import type { Field } from '@/types/field'

/**
 * Quantity field stores linkage and future payment metadata in `htmlContent` as JSON
 * (same persistence path as the product field’s `htmlContent` blob).
 */
export interface QuantityFieldConfig {
  quantityConfigVersion?: number
  /** `fieldIndex` of the product field on this form. */
  linkedProductFieldIndex: number | null
}

const CURRENT_CONFIG_VERSION = 1

const defaultConfig = (): QuantityFieldConfig => ({
  quantityConfigVersion: CURRENT_CONFIG_VERSION,
  linkedProductFieldIndex: null,
})

export function parseQuantityFieldConfig(field?: Field | null): QuantityFieldConfig {
  if (!field) {
    return defaultConfig()
  }
  const raw = field.htmlContent
  if (typeof raw !== 'string' || raw.trim() === '') {
    return defaultConfig()
  }
  try {
    const parsed = JSON.parse(raw) as Record<string, unknown>
    const linked = parsed['linkedProductFieldIndex']
    let linkedProductFieldIndex: number | null = null
    if (typeof linked === 'number' && Number.isFinite(linked) && linked >= 0) {
      linkedProductFieldIndex = Math.round(linked)
    } else if (typeof linked === 'string' && linked.trim() !== '') {
      const n = Number(linked)
      if (Number.isFinite(n) && n >= 0) {
        linkedProductFieldIndex = Math.round(n)
      }
    }

    const versionRaw = parsed['quantityConfigVersion']
    const quantityConfigVersion =
      typeof versionRaw === 'number' && Number.isFinite(versionRaw) ? versionRaw : 0

    return {
      ...defaultConfig(),
      quantityConfigVersion,
      linkedProductFieldIndex,
    }
  } catch {
    return defaultConfig()
  }
}

export function stringifyQuantityFieldConfig(config: QuantityFieldConfig): string {
  return JSON.stringify({
    quantityConfigVersion: CURRENT_CONFIG_VERSION,
    linkedProductFieldIndex: config.linkedProductFieldIndex,
  })
}