From a2e53e22bd8550608c3a0edeb5efafaaedf4af2d Mon Sep 17 00:00:00 2001
From: tatiana-yan <tatiana.kondakova@gmail.com>
Date: Tue, 16 Mar 2021 10:55:17 +0300
Subject: [PATCH] Review fixes.

---
 transit/world_feed/feed_helpers.cpp | 26 +++++++++++++++++++-------
 transit/world_feed/feed_helpers.hpp |  3 ++-
 transit/world_feed/world_feed.cpp   |  2 +-
 3 files changed, 22 insertions(+), 9 deletions(-)

diff --git a/transit/world_feed/feed_helpers.cpp b/transit/world_feed/feed_helpers.cpp
index b5bf224c08..d51c01b6f2 100644
--- a/transit/world_feed/feed_helpers.cpp
+++ b/transit/world_feed/feed_helpers.cpp
@@ -22,15 +22,17 @@ struct ProjectionData
   size_t m_indexOnShape = 0;
   // Distance from point to its projection.
   double m_distFromPoint = 0.0;
-  // Distance from start point on polyline to the projection.
+  // Distance from the first ending (start for forward direction, end for backward) point on
+  // polyline to the projection.
   double m_distFromEnding = 0.0;
   // Point on polyline almost equal to the projection can already exist, so we don't need to
   // insert projection. Or we insert it to the polyline.
   bool m_needsInsertion = false;
 };
 
-// Returns true if |p1| is much closer to start then |p2| (parameter |distDeltaStart|) and its
-// distance to projections to polyline |m_distFromPoint| is comparable.
+// Returns true if |p1| is much closer to the first ending (start for forward direction, end for
+// backward) then |p2| (parameter |distDeltaEnding|) and its distance to projections to polyline
+// |m_distFromPoint| is comparable.
 bool CloserToEndingAndOnSimilarDistToLine(ProjectionData const & p1, ProjectionData const & p2)
 {
   // Delta between two points distances from start point on polyline.
@@ -62,6 +64,8 @@ ProjectionData GetProjection(std::vector<m2::PointD> const & polyline, size_t in
   projData.m_proj = proj.m_point;
 
   auto const next = direction == Direction::Forward ? index + 1 : index - 1;
+  CHECK_GREATER_OR_EQUAL(next, 0, ());
+  CHECK_LESS(next, polyline.size(), ());
 
   if (base::AlmostEqualAbs(proj.m_point, polyline[index], kEps))
   {
@@ -86,17 +90,25 @@ void FillProjections(std::vector<m2::PointD> & polyline, size_t startIndex, size
                      m2::PointD const & point, double distStopsM, Direction direction,
                      std::vector<ProjectionData> & projections)
 {
+  CHECK_LESS_OR_EQUAL(startIndex, endIndex, ());
+
   double distTravelledM = 0.0;
   // Stop can't be further from its projection to line then |maxDistFromStopM|.
   double constexpr maxDistFromStopM = 1000;
 
   size_t const from = direction == Direction::Forward ? startIndex : endIndex;
-  auto const endCriteria = [&](size_t i) {
+
+  auto const endCriterion = [&](size_t i) {
     return direction == Direction::Forward ? i < endIndex : i > startIndex;
   };
-  auto const move = [direction](size_t & i) { direction == Direction::Forward ? ++i : --i; };
 
-  for (size_t i = from; endCriteria(i); move(i))
+  auto const move = [&](size_t & i) {
+    direction == Direction::Forward ? ++i : --i;
+    CHECK_GREATER_OR_EQUAL(i, 0, ());
+    CHECK_LESS_OR_EQUAL(i, polyline.size(), ());
+  };
+
+  for (size_t i = from; endCriterion(i); move(i))
   {
     auto const current = i;
     auto const prev = direction == Direction::Forward ? i - 1 : i + 1;
@@ -152,7 +164,7 @@ std::pair<size_t, bool> PrepareNearestPointOnTrack(m2::PointD const & point,
     if (CloserToEndingAndOnSimilarDistToLine(p2, p1))
       return false;
 
-    if (base::AlmostEqualAbs(p1.m_distFromPoint, p2.m_distFromPoint, kEps))
+    if (p1.m_distFromPoint == p2.m_distFromPoint)
       return p1.m_distFromEnding < p2.m_distFromEnding;
 
     return p1.m_distFromPoint < p2.m_distFromPoint;
diff --git a/transit/world_feed/feed_helpers.hpp b/transit/world_feed/feed_helpers.hpp
index f9e0be4b5b..ec1b5142da 100644
--- a/transit/world_feed/feed_helpers.hpp
+++ b/transit/world_feed/feed_helpers.hpp
@@ -33,7 +33,8 @@ ProjectionToShape ProjectStopOnTrack(m2::PointD const & stopPoint, m2::PointD co
 
 /// \returns index of the nearest track point to the |point| and flag if it was inserted to the
 /// shape. If this index doesn't match already existent points, the stop projection is inserted to
-/// the |polyline| and the flag is set to true.
+/// the |polyline| and the flag is set to true. New point should follow prevPoint in the direction
+/// |direction|.
 std::pair<size_t, bool> PrepareNearestPointOnTrack(m2::PointD const & point,
                                                    std::optional<m2::PointD> const & prevPoint,
                                                    size_t prevIndex, Direction direction,
diff --git a/transit/world_feed/world_feed.cpp b/transit/world_feed/world_feed.cpp
index 0a516a7a6f..529c74149a 100644
--- a/transit/world_feed/world_feed.cpp
+++ b/transit/world_feed/world_feed.cpp
@@ -957,7 +957,7 @@ bool WorldFeed::ProjectStopsToShape(
       CHECK(itStop != m_stops.m_data.end(), (stopId));
       auto const & stop = itStop->second;
 
-      size_t const prevIdx = i == 0 ? direction == Direction::Forward ? 0 : shape.size()
+      size_t const prevIdx = i == 0 ? (direction == Direction::Forward ? 0 : shape.size())
                                     : stopsToIndexes[stopIds[i - 1]].back();
       auto const [curIdx, pointInserted] =
           PrepareNearestPointOnTrack(stop.m_point, prevPoint, prevIdx, direction, shape);