/*
 * Copyright 2024, gRPC Authors All rights reserved.
 *
 * Licensed 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.
 */

/// Creates a ``SourceFile`` containing the generated code for the RPCs represented in a ``CodeGenerationRequest`` object.
public struct SourceGenerator: Sendable {
  /// The options regarding the access level, indentation for the generated code
  /// and whether to generate server and client code.
  public var configuration: Configuration

  public init(configuration: Configuration) {
    self.configuration = configuration
  }

  /// User options for the CodeGeneration.
  public struct Configuration: Sendable {
    /// The access level the generated code will have.
    public var accessLevel: AccessLevel
    /// Whether imports have explicit access levels.
    public var accessLevelOnImports: Bool
    /// The indentation of the generated code as the number of spaces.
    public var indentation: Int
    /// Whether or not client code should be generated.
    public var client: Bool
    /// Whether or not server code should be generated.
    public var server: Bool

    /// Creates a new configuration.
    ///
    /// - Parameters:
    ///   - accessLevel: The access level the generated code will have.
    ///   - accessLevelOnImports: Whether imports have explicit access levels.
    ///   - client: Whether or not client code should be generated.
    ///   - server: Whether or not server code should be generated.
    ///   - indentation: The indentation of the generated code as the number of spaces.
    public init(
      accessLevel: AccessLevel,
      accessLevelOnImports: Bool,
      client: Bool,
      server: Bool,
      indentation: Int = 4
    ) {
      self.accessLevel = accessLevel
      self.accessLevelOnImports = accessLevelOnImports
      self.indentation = indentation
      self.client = client
      self.server = server
    }

    /// The possible access levels for the generated code.
    public struct AccessLevel: Sendable, Hashable {
      internal var level: Level
      internal enum Level {
        case `internal`
        case `public`
        case `package`
      }

      /// The generated code will have `internal` access level.
      public static var `internal`: Self { Self(level: .`internal`) }

      /// The generated code will have `public` access level.
      public static var `public`: Self { Self(level: .`public`) }

      /// The generated code will have `package` access level.
      public static var `package`: Self { Self(level: .`package`) }
    }
  }

  /// The function that transforms a ``CodeGenerationRequest`` object  into a ``SourceFile`` object containing
  /// the generated code, in accordance to the configurations set by the user for the ``SourceGenerator``.
  public func generate(
    _ request: CodeGenerationRequest
  ) throws -> SourceFile {
    let translator = IDLToStructuredSwiftTranslator()
    let textRenderer = TextBasedRenderer(indentation: self.configuration.indentation)

    let structuredSwiftRepresentation = try translator.translate(
      codeGenerationRequest: request,
      accessLevel: self.configuration.accessLevel,
      accessLevelOnImports: self.configuration.accessLevelOnImports,
      client: self.configuration.client,
      server: self.configuration.server
    )
    let sourceFile = try textRenderer.render(structured: structuredSwiftRepresentation)

    return sourceFile
  }
}