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use {Entry, EntryExt};
use std;
use std::io::Write;

/// A writer that accepts entries of type `E` and writes the associated M3U format.
///
/// Entries are always written using in UTF-8.
pub struct Writer<W, E>
    where W: Write,
{
    /// The writer to which the `M3U` format is written.
    writer: W,
    /// Used for buffering lines as bytes for writing.
    line_buffer: Vec<u8>,
    /// The type of entries that will be written.
    entry: std::marker::PhantomData<E>,
}

/// A `Writer` that specifically writes `Entry`s.
pub type EntryWriter<W> = Writer<W, Entry>;
/// A `Writer` that specifically writes `EntryExt`s.
pub type EntryExtWriter<W> = Writer<W, EntryExt>;

impl<W, E> Writer<W, E>
    where W: Write,
{

    fn new_inner(writer: W, line_buffer: Vec<u8>) -> Self {
        Writer {
            writer: writer,
            line_buffer: line_buffer,
            entry: std::marker::PhantomData,
        }
    }

    /// `Flush` the `writer` output stream, ensuring that all intermediately buffered entries reach
    /// their destination.
    ///
    /// This should be called after all entries have been written.
    ///
    /// If it is not called, the destructor will finalize the file, but any errors that occur in
    /// the process cannot be handled.
    pub fn flush(mut self) -> Result<(), std::io::Error> {
        self.writer.flush()
    }

}

impl<W> EntryWriter<W>
    where W: Write,
{

    /// Create a writer that writes the original, non_extended M3U `Entry` type.
    pub fn new(writer: W) -> Self {
        Self::new_inner(writer, Vec::new())
    }

    /// Attempt to write the given `Entry` to the given `writer`.
    ///
    /// Writes the `Path` or `Url` in plain text, ending with a newline.
    pub fn write_entry(&mut self, entry: &Entry) -> Result<(), std::io::Error> {
        let Writer { ref mut writer, ref mut line_buffer, .. } = *self;
        line_buffer.clear();
        try!(write_entry(line_buffer, entry));
        writer.write_all(line_buffer)
    }

}

impl<W> EntryExtWriter<W>
    where W: Write,
{

    /// Create a writer that writes extended M3U `EntryExt`s.
    ///
    /// The `#EXTM3U` header line is written immediately.
    pub fn new_ext(mut writer: W) -> Result<Self, std::io::Error> {
        let mut line_buffer = Vec::new();
        try!(writeln!(&mut line_buffer, "#EXTM3U"));
        try!(writer.write_all(&line_buffer));
        Ok(Self::new_inner(writer, line_buffer))
    }

    /// Attempt to write the given `EntryExt` to the given `writer`.
    ///
    /// First writes the `#EXTINF:` line, then writes the entry line.
    pub fn write_entry(&mut self, entry_ext: &EntryExt) -> Result<(), std::io::Error> {
        let Writer { ref mut writer, ref mut line_buffer, .. } = *self;
        line_buffer.clear();
        let extinf = &entry_ext.extinf;
        try!(writeln!(line_buffer, "#EXTINF:{},{}", extinf.duration_secs, &extinf.name));
        try!(write_entry(line_buffer, &entry_ext.entry));
        writer.write_all(line_buffer)
    }

}

/// Write the given `Entry` into the given `line_buffer`.
///
/// Writes the `Path` or `Url` in plain text, ending with a newline.
fn write_entry(line_buffer: &mut Vec<u8>, entry: &Entry) -> Result<(), std::io::Error> {
    match *entry {
        Entry::Path(ref path) => writeln!(line_buffer, "{}", path.display()),
        Entry::Url(ref url) => writeln!(line_buffer, "{}", url),
    }
}


impl<W, E> Drop for Writer<W, E>
    where W: Write,
{
    fn drop(&mut self) {
        self.writer.flush().ok();
    }
}