You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: CBIG_MMP_compute_ABCD_permutation_p_value.m
    path of file: ./repos/CBIG/stable_projects/predict_phenotypes/Ooi2022_MMP/regression/ABCD/stats
    
    the code of the file until where you have to start completion: function p_value = CBIG_MMP_compute_ABCD_permutation_p_value(ref_dir, behav_ind, outstem, perm_dir, perm_per_file)

% p_value = CBIG_MMP_compute_ABCD_permutation_p_value(ref_dir, behav_ind, outstem, perm_dir, perm_per_file)
%
% Adapted from CBIG_TRBPC_compute_permutation_p_value.
% This function computes of p-value of permutation test.
%
% Inputs:
%   - ref_dir
%     Directory of the regression results.
%

    
function p_value = CBIG_MMP_compute_ABCD_permutation_p_value(ref_dir, behav_ind, outstem, perm_dir, perm_per_file)

% p_value = CBIG_MMP_compute_ABCD_permutation_p_value(ref_dir, behav_ind, outstem, perm_dir, perm_per_file)
%
% Adapted from CBIG_TRBPC_compute_permutation_p_value.
% This function computes of p-value of permutation test.
%
% Inputs:
%   - ref_dir
%     Directory of the regression results.
%
%   - behav_ind
%     Behaviourial indices to calculate p-value file.
%
%   - outstem
%     Name of regression results folder (e.g. KRR_features_ct).
%
%   - perm_dir
%     Directory of permutation results.
%
%   - perm_per_file
%     Number of permutations in permutation test.
%
% Outputs:
%   - p-value
%     A vector. P-value for behaviour in behav_ind.
%
% Written by Leon Ooi and CBIG under MIT license: https://github.com/ThomasYeoLab/CBIG/blob/master/LICENSE.md

%% add utilities path
addpath(fullfile(getenv('CBIG_CODE_DIR'),'stable_projects', 'predict_phenotypes', ...
    'Ooi2022_MMP', 'regression', 'ABCD', 'utilities'))

%% compare with permutation
for i = 1:length(behav_ind)
    N_worse = 0;
    behav = behav_ind(i);
    
    % load reference
    acc_vec = CBIG_MMP_ABCD_read_model_results(outstem, ref_dir, 120, behav_ind, 'corr', 0);
    ref = mean(acc_vec(i,:));
    % load permutations
    load(fullfile(perm_dir, ['acc_score' num2str(behav) '_allFolds_permStart1.mat']));
    curr_acc = squeeze(mean(stats_perm.corr,1));
    curr_N_worse = sum(curr_acc > ref);
    N_worse = N_worse + curr_N_worse;
    
    p_value(i) = (1+N_worse)/(1+perm_per_file);
end