visitor.ts

import { DMMFModels } from './dmmf'
import { Item, traverseTree } from './traverseTree'
import type { FieldConfiguration, MiddlewareParams } from './types'

interface VisitorState {
  currentModel: string
}

export interface TargetField {
  path: string
  value: string
  model: string
  field: string
  fieldConfig: FieldConfiguration
}

export type TargetFieldVisitorFn = (targetField: TargetField) => void

export const makeVisitor = (
  models: DMMFModels,
  visitor: TargetFieldVisitorFn
) =>
  function visitNode(state: VisitorState, { key, type, node, path }: Item) {
    const model = models[state.currentModel]
    if (!model || !key) {
      return state
    }
    if (type === 'string' && key in model.fields) {
      const targetField: TargetField = {
        field: key,
        model: state.currentModel,
        fieldConfig: model.fields[key],
        path: path.join('.'),
        value: node as string
      }
      visitor(targetField)
      return state
    }
    // Special case: {field}.set for updates
    if (
      type === 'object' &&
      key in model.fields &&
      typeof (node as any)?.set === 'string'
    ) {
      const value: string = (node as any).set
      const targetField: TargetField = {
        field: key,
        model: state.currentModel,
        fieldConfig: model.fields[key],
        path: path.join('.') + '.set',
        value
      }
      visitor(targetField)
      return state
    }
    if (['object', 'array'].includes(type) && key in model.connections) {
      // Follow the connection: from there on downwards, we're changing models.
      // Return a new object to break from existing references.
      return {
        currentModel: model.connections[key].modelName
      }
    }
    return state
  }

export function visitInputTargetFields(
  params: MiddlewareParams,
  models: DMMFModels,
  visitor: TargetFieldVisitorFn
) {
  traverseTree(params.args, makeVisitor(models, visitor), {
    currentModel: params.model!
  })
}

export function visitOutputTargetFields(
  params: MiddlewareParams,
  result: any,
  models: DMMFModels,
  visitor: TargetFieldVisitorFn
) {
  traverseTree(result, makeVisitor(models, visitor), {
    currentModel: params.model!
  })
}