trade.js

const assert = require('assert')
const { once } = require('../../lib/promise_utils')

module.exports = () => async (bot) => {
  function expectAmount (amount, greaterThan) {
    // TODO: 1.20.5+ does not seem to respect "Count" NBT anymore in /summon
    // ...as NBT was removed in favor of components that may have something to do
    if (bot.registry.version['>=']('1.20.5')) {
      if (amount < 1) throw new Error(`${amount} < 1`) // accept anything >=1
    } else {
      assert.strictEqual(amount, greaterThan)
    }
  }

  const Item = require('prismarine-item')(bot.registry)

  const villagerType = bot.registry.entitiesByName.villager ? 'villager' : 'Villager'
  const testFluctuations = bot.supportFeature('selectingTradeMovesItems')

  const summonCommand = bot.supportFeature('indexesVillagerRecipes')
    ? `/summon ${villagerType} ~ ~1 ~ {NoAI:1, Offers:{Recipes:[0:{maxUses:12,buy:{id:"minecraft:emerald",Count:2},sell:{id:"minecraft:pumpkin_pie",Count:2},uses: 1},1:{maxUses:12,buy:{id:"minecraft:emerald",Count:2},buyB:{id:"minecraft:pumpkin_pie",Count:2},sell:{id:"minecraft:wheat",Count:2}, uses:1},2:{maxUses:12,buy:{id:"minecraft:emerald",Count:1},sell:{id:"minecraft:glass",Count:4},uses: 1},3:{maxUses:12,buy:{id:"minecraft:emerald",Count:36},buyB:{id:"minecraft:book",Count:1},sell:{id:"minecraft:wooden_sword",Count:1},uses: 1}]}}`
    : `/summon ${villagerType} ~ ~1 ~ {NoAI:1, Offers:{Recipes:[{maxUses:12,buy:{id:"minecraft:emerald",Count:2},sell:{id:"minecraft:pumpkin_pie",Count:2},${testFluctuations ? 'demand:60,priceMultiplier:0.05f,specialPrice:-4,' : ''}uses: 1},{maxUses:12,buy:{id:"minecraft:emerald",Count:2},buyB:{id:"minecraft:pumpkin_pie",Count:2},sell:{id:"minecraft:wheat",Count:2}, uses:1},{maxUses:12,buy:{id:"minecraft:emerald",Count:1},sell:{id:"minecraft:glass",Count:4},uses: 1},{maxUses:12,buy:{id:"minecraft:emerald",Count:36},buyB:{id:"minecraft:book",Count:1},sell:{id:"minecraft:wooden_sword",Count:1},uses: 1}]}}`

  const commandBlockPos = bot.entity.position.offset(0.5, 0, 0.5)
  const redstoneBlockPos = commandBlockPos.offset(1, 0, 0)

  let shouldHaveEmeralds = 0
  for (let slot = 9; slot <= 17; slot += 1) {
    await bot.test.setInventorySlot(slot, new Item(bot.registry.itemsByName.emerald.id, 64, 0))
    shouldHaveEmeralds += 64
  }
  await bot.test.setInventorySlot(18, new Item(bot.registry.itemsByName.book.id, 11, 0))

  // A command block is needed to spawn the villager due to the chat's character limit in some versions
  bot.test.sayEverywhere(`/setblock ${commandBlockPos.toArray().join(' ')} command_block`)
  await bot.test.wait(500)
  bot.setCommandBlock(commandBlockPos, summonCommand)
  await bot.test.wait(500)
  bot.test.sayEverywhere(`/setblock ${redstoneBlockPos.toArray().join(' ')} redstone_block`) // Activate the command block

  const [entity] = await once(bot, 'entitySpawn')
  assert(entity.name === villagerType)

  const villager = await bot.openVillager(entity)
  console.log('Opened villager')
  // console.dir(villager, { depth: null })

  // Handle trade #1 -- takes 2x emerald and returns 2x pumpkin_pie
  {
    const trade = villager.trades[0]
    assert.strictEqual(trade.inputs.length, 1, 'Expected single input from villager on first trade')
    verifyTrade(trade)

    const [input] = trade.inputs
    assert.strictEqual(input.name, 'emerald')
    expectAmount(input.count, 2)

    const [output] = trade.outputs
    assert.strictEqual(output.name, 'pumpkin_pie')
    expectAmount(output.count, 2)

    await bot.trade(villager, 0, 11)
    shouldHaveEmeralds -= testFluctuations ? (2 * 2 * 11) : (2 * 11)
    expectAmount(bot.currentWindow.count(bot.registry.itemsByName.emerald.id), shouldHaveEmeralds)
    expectAmount(bot.currentWindow.count(bot.registry.itemsByName.pumpkin_pie.id), 22)
  }

  // Handle trade #2 -- takes [2x emerald, 2x pumpkin_pie] and returns 2x wheat
  {
    const trade = villager.trades[1]
    assert.strictEqual(trade.inputs.length, 2, 'Expected two inputs from villager on second trade')
    verifyTrade(trade)

    const [input1, input2] = trade.inputs
    assert.strictEqual(input1.name, 'emerald')
    expectAmount(input1.count, 2)
    assert.strictEqual(input2.name, 'pumpkin_pie')
    expectAmount(input2.count, 2)

    const [output] = trade.outputs
    assert.strictEqual(output.name, 'wheat')
    expectAmount(output.count, 2)

    await bot.trade(villager, 1, 11)
    shouldHaveEmeralds -= 11 * 2
    expectAmount(bot.currentWindow.count(bot.registry.itemsByName.emerald.id), shouldHaveEmeralds)
    assert.strictEqual(bot.currentWindow.count(bot.registry.itemsByName.pumpkin_pie.id), 0)
    expectAmount(bot.currentWindow.count(bot.registry.itemsByName.wheat.id), 22)
  }

  // Handle trade #3 -- takes 1x emerald and returns 4x glass
  {
    const trade = villager.trades[2]
    assert.strictEqual(trade.inputs.length, 1, 'Expected single input from villager on first trade')
    verifyTrade(trade)

    const [input] = trade.inputs
    assert.strictEqual(input.name, 'emerald')
    expectAmount(input.count, 1)

    const [output] = trade.outputs
    assert.strictEqual(output.name, 'glass')
    expectAmount(output.count, 4)

    await bot.trade(villager, 2, 11)
    shouldHaveEmeralds -= 11
    expectAmount(bot.currentWindow.count(bot.registry.itemsByName.emerald.id), shouldHaveEmeralds)
    expectAmount(bot.currentWindow.count(bot.registry.itemsByName.glass.id), 44)
  }

  // Handle trade #4 -- takes [36x emerald, 1x book] and returns 1x wooden sword
  {
    const trade = villager.trades[3]
    assert.strictEqual(trade.inputs.length, 2, 'Expected two inputs from villager on second trade')
    verifyTrade(trade)

    const [input1, input2] = trade.inputs
    assert.strictEqual(input1.name, 'emerald')
    expectAmount(input1.count, 36)
    assert.strictEqual(input2.name, 'book')
    assert.strictEqual(input2.count, 1)

    const [output] = trade.outputs
    assert.strictEqual(output.name, 'wooden_sword')
    assert.strictEqual(output.count, 1)

    await bot.trade(villager, 3, 11)
    shouldHaveEmeralds -= 11 * 36
    expectAmount(bot.currentWindow.count(bot.registry.itemsByName.emerald.id), shouldHaveEmeralds)
    assert.strictEqual(bot.currentWindow.count(bot.registry.itemsByName.book.id), 0)
    expectAmount(bot.currentWindow.count(bot.registry.itemsByName.wooden_sword.id), 11)
  }

  function verifyTrade (trade) {
    assert.strictEqual(trade.nbTradeUses, 1)
    assert.strictEqual(trade.maximumNbTradeUses, 12)
    assert.strictEqual(trade.tradeDisabled, false)

    const printCountInv = function (item) {
      return `${bot.currentWindow.count(bot.registry.itemsByName[item.name].id)}x ${item.displayName}`
    }
    const printCountTrade = function (item) {
      return `${item.count}x ${item.displayName}`
    }

    bot.test.sayEverywhere(`I have ${printCountInv(trade.inputItem1)} ${trade.hasItem2 ? 'and ' + printCountInv(trade.inputItem2) : ''}`)
    bot.test.sayEverywhere(`I can trade ${printCountTrade(trade.inputItem1)} ${trade.hasItem2 ? 'and ' + printCountTrade(trade.inputItem2) : ''} for ${printCountTrade(trade.outputItem)}`)
  }

  assert.rejects(bot.trade(villager, 1, 1)) // Shouldn't be able, the trade is blocked!
  villager.close()
  bot.test.sayEverywhere(`/kill @e[type=${villagerType}]`)
}