Set up documentation website generation and deployment (#253)

Generating the website is done by Jekyll with a theme called `just-the-docs`. 
Deployment of the website is done via GitHub Pages.

See:
- https://github.com/jekyll/jekyll
- https://github.com/just-the-docs/just-the-docs

.github/workflows/build.yaml

@@ -2,8 +2,7 @@ name: Build and verify
 on:
   pull_request:
   push:
-    branches:
-      - 'master'
+    branches: [$default-branch]
 permissions:
   contents: read
 jobs:

.github/workflows/deploy-website.yaml

@@ -0,0 +1,45 @@
+name: Update `error-prone.picnic.tech` website content
+on:
+  pull_request:
+  push:
+    branches: [$default-branch]
+permissions:
+  contents: read
+  id-token: write
+  pages: write
+concurrency:
+  group: pages
+  cancel-in-progress: true
+jobs:
+  build:
+    runs-on: ubuntu-22.04
+    steps:
+      - name: Check out code
+        uses: actions/checkout@v3.0.2
+      - name: Configure Github Pages
+        uses: actions/configure-pages@v2.1.1
+      - name: Generate documentation
+        run: ./generate-docs.sh
+      - name: Build website with Jekyll
+        uses: actions/jekyll-build-pages@v1.0.5
+        with:
+          source: website/
+          destination: ./_site
+      - name: Validate HTML output
+        uses: anishathalye/proof-html@v1.4.1
+        with:
+          directory: ./_site
+          check_external_hash: false
+      - name: Upload website as artifact
+        uses: actions/upload-pages-artifact@v1.0.4
+  deploy:
+    if: github.ref == format('refs/heads/{0}', github.event.repository.default_branch)
+    needs: build
+    runs-on: ubuntu-22.04
+    environment:
+      name: github-pages
+      url: ${{ steps.deployment.outputs.page_url }}
+    steps:
+      - name: Deploy to GitHub Pages
+        id: deployment
+        uses: actions/deploy-pages@v1.2.1

README.md

@@ -1,10 +1,10 @@
 <div align="center">
-
   <picture>
-  <source media="(prefers-color-scheme: dark)" srcset="logo-dark.svg">
-  <source media="(prefers-color-scheme: light)" srcset="logo.svg">
-  <img alt="Error Prone Support logo" src="logo.svg" width="50%">
+    <source media="(prefers-color-scheme: dark)" srcset="website/assets/images/logo-dark.svg">
+    <source media="(prefers-color-scheme: light)" srcset="website/assets/images/logo.svg">
+    <img alt="Error Prone Support logo" src="website/assets/images/logo.svg" width="50%">
   </picture>
+</div>
 
 # Error Prone Support
 
@@ -24,8 +24,6 @@ focussing on maintainability, consistency and avoidance of common pitfalls.
 [Developing Error Prone Support](#-developing-error-prone-support) •
 [How it works](#-how-it-works) • [Contributing](#%EF%B8%8F-contributing)
 
-</div>
-
 ---
 
 ## ⚡ Getting started
@@ -201,9 +199,9 @@ Want to report or fix a bug, suggest or add a new feature, or improve the
 documentation? That's awesome! Please read our [contribution
 guidelines][contributing].
 
-[bug-checks]: error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/
-[bug-checks-identity-conversion]: error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/IdentityConversion.java
-[contributing]: CONTRIBUTING.md
+[bug-checks]: https://github.com/PicnicSupermarket/error-prone-support/blob/master/error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/
+[bug-checks-identity-conversion]: https://github.com/PicnicSupermarket/error-prone-support/blob/master/error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/IdentityConversion.java
+[contributing]: https://github.com/PicnicSupermarket/error-prone-support/blob/master/CONTRIBUTING.md
 [error-prone-bugchecker]: https://github.com/google/error-prone/blob/master/check_api/src/main/java/com/google/errorprone/bugpatterns/BugChecker.java
 [error-prone-fork-jitpack]: https://jitpack.io/#PicnicSupermarket/error-prone
 [error-prone-fork-repo]: https://github.com/PicnicSupermarket/error-prone
@@ -215,7 +213,7 @@ guidelines][contributing].
 [google-java-format]: https://github.com/google/google-java-format
 [idea-288052]: https://youtrack.jetbrains.com/issue/IDEA-288052
 [license-badge]: https://img.shields.io/github/license/PicnicSupermarket/error-prone-support
-[license]: LICENSE.md
+[license]: https://github.com/PicnicSupermarket/error-prone-support/blob/master/LICENSE.md
 [maven-central-badge]: https://img.shields.io/maven-central/v/tech.picnic.error-prone-support/error-prone-support?color=blue
 [maven-central-search]: https://search.maven.org/artifact/tech.picnic.error-prone-support/error-prone-support
 [maven]: https://maven.apache.org
@@ -224,5 +222,5 @@ guidelines][contributing].
 [pitest-maven]: https://pitest.org/quickstart/maven
 [pr-badge]: https://img.shields.io/badge/PRs-welcome-brightgreen.svg
 [refaster]: https://errorprone.info/docs/refaster
-[refaster-templates-bigdecimal]: error-prone-contrib/src/main/java/tech/picnic/errorprone/refastertemplates/BigDecimalTemplates.java
-[refaster-templates]: error-prone-contrib/src/main/java/tech/picnic/errorprone/refastertemplates/
+[refaster-templates-bigdecimal]: https://github.com/PicnicSupermarket/error-prone-support/blob/master/error-prone-contrib/src/main/java/tech/picnic/errorprone/refastertemplates/BigDecimalTemplates.java
+[refaster-templates]: https://github.com/PicnicSupermarket/error-prone-support/blob/master/error-prone-contrib/src/main/java/tech/picnic/errorprone/refastertemplates/

generate-docs.sh

@@ -0,0 +1,27 @@
+#!/usr/bin/env bash
+
+set -e -u -o pipefail
+
+REPOSIORY_ROOT="$(git rev-parse --show-toplevel)"
+WEBSITE_ROOT="${REPOSIORY_ROOT}/website"
+
+generate_homepage() {
+    local homepage="${WEBSITE_ROOT}/index.md"
+
+    echo "Generating ${homepage}..."
+    cat - "${REPOSIORY_ROOT}/README.md" > "${homepage}" << EOF
+---
+layout: default
+title: Home
+nav_order: 1
+---
+EOF
+
+    local macos_compat=""
+    [[ "${OSTYPE}" == "darwin"* ]] && macos_compat="yes"
+    sed -i ${macos_compat:+".bak"} 's/src="website\//src="/g' "${homepage}"
+    sed -i ${macos_compat:+".bak"} 's/srcset="website\//srcset="/g' "${homepage}"
+}
+
+# Generate the website.
+generate_homepage

website/.gitignore

@@ -0,0 +1,12 @@
+# Generated by Bundler and Jekyll.
+.bundle/
+Gemfile.lock
+.jekyll-cache/
+.jekyll-metadata
+.sass-cache/
+_site/
+vendor/
+
+# Generated by `../generate-docs.sh`.
+*.bak
+index.md

website/404.md

@@ -0,0 +1,11 @@
+---
+layout: default
+title: Page not found
+permalink: /404
+nav_exclude: true
+search_exclude: true
+---
+
+## Page not found :(
+
+The requested page could not be found.

website/Gemfile

@@ -0,0 +1,5 @@
+source "https://rubygems.org"
+gem "github-pages", "227"
+gem "html-proofer", "4.4.1"
+gem "jekyll-remote-theme", "0.4.3"
+gem "rake", "13.0.6"

website/README.md

@@ -0,0 +1,38 @@
+# Error Prone Support website
+
+This directory contains the majority of the source code that powers
+[error-prone.picnic.tech][error-prone-support-website]. The website is
+statically generated using [Jekyll][jekyll].
+
+# Local development
+
+To view the website on `localhost`, first follow the [Jekyll installation
+instructions][jekyll-docs-installation]. Once done, in this directory execute:
+
+```sh
+bundle install
+../generate-docs.sh && bundle exec jekyll serve --livereload
+```
+
+The website will now be [available][localhost-port-4000] on port 4000. Source
+code modifications (including the result of rerunning `../generate-docs.sh`)
+will automatically be reflected. (An exception is `_config.yml`: changes to
+this file require a server restart.) Subsequent server restarts do not require
+running `bundle install`, unless `Gemfile` has been updated in the interim.
+
+If you are not familiar with Jekyll, be sure to check out its
+[documentation][jekyll-docs]. It is recommended to follow the provided
+step-by-step tutorial.
+
+# Deployment
+
+The website is regenerated and deployed using the
+[`deploy-website.yaml`][error-prone-support-website-deploy-workflow] GitHub
+Actions workflow any time a change is merged to `master`.
+
+[error-prone-support-website]: https://error-prone.picnic.tech
+[error-prone-support-website-deploy-workflow]: https://github.com/PicnicSupermarket/error-prone-support/actions/workflows/deploy-website.yaml
+[jekyll]: https://jekyllrb.com
+[jekyll-docs]: https://jekyllrb.com/docs/
+[jekyll-docs-installation]: https://jekyllrb.com/docs/installation/
+[localhost-port-4000]: http://127.0.0.1:4000

website/_config.yml

@@ -0,0 +1,46 @@
+# General configuration.
+title: Error Prone Support
+logo: assets/images/favicon.svg
+url: https://error-prone.picnic.tech
+description: >-
+  Error Prone extensions: extra bug checkers and a large battery of Refaster
+  templates.
+
+# XXX: Investigate dropping the remote theme by instead managing just-the-docs
+# using Bundler. This requires changes to the build setup. The upshot is that
+# local and CI build environments would then be in sync.
+# https://github.com/PicnicSupermarket/error-prone-support/pull/253#discussion_r982709523
+remote_theme: just-the-docs/just-the-docs@v0.4.0.rc2
+plugins:
+  - jekyll-remote-theme
+  - jekyll-sitemap
+
+# Files and directories not to be deployed through GitHub pages.
+exclude:
+  - Gemfile
+  - Gemfile.lock
+  - README.md
+  - vendor
+
+# See https://jekyllrb.com/docs/permalinks/#built-in-formats.
+permalink: pretty
+
+# Theme (just-the-docs) configuration.
+# See
+# https://just-the-docs.github.io/just-the-docs/docs/navigation-structure/#external-navigation-links.
+nav_external_links:
+  - title: Error Prone Support on GitHub
+    url: https://github.com/PicnicSupermarket/error-prone-support
+    hide_icon: false
+
+# SEO configuration.
+# See https://jekyll.github.io/jekyll-seo-tag/usage.
+social:
+  name: Picnic
+  links:
+    - https://github.com/PicnicSupermarket
+    - https://twitter.com/picnic
+    - https://www.linkedin.com/company/picnictechnologies
+twitter:
+  username: picnic
+  card: summary

website/_includes/footer_custom.html

@@ -0,0 +1,5 @@
+<img src="/assets/images/picnic-logo@2x.png" alt="Picnic Logo" id="logo" />
+
+<p align="center">
+    Copyright &copy; 2017-2022 Picnic Technologies BV
+</p>

website/_includes/head_custom.html

@@ -0,0 +1,18 @@
+<!-- Generated using https://realfavicongenerator.net. -->
+<link rel="apple-touch-icon" sizes="180x180" href="/assets/images/apple-touch-icon.png">
+<link rel="icon" type="image/png" sizes="32x32" href="/assets/images/favicon-32x32.png">
+<link rel="icon" type="image/png" sizes="16x16" href="/assets/images/favicon-16x16.png">
+<link rel="manifest" href="/assets/images/site.webmanifest">
+<link rel="mask-icon" href="/assets/images/safari-pinned-tab.svg" color="#5bbad5">
+<link rel="shortcut icon" href="/favicon.ico">
+<meta name="msapplication-TileColor" content="#da532c">
+<meta name="msapplication-config" content="/assets/images/browserconfig.xml">
+<meta name="theme-color" content="#ffffff">
+
+<!-- XXX: The theme does not natively support both light and dark mode. Drop
+this section once https://github.com/just-the-docs/just-the-docs/issues/234 is
+resolved. -->
+<link rel="stylesheet" href="{{ '/assets/css/just-the-docs-light.css' | relative_url }}"
+    media="(prefers-color-scheme: light)">
+<link rel="stylesheet" href="{{ '/assets/css/just-the-docs-dark.css' | relative_url }}"
+    media="(prefers-color-scheme: dark)">

website/_sass/custom/custom.scss

@@ -0,0 +1,21 @@
+// XXX: We should override `$nav-width(-md)`, but this breaks code highlighting
+// and other styles. See
+// https://github.com/just-the-docs/just-the-docs/issues/982.
+// Once the fix for the above issue is released, replace this section with the
+// approach recommended at
+// https://just-the-docs.github.io/just-the-docs/docs/customization/#custom-schemes.
+@include mq(lg) {
+    .side-bar {
+        min-width: 400px;
+    }
+
+    .site-nav, .site-header {
+        width: 400px;
+    }
+}
+
+footer > img#logo {
+    width: 2rem;
+    margin: 0 auto;
+    display: block;
+}

website/assets/images/browserconfig.xml

@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="utf-8"?>
+<browserconfig>
+    <msapplication>
+        <tile>
+            <square150x150logo src="/assets/images/mstile-150x150.png"/>
+            <TileColor>#da532c</TileColor>
+        </tile>
+    </msapplication>
+</browserconfig>

website/assets/images/safari-pinned-tab.svg

@@ -0,0 +1,88 @@
+<?xml version="1.0" standalone="no"?>
+<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 20010904//EN"
+ "http://www.w3.org/TR/2001/REC-SVG-20010904/DTD/svg10.dtd">
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+ width="2623.000000pt" height="2623.000000pt" viewBox="0 0 2623.000000 2623.000000"
+ preserveAspectRatio="xMidYMid meet">
+<metadata>
+Created by potrace 1.14, written by Peter Selinger 2001-2017
+</metadata>
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website/assets/images/site.webmanifest

@@ -0,0 +1,19 @@
+{
+    "name": "Error Prone Support documentation",
+    "short_name": "Error Prone Support",
+    "icons": [
+        {
+            "src": "/assets/images/android-chrome-192x192.png",
+            "sizes": "192x192",
+            "type": "image/png"
+        },
+        {
+            "src": "/assets/images/android-chrome-512x512.png",
+            "sizes": "512x512",
+            "type": "image/png"
+        }
+    ],
+    "theme_color": "#ffffff",
+    "background_color": "#ffffff",
+    "display": "standalone"
+}

website/bugpatterns.md

@@ -0,0 +1,8 @@
+---
+layout: default
+title: Bug Patterns
+nav_order: 2
+has_children: true
+---
+
+# Bug Patterns

website/refastertemplates.md

@@ -0,0 +1,8 @@
+---
+layout: default
+title: Refaster templates
+nav_order: 2
+has_children: true
+---
+
+# Refaster templates