use crate::disk::inode::Inode;

pub trait Block: Default + Clone {}

#[derive(Clone)]
pub struct DataBlock(pub(crate) [u8; 4096]);

impl Default for DataBlock {
    fn default() -> Self {
        Self([0; 4096])
    }
}

impl Block for DataBlock {}

#[derive(Clone)]
pub struct InodeBlock {
    pub(crate) inodes: [Inode; 16],
}

impl Default for InodeBlock {
    fn default() -> Self {
        Self {
            inodes: [
                Inode::empty(),
                Inode::empty(),
                Inode::empty(),
                Inode::empty(),
                Inode::empty(),
                Inode::empty(),
                Inode::empty(),
                Inode::empty(),
                Inode::empty(),
                Inode::empty(),
                Inode::empty(),
                Inode::empty(),
                Inode::empty(),
                Inode::empty(),
                Inode::empty(),
                Inode::empty(),
            ],
        }
    }
}

impl Block for InodeBlock {}

const FULL_MAP: u32 = 0b111_111_111_111_111;

#[derive(Clone)]
pub struct DirectoryBlock {
    entries: [[u8; 256]; 15],
    inode_ids: [usize; 15],
    occupancy_map: u32,
    reserved: [u8; 132],
}

impl Default for DirectoryBlock {
    fn default() -> Self {
        Self {
            entries: [[0; 256]; 15],
            inode_ids: [0; 15],
            occupancy_map: 0,
            reserved: [0xFF; 132],
        }
    }
}

impl Block for DirectoryBlock {}

impl DirectoryBlock {
    fn vacant(&self) -> bool {
        self.occupancy_map & FULL_MAP != FULL_MAP
    }

    fn first_free(&self) -> Option<usize> {
        todo!()
    }

    fn mark_busy(&mut self, entry_id: usize) {
        todo!()
    }

    /// 需要判断 entry_name.len() <= 255
    pub fn write_entry(&mut self, entry_name: &[u8], entry_inode_id: usize) -> Option<usize> {
        if let Some(entry_id) = self.first_free() {
            self.mark_busy(entry_id);
            self.entries[entry_id].copy_from_slice(entry_name);
            self.inode_ids[entry_id] = entry_inode_id;
            Some(entry_id)
        } else {
            None
        }
    }
}

#[derive(Clone)]
pub struct IndirectBlock {
    pub entries: [u32; 1024],
}

impl Default for IndirectBlock {
    fn default() -> Self {
        Self { entries: [0; 1024] }
    }
}

impl Block for IndirectBlock {}

impl IndirectBlock {
    pub fn full(&self) -> bool {
        todo!()
    }

    pub fn allocate(&mut self) -> Option<usize> {
        todo!()
    }
}

#[derive(Clone)]
pub struct DoubleIndirectBlock {
    pub indirect: [u32; 1024],
}

impl Default for DoubleIndirectBlock {
    fn default() -> Self {
        Self {
            indirect: [0; 1024],
        }
    }
}

impl Block for DoubleIndirectBlock {}

impl DoubleIndirectBlock {
    pub fn full(&self) -> bool {
        todo!()
    }

    pub fn allocate(&mut self) -> Option<usize> {
        todo!()
    }
}

#[derive(Clone)]
pub struct TripleIndirectBlock {
    pub double_indirect: [u32; 1024],
}

impl Default for TripleIndirectBlock {
    fn default() -> Self {
        Self {
            double_indirect: [0; 1024],
        }
    }
}

impl Block for TripleIndirectBlock {}

impl TripleIndirectBlock {
    pub fn full(&self) -> bool {
        todo!()
    }

    pub fn allocate(&mut self) -> Option<usize> {
        todo!()
    }
}