import SharedModels
import SwiftUI

public struct FlaggedMessageView: View {

  @Environment(\.flaggedMessageViewStyle) private var style

  let message: String?
  let status: Flagged.CheckResult.Status

  public init(message: String?, status: Flagged.CheckResult.Status) {
    self.message = message
    self.status = status
  }

  public var body: some View {
    style.makeBody(
      configuration: .init(message: message, status: status)
    )
  }
}

extension FlaggedMessageView {

  public init(flagged: Flagged) {
    self.init(message: flagged.message, status: flagged.status)
  }
}

@MainActor
@preconcurrency
public protocol FlaggedMessageViewStyle {
  associatedtype Body: View
  typealias Configuration = FlaggedMessageViewStyleConfiguration

  @ViewBuilder
  func makeBody(configuration: Self.Configuration) -> Self.Body
}

public struct FlaggedMessageViewStyleConfiguration {
  public let message: String?
  public let status: Flagged.CheckResult.Status

  public init(message: String?, status: Flagged.CheckResult.Status) {
    self.message = message
    self.status = status
  }
}

public struct AnyFlaggedMessageViewStyle: FlaggedMessageViewStyle {
  private let _makeBody: (Configuration) -> AnyView

  internal init(makeBody: @escaping (Configuration) -> AnyView) {
    self._makeBody = makeBody
  }

  public init<S: FlaggedMessageViewStyle>(_ style: S) {
    self.init { configuration in
      AnyView(style.makeBody(configuration: configuration))
    }
  }

  public func makeBody(configuration: Configuration) -> some View {
    _makeBody(configuration)
  }
}

public struct HorizontalFlaggedMessageViewStyle: FlaggedMessageViewStyle {

  @ViewBuilder
  public func makeBody(configuration: Configuration) -> some View {
    if configuration.message != nil {
      HStack {
        FlaggedStatusLabel(status: configuration.status)
        FlaggedMessageLabel(message: configuration.message)
      }
    }
  }
}

public struct VerticalFlaggedMessageViewStyle: FlaggedMessageViewStyle {

  @ViewBuilder
  public func makeBody(configuration: Configuration) -> some View {
    if configuration.message != nil {
      VStack(alignment: .leading) {
        FlaggedStatusLabel(status: configuration.status)
        FlaggedMessageLabel(message: configuration.message)
      }
    }
  }
}

public struct AutomaticFlaggedMessageViewStyle: FlaggedMessageViewStyle {
  
  let horizontalSizeClass: UserInterfaceSizeClass?
  
  @ViewBuilder
  public func makeBody(configuration: Configuration) -> some View {
    if horizontalSizeClass == .compact {
      VerticalFlaggedMessageViewStyle().makeBody(configuration: configuration)
    } else {
      HorizontalFlaggedMessageViewStyle().makeBody(configuration: configuration)
    }
  }
}

extension FlaggedMessageViewStyle where Self == VerticalFlaggedMessageViewStyle {
  public static var vertical: Self { .init() }
}

extension FlaggedMessageViewStyle where Self == HorizontalFlaggedMessageViewStyle {
  public static var horizontal: Self { .init() }
}

extension FlaggedMessageViewStyle where Self == AutomaticFlaggedMessageViewStyle {
  public static func automatic(horizontalSizeClass: UserInterfaceSizeClass? = nil) -> Self {
    .init(horizontalSizeClass: horizontalSizeClass)
  }
}

@MainActor
private struct FlaggedMessageViewStyleKey: @preconcurrency EnvironmentKey {

  static let defaultValue = AnyFlaggedMessageViewStyle(
    AutomaticFlaggedMessageViewStyle(horizontalSizeClass: nil)
  )
}

extension EnvironmentValues {
  public var flaggedMessageViewStyle: AnyFlaggedMessageViewStyle {
    get { self[FlaggedMessageViewStyleKey.self] }
    set { self[FlaggedMessageViewStyleKey.self] = newValue }
  }
}

extension View {
  public func flaggedMessageViewStyle(_ style: AnyFlaggedMessageViewStyle) -> some View {
    environment(\.flaggedMessageViewStyle, style)
  }

  public func flaggedMessageViewStyle<S: FlaggedMessageViewStyle>(_ style: S) -> some View {
    flaggedMessageViewStyle(AnyFlaggedMessageViewStyle(style))
  }
}

extension Flagged.CheckResult.Status {

  public var color: Color {
    switch self {
    case .good:
      return .green
    case .warning:
      return .yellow
    case .error:
      return .red
    }
  }
}