## Copyright (C) 2005 Søren Hauberg
## 
## This program 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 2 of the License, or
## (at your option) any later version.
## 
## This program 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 this program; if not, write to the Free Software
## Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA

## -*- texinfo -*-
## @deftypefn {Command} pkg list
## @deftypefnx{Command} @var{installed_packages} = pkg list
## @deftypefnx{Command} address@hidden, @var{system_packages}] = pkg list
## @deftypefnx{Command} pkg install @var{pkg-name} ...
## @deftypefnx{Command} pkg install -nodeps @var{pkg-name} ...
## @deftypefnx{Command} pkg uninstall @var{pkg-name} ...
## @deftypefnx{Command} pkg uninstall -nodeps @var{pkg-name} ...
## @deftypefnx{Command} pkg load all
## @deftypefnx{Command} pkg load @var{pkg-name} ...
## @deftypefnx{Command} pkg load -nodeps @var{pkg-name} ...
## XXX: Where's the docs?
## @end deftypefn
function [local_packages, global_packages] = pkg(varargin)
    ## Handle input
    if (length(varargin) == 0 || !iscellstr(varargin))
        print_usage("pkg");
    endif
    files = {};
    deps = true;
    action = "none";
    for i = 1:length(varargin)
        switch (varargin{i})
            case "-nodeps"
                deps = false;
            case {"list", "install", "uninstall", "load"}
                action = varargin{i};
            otherwise
                files{end+1} = varargin{i};
        endswitch
    endfor
    
    ## Take action
    switch (action)
        case "list"
            if (nargout == 0)
                installed_packages();
            elseif (nargout == 1)
                local_packages = installed_packages();
            elseif (nargout == 2)
                [local_packages, global_packages] = installed_packages();
            else
                error("Too many output arguments requested.\n");
            endif
        case "install"
            if (length(files) == 0)
                error("You must specify at least one filename when calling 'pkg install'\n");
            endif
            install(files, deps);
        case "uninstall"
            if (length(files) == 0)
                error("You must specify at least one package when calling 'pkg uninstall'\n");
            endif
            uninstall(files, deps);
        case "load"
            if (length(files) == 0)
                error("You must specify at least one package or 'all' when calling 'pkg load'\n");
            endif
            load_packages(files, deps);
        otherwise
            error("You must specify a valid action for 'pkg'. See 'help pkg' for details\n");
    endswitch
endfunction

function install(files, handle_deps)
%disp("function: install")
    ## Set parameters depending on wether or not the installation
    ## is system-wide (global) or local.
    local_list = tilde_expand("~/.octave_packages");
    global_list = [OCTAVE_HOME "share/octave/octave_packages"];
    global OCTAVE_PACKAGE_PREFIX;
    prefix_exist = (length(OCTAVE_PACKAGE_PREFIX) != 0 && ischar(OCTAVE_PACKAGE_PREFIX));

    if (issuperuser())
        global_install = true;
        if (!prefix_exist)
            OCTAVE_PACKAGE_PREFIX = [OCTAVE_HOME "share/octave/packages/"];
        endif
    else
        global_install = false;
        if (!prefix_exist)
            OCTAVE_PACKAGE_PREFIX = "~/octave/";
        endif
    endif
    prefix = tilde_expand(OCTAVE_PACKAGE_PREFIX);
    if (!prefix_exist)
        warning(["You have not defined an installation prefix, " ...
                 "so the following will be used: %s"], prefix);
    endif
 
    # Check that the directory in prefix exist. If it doesn't: create it!
    if (!exist(prefix, "dir"))
        warning("Creating installation directory %s", prefix);
        [status, msg] = mkdir(prefix);
        if (status != 1)
            error("Could not create installation directory: %s\n", msg);
        endif
    endif

    ## Get the list of installed packages
    [local_packages, global_packages] = installed_packages();
    installed_packages = {local_packages{:} global_packages{:}};        
    
    if (global_install)
        packages = global_packages;
    else
        packages = local_packages;
    endif
   
    ## Uncompress the packages and read the DESCRIPTION files
    tmpdirs = cell(1, length(files));
    packdirs = cell(1, length(files));
    descriptions = cell(1, length(files));
    try
        ## Unpack the package files and read the DESCRIPTION files
        packages_to_uninstall = [];
        for i = 1:length(files)
            tgz = files{i};
            
            ## Create a temporary directory 
            tmpdir = tmpnam();
            tmpdirs{i} = tmpdir;
            [status, msg] = mkdir(tmpdir);
            if (status != 1)
                error("Couldn't create temporary directory: %s\n", msg);
            endif

            ## Uncompress the package
            untar(tgz, tmpdir);
  
            ## Get the name of the directory produced by tar
            [dirlist, err, msg] = readdir(tmpdir);
            if (err)
                error("Couldn't read directory produced by tar: %s\n", msg);
            endif
            packdir = [tmpdir "/" dirlist{end} "/"];
            packdirs{i} = packdir;

            ## Make sure the package contains necessary files
            verify_directory(packdir);
    
            ## Read the DESCRIPTION file
            filename = [packdir "DESCRIPTION"];
            desc = get_description(filename);
            
            ## Set default installation directory
            desc.dir = [prefix "/" desc.name "-" desc.version];
            
            ## Save desc
            descriptions{i} = desc;

            ## Are any of the new packages already installed?
            ## If so we'll remove the old version.
            for j = 1:length(packages)
                if (strcmp(packages{j}.name, desc.name))
                    packages_to_uninstall(end+1) = j;
                endif
            endfor
            
        endfor
    catch
        ## Something went wrong, delete tmpdirs
        for i = 1:length(tmpdirs)
            tmpdirs{i}
            rmdir(tmpdirs{i}, "s");
        endfor
        error(lasterr()(8:end));
    end_try_catch

    ## Check dependencies
    if (handle_deps)
        ok = true;
        error_text = "";
        for i = 1:length(descriptions)
            desc = descriptions{i};
            idx1 = complement(packages_to_uninstall, 1:length(installed_packages));
            idx2 = complement(i, 1:length(descriptions));
            pseudo_installed_packages = {installed_packages{idx1} descriptions{idx2}};
            bad_deps = get_unsatisfied_deps(desc, pseudo_installed_packages);
            ## Are there any unsatisfied dependencies?
            if (!isempty(bad_deps))
                ok = false;
                for i = 1:length(bad_deps)
                    dep = bad_deps{i};
                    error_text = [error_text "  " desc.name " needs " ...
                                  dep.package  " " dep.operator " " ...
                                  dep.version  "\n"];
                endfor
            endif
        endfor
        
        ## Did we find any unsatisfied dependencies?
        if (!ok)
            error("The following dependencies where unsatisfied:\n  %s", error_text);
        endif
    endif

    ## Prepare each package for installation
    try
        for i = 1:length(descriptions)
            desc = descriptions{i};
            pdir = packdirs{i};
            prepare_installation (desc, pdir);
            configure_make (desc, pdir);
        endfor
    catch
        ## Something went wrong, delete tmpdirs
        for i = 1:length(tmpdirs)
            rmdir(tmpdirs{i}, "s");
        endfor
        error(lasterr()(8:end));
    end_try_catch

    ## Uninstall the packages that will be replaced
    try
        for i = packages_to_uninstall
            uninstall({installed_packages{i}.name}, false);
        endfor
    catch
        ## Something went wrong, delete tmpdirs
        for i = 1:length(tmpdirs)
            rmdir(tmpdirs{i}, "s");
        endfor
        error(lasterr()(8:end));
    end_try_catch

    ## Install each package
    try
        for i = 1:length(descriptions)
            desc = descriptions{i};
            pdir = packdirs{i};
            copy_files(desc, pdir);
            finish_installation (desc, pdir)
        endfor
    catch
        ## Something went wrong, delete tmpdirs
        for i = 1:length(tmpdirs)
            rmdir(tmpdirs{i}, "s");
        endfor
        error(lasterr()(8:end));
    end_try_catch

	## Add the packages to the package list
    try
	    if (global_install)
            idx = complement(packages_to_uninstall, 1:length(global_packages));
	        global_packages = {global_packages{idx} descriptions{:}};
            save(global_list, "global_packages");
        else
            idx = complement(packages_to_uninstall, 1:length(local_packages));
	        local_packages = {local_packages{idx} descriptions{:}};
            save(local_list, "local_packages");
        endif
    catch
        ## Something went wrong, delete tmpdirs
        for i = 1:length(tmpdirs)
            rmdir(tmpdirs{i}, "s");
        endfor
        for i = 1:length(descriptions)
            rmdir(descriptions{i}.dir, "s");
        endfor
        if (global_install)
            error("Couldn't append to %s: %s\n", global_list, lasterr()(8:end));
        else
            error("Couldn't append to %s: %s\n", local_list, lasterr()(8:end));
        endif
    end_try_catch

    ## All is well, let's clean up
    for i = 1:length(tmpdirs)
        [status, msg] = rmdir(tmpdirs{i}, "s");
        if (status != 1)
            warning("Couldn't clean up after my self: %s\n", msg);
        endif
    endfor

    ## Add the newly installed packages to the path, so the user
    ## can begin the using.
    dirs = cell(1, length(descriptions));
    for i = 1:length(descriptions)
        dirs{i} = descriptions{i}.dir;
    endfor
    # XXX: I guess it would be better to use addpath
    # (assuming it gets included in Octave)
    path(LOADPATH, dirs{:});
endfunction

function uninstall(pkgnames, handle_deps)
%disp("function: uninstall")
    local_list = tilde_expand("~/.octave_packages");
    global_list = [OCTAVE_HOME "share/octave/octave_packages"];
    ## Get the list of installed packages
    [local_packages, global_packages] = installed_packages();
    if (issuperuser())
        installed_packages = global_packages;
    else
        installed_packages = local_packages;
    endif
    
    num_packages = length(installed_packages);
    delete_idx = [];
    for i = 1:num_packages
        cur_name = installed_packages{i}.name;
        if (any(strcmp(cur_name, pkgnames)))
            delete_idx(end+1) = i;
        endif
    endfor
    
    ## Are all the packages that should be uninstalled already installed?
    if (length(delete_idx) != length(pkgnames))
        # XXX: We should have a better error message
        error("Some of the packages you want to uninstall are not installed.\n");
    endif

    ## Compute the packages that will remain installed
    idx = complement(delete_idx, 1:num_packages);
    remaining_packages = {installed_packages{idx}};
    
    ## Check dependencies
    if (handle_deps)
        ok = true;
        error_text = "";
        for i = 1:length(remaining_packages)
            desc = remaining_packages{i};
            bad_deps = get_unsatisfied_deps(desc, remaining_packages);
            
            ## Will the uninstallation break any dependencies?
            if (!isempty(bad_deps))
                ok = false;
                for i = 1:length(bad_deps)
                    dep = bad_deps{i};
                    error_text = [error_text "  " desc.name " needs " ...
                                  dep.package  " " dep.operator " " ...
                                  dep.version  "\n"];
                endfor
            endif
        endfor

        if (!ok)
            error("The following dependencies where unsatisfied:\n  %s", error_text);
        endif
    endif

    ## Delete the directories containing the packages
    for i = delete_idx
        desc = installed_packages{i};
        ## If an 'on_uninstall.m' exist, call it!
        if (exist([desc.dir "/packinfo/on_uninstall.m"], "file"))
            try
                wd = pwd();
                cd([desc.dir "/packinfo"]);
                on_uninstall(desc);
                cd(wd);
            catch
                # XXX: Should this rather be an error?
                warning("The 'on_uninstall' script returned the following error: %s", lasterr);
                cd(wd);
            end_try_catch
        endif
        ## Do the actual deletion
        [status, msg] = rmdir(desc.dir, "s");
        if (status != 1)
            error("Couldn't delete directory %s: %s\n", desc.dir, msg);
        endif
    endfor

    ## Write a new ~/.octave_packages
    if (issuperuser())
        if (length(remaining_packages) == 0)
            unlink(global_list);
        else
            global_packages = remaining_packages;
            save(global_list, "global_packages");
        endif
    else
        if (length(remaining_packages) == 0)
            unlink(local_list);
        else
            local_packages = remaining_packages;
            save(local_list, "local_packages");
        endif
    endif
    
endfunction

##########################################################
##         A U X I L A R Y    F U N C T I O N S         ##
##########################################################

function prepare_installation(desc, packdir)
%disp("function: function: prepare_installation")
    ## Is there a pre_install to call?
    if (exist([packdir "pre_install.m"], "file"))
        wd = pwd();
        try
            cd(packdir);
            pre_install(desc); 
            cd(wd);
        catch
            cd(wd);
            error("The pre-install function returned the following error: %s\n", lasterr);
        end_try_catch
    endif

    ## Create the installation directory
    [status, msg] = mkdir(desc.dir);
    if (status != 1)
        error("Couldn't create installation directory: %s\n", msg);
    endif

	## If the directory "inst" doesn't exist, we create it
	if (!exist([packdir "inst"], "dir"))
        [status, msg] = mkdir([packdir "inst"]);
        if (status != 1)
            rmdir(desc.dir, "s");
            error("The 'inst' directory did not exist and could not be created: %s\n", msg);
        endif
    endif
endfunction

function configure_make (desc, packdir)   
%disp("function: function: configure_make")
	## Perform ./configure, make, make install in "src"
    if (exist([packdir "src"], "dir"))
        src = [packdir "src/"];
        ## configure
        if (exist([src "configure"], "file"))
            [output, status] = system(["cd " src " ;./configure --prefix=" desc.dir]);
            if (status != 0)
                rmdir(desc.dir, "s");
                error("The configure script returned the following error: %s\n", output);
            endif
        endif

        ## make
        if (exist([src "Makefile"], "file"))
            [output, status] = system(["export INSTALLDIR=" desc.dir "; make -C " src]);
            if (status != 0)
                rmdir(desc.dir, "s");
                error("'make' returned the following error: %s\n", output);
            endif
            %# make install
            %[output, status] = system(["export INSTALLDIR=" desc.dir "; make install -C " src]);
            %if (status != 0)
            %    rmdir(desc.dir, "s");
            %    error("'make install' returned the following error: %s\n", output);
            %endif
        endif

        ## Copy files to "inst" (this is instead of 'make install')
        files = [src "FILES"];
        if (exist(files, "file"))
            [fid, msg] = fopen(files, "r");
            if (fid < 0)
                error("Couldn't open %s: %s\n", files, msg);
            endif
            filenames = char(fread(fid));
            filenames = strrep(filenames, "\n", " ");
            [output, status] = system(["cd " src "; cp " filenames " " packdir "inst/"]);
            fclose(fid);
        else
            m = dir([src "*.m"]);
            oct = dir([src "*.oct"]);
            f = "";
            if (length(m) > 0)
                f = sprintf("%s ", m.name);
            endif
            if (length(oct) > 0)
                f = [f " " sprintf("%s ", oct.name)];
            endif
            [output, status] = system(["cp " f " " packdir "inst/"]);
        endif
        if (status != 0)
            rmdir(desc.dir, "s");
            error("Couldn't copy files from 'src' to 'inst': %s\n", output);
        endif
    endif
endfunction

function copy_files	(desc, packdir)
%disp("function: function: copy_files")
    ## Copy the files from "inst" to installdir
    [output, status] = system(["cp -R " packdir "inst/* " desc.dir]);
    if (status != 0)
        rmdir(desc.dir, "s");
        error("Couldn't copy files to the installation directory\n");
    endif

    ## Create the "packinfo" directory
    packinfo = [desc.dir "/packinfo/"];
    [status, msg] = mkdir (packinfo);
    if (status != 1)
        rmdir(desc.dir, "s");
        error("Couldn't create packinfo directory: %s\n", msg);
    endif

    ## Copy DESCRIPTION
    [output, status] = system(["cp " packdir "DESCRIPTION " packinfo]);
    if (status != 0)
       rmdir(desc.dir, "s");
       error("Couldn't copy DESCRIPTION: %s\n", output);
    endif

    ## Is there an INDEX file to copy or should we generate one?
    if (exist([packdir "INDEX"], "file"))
        [output, status] = system(["cp " packdir "INDEX " packinfo]);
        if (status != 0)
            rmdir(desc.dir, "s");
            error("Couldn't copy INDEX file: %s\n", output);
        endif
    else
        try
            write_INDEX(desc, [packdir "inst"], [packinfo "INDEX"]);
        catch
            rmdir(desc.dir, "s");
            error(lasterr);
        end_try_catch
    endif
    
    ## Is there an 'on_uninstall.m' to install?
    if (exist([packdir "on_uninstall.m"], "file"))
        [output, status] = system(["cp " packdir "on_uninstall.m " packinfo]);
        if (status != 0)
            rmdir(desc.dir, "s");
            error("Couldn't copy on_uninstall.m: %s\n", output);
        endif
    endif
endfunction

function finish_installation (desc, packdir)
%disp("function: finish_installation")
    ## Is there a post-install to call?
    if (exist([packdir "post_install.m"], "file"))
        wd = pwd();
        try
            cd(packdir);
            post_install(desc);
            cd(wd);
        catch
            cd(wd);
            rmdir(desc.dir, "s");
            error("The post_install function returned the following error: %s\n", lasterr);
        end_try_catch
    endif
endfunction

function out = issuperuser()
%disp("function: issuperuser")
    out = strcmp(getenv("USER"), "root");
endfunction

## This function makes sure the package contains the
## essential files.
function verify_directory(dir)
%disp("function: verify_directory")
    needed_files = {"COPYING", "DESCRIPTION"};
    for f = needed_files
        if (!exist([dir "/" f{1}], "file"))
            error("Package is missing file: %s", f{1});
        endif
    endfor
endfunction

## This function parses the DESCRIPTION file
function desc = get_description(filename)
%disp("function: get_description")
    fid = fopen(filename, "r");
    if (fid == -1)
        error("The DESCRIPTION file %s could not be read\n", filename);
    endif

    desc = struct();
    
    line = fgetl(fid);
    while (line != -1)
        ## Comments
        if (line(1) == "#")
            # Do nothing
        ## Continuation lines
        elseif (isspace(line(1)))
            if (exist("keyword", "var") && isfield(desc, keyword))
                desc.(keyword) = [desc.(keyword) " " rstrip(line)];
            endif
        ## Keyword/value pair
        else
            colon = find(line == ":");
            if (length(colon) == 0)
                disp("Skipping line.");
            else
                colon = colon(1);
                keyword = tolower(strip(line(1:colon-1)));
                value   = strip(line(colon+1:end));
                if (length(value) == 0)
                    fclose(fid);
                    error("The keyword %s have empty value\n", desc.keywords{end});
                endif
                desc.(keyword) = value;
            endif
        endif
        line = fgetl(fid);
    endwhile    
    fclose(fid);
    
    ## Make sure all is okay
    needed_fields = {"name", "version", "date", "title", ...
                     "author", "maintainer", "description"};
    for f = needed_fields
        if (!isfield(desc, f{1}))
            error("Description is missing needed field %s\n", f{1});
        endif
    endfor
    desc.version = fix_version(desc.version);
    if (isfield(desc, "depends"))
        desc.depends = fix_depends(desc.depends);
    else
        desc.depends = "";
    endif
    desc.name = tolower(desc.name);
endfunction

## Makes sure the version string v is a valid x.y.z version string
## Examples: "0.1" => "0.1.0", "monkey" => error(...)
function out = fix_version(v)
%disp("function: fix_version")
    dots = find(v == ".");
    if (length(dots) == 1)
        major = str2num(v(1:dots-1));
        minor = str2num(v(dots+1:end));
        if (length(major) != 0 && length(minor) != 0)
            out = sprintf("%d.%d.0", major, minor);
            return
        endif
    elseif (length(dots) == 2)
        major = str2num(v(1:dots(1)-1));
        minor = str2num(v(dots(1)+1:dots(2)-1));
        rev   = str2num(v(dots(2)+1:end));
        if (length(major) != 0 && length(minor) != 0 && length(rev) != 0)
            out = sprintf("%d.%d.%d", major, minor, rev);
            return
        endif
    endif
    error("Bad version string: %s\n", v);
endfunction

## Makes sure the depends field is of the right format.
## This function returns a cell of structures with the following fields:
##   package, version, operator
function deps_cell = fix_depends(depends)
%disp("function: fix_depends")
    deps = split_by(tolower(depends), ",");
    deps_cell = cell(1, length(deps));
    
    ## For each dependency
    for i = 1:length(deps)
        dep = deps{i};
        lpar = find(dep == "(");
        rpar = find(dep == ")");
        ## Does the dependency specify a version
        ## Example: package(>= version)
        if (length(lpar) == 1 && length(rpar) == 1)
            package = tolower(strip(dep(1:lpar-1)));
            sub = dep( lpar(1)+1:rpar(1)-1 );
            parts = split_by(sub, " ");
            idx = [];
            for r = 1:size(parts,1)
                if (length(parts{r}) > 0)
                    idx(end+1) = r;
                endif
            endfor
             
            if (length(idx) != 2)
                error(["There's something wrong with the DESCRIPTION file. " ...
                       "The dependency %s has the wrong syntax.\n"], dep);
            endif
            operator = parts{idx(1)};
            if (!any(strcmp(operator, {">=", "<=", "=="}))) ## XXX: I belive we also support ">" and "<" 
                error("Unsupported operator: %s\n", operator);
            endif
            version  = fix_version(parts{idx(2)});
             
        ## If no version is specified for the dependency
        ## we say that the version should be greater than 
        ## or equal to 0.0.0
        else
            package = tolower(strip(dep));
            operator = ">=";
            version  = "0.0.0";
        endif
        deps_cell{i} = struct("package", package, "operator", operator, "version", version);
    endfor
endfunction

## Strips the text of spaces from the right
## Example: "  hello world  " => "  hello world" (XXX: is this the same as deblank?)
function text = rstrip(text)
%disp("function: rstrip")
    chars = find(!isspace(text));
    if (length(chars) > 0)
        text = text(chars(1):end); # XXX: shouldn't it be text = text(1:chars(end));
    else
        text = "";
    endif
endfunction

## Strips the text of spaces from the left and the right
## Example: "  hello world  " => "hello world"
function text = strip(text)
%disp("function: strip")
    chars = find(!isspace(text));
    if (length(chars) > 0)
        text = text(chars(1):chars(end));
    else
        text = "";
    endif
endfunction

## Splits the text into a cell array of strings by sep
## Example: "A, B" => {"A", "B"} (with sep = ",")
function out = split_by(text, sep)
%disp("function: split_by")
    text_matrix = split(text, sep);
    num_words = size(text_matrix,1);
    out = cell(num_words, 1);
    for i = 1:num_words
        out{i} = strip(text_matrix(i, :));
    endfor
endfunction

## Creates an INDEX file for a package that doesn't provide one.
##   'desc'  describes the package.
##   'dir'   is the 'inst' direcotyr in temporary directory.
##   'INDEX' is the name (including path) of resulting INDEX file.
function write_INDEX(desc, dir, INDEX)
%disp("function: write_index")
    ## Get names of functions in dir
    [files, err, msg] = readdir(dir);
    if (err)
        error("Couldn't read directory %s: %s\n", dir, msg);
    endif
    
    functions = {};
    for i = 1:length(files)
        file = files{i};
        lf = length(file);
        if (lf > 2 && strcmp( file(end-1:end), ".m" ))
            functions{end+1} = file(1:end-2);
        elseif (lf > 4 && strcmp( file(end-3:end), ".oct" ))
            functions{end+1} = file(1:end-4);
        endif
    endfor
    
    ## Does desc have a categories field?
    if (!isfield(desc, "categories"))
        error("The DESCRIPTION file must have a Categories field, when no INDEX file is given.\n");
    endif
    categories = split_by(desc.categories, ",");
    if (length(categories) < 1)
        error("The Category field is empty.\n");
    endif
    
    ## Write INDEX
    fid = fopen(INDEX, "w");
    if (fid == -1)
        error("Couldn't open %s for writing.\n", INDEX);
    endif
    fprintf(fid, "%s >> %s\n", desc.name, desc.title);
    fprintf(fid, "%s\n", categories{1});
    fprintf(fid, "  %s\n", functions{:});
    fclose(fid);
endfunction

function bad_deps = get_unsatisfied_deps(desc, installed_packages)
%disp("function: get_unsatisfied_deps")
    bad_deps = {};

    ## For each dependency
    for i = 1:length(desc.depends)
        dep = desc.depends{i};

        ## Is the current dependency Octave?
        if (strcmp(dep.package, "octave"))
            if (!compare_versions(OCTAVE_VERSION, dep.version, dep.operator))
                bad_deps{end+1} = dep;
            endif
        ## Is the current dependency not Octave?
        else
            ok = false;
            for i = 1:length(installed_packages)
                cur_name = installed_packages{i}.name;
                cur_version = installed_packages{i}.version;
                if (strcmp(dep.package, cur_name) && compare_versions(cur_version, dep.version, dep.operator))
                    ok = true;
                    break;
                endif
            endfor
            if (!ok)
                bad_deps{end+1} = dep;
            endif
        endif
    endfor
endfunction

## Compares to version string using the given operator
## Example: v1="0.1.0", v2="0.0.9", operator=">=" => true
## TODO: This function is very long and complex! Can't it be simplified?
function out = compare_versions(v1, v2, operator)
%disp("function: compare_versions")
    dot1 = find(v1 == ".");
    dot2 = find(v2 == ".");
    if (length(dot1) != 2 || length(dot2) != 2)
        error("Given version strings are not valid: %s %s", v1, v2);
    endif
    
    major1 = str2num( v1( 1:dot1(1)-1 ) );
    minor1 = str2num( v1( dot1(1)+1:dot1(2)-1 ) );
    rev1   = str2num( v1( dot1(2)+1:end ) );
    major2 = str2num( v2( 1:dot2(1)-1 ) );
    minor2 = str2num( v2( dot2(1)+1:dot2(2)-1 ) );
    rev2   = str2num( v2( dot2(2)+1:end) );
    mmr = [sign(major1-major2), sign(minor1-minor2), sign(rev1-rev2)];
    
    if (length(operator) > 1 && operator(2) == "=" && !any(mmr))
        out = 1;
        return;
    elseif (operator(1) == "<")
        mmr = -mmr;
    endif
    
    ## Now we ony need to decide if v1 > v2
    if (mmr(1) == 1)
        out = 1;
    elseif (mmr(1) == -1)
        out = 0;
    elseif (mmr(2) == 1)
        out = 1;
    elseif (mmr(2) == -1)
        out = 0;
    elseif (mmr(3) == 1)
        out = 1;
    else
        out = 0;
    endif
endfunction

function [out1, out2] = installed_packages()
%disp("function: installed_packages")

    local_list = tilde_expand("~/.octave_packages");
    global_list = [OCTAVE_HOME "share/octave/octave_packages"];
    ## Get the list of installed packages
    try
        local_packages = load(local_list).local_packages;
    catch
        local_packages = {};
    end_try_catch
    try
        global_packages = load(global_list).global_packages;
    catch
        global_packages = {};
    end_try_catch
    installed_packages = {local_packages{:} global_packages{:}};        
    
    ## Should we return something?
    if (nargout == 2)
        out1 = local_packages;
        out2 = global_packages;
        return;
    elseif (nargout == 1)
        out1 = installed_packages;
        return;
    endif
    
    ## We shouldn't return something, so we'll print something
    num_packages = length(installed_packages);
    if (num_packages == 0)
        printf("No packages installed.\n");
        return;
    endif
    
    ## Print a header
    h1 = "Package Name";
    h2 = "Version";
    h3 = "Installation directory";
    header = sprintf("%s | %s | %s\n", h1, h2, h3);
    printf(header);
    tmp = sprintf(repmat("-", 1, length(header)-1));
    tmp(length(h1)+2) = "+"; tmp(length(h1)+length(h2)+5) = "+";
    printf("%s\n", tmp);
    
    ## Compute the maximal lengths of name, version, and dir
    max_name_length = length(h1); 
    max_version_length = length(h2);
    for i = 1:num_packages
        max_name_length    = max(max_name_length, 
                                 length(installed_packages{i}.name));
        max_version_length = max(max_version_length,
                                 length(installed_packages{i}.version));
    endfor
    
    ## Print the packages
    format = sprintf("%%%ds | %%%ds | %%s\n", max_name_length, max_version_length);
    for i = 1:num_packages
        cur_name    = installed_packages{i}.name;
        cur_version = installed_packages{i}.version;
        cur_dir     = installed_packages{i}.dir;
        printf(format, cur_name, cur_version, cur_dir);
    endfor
endfunction

function load_packages(files, handle_deps)
%disp("function: load_packages")
    installed_packages = installed_packages();
    num_packages = length(installed_packages);
    
    if (length(files) == 1 && strcmp(files{1}, "all"))
        dirs = cell(1, num_packages);
        for i = 1:num_packages
            dirs{i} = installed_packages{i}.dir;
        endfor
    elseif (handle_deps)
        # XXX: implement this
        error("Currently you need to call load_packages with 'all' or '-nodeps'. This is a bug!\n");
    else
        dirs = cell(1, length(files));
        for j = 1:length(files)
            for i = 1:num_packages
                if (strcmp(installed_packages{i}.name, files{j}))
                    dirs{j} = installed_packages{i}.dir;
                endif
            endfor
            error("Package %s is not installed\n", files{j});
        endfor
    endif
    # XXX: I guess it would be better to use addpath
    # (assuming it gets included in Octave)
    path(LOADPATH, dirs{:});
endfunction