#include "config_generator.h"

#include <cstddef>
#include <fstream>
#include <iterator>
#include <optional>
#include <string>
#include <string_view>

#include "gmi/machine_identity.pb.h"
#include "one/offline_node_entities.pb.h"
#include "one/resolved_entities.pb.h"
#include "one/public_offline_node_entities.h"
#include "absl/log/log.h"
#include "absl/strings/str_cat.h"
#include "nlohmann/json.hpp"
#include "json_utils.h"
#include "zatar/certificate_metadata.h"

namespace milotic::authz {

namespace {

using ::milotic::redfish::CertificateMetadataParser;
using ::production_msv::node_entities::ReadOfflineNodeEntityInformation;
using ::production_msv::node_entities_proto::OfflineNodeEntityInformation;
using ::production_msv::node_entities_proto::ResolvedNodeEntity;
using ::security_prodid::GoogleMachineIdentityProto;

constexpr std::string_view kMachineManagerRedfishRole = "MManager";
constexpr std::string_view kComputeNodeRedfishRole = "ComputeNode";
constexpr std::string_view kEmptyConfiguration = R"(
{
  "base_privilege_registry": "Redfish_1.3.0_PrivilegeRegistry.json",
  "exchange_mappings": [],
  "name": "Empty BMC Authorization Configurations",
  "oem_privilege_mappings": [],
  "resource_owners": [],
  "role_privileges_mappings": []
}
)";
constexpr std::string_view kHwopsRole = "insecure-hwops-state";
}  // namespace

nlohmann::json::json_pointer ConfigGenerator::FindLocalNodeInOwners(
    const nlohmann::json& root, std::string_view hostname) {
  nlohmann::json::json_pointer resource_owners_ptr =
      "/resource_owners"_json_pointer;
  const nlohmann::json::array_t* resource_owners =
      GetValueAsArray(root, "resource_owners");
  if (resource_owners == nullptr) {
    return resource_owners_ptr / 0;
  }
  for (std::size_t i = 0; i < resource_owners->size(); ++i) {
    const std::string* fqdn = GetValueAsString(resource_owners->at(i), "fqdn");
    if (fqdn != nullptr &&
        *fqdn == absl::StrCat(hostname, ".prod.google.com")) {
      return resource_owners_ptr / i;
    }
  }
  return resource_owners_ptr / resource_owners->size();
}

nlohmann::json::json_pointer ConfigGenerator::FindLocalNodeInExchangeMappings(
    const nlohmann::json& root, std::string_view hostname,
    std::string_view node_redfish_role) {
  nlohmann::json::json_pointer exchange_mappings_ptr =
      "/exchange_mappings"_json_pointer;
  const nlohmann::json::array_t* exchange_mappings =
      GetValueAsArray(root, "exchange_mappings");
  if (exchange_mappings == nullptr) {
    return exchange_mappings_ptr / 0;
  }
  for (std::size_t i = 0; i < exchange_mappings->size(); ++i) {
    const std::string* redfish_role =
        GetValueAsString(exchange_mappings->at(i), "redfish_role");
    if (redfish_role != nullptr && *redfish_role == node_redfish_role) {
      return exchange_mappings_ptr / i;
    }
    const nlohmann::json* peer =
        GetValueAsJson(exchange_mappings->at(i), "peer");
    if (peer != nullptr) {
      const std::string* fqdn = GetValueAsString(*peer, "fqdn");
      if (fqdn != nullptr &&
          *fqdn == absl::StrCat(hostname, ".prod.google.com")) {
        return exchange_mappings_ptr / i;
      }
    }
  }
  return exchange_mappings_ptr / exchange_mappings->size();
}

std::optional<GoogleMachineIdentityProto> ConfigGenerator::GetGmiDataFromGmi(
    const std::string& gmi_path) {
  std::ifstream gmi_file(gmi_path);
  if (!gmi_file.is_open()) {
    LOG(ERROR) << "GMI file at '" << gmi_path << "' is missing.";
    return std::nullopt;
  }
  GoogleMachineIdentityProto gmi;
  if (!gmi.ParseFromIstream(&gmi_file)) {
    LOG(ERROR) << "GMI parsing failed at '" << gmi_path << "'";
    return std::nullopt;
  }
  return gmi;
}

// Return the role expected in the certificate.
//
// When the machine is in HWOPS, GMI reports the actual owner and
// "in_hwops_state", while certificates use insecure-hwops-state as the role
// rather than the actual owner. go/aristotle-ownership-change#owner
std::string_view GetCertNodeOwner(bool in_hwops_state,
                                  std::string_view node_owner) {
  if (in_hwops_state) {
    return kHwopsRole;
  }
  return node_owner;
}

void ConfigGenerator::UpdateMachineManagerMappingsInRoot(
    nlohmann::json& root, bool in_hwops_state,
    const OfflineNodeEntityInformation& one) {
  std::string mmanager_entity_tag =
      one.resolved_config().ecclesia_machine_manager_entity();
  ResolvedNodeEntity mmanager_entity =
      one.resolved_config().entities().at(mmanager_entity_tag);

  nlohmann::json::json_pointer mmanager_exchange_mappings_ptr =
      FindLocalNodeInExchangeMappings(root, mmanager_entity.hostname(),
                                      kMachineManagerRedfishRole);

  // If a mapping to mmanager already exists, then no-op
  if (root.contains(mmanager_exchange_mappings_ptr)) {
    return;
  }

  // Define MManager Peer object
  nlohmann::json::object_t mmanager = nlohmann::json::object();
  mmanager["spiffe_id_matcher"]["path"] = absl::StrCat(
      "/role/", GetCertNodeOwner(in_hwops_state, mmanager_entity.owner()));
  mmanager["spiffe_id_matcher"]["ca_context"] =
      CertificateMetadataParser::kCaContextNode;
  mmanager["spiffe_id_matcher"]["trust_domain_suffix"] = ".prod.google.com";
  mmanager["fqdn"] =
      absl::StrCat(mmanager_entity.hostname(), ".prod.google.com");
  root[FindLocalNodeInOwners(root, mmanager_entity.hostname())] = mmanager;

  // Define MManager Exchange mapping
  nlohmann::json::object_t mmanager_exchange = nlohmann::json::object();
  mmanager_exchange["redfish_role"] = kMachineManagerRedfishRole;
  mmanager_exchange["peer"] = mmanager;
  root[mmanager_exchange_mappings_ptr] = mmanager_exchange;
}

void ConfigGenerator::UpdateComputeNodeMappingsInRoot(
    nlohmann::json& root, bool in_hwops_state,
    const OfflineNodeEntityInformation& one) {
  nlohmann::json::json_pointer compute_node_exchange_mapping_ptr =
      FindLocalNodeInExchangeMappings(
          root, one.resolved_config().machine_name(), kComputeNodeRedfishRole);

  // If a mapping to compute node already exists, then no-op
  if (root.contains(compute_node_exchange_mapping_ptr)) {
    return;
  }

  // Define Compute Node Peer object
  //
  // TODO: this only works on machines on which the compute node hostname ==
  // machine name
  nlohmann::json::object_t compute_node = nlohmann::json::object();
  compute_node["spiffe_id_matcher"]["path"] = absl::StrCat(
      "/role/",
      GetCertNodeOwner(in_hwops_state, one.resolved_config().machine_owner()));
  compute_node["spiffe_id_matcher"]["ca_context"] =
      CertificateMetadataParser::kCaContextNode;
  compute_node["spiffe_id_matcher"]["trust_domain_suffix"] = ".prod.google.com";
  compute_node["fqdn"] =
      absl::StrCat(one.resolved_config().machine_name(), ".prod.google.com");
  root[FindLocalNodeInOwners(root, one.resolved_config().machine_name())] =
      compute_node;

  // Define Compute Node Exchange mapping
  nlohmann::json::object_t compute_node_exchange = nlohmann::json::object();
  compute_node_exchange["redfish_role"] = kComputeNodeRedfishRole;
  compute_node_exchange["peer"] = compute_node;
  root[compute_node_exchange_mapping_ptr] = compute_node_exchange;
}

nlohmann::json ConfigGenerator::ReadConfigAndAddRuntimeSubstitutions(
    const std::string& base_config_path, bool in_hwops_state,
    const OfflineNodeEntityInformation& one) {
  std::ifstream template_file(base_config_path);
  if (!template_file.is_open()) {
    LOG(ERROR) << "Authorization configuration file at '" << base_config_path
               << "' is missing.";
    return nlohmann::json::object();
  }
  std::string template_content((std::istreambuf_iterator<char>(template_file)),
                               std::istreambuf_iterator<char>());

  nlohmann::json root = nlohmann::json::parse(template_content, nullptr, false);
  if (root.is_discarded()) {
    LOG(ERROR) << "Authorization configuration is not a JSON! |content|="
               << template_content;
    return nlohmann::json::object();
  }

  UpdateMachineManagerMappingsInRoot(root, in_hwops_state, one);
  UpdateComputeNodeMappingsInRoot(root, in_hwops_state, one);

  return root;
}

nlohmann::json ConfigGenerator::EmptyConfiguration() {
  return nlohmann::json::parse(kEmptyConfiguration, nullptr, false);
}

nlohmann::json ConfigGenerator::GenerateConfiguration(
    const GeneratorOptions& options) {
  std::optional<GoogleMachineIdentityProto> gmi =
      GetGmiDataFromGmi(options.gmi_path);
  if (!gmi) {
    return nlohmann::json::object();
  }
  absl::StatusOr<OfflineNodeEntityInformation> one =
      ReadOfflineNodeEntityInformation(options.offline_node_entities_path);
  if (!one.ok()) {
    LOG(ERROR) << "Could not read offline node entities information: "
               << one.status().message();
    return nlohmann::json::object();
  }
  return ReadConfigAndAddRuntimeSubstitutions(options.authz_configuration_path,
                                              gmi->in_hwops_state(), *one);
}
}  // namespace milotic::authz