#include "csp/controllers/submission_controller.h"

#include "csp/app_state.h"
#include "csp/domain/enum_strings.h"
#include "csp/domain/json.h"
#include "csp/services/contest_service.h"
#include "csp/services/problem_service.h"
#include "csp/services/solution_access_service.h"
#include "csp/services/submission_feedback_runner.h"
#include "csp/services/submission_feedback_service.h"
#include "csp/services/submission_service.h"
#include "http_auth.h"

#include <algorithm>
#include <cctype>
#include <exception>
#include <memory>
#include <optional>
#include <string>

namespace csp::controllers {

namespace {

drogon::HttpResponsePtr JsonError(drogon::HttpStatusCode code,
                                  const std::string& msg) {
  Json::Value j;
  j["ok"] = false;
  j["error"] = msg;
  auto resp = drogon::HttpResponse::newHttpJsonResponse(j);
  resp->setStatusCode(code);
  return resp;
}

drogon::HttpResponsePtr JsonOk(const Json::Value& data) {
  Json::Value j;
  j["ok"] = true;
  j["data"] = data;
  auto resp = drogon::HttpResponse::newHttpJsonResponse(j);
  resp->setStatusCode(drogon::k200OK);
  return resp;
}

int ParseClampedInt(const std::string& s,
                    int default_value,
                    int min_value,
                    int max_value) {
  if (s.empty()) return default_value;
  const int v = std::stoi(s);
  return std::max(min_value, std::min(max_value, v));
}

std::optional<int64_t> ParseOptionalInt64(const std::string& s) {
  if (s.empty()) return std::nullopt;
  return std::stoll(s);
}

bool ParseBoolLike(const std::string& s, bool default_value) {
  if (s.empty()) return default_value;
  std::string v = s;
  std::transform(v.begin(), v.end(), v.begin(), [](unsigned char c) {
    return static_cast<char>(std::tolower(c));
  });
  if (v == "1" || v == "true" || v == "yes" || v == "on") return true;
  if (v == "0" || v == "false" || v == "no" || v == "off") return false;
  return default_value;
}

Json::Value ParseLinksArray(const std::string& links_json) {
  Json::CharReaderBuilder builder;
  Json::Value parsed;
  std::string errs;
  std::unique_ptr<Json::CharReader> reader(builder.newCharReader());
  if (!reader->parse(links_json.data(),
                     links_json.data() + links_json.size(),
                     &parsed,
                     &errs) ||
      !parsed.isArray()) {
    return Json::Value(Json::arrayValue);
  }
  return parsed;
}

}  // namespace

void SubmissionController::submitProblem(
    const drogon::HttpRequestPtr& req,
    std::function<void(const drogon::HttpResponsePtr&)>&& cb,
    int64_t problem_id) {
  try {
    std::string auth_error;
    const auto user_id = GetAuthedUserId(req, auth_error);
    if (!user_id.has_value()) {
      cb(JsonError(drogon::k401Unauthorized, auth_error));
      return;
    }

    const auto json = req->getJsonObject();
    if (!json) {
      cb(JsonError(drogon::k400BadRequest, "body must be json"));
      return;
    }

    services::SubmissionCreateRequest create;
    create.user_id = *user_id;
    create.problem_id = problem_id;
    create.language = (*json).get("language", "cpp").asString();
    create.code = (*json).get("code", "").asString();

    if ((*json).isMember("contest_id") && !(*json)["contest_id"].isNull()) {
      create.contest_id = (*json)["contest_id"].asInt64();
      services::ContestService contest(csp::AppState::Instance().db());

      if (!contest.GetContest(*create.contest_id).has_value()) {
        cb(JsonError(drogon::k400BadRequest, "contest not found"));
        return;
      }
      if (!contest.ContainsProblem(*create.contest_id, problem_id)) {
        cb(JsonError(drogon::k400BadRequest, "problem not in contest"));
        return;
      }
      if (!contest.IsRegistered(*create.contest_id, *user_id)) {
        cb(JsonError(drogon::k403Forbidden, "user is not registered for contest"));
        return;
      }
      if (!contest.IsRunning(*create.contest_id)) {
        cb(JsonError(drogon::k403Forbidden, "contest is not running"));
        return;
      }
    }

    services::SubmissionService svc(csp::AppState::Instance().db());
    auto s = svc.CreateAndJudge(create);

    // Auto-enqueue LLM feedback generation in background.
    services::SubmissionFeedbackRunner::Instance().Enqueue(s.id);

    cb(JsonOk(domain::ToJson(s)));
  } catch (const std::invalid_argument&) {
    cb(JsonError(drogon::k400BadRequest, "invalid numeric field"));
  } catch (const std::out_of_range&) {
    cb(JsonError(drogon::k400BadRequest, "numeric field out of range"));
  } catch (const std::runtime_error& e) {
    cb(JsonError(drogon::k400BadRequest, e.what()));
  } catch (const std::exception& e) {
    cb(JsonError(drogon::k500InternalServerError, e.what()));
  }
}

void SubmissionController::listSubmissions(
    const drogon::HttpRequestPtr& req,
    std::function<void(const drogon::HttpResponsePtr&)>&& cb) {
  try {
    const auto user_id = ParseOptionalInt64(req->getParameter("user_id"));
    const auto problem_id = ParseOptionalInt64(req->getParameter("problem_id"));
    const auto contest_id = ParseOptionalInt64(req->getParameter("contest_id"));
    const int page = ParseClampedInt(req->getParameter("page"), 1, 1, 100000);
    const int page_size =
        ParseClampedInt(req->getParameter("page_size"), 20, 1, 200);

    services::SubmissionService svc(csp::AppState::Instance().db());
    const auto rows = svc.List(user_id, problem_id, contest_id, page, page_size);

    Json::Value arr(Json::arrayValue);
    for (const auto& s : rows) arr.append(domain::ToJson(s));

    Json::Value payload;
    payload["items"] = arr;
    payload["page"] = page;
    payload["page_size"] = page_size;
    cb(JsonOk(payload));
  } catch (const std::invalid_argument&) {
    cb(JsonError(drogon::k400BadRequest, "invalid query parameter"));
  } catch (const std::out_of_range&) {
    cb(JsonError(drogon::k400BadRequest, "query parameter out of range"));
  } catch (const std::exception& e) {
    cb(JsonError(drogon::k500InternalServerError, e.what()));
  }
}

void SubmissionController::getSubmission(
    const drogon::HttpRequestPtr& /*req*/,
    std::function<void(const drogon::HttpResponsePtr&)>&& cb,
    int64_t submission_id) {
  try {
    services::SubmissionService svc(csp::AppState::Instance().db());
    const auto s = svc.GetById(submission_id);
    if (!s.has_value()) {
      cb(JsonError(drogon::k404NotFound, "submission not found"));
      return;
    }
    Json::Value payload = domain::ToJson(*s);
    payload["code"] = s->code;

    // Attach problem title for frontend linking.
    {
      services::ProblemService psvc(csp::AppState::Instance().db());
      if (const auto p = psvc.GetById(s->problem_id); p.has_value()) {
        payload["problem_title"] = p->title;
      }
    }

    services::SolutionAccessService access_svc(csp::AppState::Instance().db());
    const auto stats =
        access_svc.QueryUserProblemViewStats(s->user_id, s->problem_id);
    payload["has_viewed_answer"] = stats.has_viewed;
    payload["answer_view_count"] = stats.total_views;
    payload["answer_view_total_cost"] = stats.total_cost;
    if (stats.last_viewed_at.has_value()) {
      payload["last_answer_view_at"] = Json::Int64(*stats.last_viewed_at);
    } else {
      payload["last_answer_view_at"] = Json::nullValue;
    }

    services::SubmissionFeedbackService feedback_svc(csp::AppState::Instance().db());
    if (const auto feedback = feedback_svc.GetBySubmissionId(s->id);
        feedback.has_value()) {
      Json::Value analysis;
      analysis["feedback_md"] = feedback->feedback_md;
      analysis["links"] = ParseLinksArray(feedback->links_json);
      analysis["model_name"] = feedback->model_name;
      analysis["status"] = feedback->status;
      analysis["created_at"] = Json::Int64(feedback->created_at);
      analysis["updated_at"] = Json::Int64(feedback->updated_at);
      payload["analysis"] = analysis;
    } else {
      payload["analysis"] = Json::nullValue;
    }

    cb(JsonOk(payload));
  } catch (const std::exception& e) {
    cb(JsonError(drogon::k500InternalServerError, e.what()));
  }
}

void SubmissionController::analyzeSubmission(
    const drogon::HttpRequestPtr& req,
    std::function<void(const drogon::HttpResponsePtr&)>&& cb,
    int64_t submission_id) {
  try {
    std::string auth_error;
    if (!GetAuthedUserId(req, auth_error).has_value()) {
      cb(JsonError(drogon::k401Unauthorized, auth_error));
      return;
    }

    bool force_refresh = ParseBoolLike(req->getParameter("refresh"), false);
    if (const auto json = req->getJsonObject();
        json && (*json).isMember("refresh")) {
      force_refresh = (*json)["refresh"].asBool();
    }

    services::SubmissionService submission_svc(csp::AppState::Instance().db());
    const auto submission = submission_svc.GetById(submission_id);
    if (!submission.has_value()) {
      cb(JsonError(drogon::k404NotFound, "submission not found"));
      return;
    }

    services::ProblemService problem_svc(csp::AppState::Instance().db());
    const auto problem = problem_svc.GetById(submission->problem_id);
    if (!problem.has_value()) {
      cb(JsonError(drogon::k404NotFound, "problem not found"));
      return;
    }

    services::SubmissionFeedbackService feedback_svc(csp::AppState::Instance().db());
    const auto feedback =
        feedback_svc.GenerateAndSave(*submission, *problem, force_refresh);

    Json::Value payload;
    payload["submission_id"] = Json::Int64(feedback.submission_id);
    payload["feedback_md"] = feedback.feedback_md;
    payload["links"] = ParseLinksArray(feedback.links_json);
    payload["model_name"] = feedback.model_name;
    payload["status"] = feedback.status;
    payload["created_at"] = Json::Int64(feedback.created_at);
    payload["updated_at"] = Json::Int64(feedback.updated_at);
    payload["refresh"] = force_refresh;
    cb(JsonOk(payload));
  } catch (const std::invalid_argument&) {
    cb(JsonError(drogon::k400BadRequest, "invalid request field"));
  } catch (const std::runtime_error& e) {
    cb(JsonError(drogon::k400BadRequest, e.what()));
  } catch (const std::exception& e) {
    cb(JsonError(drogon::k500InternalServerError, e.what()));
  }
}

void SubmissionController::runCpp(
    const drogon::HttpRequestPtr& req,
    std::function<void(const drogon::HttpResponsePtr&)>&& cb) {
  try {
    const auto json = req->getJsonObject();
    if (!json) {
      cb(JsonError(drogon::k400BadRequest, "body must be json"));
      return;
    }

    const std::string code = (*json).get("code", "").asString();
    const std::string input = (*json).get("input", "").asString();

    services::SubmissionService svc(csp::AppState::Instance().db());
    const auto r = svc.RunOnlyCpp(code, input);

    Json::Value payload;
    payload["status"] = domain::ToString(r.status);
    payload["time_ms"] = r.time_ms;
    payload["stdout"] = r.stdout_text;
    payload["stderr"] = r.stderr_text;
    payload["compile_log"] = r.compile_log;
    cb(JsonOk(payload));
  } catch (const std::runtime_error& e) {
    cb(JsonError(drogon::k400BadRequest, e.what()));
  } catch (const std::exception& e) {
    cb(JsonError(drogon::k500InternalServerError, e.what()));
  }
}

}  // namespace csp::controllers