defmodule Lather.Server.EnhancedPlug do
  @moduledoc """
  Enhanced Plug implementation for SOAP server endpoints with web form interface.

  Provides comprehensive SOAP service endpoints with interactive web forms,
  multi-protocol support, and complete API documentation similar to .NET Web Services.

  ## Features

  - Interactive web forms for testing operations
  - SOAP 1.1, SOAP 1.2, and JSON protocol support
  - Enhanced WSDL generation with multi-protocol bindings
  - Service overview with complete operation documentation
  - Responsive web interface for operation testing

  ## Usage

  In Phoenix router:

      scope "/soap" do
        pipe_through :api
        match :*, "/users", Lather.Server.EnhancedPlug, service: MyApp.UserService
        match :*, "/users/*path", Lather.Server.EnhancedPlug, service: MyApp.UserService
      end

  As standalone Plug:

      plug Lather.Server.EnhancedPlug, service: MyApp.UserService

  ## URL Patterns

  - `GET /service` - Service overview with operations list
  - `GET /service?wsdl` - Standard WSDL download
  - `GET /service?wsdl&enhanced=true` - Multi-protocol WSDL
  - `GET /service?op=OperationName` - Interactive operation form
  - `POST /service` - SOAP 1.1 endpoint
  - `POST /service/v1.2` - SOAP 1.2 endpoint
  - `POST /service/api` - JSON/REST endpoint

  ## Options

  - `:service` - The SOAP service module (required)
  - `:base_path` - Base path for service (default: "/soap")
  - `:enable_forms` - Enable web form interface (default: true)
  - `:enable_json` - Enable JSON endpoints (default: true)
  - `:auth_handler` - Custom authentication handler
  - `:validate_params` - Enable parameter validation (default: true)
  """

  # Check if Jason is available for JSON support
  @jason_available Code.ensure_loaded?(Jason)

  if Code.ensure_loaded?(Plug) do
    import Plug.Conn
    require Logger

    alias Lather.Server.{
      RequestParser,
      ResponseBuilder,
      WSDLGenerator,
      EnhancedWSDLGenerator,
      FormGenerator
    }

    @behaviour Plug

    @impl Plug
    def init(opts) do
      service = Keyword.fetch!(opts, :service)

      unless function_exported?(service, :__soap_service__, 0) do
        raise ArgumentError,
              "#{service} is not a valid SOAP service module. Did you forget to `use Lather.Server`?"
      end

      %{
        service: service,
        base_path: Keyword.get(opts, :base_path, "/soap"),
        enable_forms: Keyword.get(opts, :enable_forms, true),
        enable_json: Keyword.get(opts, :enable_json, true),
        auth_handler: Keyword.get(opts, :auth_handler),
        validate_params: Keyword.get(opts, :validate_params, true)
      }
    end

    @impl Plug
    def call(conn, config) do
      case {conn.method, get_request_type(conn)} do
        # WSDL requests
        {"GET", :wsdl} ->
          handle_wsdl_request(conn, config)

        # Operation form requests
        {"GET", {:operation_form, operation_name}} ->
          handle_operation_form_request(conn, config, operation_name)

        # Service overview
        {"GET", :service_overview} ->
          handle_service_overview_request(conn, config)

        # SOAP 1.1 requests (default POST)
        {"POST", :soap_1_1} ->
          handle_soap_request(conn, config, :v1_1)

        # SOAP 1.2 requests
        {"POST", :soap_1_2} ->
          handle_soap_request(conn, config, :v1_2)

        # JSON/REST requests
        {"POST", :json} when config.enable_json ->
          handle_json_request(conn, config)

        # Unsupported methods
        _ ->
          handle_unsupported_request(conn)
      end
    rescue
      error ->
        Logger.error("Enhanced SOAP server error: #{inspect(error)}")

        conn
        |> put_resp_content_type("text/xml")
        |> send_resp(500, soap_fault_xml("Server", "Internal server error"))
    end

    # Determine request type from URL and query parameters
    defp get_request_type(conn) do
      cond do
        # WSDL request
        Map.has_key?(conn.query_params, "wsdl") ->
          :wsdl

        # Operation form request
        Map.has_key?(conn.query_params, "op") ->
          {:operation_form, conn.query_params["op"]}

        # Check path for protocol version
        String.contains?(conn.request_path, "/v1.2") ->
          :soap_1_2

        String.contains?(conn.request_path, "/api") ->
          :json

        # Default cases
        conn.method == "GET" ->
          :service_overview

        conn.method == "POST" ->
          :soap_1_1

        true ->
          :unsupported
      end
    end

    # Handle WSDL generation requests
    defp handle_wsdl_request(conn, %{service: service} = config) do
      try do
        service_info = service.__soap_service__()
        base_url = get_base_url(conn, config)

        wsdl_content =
          if Map.has_key?(conn.query_params, "enhanced") do
            # Generate enhanced multi-protocol WSDL
            EnhancedWSDLGenerator.generate(service_info, base_url,
              protocols: [:soap_1_1, :soap_1_2, :http],
              include_json: config.enable_json
            )
          else
            # Generate standard WSDL
            WSDLGenerator.generate(service_info, base_url)
          end

        conn
        |> put_resp_content_type("text/xml; charset=utf-8")
        |> put_resp_header(
          "content-disposition",
          "attachment; filename=\"#{service_info.name}.wsdl\""
        )
        |> send_resp(200, wsdl_content)
      rescue
        error ->
          Logger.error("WSDL generation failed: #{inspect(error)}")

          conn
          |> put_resp_content_type("text/xml")
          |> send_resp(500, soap_fault_xml("Server", "WSDL generation failed"))
      end
    end

    # Handle operation form requests
    defp handle_operation_form_request(
           conn,
           %{service: service, enable_forms: true} = config,
           operation_name
         ) do
      try do
        service_info = service.__soap_service__()
        base_url = get_base_url(conn, config)

        case find_operation(service_info, operation_name) do
          nil ->
            conn
            |> put_resp_content_type("text/html")
            |> send_resp(404, generate_error_page("Operation '#{operation_name}' not found"))

          operation ->
            html_content =
              FormGenerator.generate_operation_page(service_info, operation, base_url)

            conn
            |> put_resp_content_type("text/html; charset=utf-8")
            |> send_resp(200, html_content)
        end
      rescue
        error ->
          Logger.error("Operation form generation failed: #{inspect(error)}")

          conn
          |> put_resp_content_type("text/html")
          |> send_resp(500, generate_error_page("Form generation failed"))
      end
    end

    defp handle_operation_form_request(conn, _config, _operation_name) do
      conn
      |> put_resp_content_type("text/html")
      |> send_resp(404, generate_error_page("Form interface disabled"))
    end

    # Handle service overview requests
    defp handle_service_overview_request(conn, %{service: service, enable_forms: true} = config) do
      try do
        service_info = service.__soap_service__()
        base_url = get_base_url(conn, config)

        html_content = FormGenerator.generate_service_overview(service_info, base_url)

        conn
        |> put_resp_content_type("text/html; charset=utf-8")
        |> send_resp(200, html_content)
      rescue
        error ->
          Logger.error("Service overview generation failed: #{inspect(error)}")

          conn
          |> put_resp_content_type("text/html")
          |> send_resp(500, generate_error_page("Service overview generation failed"))
      end
    end

    defp handle_service_overview_request(conn, _config) do
      # If forms are disabled, redirect to WSDL
      redirect_to_wsdl(conn)
    end

    # Handle SOAP requests (1.1 and 1.2)
    defp handle_soap_request(conn, config, soap_version) do
      with {:ok, body} <- read_full_body(conn),
           {:ok, parsed_request} <- RequestParser.parse(body),
           {:ok, operation_name} <- extract_operation_name(parsed_request),
           {:ok, operation_info} <- get_operation_info(config.service, operation_name),
           {:ok, validated_params} <-
             validate_and_extract_params(parsed_request, operation_info, config),
           {:ok, result} <- call_operation(config.service, operation_name, validated_params) do
        # Format and send SOAP response
        response_xml = ResponseBuilder.build_response(result, operation_info)

        content_type =
          case soap_version do
            :v1_1 -> "text/xml; charset=utf-8"
            :v1_2 -> "application/soap+xml; charset=utf-8"
          end

        conn
        |> put_resp_content_type(content_type)
        |> send_resp(200, response_xml)
      else
        {:error, {:soap_fault, fault}} ->
          fault_xml = ResponseBuilder.build_fault(fault)

          conn
          |> put_resp_content_type("text/xml; charset=utf-8")
          |> send_resp(500, fault_xml)

        {:error, reason} ->
          Logger.warning("SOAP request failed: #{inspect(reason)}")

          fault_xml = soap_fault_xml("Client", "Invalid SOAP request")

          conn
          |> put_resp_content_type("text/xml; charset=utf-8")
          |> send_resp(400, fault_xml)
      end
    end

    # Handle JSON/REST requests
    defp handle_json_request(conn, config) do
      # Extract operation from path or query parameters
      operation_name = extract_json_operation_name(conn)

      with {:ok, body} <- read_full_body(conn),
           {:ok, json_params} <- decode_json_body(body),
           {:ok, operation_info} <- get_operation_info(config.service, operation_name),
           {:ok, validated_params} <- validate_json_params(json_params, operation_info, config),
           {:ok, result} <- call_operation(config.service, operation_name, validated_params) do
        # Format JSON response
        json_response = format_json_response(result, operation_info)

        conn
        |> put_resp_content_type("application/json; charset=utf-8")
        |> send_resp(200, encode_json(json_response))
      else
        {:error, {:soap_fault, fault}} ->
          error_response = %{
            error: %{
              code: fault.fault_code || "ServerError",
              message: fault.fault_string || "Operation failed",
              detail: fault.detail
            }
          }

          conn
          |> put_resp_content_type("application/json; charset=utf-8")
          |> send_resp(500, encode_json(error_response))

        {:error, reason} ->
          Logger.warning("JSON request failed: #{inspect(reason)}")

          error_response = %{
            error: %{
              code: "InvalidRequest",
              message: "Invalid JSON request",
              detail: inspect(reason)
            }
          }

          conn
          |> put_resp_content_type("application/json; charset=utf-8")
          |> send_resp(400, encode_json(error_response))
      end
    end

    # Handle unsupported requests
    defp handle_unsupported_request(conn) do
      conn
      |> put_resp_content_type("text/html")
      |> send_resp(405, generate_error_page("Method not allowed"))
    end

    # Helper functions

    defp get_base_url(conn, config) do
      scheme = if conn.scheme == :https, do: "https", else: "http"
      host = conn.host
      port = if conn.port in [80, 443], do: "", else: ":#{conn.port}"

      "#{scheme}://#{host}#{port}#{config.base_path}/"
    end

    defp find_operation(service_info, operation_name) do
      Enum.find(service_info.operations, &(&1.name == operation_name))
    end

    defp read_full_body(conn, body \\ "") do
      case Plug.Conn.read_body(conn) do
        {:ok, chunk, _conn} -> {:ok, body <> chunk}
        {:more, chunk, conn} -> read_full_body(conn, body <> chunk)
        {:error, reason} -> {:error, reason}
      end
    end

    defp extract_operation_name(parsed_request) do
      # Implementation depends on RequestParser format
      # This is a simplified version
      case get_in(parsed_request, ["soap:Envelope", "soap:Body"]) do
        body when is_map(body) ->
          operation_key =
            body
            |> Map.keys()
            |> Enum.find(&(not String.starts_with?(&1, "soap:")))

          if operation_key do
            {:ok, operation_key}
          else
            {:error, :operation_not_found}
          end

        _ ->
          {:error, :invalid_soap_body}
      end
    end

    defp extract_json_operation_name(conn) do
      # Extract from path like /api/getUserInfo or from query params
      case String.split(conn.request_path, "/") do
        segments when segments != [] ->
          segments |> List.last() |> String.replace(~r/[^a-zA-Z0-9]/, "")

        _ ->
          "UnknownOperation"
      end
    end

    defp get_operation_info(service_module, operation_name) do
      case service_module.__soap_operation__(operation_name) do
        nil ->
          {:error,
           {:soap_fault,
            %{fault_code: "Client", fault_string: "Operation '#{operation_name}' not found"}}}

        operation_info ->
          {:ok, operation_info}
      end
    end

    defp validate_and_extract_params(parsed_request, operation_info, config) do
      # Extract parameters from SOAP body
      case extract_soap_parameters(parsed_request) do
        {:ok, params} ->
          if config.validate_params do
            validate_operation_params(params, operation_info)
          else
            {:ok, params}
          end

        error ->
          error
      end
    end

    defp extract_soap_parameters(parsed_request) do
      # Simplified parameter extraction
      case get_in(parsed_request, ["soap:Envelope", "soap:Body"]) do
        body when is_map(body) ->
          operation_key =
            body
            |> Map.keys()
            |> Enum.find(&(not String.starts_with?(&1, "soap:")))

          if operation_key do
            params = get_in(body, [operation_key])
            {:ok, params || %{}}
          else
            {:ok, %{}}
          end

        _ ->
          {:error, :invalid_soap_body}
      end
    end

    defp validate_operation_params(params, operation_info) do
      # Use the service module's validation if available
      case Lather.Server.validate_required_params(params, operation_info) do
        :ok -> {:ok, params}
        {:error, reason} -> {:error, {:soap_fault, %{fault_code: "Client", fault_string: reason}}}
      end
    end

    # Decode JSON body
    defp decode_json_body(body) do
      case decode_json(body) do
        {:ok, json} -> {:ok, json}
        {:error, _} -> {:error, :invalid_json}
      end
    end

    # JSON encoding with graceful fallback
    defp encode_json(data) do
      if @jason_available do
        Jason.encode!(data)
      else
        # Fallback to basic JSON-like string representation
        inspect(data, pretty: true)
      end
    end

    # JSON decoding with graceful fallback
    defp decode_json(body) do
      if @jason_available do
        Jason.decode(body)
      else
        {:error, :jason_not_available}
      end
    end

    defp validate_json_params(params, operation_info, config) do
      if config.validate_params do
        validate_operation_params(params, operation_info)
      else
        {:ok, params}
      end
    end

    defp call_operation(service_module, operation_name, params) do
      function_name = String.to_atom(Macro.underscore(operation_name))

      if function_exported?(service_module, function_name, 1) do
        try do
          result = apply(service_module, function_name, [params])
          {:ok, result}
        rescue
          error ->
            {:error,
             {:soap_fault,
              %{fault_code: "Server", fault_string: "Operation failed: #{inspect(error)}"}}}
        end
      else
        {:error,
         {:soap_fault,
          %{fault_code: "Client", fault_string: "Operation '#{operation_name}' not implemented"}}}
      end
    end

    defp format_json_response(result, _operation_info) do
      case result do
        {:ok, data} -> %{success: true, data: data}
        {:error, reason} -> %{success: false, error: reason}
        data -> %{success: true, data: data}
      end
    end

    defp soap_fault_xml(fault_code, fault_string) do
      """
      <?xml version="1.0" encoding="utf-8"?>
      <soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">
      <soap:Body>
      <soap:Fault>
      <faultcode>#{fault_code}</faultcode>
      <faultstring>#{fault_string}</faultstring>
      </soap:Fault>
      </soap:Body>
      </soap:Envelope>
      """
    end

    defp generate_error_page(message) do
      """
      <!DOCTYPE html>
      <html>
      <head>
          <title>Error</title>
          <style>
              body { font-family: Arial, sans-serif; margin: 50px; }
              .error { background: #ffebee; border: 1px solid #f44336; padding: 20px; border-radius: 4px; }
          </style>
      </head>
      <body>
          <div class="error">
              <h2>Error</h2>
              <p>#{message}</p>
              <p><a href="?wsdl">View WSDL</a></p>
          </div>
      </body>
      </html>
      """
    end

    defp redirect_to_wsdl(conn) do
      conn
      |> put_resp_header("location", "?wsdl")
      |> send_resp(302, "")
    end
  else
    # Plug not available - provide helpful error message
    def init(_opts) do
      raise """
      Lather.Server.EnhancedPlug requires the :plug dependency.
      Add {:plug, "~> 1.14"} to your deps in mix.exs
      """
    end

    def call(_conn, _opts), do: nil
  end
end