const gulp = require("gulp");
const svgmin = require("gulp-svgmin");
const sass = require("gulp-sass")(require("sass"));
const footer = require("gulp-footer");
const yargs = require("yargs");
const fsPromise = require("fs").promises;
const path = require("path");

// global const
const deviconBaseCSSName = "devicon-base.css"
const deviconJSONName = "devicon.json";
const aliasSCSSName = "devicon-alias.scss";
const colorsCSSName = "devicon-colors.css";
const finalMinSCSSName = "devicon.min.scss";

//////// CSS Tasks ////////

/**
 * Create the devicon.min.css by creating needed
 * css files and compiling them together using Sass.
 */
async function createDeviconMinCSS() {
  await createCSSFiles();

  let deviconMinPath = path.join(__dirname, finalMinSCSSName);
  // recall that devicon-alias.scss imported the devicon-base.css => don't need
  // to reimport that file.
  const fileContent = `@use "${aliasSCSSName}";@use "${colorsCSSName}";`;
  await fsPromise.writeFile(deviconMinPath, fileContent, "utf8");

  return gulp
    .src(finalMinSCSSName)
    .pipe(sass.sync({ outputStyle: "compressed" }).on("error", sass.logError))
    .pipe(gulp.dest("./"));
}

/**
 * Create the devicon-alias.scss and the
 * devicon-colors.css from the devicon.json.
 */
async function createCSSFiles() {
  const deviconJson = JSON.parse(
    await fsPromise.readFile(path.join(__dirname, deviconJSONName), "utf8")
  );

  await Promise.all([
    createAliasSCSS(deviconJson),
    createColorsCSS(deviconJson)
  ]);
}

/**
 * Create an alias scss file in the root dir based on the devicon.json.
 * This function will use sass instead of normal css.
 * This is due to sass's ability to extend classes => Make it easier
 * to create aliases classes.
 * @param {Object} deviconJson, the object read from the
 * devicon.json file.
 * @return a Promise that'll resolve when the devicon-alias.scss is
 * created.
 */
function createAliasSCSS(deviconJson) {
  let statements = deviconJson.map(createAliasStatement).join(" ");
  let sass = `@use "${deviconBaseCSSName}";${statements}`;
  let sassPath = path.join(__dirname, aliasSCSSName);
  return fsPromise.writeFile(sassPath, sass, "utf8");
}

/**
 * Create the aliases statement by searching for the
 * techname in the statement and finding its aliases in
 * the deviconJson.
 * @param {Object} fontObj, a devicon font object.
 * @return a string representing a css statement of the
 * devicon-alias.scss.
 */
function createAliasStatement(fontObj) {
  let { name, aliases } = fontObj;

  return aliases
    .map(aliasObj => {
      return `.devicon-${name}-${aliasObj.alias} {
            @extend .devicon-${name}-${aliasObj.base};
        }`;
    })
    .join(" ");
}

/**
 * Create a colors css file in the root dir based on the deviconJson.
 * @param {Object} deviconJson, the object read from the
 * devicon.json file.
 * @return a Promise that'll resolve when the devicon-alias.scss is
 * created.
 */
function createColorsCSS(deviconJson) {
  // create the color statements for each font object
  let statements = deviconJson
    .map(fontObj => {
      let {
        name,
        versions: { font: fonts },
        color,
        aliases
      } = fontObj;

      if (fonts.length === 0 || typeof color !== "string") {
        console.log(`This object doesn't have a font or a color: ${name}`);
        return "";
      }

      // process the icons in the font attr
      let cssClasses = fonts.map((font) => `.devicon-${name}-${font}.colored`);

      // process the icons in the aliases attr
      aliases.forEach(aliasObj => {
        cssClasses.push(`.devicon-${name}-${aliasObj["alias"]}.colored`);
      });

      return `${cssClasses.join(",")}{color: ${color}}`;
    })
    .join(" ");

  let cssPath = path.join(__dirname, colorsCSSName);
  return fsPromise.writeFile(cssPath, statements, "utf8");
}

/**
 * Remove the devicon-alias.scss, devicon-colors.css,
 * and the devicon.min.scss.
 */
function cleanUp() {
  let fileNames = [aliasSCSSName, colorsCSSName, finalMinSCSSName];

  return Promise.all(
    fileNames.map(name => {
      try {
        let filePath = path.join(__dirname, name);
        return fsPromise.unlink(filePath);
      } catch (e) {
        console.log(e);
      }
    })
  );
}

//////// Update SVG Task ////////
/**
 * Update the svg by optimizing it
 * and prefixing its ids so it's unique across the repo.
 *
 * This requires a json list of svg file names to update.
 * This must be passed through the commandline arguments.
 */
function optimizeSvg() {
  let svgGlob = JSON.parse(yargs.argv.svgFiles);
  console.log("Optimizing these files: ", svgGlob);
  return gulp
    .src(svgGlob)
    .pipe(svgmin(configOptionCallback))
    .pipe(footer("\n"))
    .pipe(
      gulp.dest(file => {
        return file.base;
      })
    );
}

/**
 * Create a config option for each file.
 * @param {Object} file - Gulp Vinyl instance of the file
 * being processed.
 * @returns a SVGO config object.
 */
function configOptionCallback(file) {
  return {
    plugins: [
      {
        prefixIds: {
          prefix: file.stem, // add file name to ids
          delim: "-"
        },
      },
      {
        removeViewBox: false // keep viewbox
      },
      {
        removeDimensions: true // remove height and width
      }
    ]
  };
}

exports.updateCss = createDeviconMinCSS;
exports.clean = cleanUp;
exports.optimizeSvg = optimizeSvg;