From c5a5a48836994a28d7fe4e8a6f500ea1ed458e4c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C3=89milie=20Feral?= <emilie.feral@numworks.com>
Date: Fri, 27 Oct 2017 13:07:26 +0200
Subject: [PATCH] [poincare] Change 1+-6*cos(2) -> 1-6cos(2)

Change-Id: Ic5dde9bf2f8a76d17a34544be0d17beaf94f6905
---
 poincare/src/addition.cpp       |  8 ++++++--
 poincare/src/multiplication.cpp | 23 ++++++++++++++---------
 poincare/test/simplify_easy.cpp |  1 +
 3 files changed, 21 insertions(+), 11 deletions(-)

diff --git a/poincare/src/addition.cpp b/poincare/src/addition.cpp
index b9ccfbedb..95a527f40 100644
--- a/poincare/src/addition.cpp
+++ b/poincare/src/addition.cpp
@@ -135,9 +135,13 @@ Expression * Addition::immediateBeautify(Context & context, AngleUnit angleUnit)
   int index = 0;
   while (index < numberOfOperands()) {
     // a+(-1)*b+... -> a-b+...
-    if (operand(index)->type() == Type::Multiplication && operand(index)->operand(0)->type() == Type::Rational && static_cast<const Rational *>(operand(index)->operand(0))->isMinusOne()) {
+    if (operand(index)->type() == Type::Multiplication && operand(index)->operand(0)->type() == Type::Rational && operand(index)->operand(0)->sign() < 0) {
       Multiplication * m = static_cast<Multiplication *>((Expression *)operand(index));
-      m->removeOperand(m->operand(0), true);
+      if (static_cast<const Rational *>(operand(index)->operand(0))->isMinusOne()) {
+        m->removeOperand(m->operand(0), true);
+      } else {
+        const_cast<Expression *>(operand(index)->operand(0))->turnIntoPositive(context, angleUnit);
+      }
       const Expression * subtractant = m->squashUnaryHierarchy();
       if (index == 0) {
         const Expression * opOperand[1] = {subtractant};
diff --git a/poincare/src/multiplication.cpp b/poincare/src/multiplication.cpp
index 442295afe..730ab4f66 100644
--- a/poincare/src/multiplication.cpp
+++ b/poincare/src/multiplication.cpp
@@ -348,6 +348,20 @@ bool Multiplication::isUselessOperand(const Rational * r) {
 }
 
 Expression * Multiplication::immediateBeautify(Context & context, AngleUnit angleUnit) {
+  // -1*A -> -A or (-n)*A -> -n*A
+  if (operand(0)->type() == Type::Rational && operand(0)->sign() < 0) {
+    if (static_cast<const Rational *>(operand(0))->isMinusOne()) {
+      removeOperand((Expression *)operand(0), true);
+    } else {
+      const_cast<Expression *>(operand(0))->turnIntoPositive(context, angleUnit);
+    }
+    Expression * e = squashUnaryHierarchy();
+    const Expression * oppOperand[1] = {e->clone()};
+    Opposite * o = new Opposite(oppOperand, false);
+    e->replaceWith(o, true);
+    const_cast<Expression *>(o->operand(0))->immediateBeautify(context, angleUnit);
+    return o;
+  }
   // Merge negative power: a*b^-1*c^(-Pi)*d = a*(b*c^Pi)^-1
   Expression * e = mergeNegativePower(context, angleUnit);
   if (e->type() == Type::Power) {
@@ -409,15 +423,6 @@ Expression * Multiplication::immediateBeautify(Context & context, AngleUnit angl
       return d->immediateBeautify(context, angleUnit);
     }
   }
-  // -1*A -> -A
-  if (operand(0)->type() == Type::Rational && static_cast<const Rational *>(operand(0))->isMinusOne()) {
-    removeOperand((Expression *)operand(0), true);
-    Expression * e = squashUnaryHierarchy();
-    const Expression * oppOperand[1] = {e->clone()};
-    Opposite * o = new Opposite(oppOperand, false);
-    e->replaceWith(o, true);
-    return o;
-  }
   return this;
 }
 
diff --git a/poincare/test/simplify_easy.cpp b/poincare/test/simplify_easy.cpp
index a24f87976..bff8c913d 100644
--- a/poincare/test/simplify_easy.cpp
+++ b/poincare/test/simplify_easy.cpp
@@ -35,6 +35,7 @@ void assert_parsed_expression_simplify_to(const char * expression, const char *
 
 QUIZ_CASE(poincare_simplify_easy) {
   //assert_parsed_expression_simplify_to("(((R(6)-R(2))/4)/((R(6)+R(2))/4))+1", "((1/2)*R(6))/((R(6)+R(2))/4)");
+  assert_parsed_expression_simplify_to("2+13cos(2)-23cos(2)", "2-10cos(2)");
   assert_parsed_expression_simplify_to("1/(R(2)+R(3))", "-(R(2)-R(3))");
   assert_parsed_expression_simplify_to("1/(5+R(3))", "(5-R(3))/22");
   assert_parsed_expression_simplify_to("1/(R(2)+4)", "(4-R(2))/14");