import Dependencies
import Foundation
import ShellClient

@_spi(Internal)
public func findConfigurationFiles(
  env: [String: String] = ProcessInfo.processInfo.environment
) throws -> URL {
  @Dependency(\.logger) var logger
  @Dependency(\.fileClient) var fileClient

  logger.debug("Begin find configuration files.")
  logger.trace("Env: \(env)")

  let homeDir = fileClient.homeDir()

  // Check for environment variable pointing to a directory that the
  // the configuration lives.
  if let configHome = env["HPA_CONFIG_HOME"] {
    let url = URL(filePath: configHome).appending(path: "config")

    if fileClient.isReadable(url) {
      logger.debug("Found configuration from hpa config home env var.")
      return url
    }
  }

  // Check home directory for a `.hparc` file.
  let url = homeDir.appending(path: ".hparc")
  if fileClient.isReadable(url) {
    logger.debug("Found configuration in home directory")
    return url
  }

  // Check for environment variable pointing to a directory that the
  // the configuration lives.
  if let pwd = env["PWD"] {
    let url = URL(filePath: "\(pwd)").appending(path: ".hparc")
    if fileClient.isReadable(url) {
      logger.debug("Found configuration in current working directory.")
      return url
    }
  }

  // Check in xdg config home, under an hpa-playbook directory.
  if let xdgConfigHome = env["XDG_CONFIG_HOME"] {
    logger.debug("XDG Config Home: \(xdgConfigHome)")

    let url = URL(filePath: "\(xdgConfigHome)")
      .appending(path: "hpa-playbook")
      .appending(path: "config")

    logger.debug("XDG Config url: \(url.absoluteString)")

    if fileClient.isReadable(url) {
      return url
    }
  }

  // We could not find configuration in any usual places.
  throw ConfigurationError.configurationNotFound
}

func path(for url: URL) -> String {
  url.absoluteString.replacing("file://", with: "")
}

enum ConfigurationError: Error {
  case configurationNotFound
}