mod constants;
pub mod permissions;

use crate::block_device::BLOCK_SIZE;
use crate::disk::inode::{Inode, INODE_SIZE};
use crate::{AyaFS, INODE_PER_BLOCK};
use fuser::{FileAttr, FileType};
use std::time::{Duration, SystemTime, UNIX_EPOCH};

pub(crate) fn time_now() -> u32 {
    SystemTime::now()
        .duration_since(UNIX_EPOCH)
        .expect("How can current time be earlier than UNIX_EPOCH?")
        .as_secs() as u32
}

pub(crate) fn from_systime(system_time: SystemTime) -> u32 {
    system_time
        .duration_since(UNIX_EPOCH)
        .expect("How can current time be earlier than UNIX_EPOCH?")
        .as_secs() as u32
}

pub(crate) fn to_systime(time: u32) -> SystemTime {
    UNIX_EPOCH + Duration::from_secs(time as u64)
}

// File type code, one of:
// 0x0 	Unknown.
// 0x1 	Regular file.
// 0x2 	Directory.
// 0x3 	Character device file.
// 0x4 	Block device file.
// 0x5 	FIFO.
// 0x6 	Socket.
// 0x7 	Symbolic link.

pub(crate) fn from_filetype(file_type: FileType) -> u8 {
    match file_type {
        FileType::NamedPipe => 0x5,
        FileType::CharDevice => 0x3,
        FileType::BlockDevice => 0x4,
        FileType::Directory => 0x2,
        FileType::RegularFile => 0x1,
        FileType::Symlink => 0x7,
        FileType::Socket => 0x6,
    }
}

pub(crate) fn to_filetype(file_type: u8) -> Option<FileType> {
    match file_type {
        0x0 => None,
        0x1 => Some(FileType::RegularFile),
        0x2 => Some(FileType::Directory),
        0x3 => Some(FileType::CharDevice),
        0x4 => Some(FileType::BlockDevice),
        0x5 => Some(FileType::NamedPipe),
        0x6 => Some(FileType::Socket),
        0x7 => Some(FileType::Symlink),
        _ => panic!("bad filetype"),
    }
}

pub(crate) fn to_fileattr(inode_index: usize, inode: &Inode) -> FileAttr {
    FileAttr {
        ino: inode_index as u64,
        size: inode.size as u64,
        blocks: inode.n_blocks as u64,
        atime: to_systime(inode.atime),
        mtime: to_systime(inode.mtime),
        ctime: to_systime(inode.ctime),
        crtime: to_systime(inode.crtime),
        kind: inode.mode.into(),
        perm: inode.mode.perm(),
        nlink: inode.n_links as u32,
        uid: inode.uid,
        gid: inode.gid,
        rdev: 0,
        blksize: BLOCK_SIZE as u32,
        flags: inode.flags,
    }
}

impl AyaFS {
    /// 输入 inode 编号, 返回它对应的 block number 和 block 内 offset
    pub(crate) fn locate_inode(&self, inode_index: usize) -> (usize, usize) {
        let block_number =
            inode_index / INODE_PER_BLOCK + 1 + self.inode_bitmap.length + self.data_bitmap.length;
        let block_offset = inode_index % INODE_PER_BLOCK * INODE_SIZE;
        (block_number, block_offset)
    }
}