import ConfigurationClient
import Dependencies
import Foundation
import ShellClient

// TODO: Need to parse / ensure that header includes and files are in the build directory, not sure
//       exactly how to handle if they're not, but it seems reasonable to potentially allow files that are
//       outside of the build directory to be included.

public extension CliClient {

  @discardableResult
  func runPandocCommand(
    _ options: PandocOptions,
    logging loggingOptions: LoggingOptions
  ) async throws -> String {
    try await withLogger(loggingOptions) {
      @Dependency(\.configurationClient) var configurationClient
      @Dependency(\.logger) var logger

      let configuration = try await configurationClient.findAndLoad()
      logger.trace("Configuration: \(configuration)")

      let ensuredOptions = try await ensurePandocOptions(
        configuration: configuration,
        options: options
      )

      let projectDirectory = options.projectDirectory ?? ProcessInfo.processInfo.environment["PWD"]
      guard let projectDirectory else {
        throw CliClientError.generate(.projectDirectoryNotSpecified)
      }

      let outputDirectory = options.outputDirectory ?? projectDirectory
      let outputPath = "\(outputDirectory)/\(ensuredOptions.ensuredExtensionFileName)"

      var arguments = [
        "pandoc"
      ]
      arguments += ensuredOptions.includeInHeader.map {
        "--include-in-header=\(projectDirectory)/\(ensuredOptions.buildDirectory)/\($0)"
      }

      if let pdfEngine = ensuredOptions.pdfEngine {
        arguments.append("--pdf-engine=\(pdfEngine)")
      }

      arguments.append("--output=\(outputPath)")
      arguments += ensuredOptions.files.map {
        "\(projectDirectory)/\(ensuredOptions.buildDirectory)/\($0)"
      }

      if options.shouldBuild {
        logger.trace("Building project...")
        try await runPlaybookCommand(
          .init(
            arguments: [
              "--tags", "build-project",
              "--extra-vars", "project_dir=\(projectDirectory)"
            ],
            configuration: configuration,
            quiet: options.quiet,
            shell: options.shell
          ),
          logging: loggingOptions
        )
      }

      logger.trace("Running pandoc with arguments: \(arguments)")

      try await runCommand(
        quiet: options.quiet,
        shell: options.shell.orDefault,
        arguments
      )

      return outputPath
    }
  }
}

@_spi(Internal)
public struct EnsuredPandocOptions: Equatable, Sendable {
  public let buildDirectory: String
  public let files: [String]
  public let includeInHeader: [String]
  public let outputFileName: String
  public let outputFileType: CliClient.PandocOptions.FileType
  public let pdfEngine: String?

  public var ensuredExtensionFileName: String {
    let extensionString: String

    switch outputFileType {
    case .html:
      extensionString = ".html"
    case .latex:
      extensionString = ".tex"
    case .pdf:
      extensionString = ".pdf"
    }

    if !outputFileName.hasSuffix(extensionString) {
      return outputFileName + extensionString
    }
    return outputFileName
  }
}

@_spi(Internal)
public func ensurePandocOptions(
  configuration: Configuration,
  options: CliClient.PandocOptions
) async throws -> EnsuredPandocOptions {
  let defaults = Configuration.Generate.default
  let pdfEngine = parsePdfEngine(configuration.generate, defaults, options)

  return .init(
    buildDirectory: parseBuildDirectory(configuration.generate, defaults, options),
    files: parseFiles(configuration.generate, defaults, options),
    includeInHeader: parseIncludeInHeader(configuration.generate, defaults, options),
    outputFileName: parseOutputFileName(configuration.generate, defaults, options),
    outputFileType: options.outputFileType,
    pdfEngine: pdfEngine
  )
}

private func parsePdfEngine(
  _ configuration: Configuration.Generate?,
  _ defaults: Configuration.Generate,
  _ options: CliClient.PandocOptions
) -> String? {
  switch options.outputFileType {
  case .html, .latex:
    return nil
  case let .pdf(engine: engine):
    if let engine {
      return engine
    } else if let engine = configuration?.pdfEngine {
      return engine
    } else if let engine = defaults.pdfEngine {
      return engine
    } else {
      return "xelatex"
    }
  }
}

private func parseFiles(
  _ configuration: Configuration.Generate?,
  _ defaults: Configuration.Generate,
  _ options: CliClient.PandocOptions
) -> [String] {
  @Dependency(\.logger) var logger

  if let files = options.files {
    return files
  } else if let files = configuration?.files {
    return files
  } else if let files = defaults.files {
    return files
  } else {
    logger.warning("Files not specified, this could lead to errors.")
    return []
  }
}

private func parseIncludeInHeader(
  _ configuration: Configuration.Generate?,
  _ defaults: Configuration.Generate,
  _ options: CliClient.PandocOptions
) -> [String] {
  @Dependency(\.logger) var logger

  if let files = options.includeInHeader {
    return files
  } else if let files = configuration?.includeInHeader {
    return files
  } else if let files = defaults.includeInHeader {
    return files
  } else {
    logger.warning("Include in header files not specified, this could lead to errors.")
    return []
  }
}

private func parseOutputFileName(
  _ configuration: Configuration.Generate?,
  _ defaults: Configuration.Generate,
  _ options: CliClient.PandocOptions
) -> String {
  @Dependency(\.logger) var logger

  if let output = options.outputFileName {
    return output
  } else if let output = configuration?.outputFileName {
    return output
  } else if let output = defaults.outputFileName {
    return output
  } else {
    logger.warning("Output file name not specified, this could lead to errors.")
    return "Report"
  }
}

private func parseBuildDirectory(
  _ configuration: Configuration.Generate?,
  _ defaults: Configuration.Generate,
  _ options: CliClient.PandocOptions
) -> String {
  @Dependency(\.logger) var logger

  if let output = options.buildDirectory {
    return output
  } else if let output = configuration?.buildDirectory {
    return output
  } else if let output = defaults.buildDirectory {
    return output
  } else {
    logger.warning("Output file name not specified, this could lead to errors.")
    return ".build"
  }
}