/*
 *
 * Copyright 2015 gRPC authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 */

#include <map>
#include <sstream>

#include "src/compiler/config.h"
#include "src/compiler/objective_c_generator.h"
#include "src/compiler/objective_c_generator_helpers.h"

#include <google/protobuf/compiler/objectivec/objectivec_helpers.h>

using ::google::protobuf::compiler::objectivec::ClassName;
using ::grpc::protobuf::io::Printer;
using ::grpc::protobuf::MethodDescriptor;
using ::grpc::protobuf::ServiceDescriptor;
using ::std::map;

namespace grpc_objective_c_generator {
namespace {

void PrintProtoRpcDeclarationAsPragma(
    Printer *printer, const MethodDescriptor *method,
    map< ::grpc::string, ::grpc::string> vars) {
  vars["client_stream"] = method->client_streaming() ? "stream " : "";
  vars["server_stream"] = method->server_streaming() ? "stream " : "";

  printer->Print(vars,
                 "#pragma mark $method_name$($client_stream$$request_type$)"
                 " returns ($server_stream$$response_type$)\n\n");
}

template <typename DescriptorType>
static void PrintAllComments(const DescriptorType *desc, Printer *printer) {
  std::vector<grpc::string> comments;
  grpc_generator::GetComment(desc, grpc_generator::COMMENTTYPE_LEADING_DETACHED,
                             &comments);
  grpc_generator::GetComment(desc, grpc_generator::COMMENTTYPE_LEADING,
                             &comments);
  grpc_generator::GetComment(desc, grpc_generator::COMMENTTYPE_TRAILING,
                             &comments);
  if (comments.empty()) {
    return;
  }
  printer->Print("/**\n");
  for (auto it = comments.begin(); it != comments.end(); ++it) {
    printer->Print(" * ");
    size_t start_pos = it->find_first_not_of(' ');
    if (start_pos != grpc::string::npos) {
      printer->Print(it->c_str() + start_pos);
    }
    printer->Print("\n");
  }
  printer->Print(" */\n");
}

void PrintMethodSignature(Printer *printer, const MethodDescriptor *method,
                          const map< ::grpc::string, ::grpc::string> &vars) {
  // Print comment
  PrintAllComments(method, printer);

  printer->Print(vars, "- ($return_type$)$method_name$With");
  if (method->client_streaming()) {
    printer->Print("RequestsWriter:(GRXWriter *)requestWriter");
  } else {
    printer->Print(vars, "Request:($request_class$ *)request");
  }

  // TODO(jcanizales): Put this on a new line and align colons.
  if (method->server_streaming()) {
    printer->Print(vars,
                   " eventHandler:(void(^)(BOOL done, "
                   "$response_class$ *_Nullable response, NSError *_Nullable "
                   "error))eventHandler");
  } else {
    printer->Print(vars,
                   " handler:(void(^)($response_class$ *_Nullable response, "
                   "NSError *_Nullable error))handler");
  }
}

void PrintSimpleSignature(Printer *printer, const MethodDescriptor *method,
                          map< ::grpc::string, ::grpc::string> vars) {
  vars["method_name"] =
      grpc_generator::LowercaseFirstLetter(vars["method_name"]);
  vars["return_type"] = "void";
  PrintMethodSignature(printer, method, vars);
}

void PrintAdvancedSignature(Printer *printer, const MethodDescriptor *method,
                            map< ::grpc::string, ::grpc::string> vars) {
  vars["method_name"] = "RPCTo" + vars["method_name"];
  vars["return_type"] = "GRPCProtoCall *";
  PrintMethodSignature(printer, method, vars);
}

inline map< ::grpc::string, ::grpc::string> GetMethodVars(
    const MethodDescriptor *method) {
  map< ::grpc::string, ::grpc::string> res;
  res["method_name"] = method->name();
  res["request_type"] = method->input_type()->name();
  res["response_type"] = method->output_type()->name();
  res["request_class"] = ClassName(method->input_type());
  res["response_class"] = ClassName(method->output_type());
  return res;
}

void PrintMethodDeclarations(Printer *printer, const MethodDescriptor *method) {
  map< ::grpc::string, ::grpc::string> vars = GetMethodVars(method);

  PrintProtoRpcDeclarationAsPragma(printer, method, vars);

  PrintSimpleSignature(printer, method, vars);
  printer->Print(";\n\n");
  PrintAdvancedSignature(printer, method, vars);
  printer->Print(";\n\n\n");
}

void PrintSimpleImplementation(Printer *printer, const MethodDescriptor *method,
                               map< ::grpc::string, ::grpc::string> vars) {
  printer->Print("{\n");
  printer->Print(vars, "  [[self RPCTo$method_name$With");
  if (method->client_streaming()) {
    printer->Print("RequestsWriter:requestWriter");
  } else {
    printer->Print("Request:request");
  }
  if (method->server_streaming()) {
    printer->Print(" eventHandler:eventHandler] start];\n");
  } else {
    printer->Print(" handler:handler] start];\n");
  }
  printer->Print("}\n");
}

void PrintAdvancedImplementation(Printer *printer,
                                 const MethodDescriptor *method,
                                 map< ::grpc::string, ::grpc::string> vars) {
  printer->Print("{\n");
  printer->Print(vars, "  return [self RPCToMethod:@\"$method_name$\"\n");

  printer->Print("            requestsWriter:");
  if (method->client_streaming()) {
    printer->Print("requestWriter\n");
  } else {
    printer->Print("[GRXWriter writerWithValue:request]\n");
  }

  printer->Print(vars, "             responseClass:[$response_class$ class]\n");

  printer->Print("        responsesWriteable:[GRXWriteable ");
  if (method->server_streaming()) {
    printer->Print("writeableWithEventHandler:eventHandler]];\n");
  } else {
    printer->Print("writeableWithSingleHandler:handler]];\n");
  }

  printer->Print("}\n");
}

void PrintMethodImplementations(Printer *printer,
                                const MethodDescriptor *method) {
  map< ::grpc::string, ::grpc::string> vars = GetMethodVars(method);

  PrintProtoRpcDeclarationAsPragma(printer, method, vars);

  // TODO(jcanizales): Print documentation from the method.
  PrintSimpleSignature(printer, method, vars);
  PrintSimpleImplementation(printer, method, vars);

  printer->Print("// Returns a not-yet-started RPC object.\n");
  PrintAdvancedSignature(printer, method, vars);
  PrintAdvancedImplementation(printer, method, vars);
}

}  // namespace

::grpc::string GetHeader(const ServiceDescriptor *service) {
  ::grpc::string output;
  {
    // Scope the output stream so it closes and finalizes output to the string.
    grpc::protobuf::io::StringOutputStream output_stream(&output);
    Printer printer(&output_stream, '$');

    map< ::grpc::string, ::grpc::string> vars = {
        {"service_class", ServiceClassName(service)}};

    printer.Print(vars, "@protocol $service_class$ <NSObject>\n\n");

    for (int i = 0; i < service->method_count(); i++) {
      PrintMethodDeclarations(&printer, service->method(i));
    }
    printer.Print("@end\n\n");

    printer.Print(
        "/**\n"
        " * Basic service implementation, over gRPC, that only does\n"
        " * marshalling and parsing.\n"
        " */\n");
    printer.Print(vars,
                  "@interface $service_class$ :"
                  " GRPCProtoService<$service_class$>\n");
    printer.Print(
        "- (instancetype)initWithHost:(NSString *)host"
        " NS_DESIGNATED_INITIALIZER;\n");
    printer.Print("+ (instancetype)serviceWithHost:(NSString *)host;\n");
    printer.Print("@end\n");
  }
  return output;
}

::grpc::string GetSource(const ServiceDescriptor *service) {
  ::grpc::string output;
  {
    // Scope the output stream so it closes and finalizes output to the string.
    grpc::protobuf::io::StringOutputStream output_stream(&output);
    Printer printer(&output_stream, '$');

    map< ::grpc::string, ::grpc::string> vars = {
        {"service_name", service->name()},
        {"service_class", ServiceClassName(service)},
        {"package", service->file()->package()}};

    printer.Print(vars, "@implementation $service_class$\n\n");

    printer.Print("// Designated initializer\n");
    printer.Print("- (instancetype)initWithHost:(NSString *)host {\n");
    printer.Print(
        vars,
        "  return (self = [super initWithHost:host"
        " packageName:@\"$package$\" serviceName:@\"$service_name$\"]);\n");
    printer.Print("}\n\n");
    printer.Print(
        "// Override superclass initializer to disallow different"
        " package and service names.\n");
    printer.Print("- (instancetype)initWithHost:(NSString *)host\n");
    printer.Print("                 packageName:(NSString *)packageName\n");
    printer.Print("                 serviceName:(NSString *)serviceName {\n");
    printer.Print("  return [self initWithHost:host];\n");
    printer.Print("}\n\n");
    printer.Print("+ (instancetype)serviceWithHost:(NSString *)host {\n");
    printer.Print("  return [[self alloc] initWithHost:host];\n");
    printer.Print("}\n\n\n");

    for (int i = 0; i < service->method_count(); i++) {
      PrintMethodImplementations(&printer, service->method(i));
    }

    printer.Print("@end\n");
  }
  return output;
}

}  // namespace grpc_objective_c_generator
