Add /version/history endpoint to API.

Retrieves Git tag annotations.

lib/www/server/lib/version.js

@@ -103,6 +103,42 @@ async function describe () {
 	});
 }
 
+/** Return version history, from git tags
+ *
+ */
+async function history (count=5, lines=15) {
+	return new Promise( (resolve, reject) => {
+		const separator2 = String(Math.random()).substring(2)+String(Math.random()).substring(2);
+		const separator1 = separator2.repeat(2);
+		const cmd = `for tag in $(git tag --sort=-version:refname |head -n ${count}); do printf "\n${separator1}\n"; echo "$tag"; printf "\n${separator2}\n"; git --no-pager tag -n${lines} "$tag"; done`;
+
+		exec(cmd, {cwd: __dirname}, (error, stdout, stderr) => {
+			if (error) {
+				reject(error);
+			}
+
+			if (stdout) {
+				const result = stdout
+					.split(separator1)           // Separate each tag
+					.map(i => i.trim())          // Trim spaces
+					.filter(i => i)              // Filter empty lines
+					.map(i => i                  // Now for each tag…
+						.split(separator2)       // …separate the tag from the description
+						.map(i => i.trim())      // trim spaces in both
+						.filter( i => i)         // and remove empty lines
+					)
+
+				resolve(Object.fromEntries(result));
+				// resolve(result.map( ([k, v]) => ({tag: k, notes: v}) ));
+			} else {
+				// Most likely not installed from Git, use the
+				// version number in package.json.
+				resolve()
+			}
+		})
+	});
+}
+
 function version_old () {
 	return pkg.version;
 }
@@ -132,5 +168,6 @@ async function version () {
 version.compatible = compatible;
 version.name = app_name;
 version.describe = describe;
+version.history = history;
 
 module.exports = version;