/*
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 */

#include "BKE_node_tree_multi_function.hh"

#include "BLI_float3.hh"

namespace blender {
namespace bke {

/* Maybe this should be moved to BKE_node.h. */
static std::optional<fn::MFDataType> try_get_multi_function_data_type_of_socket(
    const bNodeSocket *bsocket)
{
  if (bsocket->typeinfo->get_mf_data_type == nullptr) {
    return {};
  }
  return bsocket->typeinfo->get_mf_data_type();
}

static void insert_dummy_node(CommonMFNetworkBuilderData &common, const DNode &dnode)
{
  constexpr uint stack_capacity = 10;

  Vector<fn::MFDataType, stack_capacity> input_types;
  Vector<StringRef, stack_capacity> input_names;
  Vector<const DInputSocket *, stack_capacity> input_dsockets;

  for (const DInputSocket *dsocket : dnode.inputs()) {
    if (dsocket->is_available()) {
      std::optional<fn::MFDataType> data_type = try_get_multi_function_data_type_of_socket(
          dsocket->bsocket());
      if (data_type.has_value()) {
        input_types.append(*data_type);
        input_names.append(dsocket->name());
        input_dsockets.append(dsocket);
      }
    }
  }

  Vector<fn::MFDataType, stack_capacity> output_types;
  Vector<StringRef, stack_capacity> output_names;
  Vector<const DOutputSocket *, stack_capacity> output_dsockets;

  for (const DOutputSocket *dsocket : dnode.outputs()) {
    if (dsocket->is_available()) {
      std::optional<fn::MFDataType> data_type = try_get_multi_function_data_type_of_socket(
          dsocket->bsocket());
      if (data_type.has_value()) {
        output_types.append(*data_type);
        output_names.append(dsocket->name());
        output_dsockets.append(dsocket);
      }
    }
  }

  fn::MFDummyNode &dummy_node = common.network.add_dummy(
      dnode.name(), input_types, output_types, input_names, output_names);

  common.network_map.add(input_dsockets, dummy_node.inputs());
  common.network_map.add(output_dsockets, dummy_node.outputs());
}

static bool has_data_sockets(const DNode &dnode)
{
  for (const DInputSocket *socket : dnode.inputs()) {
    if (is_multi_function_data_socket(socket->bsocket())) {
      return true;
    }
  }
  for (const DOutputSocket *socket : dnode.outputs()) {
    if (is_multi_function_data_socket(socket->bsocket())) {
      return true;
    }
  }
  return false;
}

/**
 * Expands all function nodes in the multi-function network. Nodes that don't have an expand
 * function, but do have data sockets, will get corresponding dummy nodes.
 */
static void insert_nodes(CommonMFNetworkBuilderData &common)
{
  for (const DNode *dnode : common.tree.nodes()) {
    const bNodeType *node_type = dnode->node_ref().bnode()->typeinfo;
    if (node_type->expand_in_mf_network != nullptr) {
      NodeMFNetworkBuilder builder{common, *dnode};
      node_type->expand_in_mf_network(builder);
    }
    else if (has_data_sockets(*dnode)) {
      insert_dummy_node(common, *dnode);
    }
  }
}

static void insert_group_inputs(CommonMFNetworkBuilderData &common)
{
  for (const DGroupInput *group_input : common.tree.group_inputs()) {
    bNodeSocket *bsocket = group_input->bsocket();
    if (is_multi_function_data_socket(bsocket)) {
      bNodeSocketType *socktype = bsocket->typeinfo;
      BLI_assert(socktype->expand_in_mf_network != nullptr);

      SocketMFNetworkBuilder builder{common, *group_input};
      socktype->expand_in_mf_network(builder);

      fn::MFOutputSocket *from_socket = builder.built_socket();
      BLI_assert(from_socket != nullptr);
      common.network_map.add(*group_input, *from_socket);
    }
  }
}

static fn::MFOutputSocket *try_find_origin(CommonMFNetworkBuilderData &common,
                                           const DInputSocket &to_dsocket)
{
  Span<const DOutputSocket *> from_dsockets = to_dsocket.linked_sockets();
  Span<const DGroupInput *> from_group_inputs = to_dsocket.linked_group_inputs();
  uint total_linked_amount = from_dsockets.size() + from_group_inputs.size();
  BLI_assert(total_linked_amount <= 1);

  if (total_linked_amount == 0) {
    return nullptr;
  }

  if (from_dsockets.size() == 1) {
    if (is_multi_function_data_socket(from_dsockets[0]->bsocket())) {
      return &common.network_map.lookup(*from_dsockets[0]);
    }
    else {
      return nullptr;
    }
  }
  else {
    if (is_multi_function_data_socket(from_group_inputs[0]->bsocket())) {
      return &common.network_map.lookup(*from_group_inputs[0]);
    }
    else {
      return nullptr;
    }
  }
}

static const fn::MultiFunction *try_get_conversion_function(fn::MFDataType from, fn::MFDataType to)
{
  if (from == fn::MFDataType::ForSingle<float>()) {
    if (to == fn::MFDataType::ForSingle<int32_t>()) {
      static fn::CustomMF_Convert<float, int32_t> function;
      return &function;
    }
    if (to == fn::MFDataType::ForSingle<float3>()) {
      static fn::CustomMF_Convert<float, float3> function;
      return &function;
    }
  }
  if (from == fn::MFDataType::ForSingle<float3>()) {
    if (to == fn::MFDataType::ForSingle<float>()) {
      static fn::CustomMF_SI_SO<float3, float> function{"Vector Length",
                                                        [](float3 a) { return a.length(); }};
      return &function;
    }
  }
  if (from == fn::MFDataType::ForSingle<int32_t>()) {
    if (to == fn::MFDataType::ForSingle<float>()) {
      static fn::CustomMF_Convert<int32_t, float> function;
      return &function;
    }
    if (to == fn::MFDataType::ForSingle<float3>()) {
      static fn::CustomMF_SI_SO<int32_t, float3> function{
          "int32 to float3", [](int32_t a) { return float3((float)a); }};
      return &function;
    }
  }

  return nullptr;
}

static fn::MFOutputSocket &insert_default_value_for_type(CommonMFNetworkBuilderData &common,
                                                         fn::MFDataType type)
{
  const fn::MultiFunction *default_fn;
  if (type.is_single()) {
    default_fn = &common.resources.construct<fn::CustomMF_GenericConstant>(
        AT, type.single_type(), type.single_type().default_value());
  }
  else {
    default_fn = &common.resources.construct<fn::CustomMF_GenericConstantArray>(
        AT, fn::GSpan(type.vector_base_type()));
  }

  fn::MFNode &node = common.network.add_function(*default_fn);
  return node.output(0);
}

static void insert_links(CommonMFNetworkBuilderData &common)
{
  for (const DInputSocket *to_dsocket : common.tree.input_sockets()) {
    if (!to_dsocket->is_available()) {
      continue;
    }
    if (!to_dsocket->is_linked()) {
      continue;
    }
    if (!is_multi_function_data_socket(to_dsocket->bsocket())) {
      continue;
    }

    Span<fn::MFInputSocket *> to_sockets = common.network_map.lookup(*to_dsocket);
    BLI_assert(to_sockets.size() >= 1);
    fn::MFDataType to_type = to_sockets[0]->data_type();

    fn::MFOutputSocket *from_socket = try_find_origin(common, *to_dsocket);
    if (from_socket == nullptr) {
      from_socket = &insert_default_value_for_type(common, to_type);
    }

    fn::MFDataType from_type = from_socket->data_type();

    if (from_type != to_type) {
      const fn::MultiFunction *conversion_fn = try_get_conversion_function(from_type, to_type);
      if (conversion_fn != nullptr) {
        fn::MFNode &node = common.network.add_function(*conversion_fn);
        common.network.add_link(*from_socket, node.input(0));
        from_socket = &node.output(0);
      }
      else {
        from_socket = &insert_default_value_for_type(common, to_type);
      }
    }

    for (fn::MFInputSocket *to_socket : to_sockets) {
      common.network.add_link(*from_socket, *to_socket);
    }
  }
}

static void insert_unlinked_input(CommonMFNetworkBuilderData &common, const DInputSocket &dsocket)
{
  bNodeSocket *bsocket = dsocket.bsocket();
  bNodeSocketType *socktype = bsocket->typeinfo;
  BLI_assert(socktype->expand_in_mf_network != nullptr);

  SocketMFNetworkBuilder builder{common, dsocket};
  socktype->expand_in_mf_network(builder);

  fn::MFOutputSocket *from_socket = builder.built_socket();
  BLI_assert(from_socket != nullptr);

  for (fn::MFInputSocket *to_socket : common.network_map.lookup(dsocket)) {
    common.network.add_link(*from_socket, *to_socket);
  }
}

static void insert_unlinked_inputs(CommonMFNetworkBuilderData &common)
{
  Vector<const DInputSocket *> unlinked_data_inputs;
  for (const DInputSocket *dsocket : common.tree.input_sockets()) {
    if (dsocket->is_available()) {
      if (is_multi_function_data_socket(dsocket->bsocket())) {
        if (!dsocket->is_linked()) {
          insert_unlinked_input(common, *dsocket);
        }
      }
    }
  }
}

/**
 * Expands all function nodes contained in the given node tree within the given multi-function
 * network.
 *
 * Returns a mapping between the original node tree and the generated nodes/sockets for further
 * processing.
 */
MFNetworkTreeMap insert_node_tree_into_mf_network(fn::MFNetwork &network,
                                                  const DerivedNodeTree &tree,
                                                  ResourceCollector &resources)
{
  MFNetworkTreeMap network_map{tree, network};

  CommonMFNetworkBuilderData common{resources, network, network_map, tree};

  insert_nodes(common);
  insert_group_inputs(common);
  insert_links(common);
  insert_unlinked_inputs(common);

  return network_map;
}

}  // namespace bke
}  // namespace blender