// Copyright 2022 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#[repr(C, packed)]
#[derive(Debug, Copy, Clone, Default)]
pub struct Superblock {
    pub magic0: u64,
    pub magic1: u64,
    pub version: u32,
    pub flags: u32,
    pub block_size: u32,
    pub unused: u32,
    pub data_block_count: u64,
    pub journal_block_count: u64,
    pub inode_count: u64,
    pub alloc_block_count: u64,
    pub alloc_inode_count: u64,
}

#[repr(C, packed)]
#[derive(Debug, Copy, Clone, Default)]
pub struct Extent {
    pub size: u16,
    pub offset_hi: u16,
    pub offset_lo: u32,
}

impl Extent {
    pub fn offset(&self) -> usize {
        //let hi = self.offset_hi as usize;
        //let lo = self.offset_lo as usize;
        //return (hi << 32) | lo;
        return self.offset_lo as usize;
    }
}

#[repr(C, packed)]
#[derive(Debug, Copy, Clone, Default)]
pub struct NodeHeader {
    pub flags: u16,
    pub version: u16,
    pub next_node: u32,
}

impl NodeHeader {
    pub const FLAG_INODE: u16 = 0b0000000000000001;
    pub const FLAG_EXTENT: u16 = 0b0000000000000010;
}

#[repr(C, packed)]
#[derive(Debug, Copy, Clone, Default)]
pub struct Inode {
    pub header: NodeHeader,
    pub hash0: u64,
    pub hash1: u64,
    pub hash2: u64,
    pub hash3: u64,
    pub blob_size: u64,
    pub block_count: u32,
    pub extent_count: u16,
    pub padding: u16,
    pub inline_extent: Extent,
}

#[repr(C, packed)]
#[derive(Debug, Copy, Clone)]
pub struct ExtentContainer {
    pub header: NodeHeader,
    pub previous_node: u32,
    pub extent_count: u16,
    pub reserved: u16,
    pub extents: [Extent; 6],
}

#[repr(C, packed)]
#[derive(Debug, Copy, Clone)]
pub struct Transaction {
    pub op: u16,
    pub size: u16,
    pub addr: u32,
}

#[test]
fn size_check() {
    use core::mem::*;
    assert_eq!(size_of::<Extent>(), 8);
    assert_eq!(size_of::<Inode>(), 64);
    assert_eq!(size_of::<ExtentContainer>(), 64);
}