import { ConflictException, Injectable } from '@nestjs/common';
import { InjectRepository } from '@nestjs/typeorm';
import { PipelineTask } from './pipeline-task.entity';
import { In, Repository } from 'typeorm';
import { CreatePipelineTaskInput } from './dtos/create-pipeline-task.input';
import { RedisService } from 'nestjs-redis';
import { Pipeline } from '../pipelines/pipeline.entity';
import { InjectQueue } from '@nestjs/bull';
import { PIPELINE_TASK_QUEUE } from './pipeline-tasks.constants';
import { Queue } from 'bull';
import { LockFailedException } from '../commons/exceptions/lock-failed.exception';
import { TaskStatuses } from './enums/task-statuses.enum';
import { isNil } from 'ramda';
import debug from 'debug';
import { InjectPubSub } from '../commons/pub-sub/decorators/inject-pub-sub.decorator';
import { PubSub } from '../commons/pub-sub/pub-sub';
import { observableToAsyncIterable } from '@graphql-tools/utils';

const log = debug('fennec:pipeline-tasks:service');

@Injectable()
export class PipelineTasksService {
  constructor(
    @InjectRepository(PipelineTask)
    private readonly repository: Repository<PipelineTask>,
    @InjectRepository(Pipeline)
    private readonly pipelineRepository: Repository<Pipeline>,
    @InjectQueue(PIPELINE_TASK_QUEUE)
    private readonly queue: Queue<PipelineTask>,
    private readonly redis: RedisService,
    @InjectPubSub()
    private readonly pubSub: PubSub,
  ) {}
  async addTask(dto: CreatePipelineTaskInput) {
    const pipeline = await this.pipelineRepository.findOneOrFail({
      where: { id: dto.pipelineId },
      relations: ['project'],
    });
    const hasUnfinishedTask = await this.repository
      .findOne({
        pipelineId: dto.pipelineId,
        commit: dto.commit,
        status: In([TaskStatuses.pending, TaskStatuses.working]),
      })
      .then((val) => !isNil(val));
    if (hasUnfinishedTask) {
      throw new ConflictException(
        'There are the same tasks among the unfinished tasks!',
      );
    }
    const task = await this.repository.save(this.repository.create(dto));
    task.pipeline = pipeline;

    const tasksKey = this.getRedisTokens(pipeline)[1];
    const redis = this.redis.getClient();
    await redis.lpush(tasksKey, JSON.stringify(task));
    log(
      'add task %s:%s-%s',
      task.id,
      task.pipeline.branch,
      task.commit.slice(0, 6),
    );
    await this.doNextTask(pipeline);
    return task;
  }

  async findTaskById(id: string) {
    return await this.repository.findOneOrFail({ id });
  }

  async listTasksByPipelineId(pipelineId: string) {
    return await this.repository.find({ pipelineId });
  }

  async listTasksByCommitHash(hash: string) {
    return await this.repository.find({ commit: hash });
  }

  async doNextTask(pipeline: Pipeline) {
    const [lckKey, tasksKey] = this.getRedisTokens(pipeline);
    const redis = this.redis.getClient();

    log('doNextTask()');
    const unLck = await new Promise<() => Promise<void>>(
      async (resolve, reject) => {
        const lckValue = Date.now().toString();
        for (let i = 0; i < 5; i++) {
          if (
            await redis
              .set(lckKey, 0, 'EX', lckValue, 'NX')
              .then(() => true)
              .catch(() => false)
          ) {
            resolve(async () => {
              if ((await redis.get(lckKey)) === lckValue) {
                await redis.del(lckKey);
              }
            });
            return;
          }
          await new Promise((resolve) => setTimeout(resolve, 2000));
        }
        reject(new LockFailedException(lckKey));
      },
    );

    const task = JSON.parse(
      (await redis.rpop(tasksKey).finally(() => unLck())) ?? 'null',
    );
    if (task) {
      log(
        'add task (%s:%s-%s) to queue',
        task.id,
        task.pipeline.branch,
        task.commit.slice(0, 6),
      );
      await this.queue.add(task);
    } else {
      log('task is empty');
    }
  }

  async updateTask(task: PipelineTask) {
    this.pubSub.publish(`task:${task.id}`, task);
    return await this.repository.save(task);
  }

  async watchTaskUpdated(id: string) {
    return observableToAsyncIterable(this.pubSub.message$(`task:${id}`));
  }

  getRedisTokens(pipeline: Pipeline): [string, string] {
    return [`pipeline-${pipeline.id}:lck`, `pipeline-${pipeline.id}:tasks`];
  }
}