#include "message_handler.h"
#include "query_utils.h"
#include "queue_manager.h"

namespace {
MethodType kMethodType = "textDocument/hover";

std::pair<std::string_view, std::string_view> GetCommentsAndHover(
    QueryDatabase* db,
    SymbolRef sym) {
  switch (sym.kind) {
    case SymbolKind::Type: {
      if (const auto* def = db->GetType(sym).AnyDef()) {
        return {def->comments, !def->hover.empty()
                                   ? std::string_view(def->hover)
                                   : std::string_view(def->detailed_name)};
      }
      break;
    }
    case SymbolKind::Func: {
      if (const auto* def = db->GetFunc(sym).AnyDef()) {
        return {def->comments, !def->hover.empty()
                                   ? std::string_view(def->hover)
                                   : std::string_view(def->detailed_name)};
      }
      break;
    }
    case SymbolKind::Var: {
      if (const auto* def = db->GetVar(sym).AnyDef()) {
        return {def->comments, !def->hover.empty()
                                   ? std::string_view(def->hover)
                                   : std::string_view(def->detailed_name)};
      }
      break;
    }
    case SymbolKind::File:
    case SymbolKind::Invalid: {
      assert(false && "unexpected");
      break;
    }
  }
  return {"", ""};
}

struct In_TextDocumentHover : public RequestInMessage {
  MethodType GetMethodType() const override { return kMethodType; }
  lsTextDocumentPositionParams params;
};
MAKE_REFLECT_STRUCT(In_TextDocumentHover, id, params);
REGISTER_IN_MESSAGE(In_TextDocumentHover);

struct Out_TextDocumentHover : public lsOutMessage<Out_TextDocumentHover> {
  struct Result {
    std::vector<lsMarkedString> contents;
    std::optional<lsRange> range;
  };

  lsRequestId id;
  std::optional<Result> result;
};
MAKE_REFLECT_STRUCT(Out_TextDocumentHover::Result, contents, range);
void Reflect(Writer& visitor, Out_TextDocumentHover& value) {
  REFLECT_MEMBER_START();
  REFLECT_MEMBER(jsonrpc);
  REFLECT_MEMBER(id);
  if (value.result)
    REFLECT_MEMBER(result);
  else {
    // Empty std::optional<> is elided by the default serializer, we need to write
    // |null| to be compliant with the LSP.
    visitor.Key("result");
    visitor.Null();
  }
  REFLECT_MEMBER_END();
}

struct Handler_TextDocumentHover : BaseMessageHandler<In_TextDocumentHover> {
  MethodType GetMethodType() const override { return kMethodType; }
  void Run(In_TextDocumentHover* request) override {
    QueryFile* file;
    if (!FindFileOrFail(db, project, request->id,
                        request->params.textDocument.uri.GetPath(), &file)) {
      return;
    }

    WorkingFile* working_file =
        working_files->GetFileByFilename(file->def->path);

    Out_TextDocumentHover out;
    out.id = request->id;

    for (SymbolRef sym :
         FindSymbolsAtLocation(working_file, file, request->params.position)) {
      // Found symbol. Return hover.
      std::optional<lsRange> ls_range = GetLsRange(
          working_files->GetFileByFilename(file->def->path), sym.range);
      if (!ls_range)
        continue;

      std::pair<std::string_view, std::string_view> comments_hover =
          GetCommentsAndHover(db, sym);
      if (comments_hover.first.size() || comments_hover.second.size()) {
        out.result = Out_TextDocumentHover::Result();
        if (comments_hover.first.size()) {
          out.result->contents.emplace_back(comments_hover.first);
        }
        if (comments_hover.second.size()) {
          out.result->contents.emplace_back(lsMarkedString1{
              std::string_view(file->def->language), comments_hover.second});
        }
        out.result->range = *ls_range;
        break;
      }
    }

    QueueManager::WriteStdout(kMethodType, out);
  }
};
REGISTER_MESSAGE_HANDLER(Handler_TextDocumentHover);
}  // namespace