#include <catch.hpp>

#include <torch/nn/modules.h>
#include <torch/nn/modules/linear.h>
#include <torch/nn/modules/sequential.h>
#include <torch/tensor.h>
#include <torch/utils.h>

#include <memory>
#include <vector>

using namespace torch::nn;

using Catch::StartsWith;

TEST_CASE("sequential") {
  SECTION("construction from shared pointer") {
    struct M : torch::nn::Module {
      explicit M(int value_) : value(value_) {}
      int value;
      int forward() {
        return value;
      }
    };
    Sequential sequential(
        std::make_shared<M>(1), std::make_shared<M>(2), std::make_shared<M>(3));
    REQUIRE(sequential.size() == 3);
  }
  SECTION("construction from concrete type") {
    struct M : torch::nn::Module {
      explicit M(int value_) : value(value_) {}
      int value;
      int forward() {
        return value;
      }
    };

    Sequential sequential(M(1), M(2), M(3));
    REQUIRE(sequential.size() == 3);
  }
  SECTION("construction from module holders") {
    struct MImpl : torch::nn::Module {
      explicit MImpl(int value_) : value(value_) {}
      int forward() {
        return value;
      }
      int value;
    };

    struct M : torch::nn::ModuleHolder<MImpl> {
      using torch::nn::ModuleHolder<MImpl>::ModuleHolder;
      using torch::nn::ModuleHolder<MImpl>::get;
    };

    Sequential sequential(M(1), M(2), M(3));
    REQUIRE(sequential.size() == 3);
  }
  SECTION("push_back") {
    struct M : torch::nn::Module {
      explicit M(int value_) : value(value_) {}
      int forward() {
        return value;
      }
      int value;
    };
    Sequential sequential;
    REQUIRE(sequential.size() == 0);
    REQUIRE(sequential.is_empty());
    sequential.push_back(Linear(3, 4));
    REQUIRE(sequential.size() == 1);
    sequential.push_back(std::make_shared<M>(1));
    REQUIRE(sequential.size() == 2);
    sequential.push_back(M(2));
    REQUIRE(sequential.size() == 3);
  }
  SECTION("access") {
    struct M : torch::nn::Module {
      explicit M(int value_) : value(value_) {}
      int forward() {
        return value;
      }
      int value;
    };
    std::vector<std::shared_ptr<M>> modules = {
        std::make_shared<M>(1), std::make_shared<M>(2), std::make_shared<M>(3)};

    Sequential sequential;
    for (auto& module : modules) {
      sequential.push_back(module);
    }
    REQUIRE(sequential.size() == 3);

    SECTION("at()") {
      SECTION("returns the correct module for a given index") {
        for (size_t i = 0; i < modules.size(); ++i) {
          REQUIRE(&sequential.at<M>(i) == modules[i].get());
        }
      }
      SECTION("throws for a bad index") {
        REQUIRE_THROWS_WITH(
            sequential.at<M>(modules.size() + 1),
            StartsWith("Index out of range"));
        REQUIRE_THROWS_WITH(
            sequential.at<M>(modules.size() + 1000000),
            StartsWith("Index out of range"));
      }
    }

    SECTION("ptr()") {
      SECTION("returns the correct module for a given index") {
        for (size_t i = 0; i < modules.size(); ++i) {
          REQUIRE(sequential.ptr(i).get() == modules[i].get());
          REQUIRE(sequential[i].get() == modules[i].get());
          REQUIRE(sequential.ptr<M>(i).get() == modules[i].get());
        }
      }
      SECTION("throws for a bad index") {
        REQUIRE_THROWS_WITH(
            sequential.ptr(modules.size() + 1),
            StartsWith("Index out of range"));
        REQUIRE_THROWS_WITH(
            sequential.ptr(modules.size() + 1000000),
            StartsWith("Index out of range"));
      }
    }
  }
  SECTION("forward") {
    SECTION("calling forward() on an empty sequential is disallowed") {
      Sequential empty;
      REQUIRE_THROWS_WITH(
          empty.forward<int>(),
          StartsWith("Cannot call forward() on an empty Sequential"));
    }

    SECTION("calling forward() on a non-empty sequential chains correctly") {
      struct MockModule : torch::nn::Module {
        explicit MockModule(int value) : expected(value) {}
        int expected;
        int forward(int value) {
          REQUIRE(value == expected);
          return value + 1;
        }
      };

      Sequential sequential(MockModule{1}, MockModule{2}, MockModule{3});

      REQUIRE(sequential.forward<int>(1) == 4);
    }

    SECTION("calling forward() with the wrong return type throws") {
      struct M : public torch::nn::Module {
        int forward() {
          return 5;
        }
      };

      Sequential sequential(M{});
      REQUIRE(sequential.forward<int>() == 5);
      REQUIRE_THROWS_WITH(
          sequential.forward<float>(),
          StartsWith("The type of the return value "
                     "is int, but you asked for type float"));
    }

    SECTION("The return type of forward() defaults to Tensor") {
      struct M : public torch::nn::Module {
        torch::Tensor forward(torch::Tensor v) {
          return v;
        }
      };

      Sequential sequential(M{});
      auto variable = torch::ones({3, 3}, torch::requires_grad());
      REQUIRE(sequential.forward(variable).equal(variable));
    }
  }

  SECTION("returns the last value") {
    torch::manual_seed(0);
    Sequential sequential(Linear(10, 3), Linear(3, 5), Linear(5, 100));

    auto x = torch::randn({1000, 10}, torch::requires_grad());
    auto y = sequential.forward(x);
    REQUIRE(y.ndimension() == 2);
    REQUIRE(y.size(0) == 1000);
    REQUIRE(y.size(1) == 100);
  }

  SECTION("can hold other important modules") {
    Sequential sequential(
        Linear(10, 3),
        Conv2d(1, 2, 3),
        Dropout(0.5),
        BatchNorm(5),
        Embedding(4, 10),
        LSTM(4, 5));
  }
}