#include "iterator/join_iterator.h"

#include <vector>

#include "xcode_gtest_helper.h"

using iterator::end_aware_iterator;
using iterator::joining_iterator;

using testing::Ne;

TEST(JoinIteratorTest, FirstDereferencedElemIsTheFirstInTheChain) {
  std::vector<std::vector<int>> mv{{1, 2, 3}, {4, 5, 6}};
  EXPECT_EQ(*joining_iterator(mv), mv[0][0]);
}

TEST(JoinIteratorTest, HoldsReferenceToContainedElements) {
  std::vector<std::vector<int>> mv{{1, 2, 3}, {4, 5, 6}};
  EXPECT_EQ(joining_iterator(mv).operator->(), &mv[0][0]);
}

TEST(JoinIteratorTest, EmptyContainerBeginIsEnd) {
  std::vector<std::vector<int>> mv{{1, 2, 3}, {4, 5, 6}};
  joining_iterator it(mv);
  EXPECT_NE(it, iterator::sentinel);

  mv.clear();
  EXPECT_EQ(joining_iterator(mv), iterator::sentinel);
}

// TODO: This ought to be implemented as a compiles-test
TEST(JoinIteratorTest, CanCastCompatibleIterators) {
  std::vector<std::vector<int>> mv{{1, 2, 3}, {4, 5, 6}};
  joining_iterator it(mv);
  iterator::joining_iterator<decltype(mv)::const_iterator>{it};
}

TEST(JoinIteratorTest, CanAccessInternalIterator) {
  std::vector<std::vector<int>> mv{{1, 2, 3}, {4, 5, 6}};
  auto eai = end_aware_iterator(mv);
  joining_iterator it(eai);
  EXPECT_EQ(it.outer_iterator(), eai);
}

TEST(JoinIteratorTest, CanAccessChildIterator) {
  std::vector<std::vector<int>> mv{{1, 2, 3}, {4, 5, 6}};
  joining_iterator it(mv);
  EXPECT_EQ(it.inner_iterator(), end_aware_iterator(mv[0]));
}

TEST(JoinIteratorTest, PreIncrementAdvancesIterator) {
  std::vector<std::vector<int>> mv{{1, 2, 3}, {4, 5, 6}};
  joining_iterator it(mv);
  EXPECT_EQ(*it, 1);
  EXPECT_EQ(*++it, 2);
  EXPECT_EQ(*it, 2);
}

TEST(JoinIteratorTest, PostIncrementReturnsCopyOfPrev) {
  std::vector<std::vector<int>> mv{{1, 2, 3}, {4, 5, 6}};
  joining_iterator it(mv);
  EXPECT_EQ(*it, 1);
  EXPECT_EQ(*it++, 1);
  EXPECT_EQ(*it, 2);
}

TEST(JoinIteratorTest, MovesFromListToListWhenReachingEnd) {
  std::vector<std::vector<int>> mv{{1, 2, 3}, {4, 5, 6}};
  joining_iterator it(mv);
  std::advance(it, 2);
  EXPECT_EQ(*++it, mv[1][0]);
}

TEST(JoinIteratorTest, SkipsOverEmptyElements) {
  std::vector<std::vector<int>> mv{{1, 2, 3}, {}, {4, 5, 6}};
  joining_iterator it(mv);
  std::advance(it, 2);
  EXPECT_EQ(*++it, mv[2][0]);
}