use bitflags::bitflags;
use fuser::{FileAttr, FileType};
use std::fs::File;

const DIRECT_NUMBER: usize = 15;

#[derive(Debug, Clone, Copy)]
pub struct InodeMode(u16);

bitflags! {
    impl InodeMode: u16 {
        const IXOTH = 0x0001;
        const IWOTH = 0x0002;
        const IROTH = 0x0004;
        const IXGRP = 0x0008;
        const IWGRP = 0x0010;
        const IRGRP = 0x0020;
        const IXUSR = 0x0040;
        const IWUSR = 0x0080;
        const IRUSR = 0x0100;
        const ISVTX = 0x0200;
        const ISGID = 0x0400;
        const ISUID = 0x0800;
        // These are mutually-exclusive:
        const IFIFO = 0x1000;
        const IFCHR = 0x2000;
        const IFDIR = 0x4000;
        const IFBLK = 0x6000;
        const IFREG = 0x8000;
        const IFLNK = 0xA000;
        const IFSOCK = 0xC000;
    }
}

impl InodeMode {
    pub(crate) fn perm(&self) -> u16 {
        self.0 & 0x0FFF
    }

    pub(crate) fn is_file(&self) -> bool {
        (self.0 & 0xF000) == Self::IFREG.0
    }

    pub(crate) fn is_dir(&self) -> bool {
        (self.0 & 0xF000) == Self::IFDIR.0
    }

    pub(crate) fn validate(mode_value: u16) -> Option<Self> {
        let valid_flags: [u16; 7] = [0x1000, 0x2000, 0x4000, 0x6000, 0x8000, 0xA000, 0xC000];
        valid_flags
            .contains(&(mode_value & 0xF000))
            .then(|| Self(mode_value))
    }
}

impl From<InodeMode> for FileType {
    fn from(value: InodeMode) -> Self {
        let type_flag = value.0 & 0xF000;
        match type_flag {
            0x1000 => FileType::NamedPipe,
            0x2000 => FileType::CharDevice,
            0x4000 => FileType::Directory,
            0x6000 => FileType::BlockDevice,
            0x8000 => FileType::RegularFile,
            0xA000 => FileType::Symlink,
            0xC000 => FileType::Socket,
            _ => panic!("Invalid inode mode {:x}", type_flag),
        }
    }
}

/// Pretty much the same with ext2, with minor changes:
/// - removed OS dependent attributes (osd1 & osd2)
/// - removed i_faddr since fragmentation is not supported
/// - changed uid and gid from u16 to u32
/// - added more direct blocks for a total size of 128 bytes
/// TODO: do we need to extend time precision?
#[repr(C)]
#[derive(Debug, Clone)]
pub struct Inode {
    pub mode: InodeMode,
    pub uid: u32,
    pub size: u32,
    pub atime: u32,  // access time, in seconds
    pub ctime: u32,  // change time, in seconds
    pub mtime: u32,  // modify time, in seconds
    pub crtime: u32, // create time, in seconds
    pub gid: u32,
    pub n_links: u16,
    pub n_blocks: u32,
    pub flags: u32, // TODO: do we actually need this? maybe just return 0
    pub direct: [u32; DIRECT_NUMBER],
    pub single_indirect: u32,
    pub double_indirect: u32,
    pub triple_indirect: u32,
    pub generation: u32,
    pub file_acl: u32,
    pub dir_acl: u32, // TODO do we have to implement ACL......?
}

impl Inode {
    fn new(
        mode: InodeMode,
        uid: u32,
        gid: u32,
        time: u32,
        flags: u32,
        generation: u32,
        file_acl: u32,
        dir_acl: u32,
    ) -> Self {
        Self {
            mode,
            uid,
            size: 0,
            atime: time,
            ctime: time,
            mtime: time,
            crtime: time,
            gid,
            n_links: 0,
            n_blocks: 0,
            flags,
            direct: [0; DIRECT_NUMBER],
            single_indirect: 0,
            double_indirect: 0,
            triple_indirect: 0,
            generation,
            file_acl,
            dir_acl,
        }
    }

    pub fn make_inode(
        permissions: u16,
        mode: InodeMode,
        uid: u32,
        gid: u32,
        time: u32,
        flags: u32,
        generation: u32,
        file_acl: u32,
        dir_acl: u32,
    ) -> Self {
        Self::new(
            InodeMode(permissions) | mode,
            uid,
            gid,
            time,
            flags,
            generation,
            file_acl,
            dir_acl,
        )
    }

    pub fn directory(
        permissions: u16,
        uid: u32,
        gid: u32,
        time: u32,
        flags: u32,
        generation: u32,
        file_acl: u32,
        dir_acl: u32,
    ) -> Self {
        Self::new(
            InodeMode(permissions) | InodeMode::IFDIR,
            uid,
            gid,
            time,
            flags,
            generation,
            file_acl,
            dir_acl,
        )
    }

    pub fn file(
        permissions: u16,
        uid: u32,
        gid: u32,
        time: u32,
        flags: u32,
        generation: u32,
        file_acl: u32,
        dir_acl: u32,
    ) -> Self {
        Self::new(
            InodeMode(permissions) | InodeMode::IFREG,
            uid,
            gid,
            time,
            flags,
            generation,
            file_acl,
            dir_acl,
        )
    }

    pub(crate) fn is_file(&self) -> bool {
        self.mode.is_file()
    }

    pub(crate) fn is_dir(&self) -> bool {
        self.mode.is_dir()
    }

    pub fn empty() -> Self {
        Self::new(InodeMode(0), 0, 0, 0, 0, 0, 0, 0)
    }
}
pub const INODE_SIZE: usize = std::mem::size_of::<Inode>();