const { run, parseCronItems, Logger } = require('graphile-worker')
const { Pool } = require('pg')
const { DynamicThreadPool } = require('poolifier')
const { v4: uuid } = require('uuid')
const os = require('node:os')
const path = require('node:path')

module.exports = {
  pool: null,
  runner: null,
  maxWorkers: 1,
  async init () {
    this.maxWorkers = WIKI.config.scheduler.workers === 'auto' ? os.cpus().length : WIKI.config.scheduler.workers
    WIKI.logger.info(`Initializing Worker Pool (Limit: ${this.maxWorkers})...`)
    this.pool = new DynamicThreadPool(1, this.maxWorkers, './server/worker.js', {
      errorHandler: (err) => WIKI.logger.warn(err),
      exitHandler: () => WIKI.logger.debug('A worker has gone offline.'),
      onlineHandler: () => WIKI.logger.debug('New worker is online.')
    })
    return this
  },
  async start () {
    WIKI.logger.info('Starting Scheduler...')
    this.runner = await run({
      pgPool: new Pool({
        ...(typeof WIKI.models.config === 'string') ? {
          connectionString: WIKI.models.config
        } : WIKI.models.config,
        max: this.maxWorkers + 2
      }),
      schema: WIKI.config.db.schemas.scheduler,
      concurrency: this.maxWorkers,
      noHandleSignals: true,
      logger: new Logger(scope => {
        return (level, message, meta) => {
          const prefix = (scope?.workerId) ? `[${scope.workerId}] ` : ''
          WIKI.logger[level](`${prefix}${message}`, meta)
        }
      }),
      parsedCronItems: parseCronItems(WIKI.data.jobs.map(j => ({
        ...j,
        identifier: uuid()
      }))),
      taskList: {
        simple: async (payload, helpers) => {
          // TODO: Handle task
        },
        background: async (payload, helpers) => {
          try {
            await this.pool.execute({
              id: helpers.job.id,
              name: payload.name,
              data: payload.data
            })
          } catch (err) {
            helpers.logger.warn(`Failed job: ${err.message}`)
            throw err
          }
        }
      }
    })
    WIKI.logger.info('Scheduler: [ STARTED ]')
  },
  async stop () {
    WIKI.logger.info('Stopping Scheduler...')
    await this.runner.stop()
    WIKI.logger.info('Scheduler: [ STOPPED ]')
  }
}