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use crate::io;
use crate::path::Path;
use crate::task::spawn_blocking;
use crate::utils::Context as _;

/// Reads the entire contents of a file as raw bytes.

///

/// This is a convenience function for reading entire files. It pre-allocates a buffer based on the

/// file size when available, so it is typically faster than manually opening a file and reading

/// from it.

///

/// If you want to read the contents as a string, use [`read_to_string`] instead.

///

/// This function is an async version of [`std::fs::read`].

///

/// [`read_to_string`]: fn.read_to_string.html

/// [`std::fs::read`]: https://doc.rust-lang.org/std/fs/fn.read.html

///

/// # Errors

///

/// An error will be returned in the following situations:

///

/// * `path` does not point to an existing file.

/// * The current process lacks permissions to read the file.

/// * Some other I/O error occurred.

///

/// # Examples

///

/// ```no_run

/// # fn main() -> std::io::Result<()> { async_std::task::block_on(async {

/// #

/// use async_std::fs;

///

/// let contents = fs::read("a.txt").await?;

/// #

/// # Ok(()) }) }

/// ```

pub async fn read<P: AsRef<Path>>(path: P) -> io::Result<Vec<u8>> {
    let path = path.as_ref().to_owned();
    spawn_blocking(move || {
        std::fs::read(&path).context(|| format!("could not read file `{}`", path.display()))
    })
    .await
}