const std = @import("../../std.zig");
const maxInt = std.math.maxInt;
const linux = std.os.linux;
const SYS = linux.SYS;
const iovec = std.os.iovec;
const iovec_const = std.os.iovec_const;

const pid_t = linux.pid_t;
const uid_t = linux.uid_t;
const gid_t = linux.gid_t;
const clock_t = linux.clock_t;
const stack_t = linux.stack_t;
const sigset_t = linux.sigset_t;
const sockaddr = linux.sockaddr;
const socklen_t = linux.socklen_t;
const timespec = linux.timespec;

pub fn syscall0(number: SYS) usize {
    return asm volatile ("syscall"
        : [ret] "={rax}" (-> usize),
        : [number] "{rax}" (@enumToInt(number)),
        : "rcx", "r11", "memory"
    );
}

pub fn syscall1(number: SYS, arg1: usize) usize {
    return asm volatile ("syscall"
        : [ret] "={rax}" (-> usize),
        : [number] "{rax}" (@enumToInt(number)),
          [arg1] "{rdi}" (arg1),
        : "rcx", "r11", "memory"
    );
}

pub fn syscall2(number: SYS, arg1: usize, arg2: usize) usize {
    return asm volatile ("syscall"
        : [ret] "={rax}" (-> usize),
        : [number] "{rax}" (@enumToInt(number)),
          [arg1] "{rdi}" (arg1),
          [arg2] "{rsi}" (arg2),
        : "rcx", "r11", "memory"
    );
}

pub fn syscall3(number: SYS, arg1: usize, arg2: usize, arg3: usize) usize {
    return asm volatile ("syscall"
        : [ret] "={rax}" (-> usize),
        : [number] "{rax}" (@enumToInt(number)),
          [arg1] "{rdi}" (arg1),
          [arg2] "{rsi}" (arg2),
          [arg3] "{rdx}" (arg3),
        : "rcx", "r11", "memory"
    );
}

pub fn syscall4(number: SYS, arg1: usize, arg2: usize, arg3: usize, arg4: usize) usize {
    return asm volatile ("syscall"
        : [ret] "={rax}" (-> usize),
        : [number] "{rax}" (@enumToInt(number)),
          [arg1] "{rdi}" (arg1),
          [arg2] "{rsi}" (arg2),
          [arg3] "{rdx}" (arg3),
          [arg4] "{r10}" (arg4),
        : "rcx", "r11", "memory"
    );
}

pub fn syscall5(number: SYS, arg1: usize, arg2: usize, arg3: usize, arg4: usize, arg5: usize) usize {
    return asm volatile ("syscall"
        : [ret] "={rax}" (-> usize),
        : [number] "{rax}" (@enumToInt(number)),
          [arg1] "{rdi}" (arg1),
          [arg2] "{rsi}" (arg2),
          [arg3] "{rdx}" (arg3),
          [arg4] "{r10}" (arg4),
          [arg5] "{r8}" (arg5),
        : "rcx", "r11", "memory"
    );
}

pub fn syscall6(
    number: SYS,
    arg1: usize,
    arg2: usize,
    arg3: usize,
    arg4: usize,
    arg5: usize,
    arg6: usize,
) usize {
    return asm volatile ("syscall"
        : [ret] "={rax}" (-> usize),
        : [number] "{rax}" (@enumToInt(number)),
          [arg1] "{rdi}" (arg1),
          [arg2] "{rsi}" (arg2),
          [arg3] "{rdx}" (arg3),
          [arg4] "{r10}" (arg4),
          [arg5] "{r8}" (arg5),
          [arg6] "{r9}" (arg6),
        : "rcx", "r11", "memory"
    );
}

const CloneFn = *const fn (arg: usize) callconv(.C) u8;

/// This matches the libc clone function.
pub extern fn clone(func: CloneFn, stack: usize, flags: usize, arg: usize, ptid: *i32, tls: usize, ctid: *i32) usize;

pub const restore = restore_rt;

pub fn restore_rt() callconv(.Naked) void {
    switch (@import("builtin").zig_backend) {
        .stage2_c => return asm volatile (
            \\ movl %[number], %%eax
            \\ syscall
            \\ retq
            :
            : [number] "i" (@enumToInt(SYS.rt_sigreturn)),
            : "rcx", "r11", "memory"
        ),
        else => return asm volatile ("syscall"
            :
            : [number] "{rax}" (@enumToInt(SYS.rt_sigreturn)),
            : "rcx", "r11", "memory"
        ),
    }
}

pub const mode_t = usize;
pub const time_t = isize;
pub const nlink_t = usize;
pub const blksize_t = isize;
pub const blkcnt_t = isize;

pub const O = struct {
    pub const CREAT = 0o100;
    pub const EXCL = 0o200;
    pub const NOCTTY = 0o400;
    pub const TRUNC = 0o1000;
    pub const APPEND = 0o2000;
    pub const NONBLOCK = 0o4000;
    pub const DSYNC = 0o10000;
    pub const SYNC = 0o4010000;
    pub const RSYNC = 0o4010000;
    pub const DIRECTORY = 0o200000;
    pub const NOFOLLOW = 0o400000;
    pub const CLOEXEC = 0o2000000;

    pub const ASYNC = 0o20000;
    pub const DIRECT = 0o40000;
    pub const LARGEFILE = 0;
    pub const NOATIME = 0o1000000;
    pub const PATH = 0o10000000;
    pub const TMPFILE = 0o20200000;
    pub const NDELAY = NONBLOCK;
};

pub const F = struct {
    pub const DUPFD = 0;
    pub const GETFD = 1;
    pub const SETFD = 2;
    pub const GETFL = 3;
    pub const SETFL = 4;
    pub const GETLK = 5;
    pub const SETLK = 6;
    pub const SETLKW = 7;
    pub const SETOWN = 8;
    pub const GETOWN = 9;
    pub const SETSIG = 10;
    pub const GETSIG = 11;

    pub const SETOWN_EX = 15;
    pub const GETOWN_EX = 16;
    pub const GETOWNER_UIDS = 17;

    pub const RDLCK = 0;
    pub const WRLCK = 1;
    pub const UNLCK = 2;
};

pub const MAP = struct {
    /// only give out 32bit addresses
    pub const @"32BIT" = 0x40;
    /// stack-like segment
    pub const GROWSDOWN = 0x0100;
    /// ETXTBSY
    pub const DENYWRITE = 0x0800;
    /// mark it as an executable
    pub const EXECUTABLE = 0x1000;
    /// pages are locked
    pub const LOCKED = 0x2000;
    /// don't check for reservations
    pub const NORESERVE = 0x4000;
};

pub const VDSO = struct {
    pub const CGT_SYM = "__vdso_clock_gettime";
    pub const CGT_VER = "LINUX_2.6";

    pub const GETCPU_SYM = "__vdso_getcpu";
    pub const GETCPU_VER = "LINUX_2.6";
};

pub const ARCH = struct {
    pub const SET_GS = 0x1001;
    pub const SET_FS = 0x1002;
    pub const GET_FS = 0x1003;
    pub const GET_GS = 0x1004;
};

pub const REG = struct {
    pub const R8 = 0;
    pub const R9 = 1;
    pub const R10 = 2;
    pub const R11 = 3;
    pub const R12 = 4;
    pub const R13 = 5;
    pub const R14 = 6;
    pub const R15 = 7;
    pub const RDI = 8;
    pub const RSI = 9;
    pub const RBP = 10;
    pub const RBX = 11;
    pub const RDX = 12;
    pub const RAX = 13;
    pub const RCX = 14;
    pub const RSP = 15;
    pub const RIP = 16;
    pub const EFL = 17;
    pub const CSGSFS = 18;
    pub const ERR = 19;
    pub const TRAPNO = 20;
    pub const OLDMASK = 21;
    pub const CR2 = 22;
};

pub const LOCK = struct {
    pub const SH = 1;
    pub const EX = 2;
    pub const NB = 4;
    pub const UN = 8;
};

pub const Flock = extern struct {
    type: i16,
    whence: i16,
    start: off_t,
    len: off_t,
    pid: pid_t,
};

pub const msghdr = extern struct {
    name: ?*sockaddr,
    namelen: socklen_t,
    iov: [*]iovec,
    iovlen: i32,
    __pad1: i32 = 0,
    control: ?*anyopaque,
    controllen: socklen_t,
    __pad2: socklen_t = 0,
    flags: i32,
};

pub const msghdr_const = extern struct {
    name: ?*const sockaddr,
    namelen: socklen_t,
    iov: [*]const iovec_const,
    iovlen: i32,
    __pad1: i32 = 0,
    control: ?*const anyopaque,
    controllen: socklen_t,
    __pad2: socklen_t = 0,
    flags: i32,
};

pub const off_t = i64;
pub const ino_t = u64;
pub const dev_t = u64;

// The `stat` definition used by the Linux kernel.
pub const Stat = extern struct {
    dev: dev_t,
    ino: ino_t,
    nlink: usize,

    mode: u32,
    uid: uid_t,
    gid: gid_t,
    __pad0: u32,
    rdev: dev_t,
    size: off_t,
    blksize: isize,
    blocks: i64,

    atim: timespec,
    mtim: timespec,
    ctim: timespec,
    __unused: [3]isize,

    pub fn atime(self: @This()) timespec {
        return self.atim;
    }

    pub fn mtime(self: @This()) timespec {
        return self.mtim;
    }

    pub fn ctime(self: @This()) timespec {
        return self.ctim;
    }
};

pub const timeval = extern struct {
    tv_sec: isize,
    tv_usec: isize,
};

pub const timezone = extern struct {
    tz_minuteswest: i32,
    tz_dsttime: i32,
};

pub const Elf_Symndx = u32;

pub const greg_t = usize;
pub const gregset_t = [23]greg_t;
pub const fpstate = extern struct {
    cwd: u16,
    swd: u16,
    ftw: u16,
    fop: u16,
    rip: usize,
    rdp: usize,
    mxcsr: u32,
    mxcr_mask: u32,
    st: [8]extern struct {
        significand: [4]u16,
        exponent: u16,
        padding: [3]u16 = undefined,
    },
    xmm: [16]extern struct {
        element: [4]u32,
    },
    padding: [24]u32 = undefined,
};
pub const fpregset_t = *fpstate;
pub const sigcontext = extern struct {
    r8: usize,
    r9: usize,
    r10: usize,
    r11: usize,
    r12: usize,
    r13: usize,
    r14: usize,
    r15: usize,

    rdi: usize,
    rsi: usize,
    rbp: usize,
    rbx: usize,
    rdx: usize,
    rax: usize,
    rcx: usize,
    rsp: usize,
    rip: usize,
    eflags: usize,

    cs: u16,
    gs: u16,
    fs: u16,
    pad0: u16 = undefined,

    err: usize,
    trapno: usize,
    oldmask: usize,
    cr2: usize,

    fpstate: *fpstate,
    reserved1: [8]usize = undefined,
};

pub const mcontext_t = extern struct {
    gregs: gregset_t,
    fpregs: fpregset_t,
    reserved1: [8]usize = undefined,
};

pub const ucontext_t = extern struct {
    flags: usize,
    link: ?*ucontext_t,
    stack: stack_t,
    mcontext: mcontext_t,
    sigmask: sigset_t,
    fpregs_mem: [64]usize,
};