function str = print_equations(variable_name, withexpansion)

% Prints equations where the variable appears in.
%
% INPUTS
% - variable_name       [string]    Name of the variable to be traced.
% - withexpansion       [logical]   Prints expanded equation of the VAR_EXPECTATION or PAC_EXPECTATION term if true.
%
% OUTPUTS
% None

% Copyright © 2019-2021 Dynare Team
%
% This file is part of Dynare.
%
% Dynare is free software: you can redistribute it and/or modify
% it under the terms of the GNU General Public License as published by
% the Free Software Foundation, either version 3 of the License, or
% (at your option) any later version.
%
% Dynare is distributed in the hope that it will be useful,
% but WITHOUT ANY WARRANTY; without even the implied warranty of
% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
% GNU General Public License for more details.
%
% You should have received a copy of the GNU General Public License
% along with Dynare.  If not, see <https://www.gnu.org/licenses/>.

global M_

if nargin == 0
    error('Provide variable name as input argument.');
elseif nargin == 1
    % Assign default value for VAR_EXPECTATION/PAC_EXPECTATION expression expansion.
    withexpansion = false;
elseif nargin == 2
    if ~islogical(withexpansion)
        error('Second input argument must be Boolean.');
    end
end

% Check if corresponding JSON file exists.
fname = [M_.fname filesep 'model' filesep 'json' filesep 'modfile-original.json'];
if exist(fname, 'file') ~= 2
    error('Could not find %s! Please use the json option (See the Dynare invocation section in the reference manual).', fname);
end

% Check that the first input is a character array.
if ~ischar(variable_name)
    error('First input argument must be a string.');
end
    
% Check that the variable is actually a variable in the model.
if ~ismember(variable_name, [M_.exo_names; M_.endo_names])
    error('There is no variable named %s!', variable_name);
end

% Load the JSON file.
jsonfile = loadjson_(fname);
model = jsonfile.model;

% Print the equations the variable appears in.
for it = 1:length(M_.mapping.(variable_name).eqidx)
    if M_.mapping.(variable_name).eqidx(it)>length(model)
        % Equations appended by the preprocessor for auxiliary variables are not displayed, except if it is an aux variable
        % for the PAC expectation.
        % TODO Probably should do the same for VAR expectation.
        if isfield(M_, 'lhs') && isequal(M_.lhs{M_.mapping.(variable_name).eqidx(it)}(1:16), 'pac_expectation_')
            id = M_.mapping.(M_.lhs{M_.mapping.(variable_name).eqidx(it)}).eqidx(1);
        else
            continue
        end
    else
        id = M_.mapping.(variable_name).eqidx(it);
    end
    rhs = model{id}.rhs;
    if withexpansion
        if isfield(M_, 'pac') && contains(rhs, 'pac_expectation')
            % Get the index of the equation's PAC model.
            models = fieldnames(M_.pac);
            idx = find(~cellfun('isempty',cellfun(@(s)find(contains(rhs,s)),models,'uni',0)));
            % Get the expanded PAC_EXPECTATION term.
            [pac_expression, growthneutralitycorrection] = write_expectations(models{idx}, 'pac', true);
            expression = [sprintf('\n\t + %s', growthneutralitycorrection) TransformExpandedExpr(pac_expression)];
            rhs = strrep(rhs, ['+pac_expectation(model_name = ' models{idx} ')'], expression);
        elseif isfield(M_, 'var_expectation') && contains(rhs, 'var_expectation')
            % Get the index of the equation's VAR model.
            models = fieldnames(M_.var_expectation);
            idx = find(~cellfun('isempty',cellfun(@(s)find(contains(rhs,s)),models,'uni',0)));
            % Get the expanded VAR_EXPECTATION term.
            expression = write_expectations(models{idx}, 'var', true);
            expression = TransformExpandedExpr(expression);
            rhs = strrep(rhs, ['+var_expectation(model_name = ' models{idx} ')'], expression);
        elseif ~isfield(M_, 'pac') && ~isfield(M_, 'var_expectation')
            warning('No VAR or PAC expectations found, continuing without expansion');
            withexpansion = false;
        end
    end
    if nargout
        str = sprintf('%s = %s;\n', model{M_.mapping.(variable_name).eqidx(it)}.lhs, rhs);
    end
    fprintf('%s = %s;\n', model{id}.lhs, rhs);
end

function [transformed_expression] = TransformExpandedExpr(expression)
    transformed_expression = splitlines(expression);
    transformed_expression{1} = sprintf(' + %s', transformed_expression{1});
    transformed_expression = sprintf('\n\t%s', transformed_expression{:});