exports.activate = function () {
  if (!atom.grammars.addInjectionPoint) return;

  atom.grammars.addInjectionPoint('source.js', {
    type: 'call_expression',

    language(callExpression) {
      const { firstChild } = callExpression;
      switch (firstChild.type) {
        case 'identifier':
          return languageStringForTemplateTag(firstChild.text);
        case 'call_expression':
          return languageStringForTemplateTag(firstChild.children[0].text);
        case 'member_expression':
          if (firstChild.startPosition.row === firstChild.endPosition.row) {
            return languageStringForTemplateTag(firstChild.text);
          }
      }
    },

    content(callExpression) {
      const { lastChild } = callExpression;
      if (lastChild.type === 'template_string') {
        return stringFragmentsOfTemplateString(lastChild);
      }
    }
  });

  atom.grammars.addInjectionPoint('source.js', {
    type: 'assignment_expression',

    language(expression) {
      const { firstChild } = expression;
      if (firstChild.type === 'member_expression') {
        if (firstChild.lastChild.text === 'innerHTML') {
          return 'html';
        }
      }
    },

    content(expression) {
      const { lastChild } = expression;
      if (lastChild.type === 'template_string') {
        return stringFragmentsOfTemplateString(lastChild);
      }
    }
  });

  atom.grammars.addInjectionPoint('source.js', {
    type: 'regex_pattern',
    language() {
      return 'js-regex';
    },
    content(regex) {
      return regex;
    },
    languageScope: null
  });

  atom.grammars.addInjectionPoint('source.js', {
    type: 'comment',
    language(comment) {
      if (comment.text.startsWith('/**')) return 'jsdoc';
    },
    content(comment) {
      return comment;
    },
    languageScope: null,
    coverShallowerScopes: true
  });
};

exports.consumeHyperlinkInjection = (hyperlink) => {
  hyperlink.addInjectionPoint('source.js', {
    types: ['comment', 'template_string', 'string_fragment']
  });
};

exports.consumeTodoInjection = (todo) => {
  todo.addInjectionPoint('source.js', { types: ['comment'] });
};

const CSS_REGEX = /\bstyled\b|\bcss\b/i;
const GQL_REGEX = /\bgraphql\b|\bgql\b/i;
const SQL_REGEX = /\bsql\b/i;

function languageStringForTemplateTag(tag) {
  if (CSS_REGEX.test(tag)) {
    return 'CSS';
  } else if (GQL_REGEX.test(tag)) {
    return 'GraphQL';
  } else if (SQL_REGEX.test(tag)) {
    return 'SQL';
  } else {
    return tag;
  }
}

function stringFragmentsOfTemplateString(templateStringNode) {
  return templateStringNode.children.filter(
    c => c.type === 'string_fragment'
  );
}