export function camelCaseToDash(str) {
  return str.replace(/([A-Z])/g, (g) => `-${g[0].toLowerCase()}`);
}

export function makeDataAttributeString(props) {
  const keys = Object.keys(props);

  return keys
    .map((key) => {
      const _key = camelCaseToDash(key);
      const val = props[key];

      if (val === undefined) return '';
      return `data-${_key}="${val}" `;
    })
    .join('')
    .trim();
}

export function getDefault(a, b) {
  return a !== undefined ? a : b;
}

export function escapeRegExp(str) {
  // https://stackoverflow.com/a/6969486
  return str.replace(/[\-\[\]\/\{\}\(\)\*\+\?\.\\\^\$\|]/g, '\\$&');
}

export function getCSSString(styleMap) {
  let style = '';

  for (const prop in styleMap) {
    if (styleMap.hasOwnProperty(prop)) {
      style += `${prop}: ${styleMap[prop]}; `;
    }
  }

  return style.trim();
}

export function getCSSRuleBlock(rule, styleMap) {
  return `${rule} { ${getCSSString(styleMap)} }`;
}

export function buildCSSRule(rule, styleMap, cssRulesString = '') {
  // build css rules efficiently,
  // append new rule if doesnt exist,
  // update existing ones

  const rulePatternStr = `${escapeRegExp(rule)} {([^}]*)}`;
  const rulePattern = new RegExp(rulePatternStr, 'g');

  if (cssRulesString && cssRulesString.match(rulePattern)) {
    for (const property in styleMap) {
      const value = styleMap[property];
      const propPattern = new RegExp(`${escapeRegExp(property)}:([^;]*);`);

      cssRulesString = cssRulesString.replace(rulePattern, function (match, propertyStr) {
        if (propertyStr.match(propPattern)) {
          // property exists, replace value with new value
          propertyStr = propertyStr.replace(propPattern, (match, valueStr) => {
            return `${property}: ${value};`;
          });
        }
        propertyStr = propertyStr.trim();

        const replacer =
          `${rule} { ${propertyStr} }`;

        return replacer;
      });
    }

    return cssRulesString;
  }
  // no match, append new rule block
  return `${cssRulesString}${getCSSRuleBlock(rule, styleMap)}`;
}

export function removeCSSRule(rule, cssRulesString = '') {
  const rulePatternStr = `${escapeRegExp(rule)} {([^}]*)}`;
  const rulePattern = new RegExp(rulePatternStr, 'g');
  let output = cssRulesString;

  if (cssRulesString && cssRulesString.match(rulePattern)) {
    output = cssRulesString.replace(rulePattern, '');
  }

  return output.trim();
}

export function copyTextToClipboard(text) {
  // https://stackoverflow.com/a/30810322/5353542
  var textArea = document.createElement('textarea');

  //
  // *** This styling is an extra step which is likely not required. ***
  //
  // Why is it here? To ensure:
  // 1. the element is able to have focus and selection.
  // 2. if element was to flash render it has minimal visual impact.
  // 3. less flakyness with selection and copying which **might** occur if
  //    the textarea element is not visible.
  //
  // The likelihood is the element won't even render, not even a flash,
  // so some of these are just precautions. However in IE the element
  // is visible whilst the popup box asking the user for permission for
  // the web page to copy to the clipboard.
  //

  // Place in top-left corner of screen regardless of scroll position.
  textArea.style.position = 'fixed';
  textArea.style.top = 0;
  textArea.style.left = 0;

  // Ensure it has a small width and height. Setting to 1px / 1em
  // doesn't work as this gives a negative w/h on some browsers.
  textArea.style.width = '2em';
  textArea.style.height = '2em';

  // We don't need padding, reducing the size if it does flash render.
  textArea.style.padding = 0;

  // Clean up any borders.
  textArea.style.border = 'none';
  textArea.style.outline = 'none';
  textArea.style.boxShadow = 'none';

  // Avoid flash of white box if rendered for any reason.
  textArea.style.background = 'transparent';

  textArea.value = text;

  document.body.appendChild(textArea);

  textArea.select();

  try {
    document.execCommand('copy');
  } catch (err) {
    console.log('Oops, unable to copy');
  }

  document.body.removeChild(textArea);
}

export function isNumeric(val) {
  return !isNaN(val);
}

// https://stackoverflow.com/a/27078401
export function throttle(func, wait, options) {
  var context, args, result;
  var timeout = null;
  var previous = 0;
  if (!options) options = {};

  let later = function () {
    previous = options.leading === false ? 0 : Date.now();
    timeout = null;
    result = func.apply(context, args);
    if (!timeout) context = args = null;
  };

  return function () {
    var now = Date.now();
    if (!previous && options.leading === false) previous = now;
    let remaining = wait - (now - previous);
    context = this;
    args = arguments;
    if (remaining <= 0 || remaining > wait) {
      if (timeout) {
        clearTimeout(timeout);
        timeout = null;
      }
      previous = now;
      result = func.apply(context, args);
      if (!timeout) context = args = null;
    } else if (!timeout && options.trailing !== false) {
      timeout = setTimeout(later, remaining);
    }
    return result;
  };
};

export function promisify(fn, context = null) {
  return (...args) => {
    return new Promise(resolve => {
      setTimeout(() => {
        fn.apply(context, args);
        resolve('done', fn.name);
      }, 0);
    });
  };
};

export function chainPromises(promises) {
  return promises.reduce(
    (prev, cur) => prev.then(cur), Promise.resolve()
  );
};

export function linkProperties(target, source, properties) {
  const props = properties.reduce((acc, prop) => {
    acc[prop] = {
      get() {
        return source[prop];
      }
    };
    return acc;
  }, {});
  Object.defineProperties(target, props);
};