use chrono::{FixedOffset, TimeZone};
use regex::Regex;
use rocket::http::RawStr;
use rocket::request::FromFormValue;
use serde::ser::Serializer;
use serde::Serialize;
use std::convert::TryFrom;

/// Represents a very simple Timezoneless date. Considering the timezone will
/// always be CEST (aka Belgium's timezone), this is good enough. I use this
/// instead of a NaiveDate to avoid E0117.
pub struct BasicDate {
    year: u32,
    month: u8,
    day: u8,
}

impl BasicDate {
    /// Return the seconds since epoch for this date
    pub fn epoch(&self) -> i64 {
        // Timezone of Brussels is UTC + 2 hours in the western hemisphere
        FixedOffset::west(7_200)
            .ymd(self.year as i32, self.month as u32, self.day as u32)
            // For some reason, I couldn't get .timestamp() to work on a Date
            // without a time component, even though the docs seemed to
            // indicate this was possible
            .and_hms(0, 0, 0)
            .timestamp()
    }
}

/// This allows us to use BasicDate as a query parameter in our routes.
impl<'v> FromFormValue<'v> for BasicDate {
    type Error = &'v RawStr;

    fn from_form_value(form_value: &'v RawStr) -> Result<BasicDate, Self::Error> {
        match BasicDate::try_from(form_value.as_str()) {
            Err(_) => Err(form_value),
            Ok(date) => Ok(date),
        }
    }
}

/// We need this when deserializing BasicDate.
impl ToString for BasicDate {
    fn to_string(&self) -> String {
        format!("{}-{}-{}", self.year, self.month, self.day)
    }
}

/// This is used to serialize BasicDate.
impl TryFrom<&str> for BasicDate {
    type Error = ();

    fn try_from(s: &str) -> Result<BasicDate, Self::Error> {
        let re = Regex::new(r"^(\d{4})-(\d{2})-(\d{2})$").unwrap();

        match re.captures(s) {
            None => Err(()),
            Some(caps) => Ok(BasicDate {
                // TODO change this to ? operator if possible
                year: caps.get(1).unwrap().as_str().parse().unwrap(),
                month: caps.get(2).unwrap().as_str().parse().unwrap(),
                day: caps.get(3).unwrap().as_str().parse().unwrap(),
            }),
        }
    }
}

impl Serialize for BasicDate {
    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
    where
        S: Serializer,
    {
        serializer.serialize_str(&self.to_string())
    }
}