//! Disc file format related logic (ISO, NFS, etc)

use std::{fs, io};
use std::path::Path;

use crate::{Error, Result};
use crate::io::{iso::new_disc_io_iso, nfs::new_disc_io_nfs};
use crate::streams::ReadStream;

pub(crate) mod iso;
pub(crate) mod nfs;

/// Abstraction over supported disc file types.
pub trait DiscIO {
    /// Opens a new read stream for the disc file(s).
    /// Generally does _not_ need to be used directly.
    fn begin_read_stream(&self, offset: u64) -> io::Result<Box<dyn ReadStream + '_>>;

    /// If false, the file format does not use standard Wii partition encryption. (e.g. NFS)
    fn has_wii_crypto(&self) -> bool { true }
}

/// Helper function for checking a file extension.
#[inline(always)]
pub fn has_extension(filename: &Path, extension: &str) -> bool {
    if let Some(ext) = filename.extension() {
        // TODO use with Rust 1.53+
        // ext.eq_ignore_ascii_case(extension)
        ext.to_str().unwrap_or("").eq_ignore_ascii_case(extension)
    } else { false }
}

/// Creates a new [`DiscIO`] instance.
///
/// # Examples
///
/// Basic usage:
/// ```
/// use nod::io::new_disc_io;
///
/// let mut disc_io = new_disc_io("path/to/file".as_ref())?;
/// ```
pub fn new_disc_io(filename: &Path) -> Result<Box<dyn DiscIO>> {
    let path_result = fs::canonicalize(filename);
    if path_result.is_err() {
        return Result::Err(Error::Io(
            format!("Failed to open {}", filename.to_string_lossy()),
            path_result.unwrap_err(),
        ));
    }
    let path = path_result.as_ref().unwrap();
    let meta = fs::metadata(path);
    if meta.is_err() {
        return Result::Err(Error::Io(
            format!("Failed to open {}", filename.to_string_lossy()),
            meta.unwrap_err(),
        ));
    }
    if !meta.unwrap().is_file() {
        return Result::Err(Error::DiscFormat(
            format!("Input is not a file: {}", filename.to_string_lossy())
        ));
    }
    if has_extension(path, "iso") {
        Result::Ok(Box::from(new_disc_io_iso(path)?))
    } else if has_extension(path, "nfs") {
        if matches!(path.parent(), Some(parent) if parent.is_dir()) {
            Result::Ok(Box::from(new_disc_io_nfs(path.parent().unwrap())?))
        } else {
            Result::Err(Error::DiscFormat("Failed to locate NFS parent directory".to_string()))
        }
    } else {
        Result::Err(Error::DiscFormat("Unknown file type".to_string()))
    }
}