Implement basic version of likes

app/javascript/components/LikeButton/LikeButtonP.tsx

@@ -0,0 +1,37 @@
+import * as React from 'react';
+
+interface Props {
+  postId: number;
+  likesCount: number;
+  liked: number;
+  handleLikeSubmit(
+    postId: number,
+    isLike: boolean,
+    authenticityToken: string,
+  ): void;
+  authenticityToken: string;
+  isLoggedIn: boolean;
+}
+
+const LikeButtonP = ({
+  postId,
+  likesCount,
+  liked,
+  handleLikeSubmit,
+  authenticityToken,
+  isLoggedIn,
+}: Props) => (
+  <div className="likeButtonContainer">
+    <button onClick={() =>
+      isLoggedIn ?
+        handleLikeSubmit(postId, !liked, authenticityToken)
+        :
+        window.location.href = `/users/sign_in`
+    }>
+      { liked ? 'down' : 'up' }
+    </button>
+    <span className="likesCountLabel">{likesCount}</span>
+  </div>
+);
+
+export default LikeButtonP;