use chrono::Timelike;
use chrono::{NaiveDate, NaiveTime};

pub static DATE_FORMAT: &str = "%d/%m/%Y";

#[derive(Debug, Clone)]
pub struct Event {
    pub date: NaiveDate,
    pub start: Option<NaiveTime>,
    pub end: Option<NaiveTime>,
    pub name: String,
}

impl Event {
    pub fn pprint(&self) -> String {
        let start = self.start.map(pprint_time).unwrap_or_default();
        let end = self
            .end
            .map(|t| format!("-{}", pprint_time(t)))
            .unwrap_or_default();
        let space = if self.start.is_some() || self.end.is_some() {
            " "
        } else {
            ""
        };
        format!("{}{}{}{}", start, end, space, self.name)
    }
}

fn pprint_time(t: NaiveTime) -> String {
    if t.minute() == 0 {
        format!("{}h", t.hour())
    } else {
        format!("{}h{}", t.hour(), t.minute())
    }
}

fn parse_time(t: &str) -> Option<NaiveTime> {
    match t.split('h').collect::<Vec<&str>>()[..] {
        [hours, minutes] => {
            if minutes.trim().is_empty() {
                NaiveTime::from_hms_opt(hours.parse().ok()?, 0, 0)
            } else {
                NaiveTime::from_hms_opt(hours.parse().ok()?, minutes.parse().ok()?, 0)
            }
        }
        _ => None,
    }
}

// Validation

pub fn validate(date: String, name: String, start: String, end: String) -> Option<Event> {
    let start = validate_time(start)?;
    let end = validate_time(end)?;

    match (start, end) {
        (Some(s), Some(e)) if s > e => None?,
        _ => (),
    }

    Some(Event {
        date: NaiveDate::parse_from_str(&date, DATE_FORMAT).ok()?,
        name: validate_name(name)?,
        start,
        end,
    })
}

fn validate_time(time: String) -> Option<Option<NaiveTime>> {
    let time = time.trim();
    if time.is_empty() {
        Some(None)
    } else {
        parse_time(time).map(|t| Some(t))
    }
}

fn validate_name(name: String) -> Option<String> {
    let name = name.trim();
    if name.is_empty() {
        None
    } else {
        Some(name.to_string())
    }
}