import Fluent
import Vapor

// An intermediate between our api and view controllers that interacts with the
// database.
struct PurchaseOrderDB {

  func create(
    _ model: PurchaseOrder.Create,
    createdById: User.IDValue,
    on db: any Database
  ) async throws -> PurchaseOrder.DTO {
    guard let employee = try await Employee.find(model.createdForID, on: db) else {
      throw Abort(.notFound, reason: "Employee not found.")
    }

    guard employee.active else {
      throw Abort(.badRequest, reason: "Employee is not active, unable to generate a PO for in-active employees")
    }

    let purchaseOrder = model.toModel(createdByID: createdById)
    try await purchaseOrder.save(on: db)
    guard let loaded = try await get(id: purchaseOrder.requireID(), on: db) else {
      return purchaseOrder.toDTO()
    }
    return loaded
  }

  func fetchAll(on db: any Database) async throws -> [PurchaseOrder.DTO] {
    try await PurchaseOrder.allQuery(on: db)
      .sort(\.$id, .descending)
      .all().map { $0.toDTO() }
  }

  func fetchPage(_ page: Int, limit: Int, on db: any Database) async throws -> Page<PurchaseOrder.DTO> {
    try await PurchaseOrder.allQuery(on: db)
      .sort(\.$id, .descending)
      .paginate(PageRequest(page: page, per: limit))
      .map { $0.toDTO() }
  }

  func get(id: PurchaseOrder.IDValue, on db: any Database) async throws -> PurchaseOrder.DTO? {
    try await PurchaseOrder.allQuery(on: db)
      .filter(\.$id == id)
      .first()?.toDTO()
  }

  func delete(id: PurchaseOrder.IDValue, on db: any Database) async throws {
    guard let purchaseOrder = try await PurchaseOrder.find(id, on: db) else {
      throw Abort(.notFound)
    }
    try await purchaseOrder.delete(on: db)
  }
}

private extension PurchaseOrder {
  static func allQuery(on db: any Database) -> QueryBuilder<PurchaseOrder> {
    PurchaseOrder.query(on: db)
      .with(\.$createdBy)
      .with(\.$createdFor)
      .with(\.$vendorBranch) { branch in
        branch.with(\.$vendor)
      }
  }
}