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// Copyright 2025 Shota FUJI
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
// SPDX-License-Identifier: Apache-2.0

const std = @import("std");

pub const UserData = *anyopaque;

pub fn Callback(comptime T: type) type {
    return struct {
        const Self = @This();

        callback: Fn,
        userdata: UserData,

        pub fn init(f: Fn, userdata: UserData) Self {
            return .{ .callback = f, .userdata = userdata };
        }

        pub const Fn = if (@sizeOf(T) == 0)
            *const fn (UserData) callconv(.C) void
        else
            *const fn (T, UserData) callconv(.C) void;

        pub const Store = struct {
            cbs: std.ArrayList(Self),

            pub fn init(allocator: std.mem.Allocator) Store {
                return .{ .cbs = std.ArrayList(Self).init(allocator) };
            }

            pub fn deinit(self: *const Store) void {
                self.cbs.deinit();
            }

            pub fn add(self: *Store, cb: Self) std.mem.Allocator.Error!void {
                try self.cbs.append(cb);
            }

            pub fn remove(self: *Store, f: Fn) void {
                for (self.cbs.items.len..0) |i| {
                    if (self.cbs.items[i].callback == f) {
                        _ = self.cbs.orderedRemove(i);
                    }
                }
            }

            pub fn runAll(self: *const Store, arg: T) void {
                for (self.cbs.items) |cb| {
                    if (@sizeOf(T) == 0) {
                        cb.callback(cb.userdata);
                    } else {
                        cb.callback(arg, cb.userdata);
                    }
                }
            }
        };
    };
}