var CleanCSS = require('clean-css');
var input = 'a{font-weight:bold;}';
var options = { /* options */ };
var output = new CleanCSS(options).minify(input);

new CleanCSS({
  compatibility: {
    colors: {
      hexAlpha: false, // controls 4- and 8-character hex color support
      opacity: true // controls `rgba()` / `hsla()` color support
    },
    properties: {
      backgroundClipMerging: true, // controls background-clip merging into shorthand
      backgroundOriginMerging: true, // controls background-origin merging into shorthand
      backgroundSizeMerging: true, // controls background-size merging into shorthand
      colors: true, // controls color optimizations
      ieBangHack: false, // controls keeping IE bang hack
      ieFilters: false, // controls keeping IE `filter` / `-ms-filter`
      iePrefixHack: false, // controls keeping IE prefix hack
      ieSuffixHack: false, // controls keeping IE suffix hack
      merging: true, // controls property merging based on understandability
      shorterLengthUnits: false, // controls shortening pixel units into `pc`, `pt`, or `in` units
      spaceAfterClosingBrace: true, // controls keeping space after closing brace - `url() no-repeat` into `url()no-repeat`
      urlQuotes: true, // controls keeping quoting inside `url()`
      zeroUnits: true // controls removal of units `0` value
    },
    selectors: {
      adjacentSpace: false, // controls extra space before `nav` element
      ie7Hack: true, // controls removal of IE7 selector hacks, e.g. `*+html...`
      mergeablePseudoClasses: [':active', ...], // controls a whitelist of mergeable pseudo classes
      mergeablePseudoElements: ['::after', ...], // controls a whitelist of mergeable pseudo elements
      mergeLimit: 8191, // controls maximum number of selectors in a single rule (since 4.1.0)
      multiplePseudoMerging: true // controls merging of rules with multiple pseudo classes / elements (since 4.1.0)
    },
    units: {
      ch: true, // controls treating `ch` as a supported unit
      in: true, // controls treating `in` as a supported unit
      pc: true, // controls treating `pc` as a supported unit
      pt: true, // controls treating `pt` as a supported unit
      rem: true, // controls treating `rem` as a supported unit
      vh: true, // controls treating `vh` as a supported unit
      vm: true, // controls treating `vm` as a supported unit
      vmax: true, // controls treating `vmax` as a supported unit
      vmin: true // controls treating `vmin` as a supported unit
    }
  }
})

new CleanCSS({
  compatibility: 'ie9,-properties.merging' // sets compatibility to IE9 mode with disabled property merging
})

var request = require('request');
var source = '@import url(http://example.com/path/to/stylesheet.css);';
new CleanCSS({
  fetch: function (uri, inlineRequest, inlineTimeout, callback) {
    request(uri, function (error, response, body) {
      if (error) {
        callback(error, null);
      } else if (response && response.statusCode != 200) {
        callback(response.statusCode, null);
      } else {
        callback(null, body);
      }
    });
  }
}).minify(source);

new CleanCSS({
  format: 'beautify' // formats output in a really nice way
})

new CleanCSS({
  format: 'keep-breaks' // formats output the default way but adds line breaks for improved readability
})

new CleanCSS({
  format: {
    breaks: { // controls where to insert breaks
      afterAtRule: false, // controls if a line break comes after an at-rule; e.g. `@charset`; defaults to `false`
      afterBlockBegins: false, // controls if a line break comes after a block begins; e.g. `@media`; defaults to `false`
      afterBlockEnds: false, // controls if a line break comes after a block ends, defaults to `false`
      afterComment: false, // controls if a line break comes after a comment; defaults to `false`
      afterProperty: false, // controls if a line break comes after a property; defaults to `false`
      afterRuleBegins: false, // controls if a line break comes after a rule begins; defaults to `false`
      afterRuleEnds: false, // controls if a line break comes after a rule ends; defaults to `false`
      beforeBlockEnds: false, // controls if a line break comes before a block ends; defaults to `false`
      betweenSelectors: false // controls if a line break comes between selectors; defaults to `false`
    },
    breakWith: '\n', // controls the new line character, can be `'\r\n'` or `'\n'` (aliased as `'windows'` and `'unix'` or `'crlf'` and `'lf'`); defaults to system one, so former on Windows and latter on Unix
    indentBy: 0, // controls number of characters to indent with; defaults to `0`
    indentWith: 'space', // controls a character to indent with, can be `'space'` or `'tab'`; defaults to `'space'`
    spaces: { // controls where to insert spaces
      aroundSelectorRelation: false, // controls if spaces come around selector relations; e.g. `div > a`; defaults to `false`
      beforeBlockBegins: false, // controls if a space comes before a block begins; e.g. `.block {`; defaults to `false`
      beforeValue: false // controls if a space comes before a value; e.g. `width: 1rem`; defaults to `false`
    },
    wrapAt: false, // controls maximum line length; defaults to `false`
    semicolonAfterLastProperty: false // controls removing trailing semicolons in rule; defaults to `false` - means remove
  }
})

  new CleanCSS({
    format: {
      breaks: {
        afterAtRule: 2,
        afterBlockBegins: 1, // 1 is synonymous with `true`
        afterBlockEnds: 2,
        afterComment: 1,
        afterProperty: 1,
        afterRuleBegins: 1,
        afterRuleEnds: 1,
        beforeBlockEnds: 1,
        betweenSelectors: 0 // 0 is synonymous with `false`
      }
    }
  })

new CleanCSS({
  inline: ['local'] // default; enables local inlining only
})

new CleanCSS({
  inline: ['none'] // disables all inlining
})

// introduced in clean-css 4.1.0

new CleanCSS({
  inline: false // disables all inlining (alias to `['none']`)
})

new CleanCSS({
  inline: ['all'] // enables all inlining, same as ['local', 'remote']
})

new CleanCSS({
  inline: ['local', 'mydomain.example.com'] // enables local inlining plus given remote source
})

new CleanCSS({
  inline: ['local', 'remote', '!fonts.googleapis.com'] // enables all inlining but from given remote source
})

new CleanCSS({
  level: 2
})

new CleanCSS({
  level: {
    1: {
      cleanupCharsets: true, // controls `@charset` moving to the front of a stylesheet; defaults to `true`
      normalizeUrls: true, // controls URL normalization; defaults to `true`
      optimizeBackground: true, // controls `background` property optimizations; defaults to `true`
      optimizeBorderRadius: true, // controls `border-radius` property optimizations; defaults to `true`
      optimizeFilter: true, // controls `filter` property optimizations; defaults to `true`
      optimizeFont: true, // controls `font` property optimizations; defaults to `true`
      optimizeFontWeight: true, // controls `font-weight` property optimizations; defaults to `true`
      optimizeOutline: true, // controls `outline` property optimizations; defaults to `true`
      removeEmpty: true, // controls removing empty rules and nested blocks; defaults to `true`
      removeNegativePaddings: true, // controls removing negative paddings; defaults to `true`
      removeQuotes: true, // controls removing quotes when unnecessary; defaults to `true`
      removeWhitespace: true, // controls removing unused whitespace; defaults to `true`
      replaceMultipleZeros: true, // controls removing redundant zeros; defaults to `true`
      replaceTimeUnits: true, // controls replacing time units with shorter values; defaults to `true`
      replaceZeroUnits: true, // controls replacing zero values with units; defaults to `true`
      roundingPrecision: false, // rounds pixel values to `N` decimal places; `false` disables rounding; defaults to `false`
      selectorsSortingMethod: 'standard', // denotes selector sorting method; can be `'natural'` or `'standard'`, `'none'`, or false (the last two since 4.1.0); defaults to `'standard'`
      specialComments: 'all', // denotes a number of /*! ... */ comments preserved; defaults to `all`
      tidyAtRules: true, // controls at-rules (e.g. `@charset`, `@import`) optimizing; defaults to `true`
      tidyBlockScopes: true, // controls block scopes (e.g. `@media`) optimizing; defaults to `true`
      tidySelectors: true, // controls selectors optimizing; defaults to `true`,
      variableValueOptimizers: [] // controls value optimizers which are applied to variables
    }
  }
});

new CleanCSS({
  level: {
    1: {
      all: false, // set all values to `false`
      tidySelectors: true // turns on optimizing selectors
    }
  }
});

new CleanCSS({
  level: {
    2: {
      mergeAdjacentRules: true, // controls adjacent rules merging; defaults to true
      mergeIntoShorthands: true, // controls merging properties into shorthands; defaults to true
      mergeMedia: true, // controls `@media` merging; defaults to true
      mergeNonAdjacentRules: true, // controls non-adjacent rule merging; defaults to true
      mergeSemantically: false, // controls semantic merging; defaults to false
      overrideProperties: true, // controls property overriding based on understandability; defaults to true
      removeEmpty: true, // controls removing empty rules and nested blocks; defaults to `true`
      reduceNonAdjacentRules: true, // controls non-adjacent rule reducing; defaults to true
      removeDuplicateFontRules: true, // controls duplicate `@font-face` removing; defaults to true
      removeDuplicateMediaBlocks: true, // controls duplicate `@media` removing; defaults to true
      removeDuplicateRules: true, // controls duplicate rules removing; defaults to true
      removeUnusedAtRules: false, // controls unused at rule removing; defaults to false (available since 4.1.0)
      restructureRules: false, // controls rule restructuring; defaults to false
      skipProperties: [] // controls which properties won't be optimized, defaults to `[]` which means all will be optimized (since 4.1.0)
    }
  }
});

new CleanCSS({
  level: {
    2: {
      all: false, // sets all values to `false`
      removeDuplicateRules: true // turns on removing duplicate rules
    }
  }
});

var myPlugin = {
  level1: {
    property: function removeRepeatedBackgroundRepeat(_rule, property, _options) {
      // So `background-repeat:no-repeat no-repeat` becomes `background-repeat:no-repeat`
      if (property.name == 'background-repeat' && property.value.length == 2 && property.value[0][1] == property.value[1][1]) {
        property.value.pop();
        property.dirty = true;
      }
    }
  }
}

new CleanCSS({plugins: [myPlugin]})

var output = new CleanCSS(options).minify(source);

console.log(output.styles); // optimized output CSS as a string
console.log(output.sourceMap); // output source map if requested with `sourceMap` option
console.log(output.errors); // a list of errors raised
console.log(output.warnings); // a list of warnings raised
console.log(output.stats.originalSize); // original content size after import inlining
console.log(output.stats.minifiedSize); // optimized content size
console.log(output.stats.timeSpent); // time spent on optimizations in milliseconds
console.log(output.stats.efficiency); // `(originalSize - minifiedSize) / originalSize`, e.g. 0.25 if size is reduced from 100 bytes to 75 bytes

const CleanCSS = require("clean-css");

const output = new CleanCSS().minify(`

  a {
    color: blue;
  }
  div {
    margin: 5px
  }

`);

console.log(output);

// Log:
{
  styles: 'a{color:#00f}div{margin:5px}',
  stats: {
    efficiency: 0.6704545454545454,
    minifiedSize: 29,
    originalSize: 88,
    timeSpent: 6
  },
  errors: [],
  inlinedStylesheets: [],
  warnings: []
}

var output = new CleanCSS(options).minify(source, inputSourceMap);

new CleanCSS(options).minify(source, function (error, output) {
  // `output` is the same as in the synchronous call above
});

var output = new CleanCSS(options).minify(['path/to/file.css'])

new CleanCSS({ returnPromise: true })
  .minify(source)
  .then(function (output) { console.log(output.styles); })
  .catch(function (error) { // deal with errors });

new CleanCSS().minify(['path/to/file/one', 'path/to/file/two']);

new CleanCSS().minify({
  'path/to/file/one': {
    styles: 'contents of file one'
  },
  'path/to/file/two': {
    styles: 'contents of file two'
  }
});

new CleanCSS().minify([
  {'path/to/file/one': {styles: 'contents of file one'}},
  {'path/to/file/two': {styles: 'contents of file two'}}
]);

var output = new CleanCSS({ batch: true }).minify(['path/to/file/one', 'path/to/file/two']);
var outputOfFile1 = output['path/to/file/one'].styles // all other fields, like errors, warnings, or stats are there too
var outputOfFile2 = output['path/to/file/two'].styles

var source = '@import url(http://example.com/path/to/remote/styles);';
new CleanCSS({ inline: ['remote'] }).minify(source, function (error, output) {
  // output.styles
});

new CleanCSS({
  level: {
    1: {
      roundingPrecision: 'all=3,px=5'
    }
  }
}).minify(source)

new CleanCSS({
  compatibility: {
    customUnits: {
      rpx: true
    }
  }
}).minify(source)

new CleanCSS({ sourceMap: true, rebaseTo: pathToOutputDirectory })
  .minify(source, function (error, output) {
    // access output.sourceMap for SourceMapGenerator object
    // see https://github.com/mozilla/source-map/#sourcemapgenerator for more details
});

new CleanCSS({ sourceMap: true, rebaseTo: pathToOutputDirectory })
  .minify(source, inputSourceMap, function (error, output) {
    // access output.sourceMap to access SourceMapGenerator object
    // see https://github.com/mozilla/source-map/#sourcemapgenerator for more details
});

new CleanCSS({ sourceMap: true, rebaseTo: pathToOutputDirectory }).minify({
  'path/to/source/1': {
    styles: '...styles...',
    sourceMap: '...source-map...'
  },
  'path/to/source/2': {
    styles: '...styles...',
    sourceMap: '...source-map...'
  }
}, function (error, output) {
  // access output.sourceMap as above
});

new CleanCSS({
  level: {
    1: {
      all: true,
      normalizeUrls: false
    },
    2: {
      restructureRules: true
    }
  }
})

const CleanCSS = require("clean-css");

const output = new CleanCSS().minify(`

  a {
    -notarealproperty-: 5px;
    color:
  }
  div {
    margin: 5px
  }

`);

console.log(output);

// Log:
{
  styles: 'div{margin:5px}',
  stats: {
    efficiency: 0.8695652173913043,
    minifiedSize: 15,
    originalSize: 115,
    timeSpent: 1
  },
  errors: [],
  inlinedStylesheets: [],
  warnings: [
    "Invalid property name '-notarealproperty-' at 4:8. Ignoring.",
    "Empty property 'color' at 5:8. Ignoring."
  ]
}

const CleanCSS = require("clean-css");

const output = new CleanCSS().minify(`

  @import "idontexist.css";
  a {
    color: blue;
  }
  div {
    margin: 5px
  }

`);

console.log(output);

// Log:
{
  styles: 'a{color:#00f}div{margin:5px}',
  stats: {
    efficiency: 0.7627118644067796,
    minifiedSize: 28,
    originalSize: 118,
    timeSpent: 2
  },
  errors: [
    'Ignoring local @import of "idontexist.css" as resource is missing.'
  ],
  inlinedStylesheets: [],
  warnings: []
}

const { src, dest, series } = require('gulp');
const CleanCSS = require('clean-css');
const concat = require('gulp-concat');

function css() {
    const options = {
        compatibility: '*', // (default) - Internet Explorer 10+ compatibility mode
        inline: ['all'], // enables all inlining, same as ['local', 'remote']
        level: 2 // Optimization levels. The level option can be either 0, 1 (default), or 2, e.g.
        // Please note that level 1 optimization options are generally safe while level 2 optimizations should be safe for most users.
    };

    return src('app/**/*.css')
        .pipe(concat('style.min.css'))
        .on('data', function(file) {
            const bufferFile = new CleanCSS(options).minify(file.contents)
            return file.contents = Buffer.from(bufferFile.styles)
        })
        .pipe(dest('build'))
}
exports.css = series(css)