/*
 *  This file is part of SYZOJ.
 *
 *  Copyright (c) 2016 Menci <huanghaorui301@gmail.com>
 *
 *  SYZOJ is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU Affero General Public License as
 *  published by the Free Software Foundation, either version 3 of the
 *  License, or (at your option) any later version.
 *
 *  SYZOJ is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU Affero General Public License for more details.
 *
 *  You should have received a copy of the GNU Affero General Public
 *  License along with SYZOJ. If not, see <http://www.gnu.org/licenses/>.
 */

'use strict';

let Problem = syzoj.model('problem');
let JudgeState = syzoj.model('judge_state');
let WaitingJudge = syzoj.model('waiting_judge');
let Contest = syzoj.model('contest');
let ProblemTag = syzoj.model('problem_tag');
let ProblemTagMap = syzoj.model('problem_tag_map');

app.get('/problems', async (req, res) => {
  try {
    let where = {};
    if (!res.locals.user || !await res.locals.user.hasPrivilege('manage_problem')) {
      if (res.locals.user) {
        where = {
          $or: {
            is_public: 1,
            user_id: res.locals.user.id
          }
        };
      } else {
        where = {
          is_public: 1
        };
      }
    }

    let paginate = syzoj.utils.paginate(await Problem.count(where), req.query.page, syzoj.config.page.problem);
    let problems = await Problem.query(paginate, where);

    await problems.forEachAsync(async problem => {
      problem.allowedEdit = await problem.isAllowedEditBy(res.locals.user);
      problem.judge_state = await problem.getJudgeState(res.locals.user, true);
      problem.tags = await problem.getTags();
    });

    res.render('problems', {
      allowedManageTag: res.locals.user && await res.locals.user.hasPrivilege('manage_problem_tag'),
      problems: problems,
      paginate: paginate
    });
  } catch (e) {
    syzoj.log(e);
    res.render('error', {
      err: e
    });
  }
});

app.get('/problems/search', async (req, res) => {
  try {
    let id = parseInt(req.query.keyword) || 0;

    let where = {
      $or: {
        title: { like: `%${req.query.keyword}%` },
        id: id
      }
    };

    if (!res.locals.user || !await res.locals.user.hasPrivilege('manage_problem')) {
      if (res.locals.user) {
        where = {
          $and: [
            where,
            {
              $or: {
                is_public: 1,
                user_id: res.locals.user.id
              }
            }
          ]
        };
      } else {
        where = {
          $and: [
            where,
            {
              is_public: 1
            }
          ]
        };
      }
    }

    let order = [syzoj.db.literal('`id` = ' + id + ' DESC')];

    let paginate = syzoj.utils.paginate(await Problem.count(where), req.query.page, syzoj.config.page.problem);
    let problems = await Problem.query(paginate, where, order);

    await problems.forEachAsync(async problem => {
      problem.allowedEdit = await problem.isAllowedEditBy(res.locals.user);
      problem.judge_state = await problem.getJudgeState(res.locals.user, true);
      problem.tags = await problem.getTags();
    });

    res.render('problems', {
      allowedManageTag: res.locals.user && await res.locals.user.hasPrivilege('manage_problem_tag'),
      problems: problems,
      paginate: paginate
    });
  } catch (e) {
    syzoj.log(e);
    res.render('error', {
      err: e
    });
  }
});

app.get('/problems/tag/:tagIDs', async (req, res) => {
  try {
    let tagIDs = Array.from(new Set(req.params.tagIDs.split(',').map(x => parseInt(x))));
    let tags = await tagIDs.mapAsync(async tagID => ProblemTag.fromID(tagID));

    // Validate the tagIDs
    for (let tag of tags) {
      if (!tag) {
        return res.redirect(syzoj.utils.makeUrl(['problems']));
      }
    }

    let sql = 'SELECT * FROM `problem` WHERE\n';
    for (let tagID of tagIDs) {
      if (tagID !== tagIDs[0]) {
        sql += 'AND\n';
      }

      sql += '`problem`.`id` IN (SELECT `problem_id` FROM `problem_tag_map` WHERE `tag_id` = ' + tagID + ')';
    }

    if (!res.locals.user || !await res.locals.user.hasPrivilege('manage_problem')) {
      if (res.locals.user) {
        sql += 'AND (`problem`.`is_public` = 1 OR `problem`.`user_id` = ' + res.locals.user.id + ')';
      } else {
        sql += 'AND (`problem`.`is_public` = 1)';
      }
    }

    let paginate = syzoj.utils.paginate(await Problem.count(sql), req.query.page, syzoj.config.page.problem);
    let problems = await Problem.query(sql + paginate.toSQL());

    await problems.forEachAsync(async problem => {
      problem.allowedEdit = await problem.isAllowedEditBy(res.locals.user);
      problem.judge_state = await problem.getJudgeState(res.locals.user, true);
      problem.tags = await problem.getTags();
    });

    res.render('problems', {
      allowedManageTag: res.locals.user && await res.locals.user.hasPrivilege('manage_problem_tag'),
      problems: problems,
      tags: tags,
      paginate: paginate
    });
  } catch (e) {
    syzoj.log(e);
    res.render('error', {
      err: e
    });
  }
});

app.get('/problem/:id', async (req, res) => {
  try {
    let id = parseInt(req.params.id);
    let problem = await Problem.fromID(id);
    if (!problem) throw new ErrorMessage('无此题目。');

    if (!await problem.isAllowedUseBy(res.locals.user)) {
      throw new ErrorMessage('您没有权限进行此操作。');
    }

    problem.allowedEdit = await problem.isAllowedEditBy(res.locals.user);
    problem.allowedManage = await problem.isAllowedManageBy(res.locals.user);

    if (problem.is_public || problem.allowedEdit) {
      await syzoj.utils.markdown(problem, [ 'description', 'input_format', 'output_format', 'example', 'limit_and_hint' ]);
    } else {
      throw new ErrorMessage('您没有权限进行此操作。');
    }

    let state = await problem.getJudgeState(res.locals.user, false);

    problem.tags = await problem.getTags();
    await problem.loadRelationships();

    let testcases = await syzoj.utils.parseTestdata(problem.getTestdataPath(), problem.type === 'submit-answer');

    res.render('problem', {
      problem: problem,
      state: state,
      lastLanguage: res.locals.user ? await res.locals.user.getLastSubmitLanguage() : null,
      testcases: testcases
    });
  } catch (e) {
    syzoj.log(e);
    res.render('error', {
      err: e
    });
  }
});

app.get('/problem/:id/export', async (req, res) => {
  try {
    let id = parseInt(req.params.id);
    let problem = await Problem.fromID(id);
    if (!problem || !problem.is_public) throw new ErrorMessage('无此题目。');

    let obj = {
      title: problem.title,
      description: problem.description,
      input_format: problem.input_format,
      output_format: problem.output_format,
      example: problem.example,
      limit_and_hint: problem.limit_and_hint,
      time_limit: problem.time_limit,
      memory_limit: problem.memory_limit,
      file_io: problem.file_io,
      file_io_input_name: problem.file_io_input_name,
      file_io_output_name: problem.file_io_output_name,
      tags: []
    };

    let tags = await problem.getTags();

    obj.tags = tags.map(tag => tag.name);

    res.send({ success: true, obj: obj });
  } catch (e) {
    syzoj.log(e);
    res.send({ success: false, error: e });
  }
});

app.get('/problem/:id/edit', async (req, res) => {
  try {
    let id = parseInt(req.params.id) || 0;
    let problem = await Problem.fromID(id);

    if (!problem) {
      if (!res.locals.user) throw new ErrorMessage('请登录后继续。', { '登录': syzoj.utils.makeUrl(['login'], { 'url': req.originalUrl }) });
      problem = await Problem.create();
      problem.id = id;
      problem.allowedEdit = true;
      problem.tags = [];
      problem.new = true;
    } else {
      if (!await problem.isAllowedUseBy(res.locals.user)) throw new ErrorMessage('您没有权限进行此操作。');
      problem.allowedEdit = await problem.isAllowedEditBy(res.locals.user);
      problem.tags = await problem.getTags();
    }

    problem.allowedManage = await problem.isAllowedManageBy(res.locals.user);

    res.render('problem_edit', {
      problem: problem
    });
  } catch (e) {
    syzoj.log(e);
    res.render('error', {
      err: e
    });
  }
});

app.post('/problem/:id/edit', async (req, res) => {
  try {
    let id = parseInt(req.params.id) || 0;
    let problem = await Problem.fromID(id);
    if (!problem) {
      if (!res.locals.user) throw new ErrorMessage('请登录后继续。', { '登录': syzoj.utils.makeUrl(['login'], { 'url': req.originalUrl }) });

      problem = await Problem.create();

      if (await res.locals.user.hasPrivilege('manage_problem')) {
        let customID = parseInt(req.body.id);
        if (customID) {
          if (await Problem.fromID(customID)) throw new ErrorMessage('ID 已被使用。');
          problem.id = customID;
        } else if (id) problem.id = id;
      }

      problem.user_id = res.locals.user.id;
      problem.publicizer_id = res.locals.user.id;
    } else {
      if (!await problem.isAllowedUseBy(res.locals.user)) throw new ErrorMessage('您没有权限进行此操作。');
      if (!await problem.isAllowedEditBy(res.locals.user)) throw new ErrorMessage('您没有权限进行此操作。');

      if (await res.locals.user.hasPrivilege('manage_problem')) {
        let customID = parseInt(req.body.id);
        if (customID && customID !== id) {
          if (await Problem.fromID(customID)) throw new ErrorMessage('ID 已被使用。');
          await problem.changeID(customID);
        }
      }
    }

    if (!req.body.title.trim()) throw new ErrorMessage('题目名不能为空。');
    problem.title = req.body.title;
    problem.description = req.body.description;
    problem.input_format = req.body.input_format;
    problem.output_format = req.body.output_format;
    problem.example = req.body.example;
    problem.limit_and_hint = req.body.limit_and_hint;
    problem.is_anonymous = (req.body.is_anonymous === 'on');

    // Save the problem first, to have the `id` allocated
    await problem.save();

    if (!req.body.tags) {
      req.body.tags = [];
    } else if (!Array.isArray(req.body.tags)) {
      req.body.tags = [req.body.tags];
    }

    let newTagIDs = await req.body.tags.map(x => parseInt(x)).filterAsync(async x => ProblemTag.fromID(x));
    await problem.setTags(newTagIDs);

    res.redirect(syzoj.utils.makeUrl(['problem', problem.id]));
  } catch (e) {
    syzoj.log(e);
    res.render('error', {
      err: e
    });
  }
});

app.get('/problem/:id/import', async (req, res) => {
  try {
    let id = parseInt(req.params.id) || 0;
    let problem = await Problem.fromID(id);

    if (!problem) {
      if (!res.locals.user) throw new ErrorMessage('请登录后继续。', { '登录': syzoj.utils.makeUrl(['login'], { 'url': req.originalUrl }) });

      problem = await Problem.create();
      problem.id = id;
      problem.new = true;
      problem.user_id = res.locals.user.id;
      problem.publicizer_id = res.locals.user.id;
    } else {
      if (!await problem.isAllowedUseBy(res.locals.user)) throw new ErrorMessage('您没有权限进行此操作。');
      if (!await problem.isAllowedEditBy(res.locals.user)) throw new ErrorMessage('您没有权限进行此操作。');
    }

    problem.allowedManage = await problem.isAllowedManageBy(res.locals.user);

    res.render('problem_import', {
      problem: problem
    });
  } catch (e) {
    syzoj.log(e);
    res.render('error', {
      err: e
    });
  }
});

app.post('/problem/:id/import', async (req, res) => {
  try {
    let id = parseInt(req.params.id) || 0;
    let problem = await Problem.fromID(id);
    if (!problem) {
      if (!res.locals.user) throw new ErrorMessage('请登录后继续。', { '登录': syzoj.utils.makeUrl(['login'], { 'url': req.originalUrl }) });

      problem = await Problem.create();

      if (await res.locals.user.hasPrivilege('manage_problem')) {
        let customID = parseInt(req.body.id);
        if (customID) {
          if (await Problem.fromID(customID)) throw new ErrorMessage('ID 已被使用。');
          problem.id = customID;
        } else if (id) problem.id = id;
      }

      problem.user_id = res.locals.user.id;
      problem.publicizer_id = res.locals.user.id;
    } else {
      if (!await problem.isAllowedUseBy(res.locals.user)) throw new ErrorMessage('您没有权限进行此操作。');
      if (!await problem.isAllowedEditBy(res.locals.user)) throw new ErrorMessage('您没有权限进行此操作。');
    }

    let request = require('request-promise');
    let url = require('url');

    let json = await request({
      uri: req.body.url + (req.body.url.endsWith('/') ? 'export' : '/export'),
      timeout: 1500,
      json: true
    });

    if (!json.success) throw new ErrorMessage('题目加载失败。', null, json.error);

    if (!json.obj.title.trim()) throw new ErrorMessage('题目名不能为空。');
    problem.title = json.obj.title;
    problem.description = json.obj.description;
    problem.input_format = json.obj.input_format;
    problem.output_format = json.obj.output_format;
    problem.example = json.obj.example;
    problem.limit_and_hint = json.obj.limit_and_hint;
    problem.time_limit = json.obj.time_limit;
    problem.memory_limit = json.obj.memory_limit;
    problem.file_io = json.obj.file_io;
    problem.file_io_input_name = json.obj.file_io_input_name;
    problem.file_io_output_name = json.obj.file_io_output_name;

    let validateMsg = await problem.validate();
    if (validateMsg) throw new ErrorMessage('无效的题目数据配置。', null, validateMsg);

    await problem.save();

    let tagIDs = (await json.obj.tags.mapAsync(name => ProblemTag.findOne({ where: { name: name } }))).filter(x => x).map(tag => tag.id);
    await problem.setTags(tagIDs);

    let download = require('download');
    let tmp = require('tmp-promise');
    let tmpFile = await tmp.file();
    let fs = require('bluebird').promisifyAll(require('fs'));

    try {
      let data = await download(req.body.url + (req.body.url.endsWith('/') ? 'testdata/download' : '/testdata/download'));
      await fs.writeFileAsync(tmpFile.path, data);
      await problem.updateTestdata(tmpFile.path, await res.locals.user.hasPrivilege('manage_problem'));
    } catch (e) {
      syzoj.log(e);
    }

    res.redirect(syzoj.utils.makeUrl(['problem', problem.id]));
  } catch (e) {
    syzoj.log(e);
    res.render('error', {
      err: e
    });
  }
});

// The 'manage' is not `allow manage`'s 'manage', I just have no better name for it.
app.get('/problem/:id/manage', async (req, res) => {
  try {
    let id = parseInt(req.params.id);
    let problem = await Problem.fromID(id);

    if (!problem) throw new ErrorMessage('无此题目。');
    if (!await problem.isAllowedEditBy(res.locals.user)) throw new ErrorMessage('您没有权限进行此操作。');

    await problem.loadRelationships();

    let testcases = await syzoj.utils.parseTestdata(problem.getTestdataPath(), problem.type === 'submit-answer');

    res.render('problem_manage', {
      problem: problem,
      testcases: testcases
    });
  } catch (e) {
    syzoj.log(e);
    res.render('error', {
      err: e
    });
  }
});

app.post('/problem/:id/manage', app.multer.fields([{ name: 'testdata', maxCount: 1 }, { name: 'additional_file', maxCount: 1 }]), async (req, res) => {
  try {
    let id = parseInt(req.params.id);
    let problem = await Problem.fromID(id);

    if (!problem) throw new ErrorMessage('无此题目。');
    if (!await problem.isAllowedEditBy(res.locals.user)) throw new ErrorMessage('您没有权限进行此操作。');

    await problem.loadRelationships();

    problem.time_limit = req.body.time_limit;
    problem.memory_limit = req.body.memory_limit;
    problem.file_io = req.body.io_method === 'file-io';
    problem.file_io_input_name = req.body.file_io_input_name;
    problem.file_io_output_name = req.body.file_io_output_name;

    if (req.body.type === 'interaction') {
      throw new ErrorMessage('暂不支持该题目类型。');
    }

    if (problem.type === 'submit-answer' && req.body.type !== 'submit-answer' || problem.type !== 'submit-answer' && req.body.type === 'submit-answer') {
      if (await JudgeState.count({ problem_id: id }) !== 0) {
        throw new ErrorMessage('已有提交的题目不允许在提交答案和非提交答案之间更改。');
      }
    }
    problem.type = req.body.type;

    let validateMsg = await problem.validate();
    if (validateMsg) throw new ErrorMessage('无效的题目数据配置。', null, validateMsg);

    if (req.files['testdata']) {
      await problem.updateTestdata(req.files['testdata'][0].path, await res.locals.user.hasPrivilege('manage_problem'));
    }

    if (req.files['additional_file']) {
      await problem.updateFile(req.files['additional_file'][0].path, 'additional_file', await res.locals.user.hasPrivilege('manage_problem'));
    }

    await problem.save();

    res.redirect(syzoj.utils.makeUrl(['problem', id, 'manage']));
  } catch (e) {
    syzoj.log(e);
    res.render('error', {
      err: e
    });
  }
});

// Set problem public
async function setPublic(req, res, is_public) {
  try {
    let id = parseInt(req.params.id);
    let problem = await Problem.fromID(id);
    if (!problem) throw new ErrorMessage('无此题目。');

    let allowedManage = await problem.isAllowedManageBy(res.locals.user);
    if (!allowedManage) throw new ErrorMessage('您没有权限进行此操作。');

    problem.is_public = is_public;
    problem.publicizer_id = res.locals.user.id;
    await problem.save();

    res.redirect(syzoj.utils.makeUrl(['problem', id]));
  } catch (e) {
    syzoj.log(e);
    res.render('error', {
      err: e
    });
  }
}

app.get('/problem/:id/public', async (req, res) => {
  await setPublic(req, res, true);
});

app.get('/problem/:id/dis_public', async (req, res) => {
  await setPublic(req, res, false);
});

app.post('/problem/:id/submit', app.multer.fields([{ name: 'answer', maxCount: 1 }]), async (req, res) => {
  try {
    let id = parseInt(req.params.id);
    let problem = await Problem.fromID(id);

    if (!problem) throw new ErrorMessage('无此题目。');
    if (problem.type !== 'submit-answer' && !syzoj.config.languages[req.body.language]) throw new ErrorMessage('不支持该语言。');
    if (!res.locals.user) throw new ErrorMessage('请登录后继续。', { '登录': syzoj.utils.makeUrl(['login'], { 'url': syzoj.utils.makeUrl(['problem', id]) }) });

    let judge_state;
    if (problem.type === 'submit-answer') {
      let File = syzoj.model('file'), path;
      if (!req.files['answer']) {
        // Submited by editor
        try {
          path = await File.zipFiles(JSON.parse(req.body.answer_by_editor));
        } catch (e) {
          throw new ErrorMessage('无法解析提交数据。');
        }
      } else {
        if (req.files['answer'][0].size > syzoj.config.limit.submit_answer) throw new ErrorMessage('答案文件太大。');
        path = req.files['answer'][0].path;
      }

      let file = await File.upload(path, 'answer');
      let size = await file.getUnzipSize();

      if (size > syzoj.config.limit.submit_answer) throw new ErrorMessage('答案文件太大。');

      if (!file.md5) throw new ErrorMessage('上传答案文件失败。');
      judge_state = await JudgeState.create({
        code: file.md5,
        max_memory: size,
        language: '',
        user_id: res.locals.user.id,
        problem_id: req.params.id
      });
    } else {
      let code;
      if (req.files['answer']) {
        if (req.files['answer'][0].size > syzoj.config.limit.submit_code) throw new ErrorMessage('代码文件太大。');
        let fs = Promise.promisifyAll(require('fs'));
        code = (await fs.readFileAsync(req.files['answer'][0].path)).toString();
      } else {
        if (req.body.code.length > syzoj.config.limit.submit_code) throw new ErrorMessage('代码太长。');
        code = req.body.code;
      }

      judge_state = await JudgeState.create({
        code: code,
        language: req.body.language,
        user_id: res.locals.user.id,
        problem_id: req.params.id
      });
    }

    let contest_id = parseInt(req.query.contest_id), redirectToContest = false;
    if (contest_id) {
      let contest = await Contest.fromID(contest_id);
      if (!contest) throw new ErrorMessage('无此比赛。');
      if (!await contest.isRunning()) throw new ErrorMessage('比赛未开始或已结束。');
      let problems_id = await contest.getProblems();
      if (!problems_id.includes(id)) throw new ErrorMessage('无此题目。');

      judge_state.type = 1;
      judge_state.type_info = contest_id;

      await judge_state.save();
    } else {
      if (!await problem.isAllowedUseBy(res.locals.user)) throw new ErrorMessage('您没有权限进行此操作。');
      judge_state.type = problem.is_public ? 0 : 2;
      await judge_state.save();
    }
    await judge_state.updateRelatedInfo(true);

    let waiting_judge = await WaitingJudge.create({
      judge_id: judge_state.id
    });

    await waiting_judge.save();

    res.redirect(syzoj.utils.makeUrl(['submission', judge_state.id]));
  } catch (e) {
    syzoj.log(e);
    res.render('error', {
      err: e
    });
  }
});

app.get('/problem/:id/testdata', async (req, res) => {
  try {
    let id = parseInt(req.params.id);
    let problem = await Problem.fromID(id);

    if (!problem) throw new ErrorMessage('无此题目。');
    if (!await problem.isAllowedUseBy(res.locals.user)) throw new ErrorMessage('您没有权限进行此操作。');

    let testdata = await problem.listTestdata();
    let testcases = await syzoj.utils.parseTestdata(problem.getTestdataPath(), problem.type === 'submit-answer');

    problem.allowedEdit = await problem.isAllowedEditBy(res.locals.user)

    res.render('problem_data', {
      problem: problem,
      testdata: testdata,
      testcases: testcases
    });
  } catch (e) {
    syzoj.log(e);
    res.status(404);
    res.render('error', {
      err: e
    });
  }
});

app.post('/problem/:id/testdata/upload', app.multer.array('file'), async (req, res) => {
  try {
    let id = parseInt(req.params.id);
    let problem = await Problem.fromID(id);

    if (!problem) throw new ErrorMessage('无此题目。');
    if (!await problem.isAllowedEditBy(res.locals.user)) throw new ErrorMessage('您没有权限进行此操作。');

    if (req.files) {
      for (let file of req.files) {
        await problem.uploadTestdataSingleFile(file.originalname, file.path, file.size, await res.locals.user.hasPrivilege('manage_problem'));
      }
    }

    res.redirect(syzoj.utils.makeUrl(['problem', id, 'testdata']));
  } catch (e) {
    syzoj.log(e);
    res.render('error', {
      err: e
    });
  }
});

app.get('/problem/:id/testdata/delete/:filename', async (req, res) => {
  try {
    let id = parseInt(req.params.id);
    let problem = await Problem.fromID(id);

    if (!problem) throw new ErrorMessage('无此题目。');
    if (!await problem.isAllowedEditBy(res.locals.user)) throw new ErrorMessage('您没有权限进行此操作。');

    await problem.deleteTestdataSingleFile(req.params.filename);

    res.redirect(syzoj.utils.makeUrl(['problem', id, 'testdata']));
  } catch (e) {
    syzoj.log(e);
    res.render('error', {
      err: e
    });
  }
});

app.get('/problem/:id/testdata/download/:filename?', async (req, res) => {
  try {
    let id = parseInt(req.params.id);
    let problem = await Problem.fromID(id);

    if (!problem) throw new ErrorMessage('无此题目。');
    if (!await problem.isAllowedUseBy(res.locals.user)) throw new ErrorMessage('您没有权限进行此操作。');

    if (!req.params.filename) {
      if (!await syzoj.utils.isFile(problem.getTestdataPath() + '.zip')) {
        await problem.makeTestdataZip();
      }
    }

    let path = require('path');
    let filename = req.params.filename ? path.join(problem.getTestdataPath(), req.params.filename) : (problem.getTestdataPath() + '.zip');
    if (!await syzoj.utils.isFile(filename)) throw new ErrorMessage('文件不存在。');
    res.download(filename, path.basename(filename));
  } catch (e) {
    syzoj.log(e);
    res.status(404);
    res.render('error', {
      err: e
    });
  }
});

app.get('/problem/:id/download/additional_file', async (req, res) => {
  try {
    let id = parseInt(req.params.id);
    let problem = await Problem.fromID(id);

    if (!problem) throw new ErrorMessage('无此题目。');

    // XXX: Reduce duplication (see the '/problem/:id/submit' handler)
    let contest_id = parseInt(req.query.contest_id);
    if (contest_id) {
      let contest = await Contest.fromID(contest_id);
      if (!contest) throw new ErrorMessage('无此比赛。');
      if (!await contest.isRunning()) throw new ErrorMessage('比赛未开始或已结束。');
      let problems_id = await contest.getProblems();
      if (!problems_id.includes(id)) throw new ErrorMessage('无此题目。');
    } else {
      if (!await problem.isAllowedUseBy(res.locals.user)) throw new ErrorMessage('您没有权限进行此操作。');
    }

    await problem.loadRelationships();

    if (!problem.additional_file) throw new ErrorMessage('无附加文件。');

    res.download(problem.additional_file.getPath(), `additional_file_${id}.zip`);
  } catch (e) {
    syzoj.log(e);
    res.status(404);
    res.render('error', {
      err: e
    });
  }
});

app.get('/problem/:id/statistics/:type', async (req, res) => {
  try {
    let id = parseInt(req.params.id);
    let problem = await Problem.fromID(id);

    if (!problem) throw new ErrorMessage('无此题目。');
    if (!await problem.isAllowedUseBy(res.locals.user)) throw new ErrorMessage('您没有权限进行此操作。');

    let count = await problem.countStatistics(req.params.type);
    if (count === null) throw new ErrorMessage('无此统计类型。');

    let paginate = syzoj.utils.paginate(count, req.query.page, syzoj.config.page.problem_statistics);
    let statistics = await problem.getStatistics(req.params.type, paginate);

    await statistics.judge_state.forEachAsync(async x => x.loadRelationships());

    res.render('statistics', {
      statistics: statistics,
      paginate: paginate,
      problem: problem
    });
  } catch (e) {
    syzoj.log(e);
    res.render('error', {
      err: e
    });
  }
});