#include <enum.h>

#include <daggy/Serialization.hpp>
#include <daggy/Utilities.hpp>
#include <daggyd/Server.hpp>
#include <fstream>
#include <iomanip>
#include <mutex>
#include <numeric>
#include <stdexcept>
#include <thread>
#include <utility>

#define REQ_RESPONSE(code, msg)                         \
  std::stringstream ss;                                 \
  ss << R"({"message": )" << std::quoted(msg) << "}\n"; \
  response.send(Pistache::Http::Code::code, ss.str());  \
  return;

using namespace Pistache;

namespace daggy::daggyd {

  void addResponseHeaders(Pistache::Http::ResponseWriter &response)
  {
    response.headers().add(
        std::make_shared<Pistache::Http::Header::AccessControlAllowOrigin>(
            "*"));
    response.headers().add(
        std::make_shared<Pistache::Http::Header::AccessControlAllowHeaders>(
            "content-type"));
    response.headers().add(
        std::make_shared<Pistache::Http::Header::AccessControlAllowMethods>(
            "PUT, OPTIONS, PATCH, GET, HEAD, CONNECT, DELETE, POST, TRACE"));
    response.headers().add(
        std::make_shared<Pistache::Http::Header::ContentType>(
            "application/javascript"));
  }

  void Server::init(size_t threads)
  {
    auto opts = Http::Endpoint::options()
                    .threads(threads)
                    .flags(Pistache::Tcp::Options::ReuseAddr |
                           Pistache::Tcp::Options::ReusePort)
                    .maxRequestSize(4294967296)
                    .maxResponseSize(4294967296);
    endpoint_.init(opts);
    createDescription();
  }

  Server::Server(const Pistache::Address &listenSpec,
                 loggers::dag_run::DAGRunLogger &logger,
                 executors::task::TaskExecutor &executor, size_t nDAGRunners,
                 const fs::path &staticAssetsDir)
    : endpoint_(listenSpec)
    , desc_("Daggy API", "0.1")
    , logger_(logger)
    , executor_(executor)
    , runnerPool_(nDAGRunners)
    , staticAssetsDir_(staticAssetsDir)
  {
  }

  Server::~Server()
  {
    shutdown();
  }

  void Server::start()
  {
    router_.initFromDescription(desc_);

    endpoint_.setHandler(router_.handler());
    endpoint_.serveThreaded();
  }

  Server &Server::setSSLCertificates(const fs::path &cert, const fs::path &key)
  {
    endpoint_.useSSL(cert, key);
    return *this;
  }

  void Server::shutdown()
  {
    endpoint_.shutdown();
    runnerPool_.shutdown();
  }

  uint16_t Server::getPort() const
  {
    return endpoint_.getPort();
  }

  void Server::createDescription()
  {
    desc_.info().license("MIT", "https://opensource.org/licenses/MIT");

    auto backendErrorResponse =
        desc_.response(Http::Code::Internal_Server_Error,
                       R"({"error": "An error occurred with the backend"})");

    desc_.route(desc_.get("/"))
        .bind(&Server::handleStatic, this)
        .response(Http::Code::Ok, "Serve static assets")
        .hide();
    desc_.route(desc_.get("/*"))
        .bind(&Server::handleStatic, this)
        .response(Http::Code::Ok, "Serve static assets")
        .hide();
    desc_.route(desc_.get("/*/*"))
        .bind(&Server::handleStatic, this)
        .response(Http::Code::Ok, "Serve static assets")
        .hide();

    desc_.schemes(Rest::Scheme::Http)
        .basePath("/v1")
        .produces(MIME(Application, Json))
        .consumes(MIME(Application, Json));

    desc_.route(desc_.get("/ready"))
        .bind(&Server::handleReady, this)
        .response(Http::Code::Ok, "Response to the /ready call")
        .hide();

    auto versionPath = desc_.path("/v1");

    /*
       DAG Run Summaries
    */
    auto dagRunsPath = versionPath.path("/dagruns");

    dagRunsPath.route(desc_.options("/")).bind(&Server::handleCORS, this);
    dagRunsPath.route(desc_.get("/"))
        .bind(&Server::handleQueryDAGs, this)
        .produces(MIME(Application, Json))
        .response(Http::Code::Ok, "List summaries DAGs");

    /*
       Individual DAG Run routes
    */
    auto dagRunPath = versionPath.path("/dagrun");

    dagRunPath.route(desc_.options("/")).bind(&Server::handleCORS, this);
    dagRunPath.route(desc_.post("/"))
        .bind(&Server::handleRunDAG, this)
        .produces(MIME(Application, Json))
        .response(Http::Code::Ok, "Run a DAG");

    dagRunPath.route(desc_.options("/validate"))
        .bind(&Server::handleCORS, this);
    dagRunPath.route(desc_.post("/validate"))
        .bind(&Server::handleValidateDAG, this)
        .produces(MIME(Application, Json))
        .response(Http::Code::Ok, "Validate a DAG Run Spec");

    /*
       Management of a specific DAG
    */
    auto specificDAGRunPath = dagRunPath.path("/:runID");

    specificDAGRunPath.route(desc_.options("/"))
        .bind(&Server::handleCORS, this);
    specificDAGRunPath.route(desc_.del("/"))
        .bind(&Server::handleStopDAGRun, this)
        .produces(MIME(Application, Json))
        .response(Http::Code::Ok, "Kill a running dag");

    specificDAGRunPath.route(desc_.get("/"))
        .bind(&Server::handleGetDAGRun, this)
        .produces(MIME(Application, Json))
        .response(Http::Code::Ok, "Full DAG Run");

    specificDAGRunPath.route(desc_.options("/state"))
        .bind(&Server::handleCORS, this);
    specificDAGRunPath.route(desc_.get("/state"))
        .bind(&Server::handleGetDAGRunState, this)
        .produces(MIME(Application, Json))
        .response(Http::Code::Ok,
                  "Structure of a DAG and DAG and Task run states");

    specificDAGRunPath.route(desc_.options("/state/:state"))
        .bind(&Server::handleCORS, this);
    specificDAGRunPath.route(desc_.patch("/state/:state"))
        .bind(&Server::handleSetDAGRunState, this)
        .produces(MIME(Application, Json))
        .response(Http::Code::Ok, "Change the state of a DAG");

    /*
       Task paths
    */
    auto taskPath = specificDAGRunPath.path("/task/:taskName");
    taskPath.route(desc_.options("/")).bind(&Server::handleCORS, this);
    taskPath.route(desc_.get("/"))
        .bind(&Server::handleGetTask, this)
        .produces(MIME(Application, Json))
        .response(Http::Code::Ok, "Details of a specific task");
    taskPath.route(desc_.del("/"))
        .bind(&Server::handleStopTask, this)
        .produces(MIME(Application, Json))
        .response(Http::Code::Ok, "Kill a specific task");

    /*
       Task State paths
    */
    auto taskStatePath = taskPath.path("/state");

    taskStatePath.route(desc_.options("/")).bind(&Server::handleCORS, this);
    taskStatePath.route(desc_.get("/"))
        .bind(&Server::handleGetTaskState, this)
        .produces(MIME(Application, Json))
        .response(Http::Code::Ok, "Get a task state");

    taskStatePath.route(desc_.options("/:state"))
        .bind(&Server::handleCORS, this);
    taskStatePath.route(desc_.patch("/:state"))
        .bind(&Server::handleSetTaskState, this)
        .produces(MIME(Application, Json))
        .response(Http::Code::Ok, "Set a task state");
  }

  void Server::handleCORS(const Pistache::Rest::Request &request,
                          Pistache::Http::ResponseWriter response)
  {
    addResponseHeaders(response);
    response.send(Pistache::Http::Code::Ok, "");
  }

  void Server::handleRunDAG(const Pistache::Rest::Request &request,
                            Pistache::Http::ResponseWriter response)
  {
    if (!handleAuth(request))
      return;
    addResponseHeaders(response);

    DAGRunID runID = 0;
    try {
      DAGSpec dagSpec;
      dagSpec = dagFromJSON(request.body());
      dagSpec.tasks =
          expandTaskSet(dagSpec.tasks, executor_, dagSpec.taskConfig.variables);
      // Get a run ID
      runID    = logger_.startDAGRun(dagSpec);
      auto dag = buildDAGFromTasks(dagSpec.tasks);
      queueDAG_(runID, dag, dagSpec.taskConfig);
    }
    catch (std::runtime_error &e) {
      REQ_RESPONSE(Not_Acceptable, e.what());
    }

    response.send(Pistache::Http::Code::Ok,
                  R"({"runID": )" + std::to_string(runID) + "}\n");
  }

  void Server::handleValidateDAG(const Pistache::Rest::Request &request,
                                 Pistache::Http::ResponseWriter response)
  {
    addResponseHeaders(response);
    try {
      dagFromJSON(request.body());
      response.send(Pistache::Http::Code::Ok, R"({"valid": true}\n)");
    }
    catch (std::exception &e) {
      std::string error = e.what();
      response.send(
          Pistache::Http::Code::Ok,
          std::string{R"({"valid": false, "error": })"} + error + "}\n");
    }
  }

  void Server::handleQueryDAGs(const Pistache::Rest::Request &request,
                               Pistache::Http::ResponseWriter response)
  {
    addResponseHeaders(response);
    if (!handleAuth(request))
      return;

    bool all        = false;
    std::string tag = "";

    if (request.query().has("tag")) {
      tag = request.query().get("tag").value();
    }

    if (request.query().has("all")) {
      auto val = request.query().get("all").value();
      if (val == "true" or val == "1") {
        all = true;
      }
    }

    auto dagRuns = logger_.queryDAGRuns(tag, all);
    std::stringstream ss;
    // default to json
    ss << '[';

    bool first = true;
    for (const auto &run : dagRuns) {
      if (first) {
        first = false;
      }
      else {
        ss << ", ";
      }

      ss << " {"
         << R"("runID": )" << run.runID << ',' << R"("tag": )"
         << std::quoted(run.tag) << ","
         << R"("state": )" << std::quoted(run.runState._to_string()) << ","
         << R"("startTime": )" << std::quoted(timePointToString(run.startTime))
         << ',' << R"("lastUpdate": )"
         << std::quoted(timePointToString(run.lastUpdate)) << ','
         << R"("taskCounts": {)";
      bool firstState = true;
      for (const auto &[state, count] : run.taskStateCounts) {
        if (firstState) {
          firstState = false;
        }
        else {
          ss << ", ";
        }
        ss << std::quoted(state._to_string()) << ':' << count;
      }
      ss << '}'   // end of taskCounts
         << '}';  // end of item
    }
    ss << "]\n";
    response.send(Pistache::Http::Code::Ok, ss.str());
  }

  void Server::handleGetDAGRun(const Pistache::Rest::Request &request,
                               Pistache::Http::ResponseWriter response)
  {
    addResponseHeaders(response);
    if (!handleAuth(request))
      return;
    if (!request.hasParam(":runID")) {
      REQ_RESPONSE(Not_Found, "No runID provided in URL");
    }
    auto runID = request.param(":runID").as<size_t>();
    auto run   = logger_.getDAGRun(runID);

    std::optional<RunState> filterState;
    if (request.query().has("state")) {
      auto val    = request.query().get("state").value();
      filterState = RunState::_from_string(val.c_str());
    }

    std::stringstream ss;
    bool first = true;
    ss << "{"
       << R"("runID": )" << runID << ',' << R"("tag": )"
       << std::quoted(run.dagSpec.tag) << ',' << R"("tasks": )"
       << tasksToJSON(run.dagSpec.tasks) << ',';

    // task run states
    ss << R"("taskStates": { )";
    first = true;
    for (const auto &[name, state] : run.taskRunStates) {
      if (first) {
        first = false;
      }
      else {
        ss << ',';
      }
      ss << std::quoted(name) << ": " << std::quoted(state._to_string());
    }
    ss << "},";

    // Attempt records
    first = true;
    ss << R"("taskAttempts": { )";
    for (const auto &[taskName, attempts] : run.taskAttempts) {
      if (first) {
        first = false;
      }
      else {
        ss << ',';
      }
      ss << std::quoted(taskName) << ": [";
      bool firstAttempt = true;
      for (const auto &attempt : attempts) {
        if (firstAttempt) {
          firstAttempt = false;
        }
        else {
          ss << ',';
        }
        ss << attemptRecordToJSON(attempt);
      }
      ss << ']';
    }
    ss << "},";

    // DAG state changes
    first = true;
    ss << R"("dagStateChanges": [ )";
    for (const auto &change : run.dagStateChanges) {
      if (first) {
        first = false;
      }
      else {
        ss << ',';
      }
      ss << stateUpdateRecordToJSON(change);
    }
    ss << "]";
    ss << "}\n";
    response.send(Pistache::Http::Code::Ok, ss.str());
  }

  void Server::handleStopDAGRun(const Pistache::Rest::Request &request,
                                Pistache::Http::ResponseWriter response)
  {
    addResponseHeaders(response);
    if (!handleAuth(request))
      return;
    if (!request.hasParam(":runID")) {
      REQ_RESPONSE(Not_Found, "No runID provided in URL");
    }
    auto runID = request.param(":runID").as<size_t>();

    {
      std::lock_guard<std::mutex> lock(runnerGuard_);
      auto it = runners_.find(runID);
      if (it != runners_.end()) {
        it->second->stop(true, false);
      }
    }

    response.send(Pistache::Http::Code::Ok, "");
  }

  void Server::handleGetDAGRunState(const Pistache::Rest::Request &request,
                                    Pistache::Http::ResponseWriter response)
  {
    if (!handleAuth(request))
      return;

    DAGRunID runID = request.param(":runID").as<DAGRunID>();
    RunState state = RunState::QUEUED;
    try {
      state = logger_.getDAGRunState(runID);
      std::stringstream ss;
      ss << R"({ "runID": )" << runID << R"(, "state": )"
         << std::quoted(state._to_string()) << '}';
      response.send(Pistache::Http::Code::Ok, ss.str());
    }
    catch (std::exception &e) {
      REQ_RESPONSE(Not_Found, e.what());
    }
  }

  void Server::queueDAG_(DAGRunID runID, const TaskDAG &dag,
                         const TaskParameters &taskParameters)
  {
    std::lock_guard<std::mutex> lock(runnerGuard_);
    /*
    auto it = runners_.emplace(
        std::piecewise_construct, std::forward_as_tuple(runID),
        std::forward_as_tuple(runID, executor_, logger_, dag,
    taskParameters));
        */
    auto it = runners_.emplace(
        runID, std::make_shared<DAGRunner>(runID, executor_, logger_, dag,
                                           taskParameters));

    if (!it.second)
      throw std::runtime_error("A DAGRun with the same ID is already running");
    auto runner = it.first->second;
    runnerPool_.addTask([runner, runID, this]() {
      runner->run();
      std::lock_guard<std::mutex> lock(this->runnerGuard_);
      this->runners_.extract(runID);
    });
  }

  void Server::handleSetDAGRunState(const Pistache::Rest::Request &request,
                                    Pistache::Http::ResponseWriter response)
  {
    if (!handleAuth(request))
      return;
    addResponseHeaders(response);

    // TODO handle state transition
    DAGRunID runID    = request.param(":runID").as<DAGRunID>();
    RunState newState = RunState::_from_string(
        request.param(":state").as<std::string>().c_str());

    std::shared_ptr<DAGRunner> runner{nullptr};
    {
      std::lock_guard<std::mutex> lock(runnerGuard_);
      auto it = runners_.find(runID);
      if (runners_.find(runID) != runners_.end()) {
        runner = it->second;
      }
    }

    if (runner) {
      switch (newState) {
        case RunState::PAUSED:
        case RunState::KILLED: {
          runner->stop(true, true);
          logger_.updateDAGRunState(runID, newState);
          break;
        }
        default: {
          REQ_RESPONSE(Method_Not_Allowed,
                       std::string{"Cannot transition to state "} +
                           newState._to_string());
        }
      }
    }
    else {
      switch (newState) {
        case RunState::QUEUED: {
          auto dagRun = logger_.getDAGRun(runID);
          auto dag =
              buildDAGFromTasks(dagRun.dagSpec.tasks, dagRun.taskStateChanges);
          dag.resetRunning();
          queueDAG_(runID, dag, dagRun.dagSpec.taskConfig);
          break;
        }
        default:
          REQ_RESPONSE(
              Method_Not_Allowed,
              std::string{"DAG not running, cannot transition to state "} +
                  newState._to_string());
      }
    }
    REQ_RESPONSE(Ok, "");
  }

  void Server::handleGetTask(const Pistache::Rest::Request &request,
                             Pistache::Http::ResponseWriter response)
  {
    addResponseHeaders(response);
    if (!handleAuth(request))
      return;

    auto runID    = request.param(":runID").as<DAGRunID>();
    auto taskName = request.param(":taskName").as<std::string>();

    std::stringstream ss;
    Task task;
    try {
      task = logger_.getTask(runID, taskName);
    }
    catch (std::exception &e) {
      REQ_RESPONSE(Not_Found, e.what());
    }
    ss << taskToJSON(task);
    response.send(Pistache::Http::Code::Ok, ss.str());
  }

  void Server::handleStopTask(const Pistache::Rest::Request &request,
                              Pistache::Http::ResponseWriter response)
  {
    addResponseHeaders(response);
    if (!handleAuth(request))
      return;

    auto runID    = request.param(":runID").as<DAGRunID>();
    auto taskName = request.param(":taskName").as<std::string>();

    std::shared_ptr<DAGRunner> runner{nullptr};
    {
      std::lock_guard<std::mutex> lock(runnerGuard_);
      auto it = runners_.find(runID);
      if (runners_.find(runID) != runners_.end()) {
        runner = it->second;
      }
    }

    if (runner) {
      runner->stopTask(taskName);
    }
    REQ_RESPONSE(Ok, "");
  }

  void Server::handleGetTaskState(const Pistache::Rest::Request &request,
                                  Pistache::Http::ResponseWriter response)
  {
    addResponseHeaders(response);
    if (!handleAuth(request))
      return;

    auto runID    = request.param(":runID").as<DAGRunID>();
    auto taskName = request.param(":taskName").as<std::string>();

    try {
      auto state = logger_.getTaskState(runID, taskName);
      std::stringstream ss;
      ss << R"({ "runID": )" << runID << R"(, "taskName": )"
         << std::quoted(taskName) << R"(, "state": )"
         << std::quoted(state._to_string()) << "}\n";
      response.send(Pistache::Http::Code::Ok, ss.str());
    }
    catch (std::exception &e) {
      REQ_RESPONSE(Not_Found, e.what());
    }
  }

  void Server::handleSetTaskState(const Pistache::Rest::Request &request,
                                  Pistache::Http::ResponseWriter response)
  {
    addResponseHeaders(response);
    if (!handleAuth(request))
      return;

    // TODO implement handling of task state
    auto runID     = request.param(":runID").as<DAGRunID>();
    auto taskName  = request.param(":taskName").as<std::string>();
    RunState state = RunState::_from_string(
        request.param(":state").as<std::string>().c_str());

    try {
      logger_.updateTaskState(runID, taskName, state);
      response.send(Pistache::Http::Code::Ok, "");
    }
    catch (std::exception &e) {
      REQ_RESPONSE(Not_Found, e.what());
    }
  }

  void Server::handleReady(const Pistache::Rest::Request &request,
                           Pistache::Http::ResponseWriter response)
  {
    addResponseHeaders(response);
    REQ_RESPONSE(Ok, "Ya like DAGs?");
  }

  void Server::handleStatic(const Pistache::Rest::Request &request,
                            Pistache::Http::ResponseWriter response)
  {
    addResponseHeaders(response);
    std::string file = "index.html";

    auto splats = request.splat();
    if (!splats.empty()) {
      file = splats[0].as<std::string>();
      for (size_t i = 1; i < splats.size(); ++i)
        file += "/" + splats[i].as<std::string>();
    }

    auto fn = staticAssetsDir_ / file;

    auto ext = fn.extension();

    if (!fs::exists(fn)) {
      std::cout << "Can't find " << fn << std::endl;
      REQ_RESPONSE(Not_Found, "");
    }

    std::string contentType;
    if (ext == ".svg") {
      contentType = "image/svg+xml";
    }
    else if (ext == ".html") {
      contentType = "text/html";
    }
    else if (ext == ".css") {
      contentType = "text/css";
    }
    else if (ext == ".js") {
      contentType = "text/javascript";
    }
    else {
      REQ_RESPONSE(Bad_Request, "I don't know how to serve that kind of file");
    }

    response.headers().remove<Pistache::Http::Header::ContentType>();
    response.headers().add(
        std::make_shared<Pistache::Http::Header::ContentType>(contentType));

    std::stringstream ss;
    std::ifstream ifh;
    ifh.open(fn, std::ios::binary);
    ss << ifh.rdbuf();

    response.send(Pistache::Http::Code::Ok, ss.str());
  }

  /*
   * handleAuth will check any auth methods and handle any responses in the
   * case of failed auth. If it returns false, callers should cease handling
   * the response
   */
  bool Server::handleAuth(const Pistache::Rest::Request &request)
  {
    return true;
  }
}  // namespace daggy::daggyd