# Nick's web site: Helper to retrieve global style variables in ruby.
#
# Copyright © 2020, 2022 Nick Bowler
#
# 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 3 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, see <https://www.gnu.org/licenses/>.

require 'sass'

class GetSCSSGlobals < Sass::Tree::Visitors::Perform
    def self.visit(root, name = nil)
        x = new(nil)
        x.send(:visit, root)
        result = x.instance_variable_get(:@globals)
        return result.freeze if name.nil?

        x.send(:rubify_result, result[name])
    end

    protected

    def initialize(environment)
        @globals = {}
        @globals.default_proc = proc { |h, k|
            if h.key? k.to_s then h[k.to_s] end }
        super
    end

    def visit_variable(node)
        super

        x = @environment.global_env.var(node.name)
        @globals[node.name] = x unless x.nil?
    end

    # Convert SASS maps and lists to ruby equivalents that are actually usable.
    def rubify_result(val)
        case val
        when Sass::Script::Value::Map
            val.to_h.each_with_object({}) do |(k, v), h|
                h[k.to_s.to_sym] = rubify_result(v)
            end
        when Sass::Script::Value::List
            val.to_a.map { |v| rubify_result(v) }
        else
            val
        end
    end
end

def scss_get_var(variable, item = @items["/style.scss"])
    engine = Sass::Engine.for_file(item.raw_filename, {
        :syntax => :scss,
        :load_paths => ["."],
    })
    return GetSCSSGlobals.visit(engine.to_tree, variable)
end

def scss_get_colour(colour, index = 0, item = @items["/style.scss"])
    cmap = scss_get_var(:colourmap, item);
    [cmap[colour]].flatten[index]
end