Extract wiki page layout

src/components/tree/List.astro

@@ -1,11 +1,11 @@
 ---
-import { Tree, pathify } from "@utils/tree";
-import type { Maybe } from "purify-ts";
+import { PageTree, pathify } from "@utils/tree";
+import { Maybe } from "purify-ts";
 
 
 interface Props {
-  tree: Tree;
-  slug: string;
+  tree: PageTree;
+  slug: Maybe<string>;
   prefix: Maybe<string>;
 }
 
@@ -17,6 +17,12 @@ function compare(a: {title: string}, b: {title: string}) {
     sensitivity: "base",
   });
 }
+
+function checkCurrent(checked: Maybe<string>)  {
+  return Maybe
+    .sequence([checked, slug])
+    .mapOrDefault(([a, b]) => a == pathify(b), false)
+}
 ---
 
 {tree.children
@@ -26,7 +32,7 @@ function compare(a: {title: string}, b: {title: string}) {
     <ul class="link-tree__nav-list">
       {pages
         .sort(compare)
-        .map(page => ({...page, current: page.slug.mapOrDefault(other => other === pathify(slug), false)}))
+        .map(page => ({...page, current: checkCurrent(page.slug) }))
         .map(page => 
           <li class="link-tree__nav-list-item">
             {page.slug

src/components/tree/Tree.astro

@@ -1,13 +1,13 @@
 ---
 import List from "./List.astro";
-import { Tree, pathify } from "@utils/tree";
+import { PageTree, pathify } from "@utils/tree";
 import type { Maybe } from "purify-ts";
 
 
 interface Props {
   heading: string;
-  tree: Tree;
-  slug: string;
+  tree: PageTree;
+  slug: Maybe<string>;
   prefix: Maybe<string>;
 }
 

src/layouts/Wiki.astro

@@ -0,0 +1,48 @@
+---
+import Base from "@layouts/Base.astro";
+import Tree from "@components/tree/Tree.astro";
+import { getCollection } from "astro:content";
+import { Maybe, MaybeAsync } from "purify-ts";
+import { collapse, type PageTree } from "@utils/tree";
+
+
+interface Props {
+  frontmatter: {
+    title: string;
+  };
+  slug?: string;
+  tree?: PageTree;
+}
+
+const {
+  frontmatter,
+  slug,
+  tree,
+} = Astro.props;
+
+
+function constructTree(tree?: PageTree) {
+  return MaybeAsync
+    .liftMaybe(Maybe.fromNullable(tree))
+    .alt(
+      MaybeAsync(async () => await getCollection('wiki'))
+        .map(collapse));
+} 
+
+const pageTree = (await constructTree(tree))
+  .orDefaultLazy(() => { throw new Error("Couldn't load page tree") });
+---
+
+<Base>
+  <main class="wiki-main">
+    <Tree heading="Personal Wiki"
+      tree={pageTree}
+      slug={Maybe.fromNullable(slug)}
+      prefix={Maybe.of("/wiki/")}
+    />
+    <article class="wiki-article markdown">
+      <h1>{frontmatter.title}</h1>
+      <slot />
+    </article>
+  </main>
+</Base>

src/pages/wiki/[...slug].astro

@@ -1,10 +1,8 @@
 ---
-import Tree from '@components/tree/Tree.astro';
-import Base from '@layouts/Base.astro';
 import type { InferGetStaticPropsType } from 'astro';
 import { getCollection } from 'astro:content';
-import { Maybe } from 'purify-ts';
 import { collapse } from '@utils/tree';
+import Wiki from '@layouts/Wiki.astro';
 
 
 type Props = InferGetStaticPropsType<typeof getStaticPaths>;
@@ -19,12 +17,6 @@ const { tree, entry } = Astro.props;
 const { Content } = await entry.render();
 ---
 
-<Base>
-  <main class="wiki-main">
-    <Tree heading="Personal Wiki" tree={tree} slug={entry.slug} prefix={Maybe.of("/wiki/")}/>
-    <article class="wiki-article markdown">
-      <h1>{entry.data.title}</h1>
-      <Content />
-    </article>
-  </main>
-</Base>
+<Wiki slug={entry.slug} frontmatter={entry.data} tree={tree}>
+  <Content />
+</Wiki>

src/pages/wiki/index.astro

@@ -1,18 +0,0 @@
----
-import Base from "@layouts/Base.astro";
-import Tree from "@components/tree/Tree.astro";
-import { collapse } from "@utils/tree";
-import { getCollection } from "astro:content";
-import { Maybe } from "purify-ts";
-
-const tree = collapse(await getCollection('wiki'));
----
-
-<Base>
-  <main class="wiki-main">
-    <Tree heading="Personal Wiki" tree={tree} slug="wiki" prefix={Maybe.of("wiki")} />
-    <article class="wiki-article">
-      siema
-    </article>
-  </main>
-</Base>

src/pages/wiki/index.md

@@ -0,0 +1,6 @@
+---
+layout: ../../layouts/Wiki.astro
+title: Wiki home page
+---
+
+Hello

src/utils/tree.ts

@@ -6,14 +6,14 @@ interface Page {
   data: { title: string };
 }
 
-export interface Tree {
+export interface PageTree {
   title: string;
   slug: Maybe<string>;
-  children: Maybe<{ [key: string]: Tree }>;
+  children: Maybe<{ [key: string]: PageTree }>;
 }
 
-export function collapse(pages: Page[]): Tree {
-  const root: Tree = { title: '', slug: Maybe.empty(), children: Maybe.empty() };
+export function collapse(pages: Page[]): PageTree {
+  const root: PageTree = { title: '', slug: Maybe.empty(), children: Maybe.empty() };
 
   for (const page of pages) {
     const ptr = page.slug.split('/')