1 files changed, 63 insertions, 0 deletions
diff --git a/packages/gitbook/lib/api/encodeProgress.js b/packages/gitbook/lib/api/encodeProgress.js
new file mode 100644
index 0000000..afa0341
--- /dev/null
+++ b/packages/gitbook/lib/api/encodeProgress.js
@@ -0,0 +1,63 @@
+var Immutable = require('immutable');
+var encodeNavigation = require('./encodeNavigation');
+
+/**
+    page.progress is a deprecated property from GitBook v2
+
+    @param {Output}
+    @param {Page}
+    @return {Object}
+*/
+function encodeProgress(output, page) {
+    var current = page.getPath();
+    var navigation = encodeNavigation(output);
+    navigation = Immutable.Map(navigation);
+
+    var n = navigation.size;
+    var percent = 0, prevPercent = 0, currentChapter = null;
+    var done = true;
+
+    var chapters = navigation
+        .map(function(nav, chapterPath) {
+            nav.path = chapterPath;
+            return nav;
+        })
+        .valueSeq()
+        .sortBy(function(nav) {
+            return nav.index;
+        })
+        .map(function(nav, i) {
+            // Calcul percent
+            nav.percent = (i * 100) / Math.max((n - 1), 1);
+
+            // Is it done
+            nav.done = done;
+            if (nav.path == current) {
+                currentChapter = nav;
+                percent = nav.percent;
+                done = false;
+            } else if (done) {
+                prevPercent = nav.percent;
+            }
+
+            return nav;
+        })
+        .toJS();
+
+    return {
+        // Previous percent
+        prevPercent: prevPercent,
+
+        // Current percent
+        percent: percent,
+
+        // List of chapter with progress
+        chapters: chapters,
+
+        // Current chapter
+        current: currentChapter
+    };
+}
+
+module.exports = encodeProgress;
+