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    use super::{get_block_cache, BlockDevice, BLOCK_SZ};
    use alloc::sync::Arc;
    use alloc::vec::Vec;
    use core::fmt::{Debug, Formatter, Result};

    const EFS_MAGIC: u32 = 0x3b800001;
    const INODE_DIRECT_COUNT: usize = 28;
    const NAME_LENGTH_LIMIT: usize = 27;
    const INODE_INDIRECT1_COUNT: usize = BLOCK_SZ / 4;
    const INODE_INDIRECT2_COUNT: usize = INODE_INDIRECT1_COUNT * INODE_INDIRECT1_COUNT;
    const DIRECT_BOUND: usize = INODE_DIRECT_COUNT;
    const INDIRECT1_BOUND: usize = DIRECT_BOUND + INODE_INDIRECT1_COUNT;
    #[allow(unused)]
    const INDIRECT2_BOUND: usize = INDIRECT1_BOUND + INODE_INDIRECT2_COUNT;

    #[repr(C)]
    pub struct SuperBlock {
        magic: u32,
        pub total_blocks: u32,
        pub inode_bitmap_blocks: u32,
        pub inode_area_blocks: u32,
        pub data_bitmap_blocks: u32,
        pub data_area_blocks: u32,
    }

    impl Debug for SuperBlock {
        fn fmt(&self, f: &mut Formatter<'_>) -> Result {
            f.debug_struct("SuperBlock")
                .field("total_blocks", &self.total_blocks)
                .field("inode_bitmap_blocks", &self.inode_bitmap_blocks)
                .field("inode_area_blocks", &self.inode_area_blocks)
                .field("data_bitmap_blocks", &self.data_bitmap_blocks)
                .field("data_area_blocks", &self.data_area_blocks)
                .finish()
        }
    }

    impl SuperBlock {
        pub fn initialize(
            &mut self,
            total_blocks: u32,
            inode_bitmap_blocks: u32,
            inode_area_blocks: u32,
            data_bitmap_blocks: u32,
            data_area_blocks: u32,
        ) {
            kprintln!("[KERN EASYFS] layout::SuperBlock::initialize() begin");
            *self = Self {
                magic: EFS_MAGIC,
                total_blocks,
                inode_bitmap_blocks,
                inode_area_blocks,
                data_bitmap_blocks,
                data_area_blocks,
            }
        }
        pub fn is_valid(&self) -> bool {
            self.magic == EFS_MAGIC
        }
    }

    #[derive(PartialEq)]
    pub enum DiskInodeType {
        File,
        Directory,
    }

    type IndirectBlock = [u32; BLOCK_SZ / 4];
    type DataBlock = [u8; BLOCK_SZ];

    #[repr(C)]
    pub struct DiskInode {
        pub size: u32,
        pub direct: [u32; INODE_DIRECT_COUNT],
        pub indirect1: u32,
        pub indirect2: u32,
        type_: DiskInodeType,
    }

    impl DiskInode {
        /// indirect1 and indirect2 block are allocated only when they are needed.
        pub fn initialize(&mut self, type_: DiskInodeType) {
            kprintln!("[KERN EASYFS] layout::DiskInode::initialize() begin");
            self.size = 0;
            self.direct.iter_mut().for_each(|v| *v = 0);
            self.indirect1 = 0;
            self.indirect2 = 0;
            self.type_ = type_;
        }
        pub fn is_dir(&self) -> bool {
            self.type_ == DiskInodeType::Directory
        }
        #[allow(unused)]
        pub fn is_file(&self) -> bool {
            self.type_ == DiskInodeType::File
        }
        /// Return block number correspond to size.
        pub fn data_blocks(&self) -> u32 {
            Self::_data_blocks(self.size)
        }
        fn _data_blocks(size: u32) -> u32 {
            (size + BLOCK_SZ as u32 - 1) / BLOCK_SZ as u32
        }
        /// Return number of blocks needed include indirect1/2.
        pub fn total_blocks(size: u32) -> u32 {
            let data_blocks = Self::_data_blocks(size) as usize;
            let mut total = data_blocks as usize;
            // indirect1
            if data_blocks > INODE_DIRECT_COUNT {
                total += 1;
            }
            // indirect2
            if data_blocks > INDIRECT1_BOUND {
                total += 1;
                // sub indirect1
                total +=
                    (data_blocks - INDIRECT1_BOUND + INODE_INDIRECT1_COUNT - 1) / INODE_INDIRECT1_COUNT;
            }
            total as u32
        }
        pub fn blocks_num_needed(&self, new_size: u32) -> u32 {
            assert!(new_size >= self.size);
            Self::total_blocks(new_size) - Self::total_blocks(self.size)
        }
        pub fn get_block_id(&self, inner_id: u32, block_device: &Arc<dyn BlockDevice>) -> u32 {
            //kprintln!("[KERN EASYFS] layout::DiskInode::get_block_id() begin");
            let inner_id = inner_id as usize;
            if inner_id < INODE_DIRECT_COUNT {
                self.direct[inner_id]
            } else if inner_id < INDIRECT1_BOUND {
                get_block_cache(self.indirect1 as usize, Arc::clone(block_device))
                    .lock()
                    .read(0, |indirect_block: &IndirectBlock| {
                        indirect_block[inner_id - INODE_DIRECT_COUNT]
                    })
            } else {
                let last = inner_id - INDIRECT1_BOUND;
                let indirect1 = get_block_cache(self.indirect2 as usize, Arc::clone(block_device))
                    .lock()
                    .read(0, |indirect2: &IndirectBlock| {
                        indirect2[last / INODE_INDIRECT1_COUNT]
                    });
                get_block_cache(indirect1 as usize, Arc::clone(block_device))
                    .lock()
                    .read(0, |indirect1: &IndirectBlock| {
                        indirect1[last % INODE_INDIRECT1_COUNT]
                    })
            }
        }
        pub fn increase_size(
            &mut self,
            new_size: u32,
            new_blocks: Vec<u32>,
            block_device: &Arc<dyn BlockDevice>,
        ) {
            kprintln!("[KERN EASYFS] layout::DiskInode::increase_size() begin");
            let mut current_blocks = self.data_blocks();
            self.size = new_size;
            let mut total_blocks = self.data_blocks();
            let mut new_blocks = new_blocks.into_iter();
            // fill direct
            while current_blocks < total_blocks.min(INODE_DIRECT_COUNT as u32) {
                self.direct[current_blocks as usize] = new_blocks.next().unwrap();
                current_blocks += 1;
            }
            // alloc indirect1
            if total_blocks > INODE_DIRECT_COUNT as u32 {
                if current_blocks == INODE_DIRECT_COUNT as u32 {
                    self.indirect1 = new_blocks.next().unwrap();
                }
                current_blocks -= INODE_DIRECT_COUNT as u32;
                total_blocks -= INODE_DIRECT_COUNT as u32;
            } else {
                return;
            }
            // fill indirect1
            get_block_cache(self.indirect1 as usize, Arc::clone(block_device))
                .lock()
                .modify(0, |indirect1: &mut IndirectBlock| {
                    while current_blocks < total_blocks.min(INODE_INDIRECT1_COUNT as u32) {
                        indirect1[current_blocks as usize] = new_blocks.next().unwrap();
                        current_blocks += 1;
                    }
                });
            // alloc indirect2
            if total_blocks > INODE_INDIRECT1_COUNT as u32 {
                if current_blocks == INODE_INDIRECT1_COUNT as u32 {
                    self.indirect2 = new_blocks.next().unwrap();
                }
                current_blocks -= INODE_INDIRECT1_COUNT as u32;
                total_blocks -= INODE_INDIRECT1_COUNT as u32;
            } else {
                return;
            }
            // fill indirect2 from (a0, b0) -> (a1, b1)
            let mut a0 = current_blocks as usize / INODE_INDIRECT1_COUNT;
            let mut b0 = current_blocks as usize % INODE_INDIRECT1_COUNT;
            let a1 = total_blocks as usize / INODE_INDIRECT1_COUNT;
            let b1 = total_blocks as usize % INODE_INDIRECT1_COUNT;
            // alloc low-level indirect1
            get_block_cache(self.indirect2 as usize, Arc::clone(block_device))
                .lock()
                .modify(0, |indirect2: &mut IndirectBlock| {
                    while (a0 < a1) || (a0 == a1 && b0 < b1) {
                        if b0 == 0 {
                            indirect2[a0] = new_blocks.next().unwrap();
                        }
                        // fill current
                        get_block_cache(indirect2[a0] as usize, Arc::clone(block_device))
                            .lock()
                            .modify(0, |indirect1: &mut IndirectBlock| {
                                indirect1[b0] = new_blocks.next().unwrap();
                            });
                        // move to next
                        b0 += 1;
                        if b0 == INODE_INDIRECT1_COUNT {
                            b0 = 0;
                            a0 += 1;
                        }
                    }
                });
        }

        /// Clear size to zero and return blocks that should be deallocated.
        ///
        /// We will clear the block contents to zero later.
        pub fn clear_size(&mut self, block_device: &Arc<dyn BlockDevice>) -> Vec<u32> {
            kprintln!("[KERN EASYFS] layout::DiskInode::clear_size() begin");
            let mut v: Vec<u32> = Vec::new();
            let mut data_blocks = self.data_blocks() as usize;
            self.size = 0;
            let mut current_blocks = 0usize;
            // direct
            while current_blocks < data_blocks.min(INODE_DIRECT_COUNT) {
                v.push(self.direct[current_blocks]);
                self.direct[current_blocks] = 0;
                current_blocks += 1;
            }
            // indirect1 block
            if data_blocks > INODE_DIRECT_COUNT {
                v.push(self.indirect1);
                data_blocks -= INODE_DIRECT_COUNT;
                current_blocks = 0;
            } else {
                return v;
            }
            // indirect1
            get_block_cache(self.indirect1 as usize, Arc::clone(block_device))
                .lock()
                .modify(0, |indirect1: &mut IndirectBlock| {
                    while current_blocks < data_blocks.min(INODE_INDIRECT1_COUNT) {
                        v.push(indirect1[current_blocks]);
                        //indirect1[current_blocks] = 0;
                        current_blocks += 1;
                    }
                });
            self.indirect1 = 0;
            // indirect2 block
            if data_blocks > INODE_INDIRECT1_COUNT {
                v.push(self.indirect2);
                data_blocks -= INODE_INDIRECT1_COUNT;
            } else {
                return v;
            }
            // indirect2
            assert!(data_blocks <= INODE_INDIRECT2_COUNT);
            let a1 = data_blocks / INODE_INDIRECT1_COUNT;
            let b1 = data_blocks % INODE_INDIRECT1_COUNT;
            get_block_cache(self.indirect2 as usize, Arc::clone(block_device))
                .lock()
                .modify(0, |indirect2: &mut IndirectBlock| {
                    // full indirect1 blocks
                    for entry in indirect2.iter_mut().take(a1) {
                        v.push(*entry);
                        get_block_cache(*entry as usize, Arc::clone(block_device))
                            .lock()
                            .modify(0, |indirect1: &mut IndirectBlock| {
                                for entry in indirect1.iter() {
                                    v.push(*entry);
                                }
                            });
                    }
                    // last indirect1 block
                    if b1 > 0 {
                        v.push(indirect2[a1]);
                        get_block_cache(indirect2[a1] as usize, Arc::clone(block_device))
                            .lock()
                            .modify(0, |indirect1: &mut IndirectBlock| {
                                for entry in indirect1.iter().take(b1) {
                                    v.push(*entry);
                                }
                            });
                        //indirect2[a1] = 0;
                    }
                });
            self.indirect2 = 0;
            kprintln!("[KERN EASYFS] layout::DiskInode::clear_size() end");
            v
        }
        pub fn read_at(
            &self,
            offset: usize,
            buf: &mut [u8],
            block_device: &Arc<dyn BlockDevice>,
        ) -> usize {
            //kprintln!("[KERN EASYFS] layout::DiskInode::read_at() begin");
            let mut start = offset;
            let end = (offset + buf.len()).min(self.size as usize);
            if start >= end {
                return 0;
            }
            let mut start_block = start / BLOCK_SZ;
            let mut read_size = 0usize;
            loop {
                // calculate end of current block
                let mut end_current_block = (start / BLOCK_SZ + 1) * BLOCK_SZ;
                end_current_block = end_current_block.min(end);
                // read and update read size
                let block_read_size = end_current_block - start;
                let dst = &mut buf[read_size..read_size + block_read_size];
                get_block_cache(
                    self.get_block_id(start_block as u32, block_device) as usize,
                    Arc::clone(block_device),
                )
                .lock()
                .read(0, |data_block: &DataBlock| {
                    let src = &data_block[start % BLOCK_SZ..start % BLOCK_SZ + block_read_size];
                    dst.copy_from_slice(src);
                });
                read_size += block_read_size;
                // move to next block
                if end_current_block == end {
                    break;
                }
                start_block += 1;
                start = end_current_block;
            }
            read_size
        }
        /// File size must be adjusted before.
        pub fn write_at(
            &mut self,
            offset: usize,
            buf: &[u8],
            block_device: &Arc<dyn BlockDevice>,
        ) -> usize {
            kprintln!("[KERN EASYFS] layout::DiskInode::write_at() begin");
            let mut start = offset;
            let end = (offset + buf.len()).min(self.size as usize);
            assert!(start <= end);
            let mut start_block = start / BLOCK_SZ;
            let mut write_size = 0usize;
            loop {
                // calculate end of current block
                let mut end_current_block = (start / BLOCK_SZ + 1) * BLOCK_SZ;
                end_current_block = end_current_block.min(end);
                // write and update write size
                let block_write_size = end_current_block - start;
                get_block_cache(
                    self.get_block_id(start_block as u32, block_device) as usize,
                    Arc::clone(block_device),
                )
                .lock()
                .modify(0, |data_block: &mut DataBlock| {
                    let src = &buf[write_size..write_size + block_write_size];
                    let dst = &mut data_block[start % BLOCK_SZ..start % BLOCK_SZ + block_write_size];
                    dst.copy_from_slice(src);
                });
                write_size += block_write_size;
                // move to next block
                if end_current_block == end {
                    break;
                }
                start_block += 1;
                start = end_current_block;
            }
            write_size
        }
    }

    #[repr(C)]
    pub struct DirEntry {
        name: [u8; NAME_LENGTH_LIMIT + 1],
        inode_number: u32,
    }

    pub const DIRENT_SZ: usize = 32;

    impl DirEntry {
        pub fn empty() -> Self {
            Self {
                name: [0u8; NAME_LENGTH_LIMIT + 1],
                inode_number: 0,
            }
        }
        pub fn new(name: &str, inode_number: u32) -> Self {
            kprintln!("[KERN EASYFS] layout::DirEntry::new() begin");
            let mut bytes = [0u8; NAME_LENGTH_LIMIT + 1];
            bytes[..name.len()].copy_from_slice(name.as_bytes());
            Self {
                name: bytes,
                inode_number,
            }
        }
        pub fn as_bytes(&self) -> &[u8] {
            unsafe { core::slice::from_raw_parts(self as *const _ as usize as *const u8, DIRENT_SZ) }
        }
        pub fn as_bytes_mut(&mut self) -> &mut [u8] {
            unsafe { core::slice::from_raw_parts_mut(self as *mut _ as usize as *mut u8, DIRENT_SZ) }
        }
        pub fn name(&self) -> &str {
            let len = (0usize..).find(|i| self.name[*i] == 0).unwrap();
            core::str::from_utf8(&self.name[..len]).unwrap()
        }
        pub fn inode_number(&self) -> u32 {
            self.inode_number
        }
    }