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use errors::Result;
use std::fmt;
use std::fs::File;
use std::io::{self, Cursor, Read};
use std::path::{Path, PathBuf};
use std::sync::Arc;

#[derive(Debug, Clone)]
pub enum Readable {
    Empty,
    Bytes(Arc<Vec<u8>>),
    Path(Arc<PathBuf>),
    Stdin,
}

impl Readable {
    /// Open a reader for this readable.
    fn read(&self) -> Result<Box<Read>> {
        use self::Readable::*;

        let out: Box<Read> = match *self {
            Empty => Box::new(Cursor::new(&[])),
            Bytes(ref bytes) => Box::new(Cursor::new(ArcCursor(Arc::clone(&bytes)))),
            Path(ref path) => Box::new(File::open(path.as_ref())?),
            Stdin => Box::new(io::stdin()),
        };

        Ok(out)
    }
}

impl fmt::Display for Readable {
    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
        use self::Readable::*;

        match *self {
            Empty => "empty".fmt(fmt),
            Bytes(ref bytes) => write!(fmt, "bytes:{}", bytes.len()),
            Path(ref path) => write!(fmt, "path:{}", path.display()),
            Stdin => "stdin".fmt(fmt),
        }
    }
}

#[derive(Debug, Clone)]
pub struct Source {
    name: Option<Arc<String>>,
    path: Option<Arc<PathBuf>>,
    readable: Readable,
}

impl Source {
    /// Create a new empty source.
    pub fn empty<S: AsRef<str>>(name: S) -> Self {
        Self {
            name: Some(Arc::new(name.as_ref().to_string())),
            path: None,
            readable: Readable::Empty,
        }
    }

    /// Create a new bytes source.
    pub fn bytes<S: AsRef<str>>(name: S, bytes: Vec<u8>) -> Self {
        Self {
            name: Some(Arc::new(name.as_ref().to_string())),
            path: None,
            readable: Readable::Bytes(Arc::new(bytes)),
        }
    }

    /// Create a new path source.
    pub fn from_path<P: AsRef<Path>>(path: P) -> Self {
        Self {
            name: None,
            path: None,
            readable: Readable::Path(Arc::new(path.as_ref().to_owned())),
        }
    }

    /// Create an source from stdin.
    pub fn stdin() -> Self {
        Self {
            name: None,
            path: None,
            readable: Readable::Stdin,
        }
    }

    /// Access the path of the source.
    pub fn path(&self) -> Option<&Path> {
        if let Some(path) = self.path.as_ref() {
            return Some(path.as_ref());
        }

        if let Readable::Path(ref path) = self.readable {
            return Some(path.as_ref());
        }

        None
    }

    /// Open up a readable.
    pub fn read(&self) -> Result<Box<Read>> {
        self.readable.read()
    }

    /// Create a copy of this source that has a different name.
    pub fn with_name(&self, name: String) -> Self {
        Self {
            name: Some(Arc::new(name)),
            path: self.path.as_ref().map(Arc::clone),
            readable: self.readable.clone(),
        }
    }
}

impl fmt::Display for Source {
    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
        if let Readable::Path(ref path) = self.readable {
            return path.display().fmt(fmt);
        }

        match self.name {
            Some(ref name) => write!(fmt, "<{} {}>", name, self.readable),
            None => write!(fmt, "<{}>", self.readable),
        }
    }
}

/// Adapt a vector in an Arc to be used in a Cursor.
struct ArcCursor(Arc<Vec<u8>>);

impl AsRef<[u8]> for ArcCursor {
    fn as_ref(&self) -> &[u8] {
        self.0.as_ref()
    }
}