use crate::types::ProtocolVersion;
use crate::{Error, ErrorKind, Result};
use std::fmt;
use std::str::FromStr;
use std::time::Duration;
use trackable::error::ErrorKindExt;

/// [4.3.3.1. EXT-X-TARGETDURATION]
///
/// [4.3.3.1. EXT-X-TARGETDURATION]: https://tools.ietf.org/html/rfc8216#section-4.3.3.1
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
pub struct ExtXTargetDuration {
    duration: Duration,
}

impl ExtXTargetDuration {
    pub(crate) const PREFIX: &'static str = "#EXT-X-TARGETDURATION:";

    /// Makes a new `ExtXTargetduration` tag.
    ///
    /// Note that the nanoseconds part of the `duration` will be discarded.
    pub fn new(duration: Duration) -> Self {
        let duration = Duration::from_secs(duration.as_secs());
        ExtXTargetDuration { duration }
    }

    /// Returns the maximum media segment duration in the associated playlist.
    pub fn duration(&self) -> Duration {
        self.duration
    }

    /// Returns the protocol compatibility version that this tag requires.
    pub fn requires_version(&self) -> ProtocolVersion {
        ProtocolVersion::V1
    }
}

impl fmt::Display for ExtXTargetDuration {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(f, "{}{}", Self::PREFIX, self.duration.as_secs())
    }
}

impl FromStr for ExtXTargetDuration {
    type Err = Error;
    fn from_str(s: &str) -> Result<Self> {
        track_assert!(s.starts_with(Self::PREFIX), ErrorKind::InvalidInput);
        let duration = may_invalid!(s.split_at(Self::PREFIX.len()).1.parse())?;
        Ok(ExtXTargetDuration {
            duration: Duration::from_secs(duration),
        })
    }
}

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

    #[test]
    fn ext_x_targetduration() {
        let tag = ExtXTargetDuration::new(Duration::from_secs(5));
        let text = "#EXT-X-TARGETDURATION:5";
        assert_eq!(text.parse().ok(), Some(tag));
        assert_eq!(tag.to_string(), text);
        assert_eq!(tag.requires_version(), ProtocolVersion::V1);
    }
}