struct Solution
    t::Vector{Float64}
    center::Matrix{Vector{Float64}}
    φ::Matrix{Float64}

    function Solution(N::Int64, n_frames::Int64)
        return new(zeros(n_frames), [zeros(2) for i in 1:N, j in 1:n_frames], zeros((N, n_frames)))
    end
end

function save_frame!(sol, frame, t, particles)
    frame += 1

    sol.t[frame] = t

    @simd for p in particles
        p_id = p.id

        pre_pos = sol.center[p_id, frame]
        
        @simd for i in 1:2
            pre_pos[i] = p.c[i]
        end

        sol.φ[p_id, frame] = p.φ
    end

    return frame
end

function save_data_jld(sol, args, name_part)
    println("Saving data...")

    data_path = "exports/$name_part.jld2"
    jldsave(data_path; sol, args, name_part)

    println("Data saved to $data_path.")

    return nothing
end