feat: initial implementation (#2)

* feat: add blog card

* chore: update package-lock

index.js

@@ -0,0 +1,60 @@
+
+const visit = require(`unist-util-visit`);
+
+module.exports = ({markdownAST}, options = {}) => {
+  const template = (prop) => `
+  <iframe 
+    style="width:100%;height:155px;max-width:680px;"
+    title="${prop.title}"
+    src="https://hatenablog-parts.com/embed?url=${prop.url}"
+    width="300"
+    height="200"
+    frameborder="0"
+    scrolling="no"
+    /></iframe>
+  `;
+
+  const isValidUrl = (userInput) => {
+    const match = userInput.match(
+        /(http(s)?:\/\/.)?(www\.)?[-a-zA-Z0-9@:%._\+~#=]{2,256}\.[a-z]{2,6}\b([-a-zA-Z0-9@:%_\+.~#?&//=]*)/g, /* eslint-disable-line max-len */
+    );
+    return (match !== null);
+  };
+
+  const find = (text) => {
+    const re = new RegExp(`\(blogcard\):\(\.\*\)`, 'i');
+    const match = text.match(re);
+
+    if (match == null) return null;
+
+    return match[2].trim();
+  };
+
+  const parse = (text) => {
+    const match = text.match(/\[(.*)\]\((.*)\)/);
+
+    const title = (match) ? match[1] : defaultTitle;
+    const url = (match) ? match[2] : text;
+
+    if (!isValidUrl(url)) return null;
+
+    return {
+      title: title,
+      url: url,
+    };
+  };
+  visit(markdownAST, `inlineCode`, (node) => {
+    const {value} = node;
+
+    const findValue = find(value);
+    if (findValue == null) return;
+
+    const parsedValue = parse(findValue);
+    if (parsedValue == null) return;
+
+    node.type = `html`;
+    node.value = template(parsedValue);
+  });
+
+  return markdownAST;
+};