defmodule PhoenixKit.Install.ObanConfig do
  @moduledoc """
  Handles Oban configuration for PhoenixKit installation.

  This module provides functionality to:
  - Configure Oban for background job processing
  - Set up required queues (default, emails, file_processing)
  - Add Oban.Plugins.Pruner for job cleanup
  - Add Oban to application supervisor tree
  - Ensure configuration exists during updates
  """
  use PhoenixKit.Install.IgniterCompat

  alias PhoenixKit.Install.IgniterHelpers

  @doc """
  Adds or verifies Oban configuration.

  This function ensures that Oban is properly configured for PhoenixKit's
  background job processing, including:
  1. Repo configuration (auto-detected from PhoenixKit config)
  2. Required queues for file processing and email handling
  3. Pruner plugin for automatic job cleanup

  ## Parameters
  - `igniter` - The igniter context

  ## Returns
  Updated igniter with Oban configuration and notices.
  """
  def add_oban_configuration(igniter) do
    igniter
    |> add_oban_config()
    |> add_oban_configuration_notice()
  end

  @doc """
  Checks if Oban configuration exists in config.exs.

  ## Parameters
  - `igniter` - The igniter context for detecting parent app name

  ## Returns
  Boolean indicating if configuration exists.
  """
  def oban_config_exists?(igniter) do
    config_path = "config/config.exs"
    app_name = IgniterHelpers.get_parent_app_name(igniter)

    if File.exists?(config_path) do
      content = File.read!(config_path)
      lines = String.split(content, "\n")

      # Check for active (non-commented) Oban configuration with parent app namespace
      has_oban_config =
        Enum.any?(lines, fn line ->
          trimmed = String.trim(line)
          # Not a comment and contains config :app_name, Oban
          !String.starts_with?(trimmed, "#") and
            String.contains?(line, "config :#{app_name}, Oban")
        end)

      has_queues =
        Enum.any?(lines, fn line ->
          trimmed = String.trim(line)
          # Not a comment and contains queues:
          !String.starts_with?(trimmed, "#") and String.contains?(line, "queues:")
        end)

      has_oban_config and has_queues
    else
      false
    end
  rescue
    _ -> false
  end

  # Add Oban configuration to config.exs
  defp add_oban_config(igniter) do
    # Get parent app name and repo
    app_name = IgniterHelpers.get_parent_app_name(igniter)
    repo_module = get_repo_module(igniter)

    oban_config = """

    # Configure Oban for PhoenixKit background jobs
    # Required for file processing (storage system) and email handling
    config :#{app_name}, Oban,
      repo: #{repo_module},
      queues: [
        default: 10,           # General purpose queue
        emails: 50,            # Email processing
        file_processing: 20    # File variant generation (storage system)
      ],
      plugins: [
        Oban.Plugins.Pruner    # Automatic cleanup of completed jobs
      ]
    """

    try do
      Igniter.update_file(igniter, "config/config.exs", fn source ->
        content = Rewrite.Source.get(source, :content)

        # Check if Oban config already exists
        if String.contains?(content, "config :#{app_name}, Oban") do
          source
        else
          # Find insertion point before import_config statements
          insertion_point = find_import_config_location(content)

          updated_content =
            case insertion_point do
              {:before_import, before_content, after_content} ->
                # Insert before import_config
                before_content <> oban_config <> "\n" <> after_content

              :append_to_end ->
                # No import_config found, append to end
                content <> oban_config
            end

          Rewrite.Source.update(source, :content, updated_content)
        end
      end)
    rescue
      e ->
        IO.warn("Failed to add Oban configuration: #{inspect(e)}")
        add_manual_config_notice(igniter, repo_module)
    end
  end

  # Get repo module from PhoenixKit config or use placeholder
  defp get_repo_module(_igniter) do
    config_path = "config/config.exs"

    if File.exists?(config_path) do
      content = File.read!(config_path)

      # Look for existing PhoenixKit repo config
      case Regex.run(~r/config :phoenix_kit,\s+repo:\s+([A-Za-z0-9_.]+)/, content) do
        [_, repo] -> repo
        _ -> "MyApp.Repo"
      end
    else
      "MyApp.Repo"
    end
  rescue
    _ -> "MyApp.Repo"
  end

  # Find the location to insert config before import_config statements
  defp find_import_config_location(content) do
    lines = String.split(content, "\n")

    # Look for import_config pattern
    import_index =
      Enum.find_index(lines, fn line ->
        trimmed = String.trim(line)
        String.starts_with?(trimmed, "import_config") or String.contains?(line, "import_config")
      end)

    case import_index do
      nil ->
        # No import_config found, append to end
        :append_to_end

      index ->
        # Find the start of the import_config block
        start_index = find_import_block_start(lines, index)

        # Split content at the start of import block
        before_lines = Enum.take(lines, start_index)
        after_lines = Enum.drop(lines, start_index)

        before_content = Enum.join(before_lines, "\n")
        after_content = Enum.join(after_lines, "\n")

        {:before_import, before_content, after_content}
    end
  end

  # Find the start of the import_config block (including preceding comments)
  defp find_import_block_start(lines, import_index) do
    lines
    |> Enum.take(import_index)
    |> Enum.reverse()
    |> Enum.reduce_while(import_index, fn line, current_index ->
      trimmed = String.trim(line)

      cond do
        # Comment line related to import
        String.starts_with?(trimmed, "#") and
            (String.contains?(line, "import") or String.contains?(line, "Import") or
               String.contains?(line, "bottom") or String.contains?(line, "BOTTOM") or
               String.contains?(line, "environment")) ->
          {:cont, current_index - 1}

        # Blank line
        trimmed == "" ->
          {:cont, current_index - 1}

        # config_env or similar
        String.contains?(line, "config_env()") or String.contains?(line, "env_config") ->
          {:cont, current_index - 1}

        # Stop at any other code
        true ->
          {:halt, current_index}
      end
    end)
  end

  # Add notice about Oban configuration
  defp add_oban_configuration_notice(igniter) do
    if oban_config_exists?(igniter) do
      Igniter.add_notice(
        igniter,
        "⚙️  Oban configured for background jobs (file processing, emails)"
      )
    else
      Igniter.add_notice(
        igniter,
        "⚠️  Oban configuration added - restart your server if running"
      )
    end
  end

  @doc """
  Adds Oban to the parent application's supervision tree.

  This function ensures that Oban starts automatically when the application starts,
  positioned after PhoenixKit.Supervisor to ensure PhoenixKit services are available
  before Oban workers run.

  ## Parameters
  - `igniter` - The igniter context

  ## Returns
  Updated igniter with Oban added to application supervisor.
  """
  def add_oban_supervisor(igniter) do
    app_name = IgniterHelpers.get_parent_app_name(igniter)
    app_file = "lib/#{app_name}/application.ex"
    oban_line = "      {Oban, Application.get_env(:#{app_name}, Oban)},"

    Igniter.update_file(igniter, app_file, fn source ->
      update_application_with_oban(source, app_name, oban_line)
    end)
  end

  # Update application.ex source with Oban supervisor
  defp update_application_with_oban(source, app_name, oban_line) do
    content = Rewrite.Source.get(source, :content)

    if oban_already_configured?(content, app_name) do
      source
    else
      updated_content = insert_or_replace_oban(content, oban_line)
      Rewrite.Source.update(source, :content, updated_content)
    end
  end

  # Check if Oban is already properly configured
  defp oban_already_configured?(content, app_name) do
    String.contains?(content, "{Oban, Application.get_env(:#{app_name}, Oban)}")
  end

  # Insert or replace Oban configuration in application.ex
  defp insert_or_replace_oban(content, oban_line) do
    lines = String.split(content, "\n")
    has_bare_oban = Enum.any?(lines, fn line -> String.trim(line) == "Oban," end)

    updated_lines = process_application_lines(lines, oban_line, has_bare_oban)
    Enum.join(updated_lines, "\n")
  end

  # Process each line to insert/replace Oban
  defp process_application_lines(lines, oban_line, has_bare_oban) do
    Enum.reduce(lines, [], fn line, acc ->
      trimmed = String.trim(line)

      cond do
        # Replace bare "Oban," with proper config
        trimmed == "Oban," ->
          acc ++ [oban_line]

        # Insert Oban after PhoenixKit.Supervisor ONLY if there's no bare Oban to replace
        String.contains?(line, "PhoenixKit.Supervisor") and not has_bare_oban ->
          acc ++ [line, oban_line]

        true ->
          acc ++ [line]
      end
    end)
  end

  @doc """
  Checks if Oban supervisor is configured in application.ex.

  ## Parameters
  - `igniter` - The igniter context for detecting parent app name

  ## Returns
  Boolean indicating if Oban supervisor exists in application.ex.
  """
  def oban_supervisor_exists?(igniter) do
    app_name = IgniterHelpers.get_parent_app_name(igniter)
    app_file = "lib/#{app_name}/application.ex"

    if File.exists?(app_file) do
      content = File.read!(app_file)

      # Check for Oban in children list
      String.contains?(content, "{Oban,") or
        String.contains?(content, "Application.get_env(:#{app_name}, Oban)")
    else
      false
    end
  rescue
    _ -> false
  end

  # Add notice when manual configuration is required
  defp add_manual_config_notice(igniter, repo_module) do
    app_name = IgniterHelpers.get_parent_app_name(igniter)

    notice = """
    ⚠️  Manual Configuration Required: Oban

    PhoenixKit couldn't automatically configure Oban for background jobs.

    Please add the following to config/config.exs:

      config :#{app_name}, Oban,
        repo: #{repo_module},
        queues: [
          default: 10,
          emails: 50,
          file_processing: 20
        ],
        plugins: [
          Oban.Plugins.Pruner
        ]

    And add the following to lib/#{app_name}/application.ex in the children list:

      {Oban, Application.get_env(:#{app_name}, Oban)}

    Without this configuration, the storage system cannot process uploaded files.
    Files will remain stuck in "processing" status.
    """

    Igniter.add_notice(igniter, notice)
  end
end