import Component from '#models/component'
import Computer from '#models/computer'
import InvalidComponentSelectionException from '#exceptions/invalid_component_selection_exception'

async function handleComponents(componentsId: number[], computer: Computer, userId: number) {
  const currentComponents = await computer.related('components').query()
  const currentComponentsIds = currentComponents.map((component) => component.id)
  const componentsToAdd = componentsId.filter((id) => !currentComponentsIds.includes(id))
  const componentsToRemove = currentComponentsIds.filter((id) => !componentsId.includes(id))

  const componentsToAddRecords = await Promise.all(
    componentsToAdd.map((id: number) =>
      Component.query().where('userId', userId).andWhere('id', id).preload('type').firstOrFail()
    )
  )

  // Ensure at most one component of each "unique" type ends up attached to
  // the computer once the additions/removals are applied.
  const remainingComponentIds = currentComponentsIds.filter(
    (id) => !componentsToRemove.includes(id)
  )
  const remainingComponents = remainingComponentIds.length
    ? await Component.query().whereIn('id', remainingComponentIds).preload('type')
    : []
  const finalComponents = [...remainingComponents, ...componentsToAddRecords]

  const uniqueTypeCounts = new Map<number, number>()
  for (const component of finalComponents) {
    if (!component.type.unique) continue
    const count = (uniqueTypeCounts.get(component.type.id) ?? 0) + 1
    uniqueTypeCounts.set(component.type.id, count)
    if (count > 1) {
      throw new InvalidComponentSelectionException(
        `Only one component of type "${component.type.name}" can be attached to a computer at a time.`
      )
    }
  }

  await Promise.all(
    componentsToAddRecords.map(async (component) => {
      component.computerId = computer.id
      await component.save()
    })
  )
  await Promise.all(
    componentsToRemove.map(async (id: number) => {
      const component = await Component.query()
        .where('userId', userId)
        .andWhere('id', id)
        .firstOrFail()
      component.computerId = null
      await component.save()
    })
  )
}

export { handleComponents }