% If the mip command exists, inform the user and abort.
% Note: the syntax '/mip' limits the search to non-builtin functions named mip.
if ~isempty(which('/mip'))
    fprintf('mip is already installed.\n');
    fprintf('To update mip, run ''mip update mip''.\n');
    fprintf('To uninstall mip, run ''mip uninstall mip''.\n');
    return
end

fprintf('----- Welcome to the mip installation wizard! -----\n\n');
fprintf(['This script will:\n' ...
    '- Download the latest version of mip.\n' ...
    '- Install it to a specified directory.\n' ...
    '- Save mip to your MATLAB path for future sessions.\n']);

% Non-interactive installs: the MIP_INSTALL_DIR environment variable, when
% set, selects the install location without prompting. Under matlab -batch,
% where user input is unavailable, the prompt is also skipped and the
% default location is used.
mip_install___input = getenv('MIP_INSTALL_DIR');
mip_install___batch = exist('batchStartupOptionUsed', 'builtin') ~= 0 && batchStartupOptionUsed;
if isempty(mip_install___input) && ~mip_install___batch
    % Prompt the user for custom mip location (default: <userpath>/mip)
    if ispc || isempty(getenv('HOME'))
        mip_install___input = input(strrep(sprintf('\nEnter install location for mip (%s): ', fullfile(userpath, 'mip')), '\', '\\'), 's');
    else
        mip_install___input = input(strrep(sprintf('\nEnter install location for mip (%s): ', replace(fullfile(userpath, 'mip'), getenv('HOME'), '~')), '\', '\\'), 's');
    end
end
if isempty(mip_install___input)
    mip_install___mipdir = fullfile(userpath, 'mip');
else
    mip_install___mipdir = mip_install___input;
end

if ispc || isempty(getenv('HOME'))
    mip_install___mipdirpretty = mip_install___mipdir;
else
    mip_install___mipdirpretty = replace(mip_install___mipdir, getenv('HOME'), '~');
end

mip_install___mippackagedir = fullfile(mip_install___mipdir, 'packages', 'gh', 'mip-org', 'core', 'mip');
mip_install___mipsourcedir = fullfile(mip_install___mippackagedir, 'mip');

% If the install directory already exists, adopt the mip that is already there
% instead of installing a second copy. Being absent from the path does not mean
% mip is not installed: the saved path lives in <matlabroot>/toolbox/local/pathdef.m,
% which belongs to one MATLAB installation, while mip is installed under the
% user's home directory. Installing a new MATLAB release, or running on a
% machine whose MATLAB comes and goes (a CI runner with its own MATLAB), leaves
% the installation in place with nothing on the path pointing at it. Adopting
% means adding it back to the path, which is all a fresh install does once the
% files are unpacked.
mip_install___adopt = isfolder(mip_install___mipdir);
if mip_install___adopt && ~isfile(fullfile(mip_install___mipsourcedir, 'mip.m'))
    % The directory is in the way but holds no mip to adopt. Refuse rather than
    % unpacking into it, and rather than putting a directory with no mip.m on
    % the path (which would fail later as an undefined `mip` function).
    fprintf('Directory ''%s'' already exists but does not contain a mip installation.\n', mip_install___mipdirpretty);
    fprintf('Remove it, or set the MIP_INSTALL_DIR environment variable to another location, and try again.\n');
    clear mip_install___*
    error('mip:install:dirExists', ...
          'mip install directory already exists but contains no mip installation.');
end

if mip_install___adopt
    % The banner above promised a download. Say plainly that there was none, so
    % it is clear no second copy was installed over the existing one.
    fprintf('Found an existing mip installation in ''%s''.\n', mip_install___mipdirpretty);
    fprintf('Nothing was downloaded; that installation will be used.\n');
end

if ~mip_install___adopt
    % Find all versions of mip available in the package index
    try
        mip_install___package_index = webread('https://mip-org.github.io/mip-core/index.json');
    catch
        clear mip_install___*
        error('Failed to download mip. Installation aborted.');
    end
    mip_install___versions = {};
    for mip_install___i = 1:length(mip_install___package_index.packages)
        if strcmpi(mip_install___package_index.packages{mip_install___i}.name, 'mip')
            mip_install___versions = [
                mip_install___versions ;
                mip_install___package_index.packages{mip_install___i}
            ]; %#ok<AGROW>
        end
    end
    if isempty(mip_install___versions)
        clear mip_install___*
        error('Failed to download mip. Installation aborted.');
    end

    % Select the best version of mip
    % Priority: highest numeric version > "main" > "unspecified" > alphabetically first
    mip_install___latest = [];
    mip_install___latest_numeric = '';
    for mip_install___i = 1:length(mip_install___versions)
        mip_install___v = mip_install___versions{mip_install___i}.version;
        mip_install___parts = str2double(strsplit(mip_install___v, '.'));
        if ~any(isnan(mip_install___parts))
            % Numeric version - compare to find highest
            if isempty(mip_install___latest_numeric)
                mip_install___latest = mip_install___versions{mip_install___i};
                mip_install___latest_numeric = mip_install___v;
            else
                mip_install___v1 = mip_install___parts;
                mip_install___v2 = str2double(strsplit(mip_install___latest_numeric, '.'));
                mip_install___vmaxlen = max(length(mip_install___v1), length(mip_install___v2));
                mip_install___v1(end+1:mip_install___vmaxlen) = 0;
                mip_install___v2(end+1:mip_install___vmaxlen) = 0;
                for mip_install___j = 1:mip_install___vmaxlen
                    if mip_install___v1(mip_install___j) > mip_install___v2(mip_install___j)
                        mip_install___latest = mip_install___versions{mip_install___i};
                        mip_install___latest_numeric = mip_install___v;
                        break
                    elseif mip_install___v1(mip_install___j) < mip_install___v2(mip_install___j)
                        break
                    end
                end
            end
        end
    end
    % If no numeric version found, fall back to "main", then "unspecified", then first
    if isempty(mip_install___latest)
        for mip_install___i = 1:length(mip_install___versions)
            if strcmp(mip_install___versions{mip_install___i}.version, 'main')
                mip_install___latest = mip_install___versions{mip_install___i};
                break
            end
        end
    end
    if isempty(mip_install___latest)
        for mip_install___i = 1:length(mip_install___versions)
            if strcmp(mip_install___versions{mip_install___i}.version, 'unspecified')
                mip_install___latest = mip_install___versions{mip_install___i};
                break
            end
        end
    end
    if isempty(mip_install___latest)
        mip_install___latest = mip_install___versions{1};
    end

    % Download the .mhl for the latest version of mip from the package index
    mip_install___mhl = mip_install___latest.mhl_url;
    if isempty(mip_install___mhl)
        clear mip_install___*
        error('Failed to download mip. Installation aborted.');
    end

    fprintf('Installing mip version %s to ''%s''\n', mip_install___latest.version, mip_install___mipdirpretty);

    % Unzip the .mhl to <MIPDIR>/packages/gh/mip-org/core/mip
    try
        unzip(mip_install___mhl, mip_install___mippackagedir);
    catch
        if isfolder(mip_install___mipdir)
            rmdir(mip_install___mipdir, 's');
        end
        clear mip_install___*
        error('Failed to download mip. Installation aborted.');
    end

end % if ~mip_install___adopt

% Cache the user's current path
mip_install___current_path = path;

% Add <MIPDIR>/packages/gh/mip-org/core/mip/mip to the path and save it for
% future MATLAB sessions. savepath() returns a nonzero status (rather than
% erroring) when it cannot write pathdef.m -- common on managed or shared
% installs where it is read-only. That is not fatal: mip still works in this
% session, so warn with manual instructions rather than aborting.
mip_install___saved = false;
try
    % Change the path to match what it would be if MATLAB had just started up
    path(pathdef);
    addpath(mip_install___mipsourcedir);
    mip_install___saved = savepath() == 0;
catch
end

% Restore the path to what it was before and add <MIPDIR>/packages/gh/mip-org/core/mip/mip
% to the path for the current MATLAB session (whether or not the save worked)
path(mip_install___current_path);
addpath(mip_install___mipsourcedir);

if mip_install___adopt
    fprintf('mip is now on your MATLAB path.\n');
    fprintf('To update mip, run ''mip update mip''.\n');
else
    fprintf('Installation successful!\n');
    fprintf('Type ''mip help'' to get started.\n');
end
if ~mip_install___saved
    fprintf(['\nWarning: mip could not be saved to your MATLAB path for future sessions.\n' ...
             'To load mip automatically in future sessions, add this line to your\n' ...
             'startup.m file:\n\n' ...
             '   addpath(''%s'')\n\n'], ...
            fullfile(mip_install___mipdirpretty, 'packages', 'gh', 'mip-org', 'core', 'mip', 'mip'));
end

% Clean up the workspace
clear mip_install___*