use crate::models::FileAttributes;
use std::path::Path;

/// Write CAN metadata as OS-level file attributes.
/// - Unix/macOS: Extended Attributes (xattr)
/// - Windows: NTFS Alternate Data Streams
pub fn write_attributes(path: &Path, attrs: &FileAttributes) -> std::io::Result<()> {
    #[cfg(unix)]
    {
        write_xattr(path, attrs)
    }
    #[cfg(windows)]
    {
        write_ntfs_ads(path, attrs)
    }
}

/// Read CAN metadata from OS-level file attributes.
pub fn read_attributes(path: &Path) -> std::io::Result<FileAttributes> {
    #[cfg(unix)]
    {
        read_xattr(path)
    }
    #[cfg(windows)]
    {
        read_ntfs_ads(path)
    }
}

// ── Unix implementation using xattr crate ──

#[cfg(unix)]
fn write_xattr(path: &Path, attrs: &FileAttributes) -> std::io::Result<()> {
    use xattr::FileExt;
    let file = std::fs::File::open(path)?;

    if let Some(ref v) = attrs.mime_type {
        file.set_xattr("user.can.mime_type", v.as_bytes())?;
    }
    if let Some(ref v) = attrs.application {
        file.set_xattr("user.can.application", v.as_bytes())?;
    }
    if let Some(ref v) = attrs.user {
        file.set_xattr("user.can.user", v.as_bytes())?;
    }
    if let Some(ref v) = attrs.tags {
        file.set_xattr("user.can.tags", v.as_bytes())?;
    }
    if let Some(ref v) = attrs.description {
        file.set_xattr("user.can.description", v.as_bytes())?;
    }
    if let Some(ref v) = attrs.human_filename {
        file.set_xattr("user.can.human_filename", v.as_bytes())?;
    }
    if let Some(ref v) = attrs.human_path {
        file.set_xattr("user.can.human_path", v.as_bytes())?;
    }
    Ok(())
}

#[cfg(unix)]
fn read_xattr(path: &Path) -> std::io::Result<FileAttributes> {
    use xattr::FileExt;
    let file = std::fs::File::open(path)?;

    let read_attr = |name: &str| -> Option<String> {
        file.get_xattr(name)
            .ok()
            .flatten()
            .and_then(|bytes| String::from_utf8(bytes).ok())
    };

    Ok(FileAttributes {
        mime_type: read_attr("user.can.mime_type"),
        application: read_attr("user.can.application"),
        user: read_attr("user.can.user"),
        tags: read_attr("user.can.tags"),
        description: read_attr("user.can.description"),
        human_filename: read_attr("user.can.human_filename"),
        human_path: read_attr("user.can.human_path"),
    })
}

// ── Windows implementation using NTFS Alternate Data Streams ──

#[cfg(windows)]
fn write_ntfs_ads(path: &Path, attrs: &FileAttributes) -> std::io::Result<()> {
    let base = path.to_string_lossy();

    if let Some(ref v) = attrs.mime_type {
        std::fs::write(format!("{}:can.mime_type", base), v)?;
    }
    if let Some(ref v) = attrs.application {
        std::fs::write(format!("{}:can.application", base), v)?;
    }
    if let Some(ref v) = attrs.user {
        std::fs::write(format!("{}:can.user", base), v)?;
    }
    if let Some(ref v) = attrs.tags {
        std::fs::write(format!("{}:can.tags", base), v)?;
    }
    if let Some(ref v) = attrs.description {
        std::fs::write(format!("{}:can.description", base), v)?;
    }
    if let Some(ref v) = attrs.human_filename {
        std::fs::write(format!("{}:can.human_filename", base), v)?;
    }
    if let Some(ref v) = attrs.human_path {
        std::fs::write(format!("{}:can.human_path", base), v)?;
    }
    Ok(())
}

#[cfg(windows)]
fn read_ntfs_ads(path: &Path) -> std::io::Result<FileAttributes> {
    let base = path.to_string_lossy();

    let read_stream = |name: &str| -> Option<String> {
        std::fs::read_to_string(format!("{}:{}", base, name)).ok()
    };

    Ok(FileAttributes {
        mime_type: read_stream("can.mime_type"),
        application: read_stream("can.application"),
        user: read_stream("can.user"),
        tags: read_stream("can.tags"),
        description: read_stream("can.description"),
        human_filename: read_stream("can.human_filename"),
        human_path: read_stream("can.human_path"),
    })
}

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

    #[test]
    fn test_write_and_read_attributes() {
        let file = NamedTempFile::new().unwrap();
        std::fs::write(file.path(), b"test content").unwrap();

        let attrs = FileAttributes {
            mime_type: Some("image/jpeg".to_string()),
            application: Some("TestApp".to_string()),
            user: Some("jason".to_string()),
            tags: Some("photo,vacation,2024".to_string()),
            description: Some("A test file".to_string()),
            human_filename: Some("my_photo.jpg".to_string()),
            human_path: Some("/photos/trip/".to_string()),
        };

        write_attributes(file.path(), &attrs).unwrap();
        let read_back = read_attributes(file.path()).unwrap();

        assert_eq!(read_back.mime_type, Some("image/jpeg".to_string()));
        assert_eq!(read_back.application, Some("TestApp".to_string()));
        assert_eq!(read_back.user, Some("jason".to_string()));
        assert_eq!(read_back.tags, Some("photo,vacation,2024".to_string()));
        assert_eq!(read_back.description, Some("A test file".to_string()));
        assert_eq!(read_back.human_filename, Some("my_photo.jpg".to_string()));
        assert_eq!(read_back.human_path, Some("/photos/trip/".to_string()));
    }

    #[test]
    fn test_partial_attributes() {
        let file = NamedTempFile::new().unwrap();
        std::fs::write(file.path(), b"data").unwrap();

        let attrs = FileAttributes {
            mime_type: None,
            application: Some("App".to_string()),
            user: None,
            tags: None,
            description: None,
            human_filename: None,
            human_path: None,
        };

        write_attributes(file.path(), &attrs).unwrap();
        let read_back = read_attributes(file.path()).unwrap();

        assert_eq!(read_back.application, Some("App".to_string()));
        assert_eq!(read_back.user, None);
        assert_eq!(read_back.tags, None);
    }
}