From d040b798a0217e6c58ddcb2f5d9256a2325daf1a Mon Sep 17 00:00:00 2001
From: Guillaume Ayoub <guillaume.ayoub@kozea.fr>
Date: Thu, 11 Jan 2018 01:01:14 +0100
Subject: [PATCH] Handle justify-content

---
 weasyprint/css/properties.py |  1 +
 weasyprint/css/validation.py |  8 ++++++++
 weasyprint/layout/flex.py    | 27 ++++++++++++++++++++-------
 3 files changed, 29 insertions(+), 7 deletions(-)

diff --git a/weasyprint/css/properties.py b/weasyprint/css/properties.py
index b24c091f..b92a7283 100644
--- a/weasyprint/css/properties.py
+++ b/weasyprint/css/properties.py
@@ -182,6 +182,7 @@ INITIAL_VALUES = {
     'flex_grow': 0,
     'flex_shrink': 1,
     'flex_wrap': 'nowrap',
+    'justify_content': 'flex-start',
     'order': 0,
 
     # Proprietary
diff --git a/weasyprint/css/validation.py b/weasyprint/css/validation.py
index 14a513a7..743ce7a3 100644
--- a/weasyprint/css/validation.py
+++ b/weasyprint/css/validation.py
@@ -1392,6 +1392,14 @@ def flex_wrap(keyword):
     return keyword in ('nowrap', 'wrap', 'wrap-reverse')
 
 
+@validator()
+@single_keyword
+def justify_content(keyword):
+    """``justify_content`` property validation."""
+    return keyword in (
+        'flex-start', 'flex-end', 'center', 'space-between', 'space-around')
+
+
 @validator(unstable=True)
 @single_keyword
 def image_rendering(keyword):
diff --git a/weasyprint/layout/flex.py b/weasyprint/layout/flex.py
index d6784340..45922a16 100644
--- a/weasyprint/layout/flex.py
+++ b/weasyprint/layout/flex.py
@@ -316,7 +316,7 @@ def flex_layout(context, box, max_position_y, skip_stack, containing_block,
 
     # Step 12
     free_space = available_main_space - sum(
-        child.width for line in flex_lines for child in line)
+        child.margin_width() for line in flex_lines for child in line)
 
     if free_space:
         margins = 0
@@ -326,20 +326,33 @@ def flex_layout(context, box, max_position_y, skip_stack, containing_block,
                     margins += 1
                 if child.margin_right == 'auto':
                     margins += 1
+
         if margins:
             free_space /= margins
-        else:
-            free_space = 0
+            for line in flex_lines:
+                for child in line:
+                    if child.margin_left == 'auto':
+                        child.margin_left = free_space
+                    if child.margin_right == 'auto':
+                        child.margin_right = free_space
 
     for line in flex_lines:
+        # TODO: handle rtl
         position_x = box.content_box_x()
+        if box.style['justify_content'] == 'flex-end':
+            position_x += free_space
+        elif box.style['justify_content'] == 'center':
+            position_x += free_space / 2
+        elif box.style['justify_content'] == 'space-around':
+            position_x += free_space / len(line) / 2
         for child in line:
-            if child.margin_left == 'auto':
-                child.margin_left = free_space
-            if child.margin_right == 'auto':
-                child.margin_right = free_space
             child.position_x = position_x
             position_x += child.margin_width()
+            if box.style['justify_content'] == 'space-around':
+                position_x += free_space / len(line)
+            elif box.style['justify_content'] == 'space-between':
+                if len(line) > 1:
+                    position_x += free_space / (len(line) - 1)
 
     # TODO: align according to justify-content