import {Types} from 'mongoose';
import {User} from 'discord.js';
import {logger} from '../logger';

import {Session, sessionModel} from '../models/sessions';
import {Problem, problemModel} from '../models/problems';
import {Contest, contestModel} from '../models/contests';

export async function clearContests(): Promise<void>{
  await contestModel.deleteMany({});
}

export async function clearProblems(): Promise<void>{
  await problemModel.deleteMany({});
}

export async function clearSessions(): Promise<void>{
  await sessionModel.deleteMany({});
}

export async function clearContest(channelId: string): Promise<void>{
  await contestModel.deleteOne({channelId: channelId});
}

export async function createContest(channelId: string, startTime: number): Promise<boolean>{
  const contest = await contestModel.findOne({channelId: channelId});
  if(contest){
    contest.startTime = startTime;
    await contest.save();
    return false;
  }
  const newContest = new contestModel({
    channelId: channelId,
    startTime: startTime,
    problems: [],
  });
  await newContest.save();
  return true;
}

export async function updateProblem(
  user: User, problemId: string, channelId: string,
  action: string, time: number): Promise<void>{
  // find problem
  let contest = await contestModel.findOne(
    {channelId: channelId},
    {problems: 1, _id: {"$toString": "$_id"}},
  ).populate({path: 'problems', select: 'problemId _id'});
  if(contest === null){
    logger.error(`contest didn't start`);
    throw Error();
  }
  if(contest.problems.every(p => p.problemId != problemId)){
    const newProblem = await new problemModel(
      {problemId: problemId}, {}, {new: true}
    ).save();
    await contestModel.updateOne(
      {channelId: channelId},
      {$push: {problems: newProblem}},
      {new: true}
    );
  }
  contest = await contestModel.findOne(
    {channelId: channelId},
  ).populate({path: 'problems', select: 'problemId _id'});
  const problem = (contest as Contest).problems.find(
    p => p.problemId == problemId);
  // update
  switch(action){
  case 'wa':{
    await problemModel.findByIdAndUpdate(
        (problem as Problem)._id,
        {$push: {wa: time}},
        {new: true}
    );
  }break;
  case 'ac':{
    await problemModel.findByIdAndUpdate(
        (problem as Problem)._id,
        {$set: {ac: time}},
        {new: true}
    );
  }break;
  }
}

export async function putCode(
  user: User, problemId: string, channelId: string,
  time: number, estimate: number): Promise<string>{
  // find problem
  let contest = await contestModel.findOne(
    {channelId: channelId},
    {problems: 1, _id: {"$toString": "$_id"}},
  ).populate({path: 'problems', select: 'problemId _id'});
  if(contest === null){
    logger.error(`contest didn't start`);
    throw Error();
  }
  if(contest.problems.every(p => p.problemId != problemId)){
    const newProblem = await new problemModel(
      {problemId: problemId}, {}, {new: true}
    ).save();
    await contestModel.updateOne(
      {channelId: channelId},
      {$push: {problems: newProblem}},
      {new: true}
    );
  }
  contest = await contestModel.findOne(
    {channelId: channelId},
  ).populate({path: 'problems', select: 'problemId _id'});
  const problem = (contest as Contest).problems.find(
    p => p.problemId == problemId);
  // update
  const newSession = await new sessionModel(
    {name: user.username, start: time, end: estimate}, 
    {}, {new: true, upsert: true}
  ).save();
  await problemModel.findByIdAndUpdate(
    (problem as Problem)._id,
    {$push: {code: newSession}},
    {new: true}
  );
  return newSession._id.toString();
}

export async function putRead(
  user: User, problemId: string, channelId: string, 
  time: number, estimate: number): Promise<string>{
  // find problem
  let contest = await contestModel.findOne(
    {channelId: channelId},
    {problems: 1, _id: {"$toString": "$_id"}},
  ).populate({path: 'problems', select: 'problemId _id'});
  if(contest === null){
    logger.error(`contest didn't start`);
    throw Error();
  }
  if(contest.problems.every(p => p.problemId != problemId)){
    const newProblem = await new problemModel(
      {problemId: problemId}, {}, {new: true}
    ).save();
    await contestModel.updateOne(
      {channelId: channelId},
      {$push: {problems: newProblem}},
      {new: true}
    );
  }
  contest = await contestModel.findOne(
    {channelId: channelId},
  ).populate({path: 'problems', select: 'problemId _id'});
  const problem = (contest as Contest).problems.find(
    p => p.problemId == problemId);
  // update
  const newSession = await new sessionModel(
    {name: user.username, start: time, end: estimate}, 
    {}, {new: true, upsert: true}
  ).save();
  await problemModel.findByIdAndUpdate(
    (problem as Problem)._id,
    {$push: {read: newSession}},
    {new: true}
  );
  return newSession._id.toString();
}

export async function updateSession(sessionId: string, key: string, time: number): Promise<boolean>{
  const session = await sessionModel.findOne({_id: sessionId});
  if(session === null){
    logger.error(`Session ${sessionId} not found.`);
    return false;
  }
  switch(key){
  case 'start':{
    await sessionModel.updateOne(
      {_id: sessionId}, {start: time}
    );
  }break;
  case 'end':{
    await sessionModel.updateOne(
      {_id: sessionId}, {end: time}
    );
  }break;
  }
  return true;
}

export async function getContest(channelId: string): Promise<Contest | null>{
  return await contestModel.findOne({channelId: channelId}).populate(
    {path: 'problems', select: 'problemId _id'}
  );
}

export async function getProblem(id: Types.ObjectId): Promise<Problem | null>{
  return await problemModel.findById(id).populate(
    {path: 'read code', select: 'name start end _id'}
  );
}

export async function getSession(id: Types.ObjectId): Promise<Session | null>{
  return await sessionModel.findById(id).populate('name start end _id');
}

export async function getAllSession(): Promise<Session[]>{
  return await sessionModel.find({});
}

export async function getAllProblem(): Promise<Problem[]>{
  return await problemModel.find({});
}

export async function getAllContest(): Promise<Contest[]>{
  return await contestModel.find({});
}