// Copyright 2016 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include <fstream>

#include <rapidjson/document.h>
#include <rapidjson/error/en.h>
#include <rapidjson/istreamwrapper.h>

#include "garnet/bin/trace_manager/config.h"
#include "lib/fxl/logging.h"

namespace tracing {
namespace {

constexpr char kCategories[] = "categories";
constexpr char kProviders[] = "providers";

}  // namespace

Config::Config() = default;

Config::~Config() = default;

bool Config::ReadFrom(const std::string& config_file) {
  std::ifstream in(config_file);
  rapidjson::IStreamWrapper isw(in);
  rapidjson::Document document;

  if (!document.ParseStream(isw).IsObject()) {
    FXL_LOG(ERROR) << "Failed to parse JSON object from: " << config_file;
    if (document.HasParseError()) {
      FXL_LOG(ERROR) << "Parse error "
                     << GetParseError_En(document.GetParseError()) << " ("
                     << document.GetErrorOffset() << ")";
    }
    return false;
  }

  auto categories_it = document.FindMember(kCategories);
  if (categories_it != document.MemberEnd()) {
    const auto& value = categories_it->value;
    if (!value.IsObject()) {
      FXL_LOG(ERROR) << "Expecting " << kCategories << " to be an object";
      return false;
    }
    for (auto it = value.MemberBegin(); it != value.MemberEnd(); ++it) {
      if (!(it->name.IsString() && it->value.IsString())) {
        FXL_LOG(ERROR) << "Expecting both name and value to be strings";
        return false;
      }
      known_categories_[it->name.GetString()] = it->value.GetString();
    }
  }

  auto provider_it = document.FindMember(kProviders);
  if (provider_it != document.MemberEnd()) {
    const auto& value = provider_it->value;
    if (!value.IsObject())
      return false;
    for (const auto& reg : value.GetObject()) {
      if (!reg.name.IsString())
        return false;

      auto launch_info = fuchsia::sys::LaunchInfo::New();
      if (reg.value.IsString()) {
        launch_info->url = reg.value.GetString();
      } else if (reg.value.IsArray()) {
        const auto& array = reg.value.GetArray();
        if (array.Empty() || !array[0].IsString())
          return false;
        launch_info->url = array[0].GetString();
        for (size_t i = 1; i < array.Size(); ++i) {
          if (!array[i].IsString())
            return false;
          launch_info->arguments.push_back(array[i].GetString());
        }
      } else {
        return false;
      }
      providers_.emplace(reg.name.GetString(), std::move(launch_info));
    }
  }

  return true;
}

}  // namespace tracing