use anyhow::{bail, format_err, Result};
use chrono::{DateTime, Local, LocalResult, NaiveDate, TimeZone};

#[derive(Debug)]
pub(super) struct Range {
    pub start: DateTime<Local>,
    pub end: DateTime<Local>,
}

pub(super) fn try_create_range<S: AsRef<str>>(date: S) -> Result<Range> {
    Ok(Range {
        start: create_day_bound(&date, 0, 0, 0)?,
        end: create_day_bound(date, 23, 59, 59)?,
    })
}

fn create_day_bound<S: AsRef<str>>(
    day: S,
    hour: u32,
    minute: u32,
    second: u32,
) -> Result<DateTime<Local>> {
    let ts: Vec<&str> = day.as_ref().split("-").collect();
    if ts.len() != 3 {
        bail!("Invalid date format! {}", day.as_ref())
    }
    let (year, month, day) = if let [year, month, day, ..] = &ts[..] {
        (year, month, day)
    } else {
        bail!("Invalid date format! {}", day.as_ref())
    };
    let b = Local.from_local_datetime(
        &NaiveDate::from_ymd_opt(year.parse()?, month.parse()?, day.parse()?)
            .ok_or_else(|| format_err!("Invalid date!"))?
            .and_hms_opt(hour, minute, second)
            .ok_or_else(|| format_err!("Invalid time!"))?,
    );
    if let LocalResult::Single(b) = b {
        Ok(b)
    } else {
        bail!("Cannot construct day boundary!")
    }
}