require Rails.root.join('commonlib', 'rblib', 'git')

namespace :themes do

    # Alias the module so we don't need the MySociety prefix here
    Git = MySociety::Git

    def all_themes_dir
        File.join(Rails.root,"lib","themes")
    end

    def theme_dir(theme_name)
        File.join(all_themes_dir, theme_name)
    end

    def old_all_themes_dir(theme_name)
        File.join(Rails.root, "vendor", "plugins", theme_name)
    end

    def possible_theme_dirs(theme_name)
        [theme_dir(theme_name), old_all_themes_dir(theme_name)]
    end

    def installed?(theme_name)
        possible_theme_dirs(theme_name).any? { |dir| File.directory? dir }
    end

    def usage_tag(version)
        "use-with-alaveteli-#{version}"
    end

    def uninstall(theme_name, verbose=false)
        possible_theme_dirs(theme_name).each do |dir|
            if File.directory?(dir)
                run_hook(theme_name, 'uninstall', verbose)
            end
        end
    end

    def run_hook(theme_name, hook_name, verbose=false)
        directory = theme_dir(theme_name)
        hook_file = File.join(directory, "#{hook_name}.rb")
        if File.exist? hook_file
            puts "Running #{hook_name} hook in #{directory}" if verbose
            load hook_file
        end
    end

    def move_old_theme(old_theme_directory)
        puts "There was an old-style theme at #{old_theme_directory}" if verbose
        moved_directory = "#{old_theme_directory}-moved"
        begin
            File.rename old_theme_directory, moved_directory
        rescue Errno::ENOTEMPTY, Errno::EEXIST
            raise "Tried to move #{old_theme_directory} out of the way, " \
                "but #{moved_directory} already existed"
        end
    end

    def committishes_to_try
        result = []
        theme_branch = AlaveteliConfiguration::theme_branch
        result.push "origin/#{theme_branch}" if theme_branch
        result.push usage_tag(ALAVETELI_VERSION)
        hotfix_match = /^(\d+\.\d+\.\d+)(\.\d+)+/.match(ALAVETELI_VERSION)
        result.push usage_tag(hotfix_match[1]) if hotfix_match
        minor_match = /^(\d+\.\d+)(\.\d+)+/.match(ALAVETELI_VERSION)
        result.push usage_tag(minor_match[1]) if minor_match
        result
    end

    def checkout_best_option(theme_name)
        theme_directory = theme_dir theme_name
        all_failed = true
        committishes_to_try.each do |committish|
            if Git.committish_exists? theme_directory, committish
                puts "Checking out #{committish}" if verbose
                Git.checkout theme_directory, committish
                all_failed = false
                break
            else
                puts "Failed to find #{committish}; skipping..." if verbose
            end
        end
        puts "Falling to using HEAD instead" if all_failed and verbose
    end

    def install_theme(theme_url, verbose, deprecated=false)
        FileUtils.mkdir_p all_themes_dir
        deprecation_string = deprecated ? " using deprecated THEME_URL" : ""
        theme_name = theme_url_to_theme_name theme_url
        puts "Installing theme #{theme_name}#{deprecation_string} from #{theme_url}"
        # Make sure any uninstall hooks have been run:
        uninstall(theme_name, verbose) if installed?(theme_name)
        theme_directory = theme_dir theme_name
        # Is there an old-style theme directory there?  If so, move it
        # out of the way so that there's no risk that work is lost:
        if File.directory? theme_directory
            unless Git.non_bare_repository? theme_directory
                move_old_theme theme_directory
            end
        end
        # If there isn't a directory there already, clone it into place:
        unless File.directory? theme_directory
            unless system "git", "clone", theme_url, theme_directory
                raise "Cloning from #{theme_url} to #{theme_directory} failed"
            end
        end
        # Set the URL for origin in case it has changed, and fetch from there:
        Git.remote_set_url theme_directory, 'origin', theme_url
        Git.fetch theme_directory, 'origin'
        # Check that checking-out a new commit will be safe:
        unless Git.status_clean theme_directory
            raise "There were uncommitted changes in #{theme_directory}"
        end
        unless Git.is_HEAD_pushed? theme_directory
            raise "The current work in #{theme_directory} is unpushed"
        end
        # Now try to checkout various commits in order of preference:
        checkout_best_option theme_name
        # Finally run the install hooks:
        run_hook(theme_name, 'install', verbose)
        run_hook(theme_name, 'post_install', verbose)
    end

    desc "Install themes specified in the config file's THEME_URLS"
    task :install => :environment do
        verbose = true
        AlaveteliConfiguration::theme_urls.each{ |theme_url| install_theme(theme_url, verbose) }
        if ! AlaveteliConfiguration::theme_url.blank?
            # Old version of the above, for backwards compatibility
            install_theme(AlaveteliConfiguration::theme_url, verbose, deprecated=true)
        end
    end

end