// Icon: streamline-ultimate:wifi-signal-2
// Slug: Creates a computed signal.
// Description: Creates a signal that is computed based on an expression.

import { attribute } from '@engine'
import { computed, mergePaths, mergePatch } from '@engine/signals'
import { modifyCasing } from '@utils/text'
import { updateLeaves } from '@utils/paths'

attribute({
  name: 'computed',
  requirement: {
    value: 'must',
  },
  returnsValue: true,
  apply({ key, mods, rx, error }) {
    if (key) {
      mergePaths([[modifyCasing(key, mods), computed(rx)]])
    } else {
      const patch = Object.assign({}, rx() as Record<string, () => any>)
      updateLeaves(patch, (old) => {
        if (typeof old === 'function') {
          return computed(old)
        } else {
          throw error('ComputedExpectedFunction')
        }
      })
      mergePatch(patch)
    }
  },
})