Date::new(2019, 10, 10)), Date::from_str("2019-10-10"));

        assert_eq!(Ok(Date::new(2019, 1, 1)), Date::from_str("2019-1-1"));

        assert!(Date::from_str("2019-1-1-444").is_err());

        assert_eq!(
            Ok(Date::new(2019, 1, 1)),
            Date::from_str("2019-0000000000001-00000001")
        );

        assert!(Date::from_str("XXX-400-400").is_err());

        assert!(Date::from_str("400-400-400").is_err());
    }

}