1 files changed, 55 insertions, 3 deletions
diff --git a/lib/api/encodeProgress.js b/lib/api/encodeProgress.js
index f32c8d8..2522eb5 100644
--- a/lib/api/encodeProgress.js
+++ b/lib/api/encodeProgress.js
@@ -1,4 +1,5 @@
-
+var Immutable = require('immutable');
+var encodeNavigation = require('./encodeNavigation');
 
 /**
     page.progress is a deprecated property from GitBook v2
@@ -8,8 +9,59 @@
     @return {Object}
 */
 function encodeProgress(output, page) {
-    // todo
-    return {};
+    var book = output.getBook();
+    var pages = output.getPages();
+    var summary = book.getSummary();
+    var articles = summary.getArticlesAsList();
+
+    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;