const std = @import("std");

const mem = std.mem;
const Allocator = mem.Allocator;

const Group = @This();

gid: u32,
name: [:0]const u8,
// should be [:null]const ?[:0]const u8, but it crashes the compiler. See
// https://github.com/ziglang/zig/issues/7517.
// members[members.len] is always null for cloned groups. Once the bug
// in the compiler is fixed, we should update the return type here.
members: []const ?[:0]const u8,

pub fn clone(self: *const Group, allocator: Allocator) Allocator.Error!Group {
    var members = try allocator.alloc(?[:0]const u8, self.members.len + 1);
    errdefer allocator.free(members);
    members.len = self.members.len + 1;

    for (self.members) |member, i| {
        members[i] = try allocator.dupeZ(u8, member.?);
        errdefer allocator.free(members[i]);
    }
    // workaround to include a null value at the end, even for
    // non-sentinel-terminated slice type.
    members[self.members.len] = null;
    members.len = self.members.len;

    return Group{
        .gid = self.gid,
        .name = try allocator.dupeZ(u8, self.name),
        .members = members,
    };
}

pub fn deinit(self: *Group, allocator: Allocator) void {
    allocator.free(self.name);
    for (self.members) |member| {
        allocator.free(member.?);
    }
    allocator.free(self.members);
    self.* = undefined;
}

const testing = std.testing;

test "Group.clone" {
    // TODO: how to do this on stack?
    var member1 = try testing.allocator.dupeZ(u8, "member1");
    defer testing.allocator.free(member1);

    var group = Group{
        .gid = 1,
        .name = "foo",
        .members = &[_:null]?[:0]const u8{ member1, "member2" },
    };

    var cloned = try group.clone(testing.allocator);
    defer cloned.deinit(testing.allocator);

    group.gid = 2;
    group.name = "bar";
    member1[0] = 'x';
    try testing.expectEqual(cloned.gid, 1);
    try testing.expectEqualSlices(u8, cloned.name, "foo");
    try testing.expectEqualSlices(u8, cloned.members[0].?, "member1");
}