#include "csp/controllers/me_controller.h"

#include "csp/app_state.h"
#include "csp/domain/json.h"
#include "csp/services/daily_task_service.h"
#include "csp/services/redeem_service.h"
#include "csp/services/solution_access_service.h"
#include "csp/services/user_service.h"
#include "csp/services/wrong_book_service.h"
#include "csp/services/crypto.h"
#include "csp/services/problem_service.h"
#include "csp/services/learning_note_scoring_service.h"
#include "http_auth.h"

#include <drogon/MultiPart.h>

#include <algorithm>
#include <filesystem>
#include <memory>
#include <exception>
#include <optional>
#include <stdexcept>
#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;
}

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

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

} // namespace

void MeController::profile(
    const drogon::HttpRequestPtr &req,
    std::function<void(const drogon::HttpResponsePtr &)> &&cb) {
  try {
    const auto user_id = RequireAuth(req, cb);
    if (!user_id.has_value())
      return;

    services::UserService users(csp::AppState::Instance().db());
    const auto user = users.GetById(*user_id);
    if (!user.has_value()) {
      cb(JsonError(drogon::k404NotFound, "user not found"));
      return;
    }

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

void MeController::listRedeemItems(
    const drogon::HttpRequestPtr &req,
    std::function<void(const drogon::HttpResponsePtr &)> &&cb) {
  try {
    if (!RequireAuth(req, cb).has_value())
      return;

    services::RedeemService redeem(csp::AppState::Instance().db());
    const auto items = redeem.ListItems(false);

    Json::Value arr(Json::arrayValue);
    for (const auto &item : items) {
      Json::Value j;
      j["id"] = Json::Int64(item.id);
      j["name"] = item.name;
      j["description"] = item.description;
      j["unit_label"] = item.unit_label;
      j["holiday_cost"] = item.holiday_cost;
      j["studyday_cost"] = item.studyday_cost;
      j["is_active"] = item.is_active;
      j["is_global"] = item.is_global;
      j["created_at"] = Json::Int64(item.created_at);
      j["updated_at"] = Json::Int64(item.updated_at);
      arr.append(j);
    }
    cb(JsonOk(arr));
  } catch (const std::exception &e) {
    cb(JsonError(drogon::k500InternalServerError, e.what()));
  }
}

void MeController::listRedeemRecords(
    const drogon::HttpRequestPtr &req,
    std::function<void(const drogon::HttpResponsePtr &)> &&cb) {
  try {
    const auto user_id = RequireAuth(req, cb);
    if (!user_id.has_value())
      return;

    const int limit = ParseClampedInt(req->getParameter("limit"), 100, 1, 500);
    services::RedeemService redeem(csp::AppState::Instance().db());
    const auto rows = redeem.ListRecordsByUser(*user_id, limit);

    Json::Value arr(Json::arrayValue);
    for (const auto &row : rows) {
      Json::Value j;
      j["id"] = Json::Int64(row.id);
      j["user_id"] = Json::Int64(row.user_id);
      j["item_id"] = Json::Int64(row.item_id);
      j["item_name"] = row.item_name;
      j["quantity"] = row.quantity;
      j["day_type"] = row.day_type;
      j["unit_cost"] = row.unit_cost;
      j["total_cost"] = row.total_cost;
      j["note"] = row.note;
      j["created_at"] = Json::Int64(row.created_at);
      arr.append(j);
    }
    cb(JsonOk(arr));
  } 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 MeController::createRedeemRecord(
    const drogon::HttpRequestPtr &req,
    std::function<void(const drogon::HttpResponsePtr &)> &&cb) {
  try {
    const auto user_id = RequireAuth(req, cb);
    if (!user_id.has_value())
      return;

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

    services::RedeemRequest request;
    request.user_id = *user_id;
    request.item_id = (*json).get("item_id", 0).asInt64();
    request.quantity = (*json).get("quantity", 1).asInt();
    request.day_type = (*json).get("day_type", "studyday").asString();
    request.note = (*json).get("note", "").asString();

    services::RedeemService redeem(csp::AppState::Instance().db());
    const auto row = redeem.Redeem(request);

    services::UserService users(csp::AppState::Instance().db());
    const auto user = users.GetById(*user_id);

    Json::Value j;
    j["id"] = Json::Int64(row.id);
    j["user_id"] = Json::Int64(row.user_id);
    j["item_id"] = Json::Int64(row.item_id);
    j["item_name"] = row.item_name;
    j["quantity"] = row.quantity;
    j["day_type"] = row.day_type;
    j["unit_cost"] = row.unit_cost;
    j["total_cost"] = row.total_cost;
    j["note"] = row.note;
    j["created_at"] = Json::Int64(row.created_at);
    if (user.has_value()) {
      j["rating_after"] = user->rating;
    }
    cb(JsonOk(j));
  } catch (const std::runtime_error &e) {
    cb(JsonError(drogon::k400BadRequest, e.what()));
  } catch (const std::exception &e) {
    cb(JsonError(drogon::k500InternalServerError, e.what()));
  }
}

void MeController::listDailyTasks(
    const drogon::HttpRequestPtr &req,
    std::function<void(const drogon::HttpResponsePtr &)> &&cb) {
  try {
    const auto user_id = RequireAuth(req, cb);
    if (!user_id.has_value())
      return;

    services::DailyTaskService tasks(csp::AppState::Instance().db());
    const auto rows = tasks.ListTodayTasks(*user_id);

    Json::Value arr(Json::arrayValue);
    int total_reward = 0;
    int gained_reward = 0;
    for (const auto &row : rows) {
      Json::Value j;
      j["code"] = row.code;
      j["title"] = row.title;
      j["description"] = row.description;
      j["reward"] = row.reward;
      j["completed"] = row.completed;
      if (row.completed) {
        j["completed_at"] = Json::Int64(row.completed_at);
        gained_reward += row.reward;
      } else {
        j["completed_at"] = Json::nullValue;
      }
      total_reward += row.reward;
      arr.append(j);
    }

    Json::Value out;
    out["day_key"] = tasks.CurrentDayKey();
    out["total_reward"] = total_reward;
    out["gained_reward"] = gained_reward;
    out["tasks"] = arr;
    cb(JsonOk(out));
  } catch (const std::exception &e) {
    cb(JsonError(drogon::k500InternalServerError, e.what()));
  }
}

void MeController::listWrongBook(
    const drogon::HttpRequestPtr &req,
    std::function<void(const drogon::HttpResponsePtr &)> &&cb) {
  try {
    const auto user_id = RequireAuth(req, cb);
    if (!user_id.has_value())
      return;

    services::WrongBookService wrong_book(csp::AppState::Instance().db());
    const auto rows = wrong_book.ListByUser(*user_id);

    Json::Value arr(Json::arrayValue);
    for (const auto &row : rows) {
      Json::Value item = domain::ToJson(row.item);
      item["problem_title"] = row.problem_title;
      arr.append(item);
    }

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

void MeController::upsertWrongBookNote(
    const drogon::HttpRequestPtr &req,
    std::function<void(const drogon::HttpResponsePtr &)> &&cb,
    int64_t problem_id) {
  try {
    const auto user_id = RequireAuth(req, cb);
    if (!user_id.has_value())
      return;

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

    const std::string note = (*json).get("note", "").asString();
    if (note.size() > 4000) {
      cb(JsonError(drogon::k400BadRequest, "note too long"));
      return;
    }

    services::WrongBookService wrong_book(csp::AppState::Instance().db());
    wrong_book.UpsertNote(*user_id, problem_id, note);

    Json::Value data;
    data["user_id"] = Json::Int64(*user_id);
    data["problem_id"] = Json::Int64(problem_id);
    data["note"] = note;
    cb(JsonOk(data));
  } catch (const std::exception &e) {
    cb(JsonError(drogon::k500InternalServerError, e.what()));
  }
}

void MeController::scoreWrongBookNote(
    const drogon::HttpRequestPtr &req,
    std::function<void(const drogon::HttpResponsePtr &)> &&cb,
    int64_t problem_id) {
  try {
    const auto user_id = RequireAuth(req, cb);
    if (!user_id.has_value()) return;

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

    const std::string note = (*json).get("note", "").asString();
    if (note.empty()) {
      cb(JsonError(drogon::k400BadRequest, "note required"));
      return;
    }
    if (note.size() > 8000) {
      cb(JsonError(drogon::k400BadRequest, "note too long"));
      return;
    }

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

    services::LearningNoteScoringService scorer(csp::AppState::Instance().db());
    const auto result = scorer.Score(note, *p);

    services::WrongBookService wrong_book(csp::AppState::Instance().db());
    // ensure note saved
    wrong_book.UpsertNote(*user_id, problem_id, note);

    // Get previous score to calculate rating delta
    const int prev_rating = wrong_book.GetNoteRating(*user_id, problem_id);
    wrong_book.UpsertNoteScore(*user_id, problem_id, result.score, result.rating, result.feedback_md);

    // Award (or adjust) rating points: delta = new_rating - prev_rating
    const int delta = result.rating - prev_rating;
    if (delta != 0) {
      wrong_book.AwardNoteRating(*user_id, problem_id, delta);
    }

    Json::Value data;
    data["user_id"] = Json::Int64(*user_id);
    data["problem_id"] = Json::Int64(problem_id);
    data["note"] = note;
    data["note_score"] = result.score;
    data["note_rating"] = result.rating;
    data["note_feedback_md"] = result.feedback_md;
    data["model_name"] = result.model_name;
    cb(JsonOk(data));
  } catch (const std::exception &e) {
    cb(JsonError(drogon::k500InternalServerError, e.what()));
  }
}


void MeController::uploadWrongBookNoteImages(
    const drogon::HttpRequestPtr &req,
    std::function<void(const drogon::HttpResponsePtr &)> &&cb,
    int64_t problem_id) {
  try {
    const auto user_id = RequireAuth(req, cb);
    if (!user_id.has_value()) return;

    drogon::MultiPartParser parser;
    if (parser.parse(req) != 0) {
      cb(JsonError(drogon::k400BadRequest, "bad multipart"));
      return;
    }
    const auto& files = parser.getFiles();
    if (files.empty()) {
      cb(JsonError(drogon::k400BadRequest, "no files"));
      return;
    }

    namespace fs = std::filesystem;
    const fs::path dir = "/data/note_images";
    fs::create_directories(dir);

    services::WrongBookService wrong_book(csp::AppState::Instance().db());

    Json::CharReaderBuilder rb;
    Json::Value arr(Json::arrayValue);
    {
      const std::string current = wrong_book.GetNoteImagesJson(*user_id, problem_id);
      Json::Value parsed;
      std::string errs;
      std::unique_ptr<Json::CharReader> r(rb.newCharReader());
      if (r->parse(current.data(), current.data() + current.size(), &parsed, &errs) && parsed.isArray()) {
        arr = parsed;
      }
    }

    const int kMaxImages = 9;
    if ((int)arr.size() >= kMaxImages) {
      cb(JsonError(drogon::k400BadRequest, "too many images"));
      return;
    }

    Json::Value out_items(Json::arrayValue);

    for (const auto &f : files) {
      if ((int)arr.size() >= kMaxImages) break;

      // Allow common image extensions only (frontend also restricts accept=image/*)
      std::string name_for_ext = f.getFileName();
      auto dot = name_for_ext.find_last_of('.');
      std::string ext_check = (dot == std::string::npos) ? std::string("") : name_for_ext.substr(dot);
      for (auto &c : ext_check) c = (char)std::tolower((unsigned char)c);
      if (!(ext_check==".png" || ext_check==".jpg" || ext_check==".jpeg" || ext_check==".gif" || ext_check==".webp")) {
        continue;
      }
      if (f.fileLength() > 5 * 1024 * 1024) {
        continue;
      }

      std::string ext = f.getFileName();
      auto pos = ext.find_last_of('.');
      ext = (pos == std::string::npos) ? std::string(".png") : ext.substr(pos);
      if (ext.size() > 10) ext = ".png";

      const std::string filename =
          "u" + std::to_string(*user_id) + "_p" + std::to_string(problem_id) + "_" +
          crypto::RandomHex(12) + ext;

      const fs::path dest = dir / filename;
      f.saveAs(dest.string());

      arr.append(filename);

      Json::Value it;
      it["filename"] = filename;
      it["url"] = std::string("/files/note-images/") + filename;
      out_items.append(it);
    }

    Json::StreamWriterBuilder wb;
    wb["indentation"] = "";
    const std::string new_json = Json::writeString(wb, arr);
    wrong_book.SetNoteImagesJson(*user_id, problem_id, new_json);

    Json::Value data;
    data["problem_id"] = Json::Int64(problem_id);
    data["items"] = out_items;
    data["note_images"] = arr;
    cb(JsonOk(data));
  } catch (const std::exception &e) {
    cb(JsonError(drogon::k500InternalServerError, e.what()));
  }
}

void MeController::deleteWrongBookNoteImage(
    const drogon::HttpRequestPtr &req,
    std::function<void(const drogon::HttpResponsePtr &)> &&cb,
    int64_t problem_id) {
  try {
    const auto user_id = RequireAuth(req, cb);
    if (!user_id.has_value()) return;

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

    const std::string filename = (*json).get("filename", "").asString();
    if (filename.empty() || filename.find("..") != std::string::npos || filename.find('/') != std::string::npos || filename.find('\\') != std::string::npos) {
      cb(JsonError(drogon::k400BadRequest, "bad filename"));
      return;
    }

    services::WrongBookService wrong_book(csp::AppState::Instance().db());
    const std::string current = wrong_book.GetNoteImagesJson(*user_id, problem_id);

    Json::CharReaderBuilder rb;
    Json::Value arr(Json::arrayValue);
    {
      Json::Value parsed;
      std::string errs;
      std::unique_ptr<Json::CharReader> r(rb.newCharReader());
      if (r->parse(current.data(), current.data() + current.size(), &parsed, &errs) && parsed.isArray()) {
        arr = parsed;
      }
    }

    Json::Value next(Json::arrayValue);
    bool removed = false;
    for (const auto &v : arr) {
      if (v.isString() && v.asString() == filename) {
        removed = true;
        continue;
      }
      next.append(v);
    }
    if (!removed) {
      cb(JsonError(drogon::k404NotFound, "image not found"));
      return;
    }

    namespace fs = std::filesystem;
    const fs::path full = fs::path("/data/note_images") / filename;
    if (fs::exists(full) && fs::is_regular_file(full)) {
      std::error_code ec;
      fs::remove(full, ec);
    }

    Json::StreamWriterBuilder wb;
    wb["indentation"] = "";
    wrong_book.SetNoteImagesJson(*user_id, problem_id, Json::writeString(wb, next));

    Json::Value data;
    data["problem_id"] = Json::Int64(problem_id);
    data["deleted"] = true;
    data["filename"] = filename;
    data["note_images"] = next;
    cb(JsonOk(data));
  } catch (const std::exception &e) {
    cb(JsonError(drogon::k500InternalServerError, e.what()));
  }
}


void MeController::deleteWrongBookItem(
    const drogon::HttpRequestPtr &req,
    std::function<void(const drogon::HttpResponsePtr &)> &&cb,
    int64_t problem_id) {
  try {
    const auto user_id = RequireAuth(req, cb);
    if (!user_id.has_value())
      return;

    services::WrongBookService wrong_book(csp::AppState::Instance().db());
    wrong_book.Remove(*user_id, problem_id);

    Json::Value data;
    data["user_id"] = Json::Int64(*user_id);
    data["problem_id"] = Json::Int64(problem_id);
    data["deleted"] = true;
    cb(JsonOk(data));
  } catch (const std::exception &e) {
    cb(JsonError(drogon::k500InternalServerError, e.what()));
  }
}

void MeController::listRatingHistory(
    const drogon::HttpRequestPtr &req,
    std::function<void(const drogon::HttpResponsePtr &)> &&cb) {
  try {
    const auto user_id = RequireAuth(req, cb);
    if (!user_id.has_value())
      return;

    const int limit = ParseClampedInt(req->getParameter("limit"), 100, 1, 500);
    services::SolutionAccessService access_svc(csp::AppState::Instance().db());
    const auto rows = access_svc.ListRatingHistory(*user_id, limit);

    Json::Value arr(Json::arrayValue);
    for (const auto &row : rows) {
      Json::Value j;
      j["type"] = row.type;
      j["created_at"] = Json::Int64(row.created_at);
      j["change"] = row.change;
      j["note"] = row.note;
      arr.append(j);
    }
    cb(JsonOk(arr));
  } catch (const std::exception &e) {
    cb(JsonError(drogon::k500InternalServerError, e.what()));
  }
}
} // namespace csp::controllers