'use strict';

const fs = require('fs');
const path = require('path');
const SVGO = require('svgo');
const dot = require('dot');
const LruCache = require('./lru-cache');
const isCSSColor = require('is-css-color');

// Holds widths of badge keys (left hand side of badge).
const badgeKeyWidthCache = new LruCache(1000);

// cache templates.
const templates = {};
const templateFiles = fs.readdirSync(path.join(__dirname, '..', 'templates'));
dot.templateSettings.strip = false;  // Do not strip whitespace.
templateFiles.forEach(async function(filename) {
  if (filename[0] === '.') { return; }
  const templateData = fs.readFileSync(
    path.join(__dirname, '..', 'templates', filename)).toString();
  const extension = path.extname(filename).slice(1);
  const style = filename.slice(0, -(('-template.' + extension).length));
  // Compile the template. Necessary to always have a working template.
  templates[style + '-' + extension] = dot.template(templateData);
  if (extension === 'svg') {
    // Substitute dot code.
    const mapping = new Map();
    let mappingIndex = 1;
    const untemplatedSvg = templateData.replace(/{{.*?}}/g, function(match) {
      // Weird substitution that currently works for all templates.
      const mapKey = '99999990' + mappingIndex + '.1';
      mappingIndex++;
      mapping.set(mapKey, match);
      return mapKey;
    });

    const svgo = new SVGO();
    const { data, error } = await svgo.optimize(untemplatedSvg);

    if (error !== undefined) {
      console.error(`Template ${filename}: ${error}\n` +
        '  Generated untemplated SVG:\n' +
        `---\n${untemplatedSvg}---\n`);
      return;
    }

    // Substitute dot code back.
    let svg = data;
    const unmappedKeys = [];
    mapping.forEach(function(value, key) {
      let keySubstituted = false;
      svg = svg.replace(RegExp(key, 'g'), function() {
        keySubstituted = true;
        return value;
      });
      if (!keySubstituted) {
        unmappedKeys.push(key);
      }
    });
    if (unmappedKeys.length > 0) {
      console.error(`Template ${filename} has unmapped keys ` +
        `${unmappedKeys.join(', ')}.\n` +
        '  Generated untemplated SVG:\n' +
        `---\n${untemplatedSvg}\n---\n` +
        '  Generated template:\n' +
        `---\n${svg}\n---\n`);
      return;
    }

    templates[style + '-' + extension] = dot.template(svg);
  }
});

function escapeXml(s) {
  if (s === undefined || typeof s !== 'string') {
    return undefined;
  } else {
    return s.replace(/&/g, '&')
            .replace(/</g, '&lt;')
            .replace(/>/g, '&gt;')
            .replace(/"/g, '&quot;')
            .replace(/'/g, '&apos;');
  }
}

function capitalize(s) {
  return s.charAt(0).toUpperCase() + s.slice(1);
}

// check if colorA/B is a colorscheme else check if it's a valid css3 color else return undefined and let the badge assign the default color
function assignColor(color = '', colorschemeType = 'colorB') {
  if (definedColorschemes[color] !== undefined) {
    return definedColorschemes[color][colorschemeType] || undefined;
  } else if (isCSSColor(color)) {
    return color;
  } else {
    return undefined;
  }
}

const definedColorschemes = require(path.join(__dirname, 'colorscheme.json'));

// Inject the measurer to avoid placing any persistent state in this module.
function makeBadge (measurer, {
  format,
  template,
  text,
  colorscheme,
  colorA,
  colorB,
  logo,
  logoPosition,
  logoWidth,
  links = ['', ''],
}) {
  // String coercion.
  text = text.map(value => '' + value);

  if (format !== 'json') {
    format = 'svg';
  }

  if (!(`${template}-${format}` in templates)) {
    template = format === 'svg' ? 'flat' : 'default';
  }
  if (template.startsWith('popout')) {
    if (logo){
      logoPosition = (logoPosition <= 10 && logoPosition >= -10) ? logoPosition : 0;
      logoWidth = +logoWidth || 32;
    } else {
      template = template.replace('popout', 'flat');
    }
  }
  if (template === 'social') {
    text[0] = capitalize(text[0]);
  } else if (template === 'for-the-badge') {
    text = text.map(value => value.toUpperCase());
  }

  // colorA/B have a higher priority than colorscheme
  colorA = colorA || colorscheme || undefined;
  colorB = colorB || colorscheme || undefined;
  colorA = assignColor(colorA, 'colorA');
  colorB = assignColor(colorB, 'colorB');

  const [left, right] = text;
  let leftWidth = badgeKeyWidthCache.get(left);
  if (leftWidth === undefined) {
    leftWidth = measurer.widthOf(left) | 0;
    // Increase chances of pixel grid alignment.
    if (leftWidth % 2 === 0) { leftWidth++; }
    badgeKeyWidthCache.set(left, leftWidth);
  }
  let rightWidth = measurer.widthOf(right) | 0;
  // Increase chances of pixel grid alignment.
  if (rightWidth % 2 === 0) { rightWidth++; }

  logoWidth = +logoWidth || (logo ? 14 : 0);

  let logoPadding;
  if (left.length === 0) {
    logoPadding = 0;
  } else {
    logoPadding = logo ? 3 : 0;
  }

  const context = {
    text: [left, right],
    escapedText: text.map(escapeXml),
    widths: [
      leftWidth + 10 + logoWidth + logoPadding,
      rightWidth + 10,
    ],
    links: links.map(escapeXml),
    logo,
    logoPosition,
    logoWidth,
    logoPadding,
    colorA,
    colorB,
    escapeXml,
  };

  const templateFn = templates[`${template}-${format}`];

  // The call to template() can raise an exception.
  return templateFn(context);
}

module.exports = {
  makeBadge,
  makeMakeBadgeFn: measurer => data => makeBadge(measurer, data),
  // Expose for testing.
  _badgeKeyWidthCache: badgeKeyWidthCache,
};