Sources/SparkConnect/ArrowSchema.swift

// Licensed to the Apache Software Foundation (ASF) under one
// or more contributor license agreements.  See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership.  The ASF licenses this file
// to you under the Apache License, Version 2.0 (the
// "License"); you may not use this file except in compliance
// with the License.  You may obtain a copy of the License at
//
//   http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing,
// software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied.  See the License for the
// specific language governing permissions and limitations
// under the License.

import Foundation

/// @nodoc
public class ArrowField {
  public let type: ArrowType
  public let name: String
  public let isNullable: Bool

  init(_ name: String, type: ArrowType, isNullable: Bool) {
    self.name = name
    self.type = type
    self.isNullable = isNullable
  }
}

/// @nodoc
public class ArrowSchema {
  public let fields: [ArrowField]
  public let fieldLookup: [String: Int]
  init(_ fields: [ArrowField]) {
    var fieldLookup = [String: Int]()
    for (index, field) in fields.enumerated() {
      fieldLookup[field.name] = index
    }

    self.fields = fields
    self.fieldLookup = fieldLookup
  }

  public func field(_ index: Int) -> ArrowField {
    return self.fields[index]
  }

  public func fieldIndex(_ name: String) -> Int? {
    return self.fieldLookup[name]
  }

  public class Builder {
    private var fields: [ArrowField] = []

    public init() {}

    @discardableResult
    public func addField(_ field: ArrowField) -> Builder {
      fields.append(field)
      return self
    }

    @discardableResult
    public func addField(_ name: String, type: ArrowType, isNullable: Bool) -> Builder {
      fields.append(ArrowField(name, type: type, isNullable: isNullable))
      return self
    }

    public func finish() -> ArrowSchema {
      return ArrowSchema(fields)
    }
  }
}