import { ExtendedFindConfig, FindConfig } from "../types/common"
import {
  FindManyOptions,
  FindOperator,
  FindOptionsRelations,
  FindOptionsSelect,
  FindOptionsWhere,
  In,
  IsNull,
  LessThan,
  LessThanOrEqual,
  MoreThan,
  MoreThanOrEqual,
} from "typeorm"
import { FindOptionsOrder } from "typeorm/find-options/FindOptionsOrder"
import { isObject } from "./is-object"

/**
 * Used to build TypeORM queries.
 * @param selector The selector
 * @param config The config
 * @return The QueryBuilderConfig
 */
export function buildQuery<TWhereKeys extends object, TEntity = unknown>(
  selector: TWhereKeys,
  config: FindConfig<TEntity> = {}
) {
  const query: ExtendedFindConfig<TEntity> = {
    where: buildWhere<TWhereKeys, TEntity>(selector),
  }

  if ("deleted_at" in selector) {
    query.withDeleted = true
  }

  if ("skip" in config) {
    ;(query as FindManyOptions<TEntity>).skip = config.skip
  }

  if ("take" in config) {
    ;(query as FindManyOptions<TEntity>).take = config.take
  }

  if (config.relations) {
    query.relations = buildRelations<TEntity>(config.relations)
  }

  if (config.select) {
    query.select = buildSelects<TEntity>(config.select as string[])
  }

  if (config.order) {
    query.order = buildOrder<TEntity>(config.order)
  }

  return query
}

/**
 * @param constraints
 *
 * @example
 * const q = buildWhere(
 *   {
 *     id: "1234",
 *     test1: ["123", "12", "1"],
 *     test2: Not("this"),
 *     date: { gt: date },
 *     amount: { gt: 10 },
 *   },
 *)
 *
 * // Output
 * {
 *    id: "1234",
 *    test1: In(["123", "12", "1"]),
 *    test2: Not("this"),
 *    date: MoreThan(date),
 *    amount: MoreThan(10)
 * }
 */
function buildWhere<TWhereKeys extends object, TEntity>(
  constraints: TWhereKeys
): FindOptionsWhere<TEntity> {
  const where: FindOptionsWhere<TEntity> = {}
  for (const [key, value] of Object.entries(constraints)) {
    if (value === undefined) {
      continue
    }

    if (value === null) {
      where[key] = IsNull()
      continue
    }

    if (value instanceof FindOperator) {
      where[key] = value
      continue
    }

    if (Array.isArray(value)) {
      where[key] = In(value)
      continue
    }

    if (typeof value === "object") {
      Object.entries(value).forEach(([objectKey, objectValue]) => {
        switch (objectKey) {
          case "lt":
            where[key] = LessThan(objectValue)
            break
          case "gt":
            where[key] = MoreThan(objectValue)
            break
          case "lte":
            where[key] = LessThanOrEqual(objectValue)
            break
          case "gte":
            where[key] = MoreThanOrEqual(objectValue)
            break
          default:
            if (objectValue != undefined && typeof objectValue === "object") {
              where[key] = buildWhere<any, TEntity>(objectValue)
              return
            }
            where[key] = value
        }
        return
      })

      continue
    }

    where[key] = value
  }

  return where
}

/**
 * Revert new object structure of find options to the legacy structure of previous version
 * @example
 * input: {
 *   test: {
 *     test1: true,
 *     test2: true,
 *     test3: {
 *       test4: true
 *     },
 *   },
 *   test2: true
 * }
 * output: ['test.test1', 'test.test2', 'test.test3.test4', 'test2']
 * @param input
 */
export function buildLegacyFieldsListFrom<TEntity>(
  input:
    | FindOptionsWhere<TEntity>
    | FindOptionsSelect<TEntity>
    | FindOptionsOrder<TEntity>
    | FindOptionsRelations<TEntity> = {}
): (keyof TEntity)[] {
  if (!Object.keys(input).length) {
    return []
  }

  const output: Set<string> = new Set(Object.keys(input))

  for (const key of Object.keys(input)) {
    if (input[key] != undefined && typeof input[key] === "object") {
      const deepRes = buildLegacyFieldsListFrom(input[key])

      const items = deepRes.reduce((acc, val) => {
        acc.push(`${key}.${val}`)
        return acc
      }, [] as string[])

      items.forEach((item) => output.add(item))
      continue
    }

    output.add(key)
  }

  return Array.from(output) as (keyof TEntity)[]
}

export function buildSelects<TEntity>(
  selectCollection: string[]
): FindOptionsSelect<TEntity> {
  return buildRelationsOrSelect(selectCollection) as FindOptionsSelect<TEntity>
}

export function buildRelations<TEntity>(
  relationCollection: string[]
): FindOptionsRelations<TEntity> {
  return buildRelationsOrSelect(
    relationCollection
  ) as FindOptionsRelations<TEntity>
}

export function addOrderToSelect<TEntity>(
  order: FindOptionsOrder<TEntity>,
  select: FindOptionsSelect<TEntity>
): void {
  for (const orderBy of Object.keys(order)) {
    if (isObject(order[orderBy])) {
      select[orderBy] =
        select[orderBy] && isObject(select[orderBy]) ? select[orderBy] : {}
      addOrderToSelect(order[orderBy], select[orderBy])
      continue
    }

    select[orderBy] = isObject(select[orderBy])
      ? { ...select[orderBy], id: true, [orderBy]: true }
      : true
  }
}

/**
 * Convert an collection of dot string into a nested object
 * @example
 * input: [
 *    order,
 *    order.items,
 *    order.swaps,
 *    order.swaps.additional_items,
 *    order.discounts,
 *    order.discounts.rule,
 *    order.claims,
 *    order.claims.additional_items,
 *    additional_items,
 *    additional_items.variant,
 *    return_order,
 *    return_order.items,
 *    return_order.shipping_method,
 *    return_order.shipping_method.tax_lines
 * ]
 * output: {
 *   "order": {
 *     "items": true,
 *     "swaps": {
 *       "additional_items": true
 *     },
 *     "discounts": {
 *       "rule": true
 *     },
 *     "claims": {
 *       "additional_items": true
 *     }
 *   },
 *   "additional_items": {
 *     "variant": true
 *   },
 *   "return_order": {
 *     "items": true,
 *     "shipping_method": {
 *       "tax_lines": true
 *     }
 *   }
 * }
 * @param collection
 */
function buildRelationsOrSelect<TEntity>(
  collection: string[]
): FindOptionsRelations<TEntity> | FindOptionsSelect<TEntity> {
  const output: FindOptionsRelations<TEntity> | FindOptionsSelect<TEntity> = {}

  for (const relation of collection) {
    if (relation.indexOf(".") > -1) {
      const nestedRelations = relation.split(".")

      let parent = output

      while (nestedRelations.length > 1) {
        const nestedRelation = nestedRelations.shift() as string
        parent = parent[nestedRelation] =
          parent[nestedRelation] !== true &&
          typeof parent[nestedRelation] === "object"
            ? parent[nestedRelation]
            : {}
      }

      parent[nestedRelations[0]] = true

      continue
    }

    output[relation] = output[relation] ?? true
  }

  return output
}

/**
 * Convert an order of dot string into a nested object
 * @example
 * input: { id: "ASC", "items.title": "ASC", "items.variant.title": "ASC" }
 * output: {
 *   "id": "ASC",
 *   "items": {
 *     "id": "ASC",
 *     "variant": {
 *        "title": "ASC"
 *     }
 *   },
 * }
 * @param orderBy
 */
function buildOrder<TEntity>(orderBy: {
  [k: string]: "ASC" | "DESC"
}): FindOptionsOrder<TEntity> {
  const output: FindOptionsOrder<TEntity> = {}

  const orderKeys = Object.keys(orderBy)

  for (const order of orderKeys) {
    if (order.indexOf(".") > -1) {
      const nestedOrder = order.split(".")

      let parent = output

      while (nestedOrder.length > 1) {
        const nestedRelation = nestedOrder.shift() as string
        parent = parent[nestedRelation] = parent[nestedRelation] ?? {}
      }

      parent[nestedOrder[0]] = orderBy[order]

      continue
    }

    output[order] = orderBy[order]
  }

  return output
}

export function nullableValue(value: any): FindOperator<any> {
  if (value === null) {
    return IsNull()
  } else {
    return value
  }
}