/* global API_METHODS usercss styleManager deepCopy */
/* exported usercssHelper */
'use strict';

const usercssHelper = (() => {
  API_METHODS.installUsercss = installUsercss;
  API_METHODS.editSaveUsercss = editSaveUsercss;
  API_METHODS.configUsercssVars = configUsercssVars;

  API_METHODS.buildUsercss = build;
  API_METHODS.buildUsercssMeta = buildMeta;
  API_METHODS.findUsercss = find;

  function buildMeta(style) {
    if (style.usercssData) {
      return Promise.resolve(style);
    }

    // allow sourceCode to be normalized
    const {sourceCode} = style;
    delete style.sourceCode;

    return usercss.buildMeta(sourceCode)
      .then(newStyle => Object.assign(newStyle, style));
  }

  function assignVars(style) {
    return find(style)
      .then(dup => {
        if (dup) {
          style.id = dup.id;
          // preserve style.vars during update
          return usercss.assignVars(style, dup)
            .then(() => style);
        }
        return style;
      });
  }

  /**
   * Parse the source, find the duplication, and build sections with variables
   * @param _
   * @param {String} _.sourceCode
   * @param {Boolean=} _.checkDup
   * @param {Boolean=} _.metaOnly
   * @param {Object} _.vars
   * @param {Boolean=} _.assignVars
   * @returns {Promise<{style, dup:Boolean?}>}
   */
  function build({
    styleId,
    sourceCode,
    checkDup,
    metaOnly,
    vars,
    assignVars = false,
  }) {
    return usercss.buildMeta(sourceCode)
      .then(style => {
        const findDup = checkDup || assignVars ?
          find(styleId ? {id: styleId} : style) : Promise.resolve();
        return Promise.all([
          metaOnly ? style : doBuild(style, findDup),
          findDup,
        ]);
      })
      .then(([style, dup]) => ({style, dup}));

    function doBuild(style, findDup) {
      if (vars || assignVars) {
        const getOld = vars ? Promise.resolve({usercssData: {vars}}) : findDup;
        return getOld
          .then(oldStyle => usercss.assignVars(style, oldStyle))
          .then(() => usercss.buildCode(style));
      }
      return usercss.buildCode(style);
    }
  }

  // Build the style within aditional properties then inherit variable values
  // from the old style.
  function parse(style) {
    return buildMeta(style)
      .then(buildMeta)
      .then(assignVars)
      .then(usercss.buildCode);
  }

  // FIXME: simplify this to `installUsercss(sourceCode)`?
  function installUsercss(style) {
    return parse(style)
      .then(styleManager.installStyle);
  }

  // FIXME: simplify this to `editSaveUsercss({sourceCode, exclusions})`?
  function editSaveUsercss(style) {
    return parse(style)
      .then(styleManager.editSave);
  }

  function configUsercssVars(id, vars) {
    return styleManager.get(id)
      .then(style => {
        const newStyle = deepCopy(style);
        newStyle.usercssData.vars = vars;
        return usercss.buildCode(newStyle);
      })
      .then(style => styleManager.installStyle(style, 'config'))
      .then(style => style.usercssData.vars);
  }

  /**
   * @param {Style|{name:string, namespace:string}} styleOrData
   * @returns {Style}
   */
  function find(styleOrData) {
    if (styleOrData.id) {
      return styleManager.get(styleOrData.id);
    }
    const {name, namespace} = styleOrData.usercssData || styleOrData;
    return styleManager.getAllStyles().then(styleList => {
      for (const dup of styleList) {
        const data = dup.usercssData;
        if (!data) continue;
        if (data.name === name &&
            data.namespace === namespace) {
          return dup;
        }
      }
    });
  }
})();