const std = @import("../../std.zig");
const builtin = @import("builtin");
const linux = std.os.linux;
const mem = std.mem;
const elf = std.elf;
const expect = std.testing.expect;
const expectEqual = std.testing.expectEqual;
const fs = std.fs;

test "fallocate" {
    if (builtin.cpu.arch.isMIPS64() and (builtin.abi == .gnuabin32 or builtin.abi == .muslabin32)) return error.SkipZigTest; // https://github.com/ziglang/zig/issues/23809

    var tmp = std.testing.tmpDir(.{});
    defer tmp.cleanup();

    const path = "test_fallocate";
    const file = try tmp.dir.createFile(path, .{ .truncate = true, .mode = 0o666 });
    defer file.close();

    try expect((try file.stat()).size == 0);

    const len: i64 = 65536;
    switch (linux.E.init(linux.fallocate(file.handle, 0, 0, len))) {
        .SUCCESS => {},
        .NOSYS => return error.SkipZigTest,
        .OPNOTSUPP => return error.SkipZigTest,
        else => |errno| std.debug.panic("unhandled errno: {}", .{errno}),
    }

    try expect((try file.stat()).size == len);
}

test "getpid" {
    try expect(linux.getpid() != 0);
}

test "getppid" {
    try expect(linux.getppid() != 0);
}

test "timer" {
    const epoll_fd = linux.epoll_create();
    var err: linux.E = linux.E.init(epoll_fd);
    try expect(err == .SUCCESS);

    const timer_fd = linux.timerfd_create(linux.TIMERFD_CLOCK.MONOTONIC, .{});
    try expect(linux.E.init(timer_fd) == .SUCCESS);

    const time_interval = linux.timespec{
        .sec = 0,
        .nsec = 2000000,
    };

    const new_time = linux.itimerspec{
        .it_interval = time_interval,
        .it_value = time_interval,
    };

    err = linux.E.init(linux.timerfd_settime(@as(i32, @intCast(timer_fd)), .{}, &new_time, null));
    try expect(err == .SUCCESS);

    var event = linux.epoll_event{
        .events = linux.EPOLL.IN | linux.EPOLL.OUT | linux.EPOLL.ET,
        .data = linux.epoll_data{ .ptr = 0 },
    };

    err = linux.E.init(linux.epoll_ctl(@as(i32, @intCast(epoll_fd)), linux.EPOLL.CTL_ADD, @as(i32, @intCast(timer_fd)), &event));
    try expect(err == .SUCCESS);

    const events_one: linux.epoll_event = undefined;
    var events = [_]linux.epoll_event{events_one} ** 8;

    err = linux.E.init(linux.epoll_wait(@as(i32, @intCast(epoll_fd)), &events, 8, -1));
    try expect(err == .SUCCESS);
}

test "statx" {
    var tmp = std.testing.tmpDir(.{});
    defer tmp.cleanup();

    const tmp_file_name = "just_a_temporary_file.txt";
    var file = try tmp.dir.createFile(tmp_file_name, .{});
    defer file.close();

    var statx_buf: linux.Statx = undefined;
    switch (linux.E.init(linux.statx(file.handle, "", linux.AT.EMPTY_PATH, linux.STATX_BASIC_STATS, &statx_buf))) {
        .SUCCESS => {},
        else => unreachable,
    }

    if (builtin.cpu.arch == .riscv32 or builtin.cpu.arch.isLoongArch()) return error.SkipZigTest; // No fstatat, so the rest of the test is meaningless.

    var stat_buf: linux.Stat = undefined;
    switch (linux.E.init(linux.fstatat(file.handle, "", &stat_buf, linux.AT.EMPTY_PATH))) {
        .SUCCESS => {},
        else => unreachable,
    }

    try expect(stat_buf.mode == statx_buf.mode);
    try expect(@as(u32, @bitCast(stat_buf.uid)) == statx_buf.uid);
    try expect(@as(u32, @bitCast(stat_buf.gid)) == statx_buf.gid);
    try expect(@as(u64, @bitCast(@as(i64, stat_buf.size))) == statx_buf.size);
    try expect(@as(u64, @bitCast(@as(i64, stat_buf.blksize))) == statx_buf.blksize);
    try expect(@as(u64, @bitCast(@as(i64, stat_buf.blocks))) == statx_buf.blocks);
}

test "user and group ids" {
    if (builtin.link_libc) return error.SkipZigTest;
    try expectEqual(linux.getauxval(elf.AT_UID), linux.getuid());
    try expectEqual(linux.getauxval(elf.AT_GID), linux.getgid());
    try expectEqual(linux.getauxval(elf.AT_EUID), linux.geteuid());
    try expectEqual(linux.getauxval(elf.AT_EGID), linux.getegid());
}

test "fadvise" {
    var tmp = std.testing.tmpDir(.{});
    defer tmp.cleanup();

    const tmp_file_name = "temp_posix_fadvise.txt";
    var file = try tmp.dir.createFile(tmp_file_name, .{});
    defer file.close();

    var buf: [2048]u8 = undefined;
    try file.writeAll(&buf);

    const ret = linux.fadvise(file.handle, 0, 0, linux.POSIX_FADV.SEQUENTIAL);
    try expectEqual(@as(usize, 0), ret);
}

test "sigset_t" {
    std.debug.assert(@sizeOf(linux.sigset_t) == (linux.NSIG / 8));

    var sigset = linux.sigemptyset();

    // See that none are set, then set each one, see that they're all set, then
    // remove them all, and then see that none are set.
    for (1..linux.NSIG) |i| {
        try expectEqual(linux.sigismember(&sigset, @truncate(i)), false);
    }
    for (1..linux.NSIG) |i| {
        linux.sigaddset(&sigset, @truncate(i));
    }
    for (1..linux.NSIG) |i| {
        try expectEqual(linux.sigismember(&sigset, @truncate(i)), true);
    }
    for (1..linux.NSIG) |i| {
        linux.sigdelset(&sigset, @truncate(i));
    }
    for (1..linux.NSIG) |i| {
        try expectEqual(linux.sigismember(&sigset, @truncate(i)), false);
    }

    // Kernel sigset_t is either 2+ 32-bit values or 1+ 64-bit value(s).
    const sigset_len = @typeInfo(linux.sigset_t).array.len;
    const sigset_elemis64 = 64 == @bitSizeOf(@typeInfo(linux.sigset_t).array.child);

    linux.sigaddset(&sigset, 1);
    try expectEqual(sigset[0], 1);
    if (sigset_len > 1) {
        try expectEqual(sigset[1], 0);
    }

    linux.sigaddset(&sigset, 31);
    try expectEqual(sigset[0], 0x4000_0001);
    if (sigset_len > 1) {
        try expectEqual(sigset[1], 0);
    }

    linux.sigaddset(&sigset, 36);
    if (sigset_elemis64) {
        try expectEqual(sigset[0], 0x8_4000_0001);
    } else {
        try expectEqual(sigset[0], 0x4000_0001);
        try expectEqual(sigset[1], 0x8);
    }

    linux.sigaddset(&sigset, 64);
    if (sigset_elemis64) {
        try expectEqual(sigset[0], 0x8000_0008_4000_0001);
    } else {
        try expectEqual(sigset[0], 0x4000_0001);
        try expectEqual(sigset[1], 0x8000_0008);
    }
}

test "sigfillset" {
    // unlike the C library, all the signals are set in the kernel-level fillset
    const sigset = linux.sigfillset();
    for (1..linux.NSIG) |i| {
        try expectEqual(linux.sigismember(&sigset, @truncate(i)), true);
    }
}

test "sigemptyset" {
    const sigset = linux.sigemptyset();
    for (1..linux.NSIG) |i| {
        try expectEqual(linux.sigismember(&sigset, @truncate(i)), false);
    }
}

test "sysinfo" {
    var info: linux.Sysinfo = undefined;
    const result: usize = linux.sysinfo(&info);
    try expect(std.os.linux.E.init(result) == .SUCCESS);

    try expect(info.mem_unit > 0);
    try expect(info.mem_unit <= std.heap.page_size_max);
}

comptime {
    std.debug.assert(128 == @as(u32, @bitCast(linux.FUTEX_OP{ .cmd = @enumFromInt(0), .private = true, .realtime = false })));
    std.debug.assert(256 == @as(u32, @bitCast(linux.FUTEX_OP{ .cmd = @enumFromInt(0), .private = false, .realtime = true })));

    // Check futex_param4 union is packed correctly
    const param_union = linux.futex_param4{
        .val2 = 0xaabbcc,
    };
    std.debug.assert(@intFromPtr(param_union.timeout) == 0xaabbcc);
}

test "futex v1" {
    var lock: std.atomic.Value(u32) = std.atomic.Value(u32).init(1);
    var rc: usize = 0;

    // No-op wait, lock value is not expected value
    rc = linux.futex(&lock.raw, .{ .cmd = .WAIT, .private = true }, 2, .{ .timeout = null }, null, 0);
    try expectEqual(.AGAIN, linux.E.init(rc));

    rc = linux.futex_4arg(&lock.raw, .{ .cmd = .WAIT, .private = true }, 2, null);
    try expectEqual(.AGAIN, linux.E.init(rc));

    // Short-fuse wait, timeout kicks in
    rc = linux.futex(&lock.raw, .{ .cmd = .WAIT, .private = true }, 1, .{ .timeout = &.{ .sec = 0, .nsec = 2 } }, null, 0);
    try expectEqual(.TIMEDOUT, linux.E.init(rc));

    rc = linux.futex_4arg(&lock.raw, .{ .cmd = .WAIT, .private = true }, 1, &.{ .sec = 0, .nsec = 2 });
    try expectEqual(.TIMEDOUT, linux.E.init(rc));

    // Wakeup (no waiters)
    rc = linux.futex(&lock.raw, .{ .cmd = .WAKE, .private = true }, 2, .{ .timeout = null }, null, 0);
    try expectEqual(0, rc);

    rc = linux.futex_3arg(&lock.raw, .{ .cmd = .WAKE, .private = true }, 2);
    try expectEqual(0, rc);

    // CMP_REQUEUE - val3 mismatch
    rc = linux.futex(&lock.raw, .{ .cmd = .CMP_REQUEUE, .private = true }, 2, .{ .val2 = 0 }, null, 99);
    try expectEqual(.AGAIN, linux.E.init(rc));

    // CMP_REQUEUE - requeue (but no waiters, so ... not much)
    {
        const val3 = 1;
        const wake_nr = 3;
        const requeue_max = std.math.maxInt(u31);
        var target_lock: std.atomic.Value(u32) = std.atomic.Value(u32).init(1);
        rc = linux.futex(&lock.raw, .{ .cmd = .CMP_REQUEUE, .private = true }, wake_nr, .{ .val2 = requeue_max }, &target_lock.raw, val3);
        try expectEqual(0, rc);
    }

    // WAKE_OP - just to see if we can construct the arguments ...
    {
        var lock2: std.atomic.Value(u32) = std.atomic.Value(u32).init(1);
        const wake1_nr = 2;
        const wake2_nr = 3;
        const wake_op = linux.FUTEX_WAKE_OP{
            .cmd = .ANDN,
            .arg_shift = true,
            .cmp = .LT,
            .oparg = 4,
            .cmdarg = 5,
        };

        rc = linux.futex(&lock.raw, .{ .cmd = .WAKE_OP, .private = true }, wake1_nr, .{ .val2 = wake2_nr }, &lock2.raw, @bitCast(wake_op));
        try expectEqual(0, rc);
    }

    // WAIT_BITSET
    {
        // val1 return early
        rc = linux.futex(&lock.raw, .{ .cmd = .WAIT_BITSET, .private = true }, 2, .{ .timeout = null }, null, 0xfff);
        try expectEqual(.AGAIN, linux.E.init(rc));

        // timeout wait
        const timeout: linux.timespec = .{ .sec = 0, .nsec = 2 };
        rc = linux.futex(&lock.raw, .{ .cmd = .WAIT_BITSET, .private = true }, 1, .{ .timeout = &timeout }, null, 0xfff);
        try expectEqual(.TIMEDOUT, linux.E.init(rc));
    }

    // WAKE_BITSET
    {
        rc = linux.futex(&lock.raw, .{ .cmd = .WAKE_BITSET, .private = true }, 2, .{ .timeout = null }, null, 0xfff000);
        try expectEqual(0, rc);

        // bitmask must have at least 1 bit set:
        rc = linux.futex(&lock.raw, .{ .cmd = .WAKE_BITSET, .private = true }, 2, .{ .timeout = null }, null, 0);
        try expectEqual(.INVAL, linux.E.init(rc));
    }
}

comptime {
    std.debug.assert(2 == @as(u32, @bitCast(linux.FUTEX2_FLAGS{ .size = .U32, .private = false })));
    std.debug.assert(128 == @as(u32, @bitCast(linux.FUTEX2_FLAGS{ .size = @enumFromInt(0), .private = true })));
}

test "futex2_waitv" {
    const locks = [_]std.atomic.Value(u32){
        std.atomic.Value(u32).init(1),
        std.atomic.Value(u32).init(1),
        std.atomic.Value(u32).init(1),
    };

    const futexes = [_]linux.futex2_waitone{
        .{
            .val = 1,
            .uaddr = @intFromPtr(&locks[0].raw),
            .flags = .{ .size = .U32, .private = true },
        },
        .{
            .val = 1,
            .uaddr = @intFromPtr(&locks[1].raw),
            .flags = .{ .size = .U32, .private = true },
        },
        .{
            .val = 1,
            .uaddr = @intFromPtr(&locks[2].raw),
            .flags = .{ .size = .U32, .private = true },
        },
    };

    const timeout = linux.kernel_timespec{ .sec = 0, .nsec = 2 }; // absolute timeout, so this is 1970...
    const rc = linux.futex2_waitv(&futexes, futexes.len, .{}, &timeout, .MONOTONIC);
    switch (linux.E.init(rc)) {
        .NOSYS => return error.SkipZigTest, // futex2_waitv added in kernel v5.16
        else => |err| try expectEqual(.TIMEDOUT, err),
    }
}

// Futex v2 API is only supported on recent kernels (v6.7), so skip tests if the syscalls
// return ENOSYS.
fn futex2_skip_if_unsupported() !void {
    const lock: u32 = 0;
    const rc = linux.futex2_wake(&lock, 0, 1, .{ .size = .U32, .private = true });
    if (linux.E.init(rc) == .NOSYS) {
        return error.SkipZigTest;
    }
}

test "futex2_wait" {
    var lock: std.atomic.Value(u32) = std.atomic.Value(u32).init(1);
    var rc: usize = 0;
    const mask = 0x1;

    try futex2_skip_if_unsupported();

    // The API for 8,16,64 bit futexes is defined, but as of kernel v6.14
    // (at least) they're not implemented.
    if (false) {
        rc = linux.futex2_wait(&lock.raw, 1, mask, .{ .size = .U8, .private = true }, null, .MONOTONIC);
        try expectEqual(.INVAL, linux.E.init(rc));

        rc = linux.futex2_wait(&lock.raw, 1, mask, .{ .size = .U16, .private = true }, null, .MONOTONIC);
        try expectEqual(.INVAL, linux.E.init(rc));

        rc = linux.futex2_wait(&lock.raw, 1, mask, .{ .size = .U64, .private = true }, null, .MONOTONIC);
        try expectEqual(.INVAL, linux.E.init(rc));
    }

    const flags = linux.FUTEX2_FLAGS{ .size = .U32, .private = true };
    // no-wait, lock state mismatch
    rc = linux.futex2_wait(&lock.raw, 2, mask, flags, null, .MONOTONIC);
    try expectEqual(.AGAIN, linux.E.init(rc));

    // hit timeout on wait
    rc = linux.futex2_wait(&lock.raw, 1, mask, flags, &.{ .sec = 0, .nsec = 2 }, .MONOTONIC);
    try expectEqual(.TIMEDOUT, linux.E.init(rc));

    // timeout is absolute
    {
        var curr: linux.timespec = undefined;
        rc = linux.clock_gettime(.MONOTONIC, &curr); // gettime() uses platform timespec
        try expectEqual(0, rc);

        // ... but futex2_wait always uses 64-bit timespec
        var timeout: linux.kernel_timespec = .{
            .sec = curr.sec,
            .nsec = curr.nsec + 2,
        };
        rc = linux.futex2_wait(&lock.raw, 1, mask, flags, &timeout, .MONOTONIC);
        try expectEqual(.TIMEDOUT, linux.E.init(rc));
    }

    rc = linux.futex2_wait(&lock.raw, 1, mask, flags, &.{ .sec = 0, .nsec = 2 }, .REALTIME);
    try expectEqual(.TIMEDOUT, linux.E.init(rc));
}

test "futex2_wake" {
    var lock: std.atomic.Value(u32) = std.atomic.Value(u32).init(1);

    try futex2_skip_if_unsupported();

    const rc = linux.futex2_wake(&lock.raw, 0xFF, 1, .{ .size = .U32, .private = true });
    try expectEqual(0, rc);
}

test "futex2_requeue" {
    try futex2_skip_if_unsupported();

    const locks = [_]std.atomic.Value(u32){
        std.atomic.Value(u32).init(1),
        std.atomic.Value(u32).init(1),
    };

    const futexes = [_]linux.futex2_waitone{
        .{
            .val = 1,
            .uaddr = @intFromPtr(&locks[0].raw),
            .flags = .{ .size = .U32, .private = true },
        },
        .{
            .val = 1,
            .uaddr = @intFromPtr(&locks[1].raw),
            .flags = .{ .size = .U32, .private = true },
        },
    };

    const rc = linux.futex2_requeue(&futexes, .{}, 2, 2);
    try expectEqual(0, rc);
}

test {
    _ = linux.IoUring;
}