import { emailValidator, regexValidator, requiredValidator, urlValidator } from './validators'
import { FormFieldType } from '../types/formBuilder'
import type { PublicFormField } from '../types/formBuilder'

export type Validator = (value: unknown) => true | string

/**
 * Build a list of client-side validators for a public form field.
 * Runs in VTextField `:rules` and the stepper "current step valid"
 * gate. Mirrors (a subset of) the backend relaxed rule set so the
 * submitter gets feedback before the submit round-trip.
 */
export function getValidatorsForField(field: PublicFormField): Validator[] {
  const rules: Validator[] = []
  const v = field.validation_rules ?? {}

  if (field.is_required) {
    rules.push(value => {
      const ok = requiredValidator(value)

      return ok === true ? true : 'Dit veld is verplicht.'
    })
  }

  switch (field.field_type) {
    case FormFieldType.EMAIL:
      rules.push(value => {
        const ok = emailValidator(value)

        return ok === true ? true : 'Vul een geldig e-mailadres in.'
      })
      break

    case FormFieldType.URL:
      rules.push(value => {
        const ok = urlValidator(value)

        return ok === true ? true : 'Vul een geldige URL in (beginnend met http:// of https://).'
      })
      break

    case FormFieldType.PHONE:
      rules.push(value => {
        if (value === null || value === undefined || value === '') return true
        const s = String(value).replace(/\s+/g, '')

        return /^\+?[\d()-]{6,}$/.test(s) || 'Vul een geldig telefoonnummer in.'
      })
      break

    case FormFieldType.NUMBER:
      rules.push(value => {
        if (value === null || value === undefined || value === '') return true
        const n = Number(value)

        return Number.isFinite(n) || 'Vul een geldig getal in.'
      })
      if (typeof v.min === 'number') {
        const min = v.min
        rules.push(value => {
          if (value === null || value === undefined || value === '') return true
          const n = Number(value)

          return Number.isFinite(n) && n >= min ? true : `Minimaal ${min}.`
        })
      }
      if (typeof v.max === 'number') {
        const max = v.max
        rules.push(value => {
          if (value === null || value === undefined || value === '') return true
          const n = Number(value)

          return Number.isFinite(n) && n <= max ? true : `Maximaal ${max}.`
        })
      }
      break

    case FormFieldType.TEXT:
    case FormFieldType.TEXTAREA:
      if (typeof v.min === 'number') {
        const min = v.min
        rules.push(value => {
          if (value === null || value === undefined || value === '') return true

          return String(value).length >= min ? true : `Minimaal ${min} tekens.`
        })
      }
      if (typeof v.max === 'number') {
        const max = v.max
        rules.push(value => {
          if (value === null || value === undefined || value === '') return true

          return String(value).length <= max ? true : `Maximaal ${max} tekens.`
        })
      }
      if (typeof v.pattern === 'string' && v.pattern.length > 0) {
        const pattern = v.pattern
        rules.push(value => {
          if (value === null || value === undefined || value === '') return true
          const ok = regexValidator(value, pattern)

          return ok === true ? true : 'Ongeldige invoer.'
        })
      }
      break

    case FormFieldType.MULTISELECT:
    case FormFieldType.CHECKBOX_LIST:
      if (typeof v.min_selections === 'number') {
        const min = v.min_selections
        rules.push(value => {
          const arr = Array.isArray(value) ? value : []

          return arr.length >= min ? true : `Kies er minimaal ${min}.`
        })
      }
      if (typeof v.max_selections === 'number') {
        const max = v.max_selections
        rules.push(value => {
          const arr = Array.isArray(value) ? value : []

          return arr.length <= max ? true : `Kies er maximaal ${max}.`
        })
      }
      break

    default:
      break
  }

  return rules
}

export function runValidators(rules: Validator[], value: unknown): string | true {
  for (const rule of rules) {
    const r = rule(value)
    if (r !== true) return r
  }

  return true
}

export function isFieldValueEmpty(value: unknown): boolean {
  if (value === null || value === undefined) return true
  if (typeof value === 'string') return value.trim() === ''
  if (Array.isArray(value)) return value.length === 0

  return false
}