import Fluent
import Vapor

struct ApiController: RouteCollection {
  func boot(routes: RoutesBuilder) throws {
    let api = routes.grouped("api", "v1")

    // Allows basic or token authentication.
    let protected = api.grouped(
      User.authenticator(),
      UserToken.authenticator(),
      User.guardMiddleware()
    )

    let employees = protected.grouped("employees")
    let purchaseOrders = protected.grouped("purchase-orders")

    // TODO: Need to handle the intial creation of users somehow.
    let users = protected.grouped("users")
    let vendors = protected.grouped("vendors")
    let vendorBranches = vendors.grouped(":vendorID", "branches")

    employees.get(use: employeesIndex(req:))
    employees.post(use: createEmployee(req:))
    employees.group(":employeeID") {
      $0.delete(use: self.deleteEmployee(req:))
      $0.put(use: self.updateEmployee(req:))
    }

    purchaseOrders.get(use: purchaseOrdersIndex(req:))
    purchaseOrders.post(use: createPurchaseOrder(req:))

    users.get(use: usersIndex(req:))
    api.post("users", use: createUser(req:))
    users.group("login") {
      $0.get(use: self.login(req:))
    }
    users.group(":userID") {
      $0.delete(use: self.deleteUser(req:))
    }

    vendors.get(use: vendorsIndex)
    vendors.post(use: createVendor)
    vendors.group(":vendorID") {
      $0.delete(use: self.deleteVendor)
      $0.put(use: self.updateVendor(req:))
    }

    vendorBranches.get(use: branchesIndex(req:))
    vendorBranches.post(use: createBranch(req:))

    vendorBranches.group(":branchID") {
      $0.delete(use: self.deleteBranch(req:))
      $0.put(use: self.updateBranch(req:))
    }
  }

  // MARK: - Employees

  @Sendable
  func employeesIndex(req: Request) async throws -> [Employee.DTO] {
    var dbQuery = Employee
      .query(on: req.db)
      .sort(\.$lastName)

    let params = try req.query.decode(EmployeesIndexQuery.self)
    if params.active == true {
      dbQuery = dbQuery.filter(\.$active == true)
    }

    return try await dbQuery.all().map { $0.toDTO() }
  }

  @Sendable
  func createEmployee(req: Request) async throws -> Employee.DTO {
    try Employee.Create.validate(content: req)
    let employee = try req.content.decode(Employee.Create.self).toModel()
    try await employee.save(on: req.db)
    return employee.toDTO()
  }

  @Sendable
  func deleteEmployee(req: Request) async throws -> HTTPStatus {
    guard let employee = try await Employee.find(req.parameters.get("employeeID"), on: req.db) else {
      throw Abort(.notFound)
    }
    try await employee.delete(on: req.db)
    return .ok
  }

  @Sendable
  func updateEmployee(req: Request) async throws -> Employee.DTO {
    try Employee.Update.validate(content: req)
    guard let employee = try await Employee.find(req.parameters.get("employeeID"), on: req.db) else {
      throw Abort(.notFound)
    }
    let updates = try req.content.decode(Employee.Update.self)
    employee.applyUpdates(updates)
    try await employee.save(on: req.db)
    return employee.toDTO()
  }

  // MARK: - PurchaseOrders

  // TODO: Add fetch by id.

  // TODO: Add pagination and filters.
  @Sendable
  func purchaseOrdersIndex(req: Request) async throws -> [PurchaseOrder.DTO] {
    try await PurchaseOrder.query(on: req.db)
      .with(\.$createdBy)
      .with(\.$createdFor)
      .with(\.$vendorBranch) {
        $0.with(\.$vendor)
      }
      .sort(\.$id, .descending)
      .all()
      .map { $0.toDTO() }
  }

  @Sendable
  func createPurchaseOrder(req: Request) async throws -> PurchaseOrder.DTO {
    try PurchaseOrder.Create.validate(content: req)
    let createdById = try req.auth.require(User.self).requireID()
    let create = try req.content.decode(PurchaseOrder.Create.self)

    guard let employee = try await Employee.find(create.createdForID, on: req.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 = create.toModel(createdByID: createdById)
    try await purchaseOrder.save(on: req.db)

    guard let loaded = try await PurchaseOrder.query(on: req.db)
      .filter(\.$id == purchaseOrder.requireID())
      .with(\.$createdBy)
      .with(\.$createdFor)
      .with(\.$vendorBranch, { branch in
        branch.with(\.$vendor)
      })
      .first()
    else {
      // This should really never happen, since we just created the purchase order.
      throw Abort(.noContent, reason: "Failed to load purchase order after creation")
    }
    return loaded.toDTO()
  }

  // MARK: - Users

  @Sendable
  func createUser(req: Request) async throws -> User.DTO {
    let count = try await User.query(on: req.db).count()
    if count > 0 {
      guard req.auth.get(User.self) != nil else {
        throw Abort(.unauthorized)
      }
    }

    try User.Create.validate(content: req)
    let create = try req.content.decode(User.Create.self)
    guard create.password == create.confirmPassword else {
      throw Abort(.badRequest, reason: "Passwords did not match.")
    }
    let user = try User(
      username: create.username,
      email: create.email,
      passwordHash: Bcrypt.hash(create.password)
    )
    try await user.save(on: req.db)
    return user.toDTO()
  }

  @Sendable
  func login(req: Request) async throws -> UserToken {
    let user = try req.auth.require(User.self)
    let token = try user.generateToken()
    try await token.save(on: req.db)
    return token
  }

  @Sendable
  func usersIndex(req: Request) async throws -> [User.DTO] {
    try await User.query(on: req.db).all().map { $0.toDTO() }
  }

  @Sendable
  func deleteUser(req: Request) async throws -> HTTPStatus {
    guard let user = try await User.find(req.parameters.get("userID"), on: req.db) else {
      throw Abort(.notFound)
    }

    try await user.delete(on: req.db)
    return .ok
  }

  // MARK: - Vendors

  @Sendable
  func vendorsIndex(req: Request) async throws -> [Vendor.DTO] {
    var dbQuery = Vendor.query(on: req.db)
    let params = try req.query.decode(VendorsIndexQuery.self)

    if params.branches == true {
      dbQuery = dbQuery.with(\.$branches)
    }

    return try await dbQuery
      .sort(\.$name, .ascending)
      .all()
      .map { $0.toDTO(includeBranches: params.branches) }
  }

  @Sendable
  func createVendor(req: Request) async throws -> Vendor.DTO {
    try Vendor.Create.validate(content: req)
    let vendor = try req.content.decode(Vendor.Create.self).toModel()
    try await vendor.save(on: req.db)
    return vendor.toDTO()
  }

  @Sendable
  func updateVendor(req: Request) async throws -> Vendor.DTO {
    try Vendor.Update.validate(content: req)
    let updates = try req.content.decode(Vendor.Update.self)
    guard let vendor = try await Vendor.find(req.parameters.get("vendorID"), on: req.db) else {
      throw Abort(.notFound)
    }
    vendor.applyUpdates(updates)
    try await vendor.save(on: req.db)
    return vendor.toDTO()
  }

  @Sendable
  func deleteVendor(req: Request) async throws -> HTTPStatus {
    guard let vendor = try await Vendor.find(req.parameters.get("vendorID"), on: req.db) else {
      throw Abort(.notFound)
    }

    try await vendor.delete(on: req.db)
    return .ok
  }

  // MARK: - VendorBranch

  @Sendable
  func branchesIndex(req: Request) async throws -> [VendorBranch.DTO] {
    guard let vendor = try await Vendor.find(req.parameters.get("vendorID"), on: req.db) else {
      throw Abort(.notFound)
    }
    return try await vendor.$branches.get(on: req.db).map { $0.toDTO() }
  }

  @Sendable
  func createBranch(req: Request) async throws -> VendorBranch.DTO {
    try VendorBranch.Create.validate(content: req)
    let branch = try req.content.decode(VendorBranch.Create.self).toModel()
    guard let vendor = try await Vendor.find(req.parameters.get("vendorID"), on: req.db) else {
      throw Abort(.notFound)
    }
    try await vendor.$branches.create(branch, on: req.db)
    return branch.toDTO()
  }

  @Sendable
  func deleteBranch(req: Request) async throws -> HTTPStatus {
    guard let branch = try await VendorBranch.find(req.parameters.get("branchID"), on: req.db) else {
      throw Abort(.notFound)
    }
    try await branch.delete(on: req.db)
    return .ok
  }

  @Sendable
  func updateBranch(req: Request) async throws -> VendorBranch.DTO {
    try VendorBranch.Update.validate(content: req)
    let updates = try req.content.decode(VendorBranch.Update.self)
    guard let branch = try await VendorBranch.find(req.parameters.get("branchID"), on: req.db) else {
      throw Abort(.notFound)
    }
    branch.applyUpdates(updates)
    try await branch.save(on: req.db)
    return branch.toDTO()
  }
}

struct VendorsIndexQuery: Content {
  let branches: Bool?
}

struct EmployeesIndexQuery: Content {
  let active: Bool?
}