add javascript to insert download buttons

_includes/head_custom.html

@@ -1 +1,2 @@
 <link rel="shortcut icon" href="https://raw.githubusercontent.com/f3d-app/f3d/master/resources/logo.ico" type="image/x-icon">
+<script type="application/javascript" src="{{site.baseurl}}/assets/main.js"></script>

_sass/custom/custom.scss

@@ -36,3 +36,13 @@ kbd {
     // Transition is fun
     transition: all 0.1s;
 }
+
+div.install-buttons {
+    text-align: center;
+    display: block;
+    line-height: 1;
+
+    .btn {
+        margin: .5em;
+    }
+}

assets/main.js

@@ -0,0 +1,90 @@
+function onload(event) {
+  if (window.location.pathname.endsWith("/INSTALLATION.html")) {
+    enhance_install_page();
+  }
+}
+
+function enhance_install_page() {
+  function retrieve_downloads(target_platform_re) {
+    var downloads = [];
+    for (const table of document.querySelectorAll("table")) {
+      const th = document.querySelector("th");
+      if (th) {
+        if (/Platform/i.test(th.innerText)) {
+          for (const table_row of table.querySelectorAll("tr")) {
+            const table_cols = table_row.querySelectorAll("td");
+            if (table_cols.length > 1) {
+              const link = table_cols[1].querySelector("a");
+              if (link) {
+                const platform = table_cols[0].innerText;
+                if (target_platform_re.test(platform))
+                  downloads.push([platform, link.innerText, link.href]);
+              }
+            }
+          }
+          break; // stop after first relevant table
+        }
+      }
+    }
+    return downloads;
+  }
+
+  /* check OS: first check for `?os=foo` in the URL, otherwise guess form user agent */
+  const params = new URLSearchParams(window.location.search);
+  const current_os = params.get("os") || guess_client_OS();
+
+  if (current_os == null) return;
+
+  /* find download links matching the OS */
+  const target_platform_re = RegExp(`(${current_os})`, "i");
+  const downloads = retrieve_downloads(target_platform_re);
+
+  if (downloads.length < 1) return;
+
+  /* create a box below the first header to insert buttons */
+  const header = document.querySelector("h1");
+  if (header == null) return;
+  const div = document.createElement("div");
+  div.setAttribute("class", "install-buttons");
+  header.parentNode.insertBefore(div, header.nextSibling);
+
+  /* create download button for each matching link */
+  var i = 0;
+  for ([platform, filename, url] of downloads) {
+    const bolded_platform = platform.replace(target_platform_re, "<b>$1</b>");
+    const link = document.createElement("a");
+    link.setAttribute("href", url);
+    link.setAttribute("class", i++ ? "btn" : "btn btn-primary");
+    link.innerHTML = `<div>Get <b>F3D</b> for ${bolded_platform}</div><small>${filename}</small>`;
+    div.append(link);
+  }
+  const note = document.createElement("div");
+  note.innerHTML = "<small>or see other available versions below</small>";
+  div.append(note);
+}
+
+function guess_client_OS() {
+  /* https://stackoverflow.com/a/38241481 */
+  const userAgent = window.navigator.userAgent;
+  const platform =
+    window.navigator?.userAgentData?.platform || window.navigator.platform;
+  const macosPlatforms = ["macOS", "Macintosh", "MacIntel", "MacPPC", "Mac68K"];
+  const windowsPlatforms = ["Win32", "Win64", "Windows", "WinCE"];
+  const iosPlatforms = ["iPhone", "iPad", "iPod"];
+
+  if (macosPlatforms.indexOf(platform) !== -1) {
+    return "MacOS";
+  } else if (iosPlatforms.indexOf(platform) !== -1) {
+    return "iOS";
+  } else if (windowsPlatforms.indexOf(platform) !== -1) {
+    return "Windows";
+  } else if (/Android/.test(userAgent)) {
+    return "Android";
+  } else if (/Linux/.test(platform)) {
+    return "Linux";
+  } else {
+    return null;
+  }
+}
+
+window.addEventListener("load", onload);

doc/user/INSTALLATION.md

@@ -4,12 +4,12 @@
 
 | Platform | Files |
 | -------- | ----- |
-| Windows Installer | [F3D-2.3.0-Windows.exe](https://github.com/f3d-app/f3d/releases/download/v2.3.0/F3D-2.3.0-Windows-x86_64-raytracing.exe) |
-| Windows (Portable) | [F3D-2.3.0-Windows.zip](https://github.com/f3d-app/f3d/releases/download/v2.3.0/F3D-2.3.0-Windows-x86_64-raytracing.zip) |
+| Windows (installer) | [F3D-2.3.0-Windows.exe](https://github.com/f3d-app/f3d/releases/download/v2.3.0/F3D-2.3.0-Windows-x86_64-raytracing.exe) |
+| Windows (portable) | [F3D-2.3.0-Windows.zip](https://github.com/f3d-app/f3d/releases/download/v2.3.0/F3D-2.3.0-Windows-x86_64-raytracing.zip) |
 | MacOS (Intel) | [F3D-2.3.0-macOS-x86_64.dmg](https://github.com/f3d-app/f3d/releases/download/v2.3.0/F3D-2.3.0-macOS-x86_64-raytracing.dmg) |
 | MacOS (Silicon) | [F3D-2.3.0-macOS-arm64.dmg](https://github.com/f3d-app/f3d/releases/download/v2.3.0/F3D-2.3.0-macOS-arm64.dmg) |
-| Debian-based Package | [F3D-2.3.0-Linux.deb](https://github.com/f3d-app/f3d/releases/download/v2.3.0/F3D-2.3.0-Linux-x86_64-raytracing.deb) |
-| Linux (Portable) | [F3D-2.3.0-Linux.tar.xz](https://github.com/f3d-app/f3d/releases/download/v2.3.0/F3D-2.3.0-Linux-x86_64-raytracing.tar.xz) |
+| Linux (Debian package) | [F3D-2.3.0-Linux.deb](https://github.com/f3d-app/f3d/releases/download/v2.3.0/F3D-2.3.0-Linux-x86_64-raytracing.deb) |
+| Linux (portable) | [F3D-2.3.0-Linux.tar.xz](https://github.com/f3d-app/f3d/releases/download/v2.3.0/F3D-2.3.0-Linux-x86_64-raytracing.tar.xz) |
 
 Note: MacOS package is not signed, see the [troubleshooting](LIMITATIONS_AND_TROUBLESHOOTING.md) section for a workaround if needed.