codenothing/CSSCompressor

var CSSCompressor = global.CSSCompressor,
    rnewline = /\r\n|\r|\n/,
    rvalueseparator = /^\/|,$/;

// Const
CSSCompressor.FORMAT_MED = 'medium';

// Tree rendering
function render( css, branches, indent ) {
    if ( indent === undefined ) {
        indent = '';
    }

    branches.forEach(function( branch, branchIndex ) {
        var section = [], sections = [ section ], newparts = [], nextBranch = branches[ branchIndex + 1 ], selector = '';

        // Comments
        if ( branch.comment ) {
            css += indent + branch.comment.replace( rnewline, "\n" + indent ) + "\n";
        }
        // Ruleset
        else if ( branch.selector ) {
            // Combine selector sections based on comma's
            branch.parts.forEach(function( part, i ) {
                if ( part === ',' ) {
                    sections.push( section = [] );
                    return;
                }
                else if ( CSSCompressor.isArray( part ) ) {
                    part = part.join( '' );
                }

                section.push( part );
            });

            // Join sections
            sections.forEach(function( s ) {
                newparts.push( s.join( ' ' ) );
            });

            // Add selector
            css += indent + newparts.join( ', ' ) + " {" + ( branch.rules.length ? "\n\t" + indent : '' );

            // Add rules
            branch.rules.forEach(function( rule, i ) {
                if ( i > 0 ) {
                    css += " ";
                }

                var value = '', prev, spacing;
                rule.parts.forEach(function( part, ri ) {
                    prev = rule.parts[ ri - 1 ];
                    spacing = value.length &&
                        ! rvalueseparator.exec( part ) &&
                        ( ! rvalueseparator.exec( prev ) || prev == ',' );

                    if ( spacing  ) {
                        value += ' ';
                    }

                    value += part;
                });

                // Prop:val
                css += rule.property + ":" + value;

                // Skip last semi colon
                if ( i < branch.rules.length - 1 ) {
                    css += ';';
                }
            });

            // Closing brace
            css += "\n" + indent + "}";

            // Add two lines after each ruleset
            if ( branchIndex < branches.length - 1 ) {
                css += "\n\n";
            }
        }
        // Atrules
        else if ( branch.atrule ) {
            selector = '';
            branch.parts.forEach(function( part, i ) {
                var prev = branch.parts[ i - 1 ];

                if ( selector.length && part != ',' ) {
                    selector += ' ';
                }

                selector += part;
            });

            // Actual rule block
            if ( branch.branches || branch.rules ) {
                css += indent + selector + " {" + ( branch.rules.length ? "\n\t" + indent : '' );

                // Add rules
                branch.rules.forEach(function( rule, i ) {
                    if ( i > 0 ) {
                        css += " ";
                    }

                    var value = '', prev, spacing;
                    rule.parts.forEach(function( part, ri ) {
                        prev = rule.parts[ ri - 1 ];
                        spacing = value.length &&
                            ! rvalueseparator.exec( part ) &&
                            ( ! rvalueseparator.exec( prev ) || prev == ',' );

                        if ( spacing  ) {
                            value += ' ';
                        }

                        value += part;
                    });

                    // Prop:val
                    css += rule.property + ":" + value;

                    // Skip last semi colon
                    if ( i < branch.rules.length - 1 ) {
                        css += ';';
                    }
                });

                // Handle nested selectors
                if ( branch.branches ) {
                    css += branch.rules.length ? ";\n\n" : "\n";
                    css = render( css, branch.branches, indent + "\t" );
                }

                // Closing brace
                css += "\n" + indent + "}";

                // Add two lines after each ruleset
                if ( branchIndex < branches.length - 1 && indent.length === 0 ) {
                    css += "\n\n";
                }
            }
            // One-liners, @imports
            else {
                css += indent + selector + ";\n";

                // Add extra spacing if one-liners are complete
                if ( ! nextBranch.atrule || nextBranch.branches || nextBranch.rules ) {
                    css += "\n";
                }
            }
        }
    });

    return css;
}

// Format addition
CSSCompressor.format( CSSCompressor.FORMAT_MED, function( compressor ) {
    return render( '', compressor.branches );
});