use crate::{HeaderTagFlag, HeaderTagType};
use core::fmt;
use core::fmt::{Debug, Formatter};
use core::mem::size_of;

/// This tag is taken into account only on EFI amd64 platforms when Multiboot2 image header
/// contains EFI boot services tag. Then entry point specified in ELF header and the entry address
/// tag of Multiboot2 header are ignored.
///
/// Technically, this is equivalent to the [`crate::EntryAddressHeaderTag`] but with a different
/// [`crate::HeaderTagType`].
#[derive(Copy, Clone)]
#[repr(C)]
pub struct EntryEfi64HeaderTag {
    typ: HeaderTagType,
    flags: HeaderTagFlag,
    size: u32,
    entry_addr: u32,
}

impl EntryEfi64HeaderTag {
    pub const fn new(flags: HeaderTagFlag, entry_addr: u32) -> Self {
        EntryEfi64HeaderTag {
            typ: HeaderTagType::EntryAddressEFI64,
            flags,
            size: size_of::<Self>() as u32,
            entry_addr,
        }
    }

    pub const fn typ(&self) -> HeaderTagType {
        self.typ
    }
    pub const fn flags(&self) -> HeaderTagFlag {
        self.flags
    }
    pub const fn size(&self) -> u32 {
        self.size
    }
    pub const fn entry_addr(&self) -> u32 {
        self.entry_addr
    }
}

impl Debug for EntryEfi64HeaderTag {
    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
        f.debug_struct("EntryEfi64HeaderTag")
            .field("type", &{ self.typ })
            .field("flags", &{ self.flags })
            .field("size", &{ self.size })
            .field("entry_addr", &(self.entry_addr as *const u32))
            .finish()
    }
}

#[cfg(test)]
mod tests {
    use crate::EntryEfi64HeaderTag;

    #[test]
    fn test_assert_size() {
        assert_eq!(core::mem::size_of::<EntryEfi64HeaderTag>(), 2 + 2 + 4 + 4);
    }
}