defmodule PolicyService.Aggregates.PolicyApplication do
  @moduledoc """
  Behaviour and __using__ macro for policy application aggregates.
  Each policy type implements validate_details/1 and declares its detail fields.

  Usage:
    defmodule PolicyService.Aggregates.CarPolicyApplication do
      use PolicyService.Aggregates.PolicyApplication,
        policy_type: "car"
    end
  """

  @callback validate_details(map()) :: :ok | {:error, term()}

  defmacro __using__(opts) do
    policy_type = Keyword.fetch!(opts, :policy_type)
    commands_module = Keyword.get(opts, :commands, PolicyService.Commands.Policy)

    quote do
      @behaviour Commanded.Aggregates.Aggregate

      alias unquote(commands_module).SubmitPolicyApplication
      alias unquote(commands_module).RecordProviderQuote
      alias unquote(commands_module).AcceptQuoteAndSolicit
      alias unquote(commands_module).RecordPolicyIssued

      alias PolicyService.Events.Policy.{
        PolicyApplicationSubmitted,
        QuoteRequestSent,
        ProviderQuoteReceived,
        AllQuotesReceived,
        QuoteAccepted,
        SolicitationRequestSent,
        PolicyIssued
      }

      @policy_type unquote(policy_type)

      defstruct [
        :id,
        :submitted_by,
        :applicant_info,
        :policy_details,
        :selected_providers,
        :accepted_plan_id,
        :accepted_by,
        :provider_policy_number,
        :effective_date,
        :expiry_date,
        :state,
        quotes: %{},
        endorsements: %{}
      ]

      # ── Execute ────────────────────────────────────────────────────────────

      @impl Commanded.Aggregates.Aggregate
      def execute(%__MODULE__{state: nil}, %SubmitPolicyApplication{} = cmd) do
        with :ok <- PolicyService.Aggregates.PolicyApplication.validate_policy_id(cmd.id),
             :ok <-
               PolicyService.Aggregates.PolicyApplication.validate_applicant(cmd.applicant_info),
             :ok <- validate_details(cmd.policy_details),
             :ok <-
               PolicyService.Aggregates.PolicyApplication.validate_providers(
                 cmd.selected_providers
               ) do
          quote_requests =
            Enum.map(cmd.selected_providers, fn provider ->
              %QuoteRequestSent{
                id: cmd.id,
                provider_id: provider.provider_id,
                provider_email: provider.email,
                applicant_info: cmd.applicant_info,
                policy_details: cmd.policy_details,
                requested_at: DateTime.utc_now()
              }
            end)

          [
            %PolicyApplicationSubmitted{
              id: cmd.id,
              submitted_by: cmd.submitted_by,
              applicant_info: cmd.applicant_info,
              policy_details: cmd.policy_details,
              selected_providers: cmd.selected_providers,
              submitted_at: DateTime.utc_now()
            }
            | quote_requests
          ]
        end
      end

      def execute(%__MODULE__{state: state}, %SubmitPolicyApplication{}) do
        {:error, {:invalid_state, "cannot submit in state: #{state}"}}
      end

      def execute(%__MODULE__{state: :awaiting_quotes} = agg, %RecordProviderQuote{} = cmd) do
        if Map.has_key?(agg.quotes, cmd.provider_id) do
          {:error, {:duplicate_quote, "quote from #{cmd.provider_id} already received"}}
        else
          quote_event = %ProviderQuoteReceived{
            id: cmd.id,
            recorded_by: cmd.recorded_by,
            provider_id: cmd.provider_id,
            quote_id: cmd.quote_id,
            valid_until: cmd.valid_until,
            plans: cmd.plans,
            received_at: DateTime.utc_now()
          }

          new_quote_count = map_size(agg.quotes) + 1

          if new_quote_count == length(agg.selected_providers) do
            [
              quote_event,
              %AllQuotesReceived{
                id: cmd.id,
                quote_count: new_quote_count
              }
            ]
          else
            quote_event
          end
        end
      end

      def execute(%__MODULE__{state: state}, %RecordProviderQuote{}) do
        {:error, {:invalid_state, "cannot record quote in state: #{state}"}}
      end

      def execute(%__MODULE__{state: :awaiting_quotes}, %AcceptQuoteAndSolicit{}) do
        {:error, :no_quotes_received}
      end

      def execute(%__MODULE__{state: state}, %AcceptQuoteAndSolicit{})
          when state not in [:quotes_received] do
        {:error, :invalid_state}
      end

      def execute(%__MODULE__{} = agg, %AcceptQuoteAndSolicit{} = cmd) do
        case Enum.find_value(agg.quotes, fn {provider_id, quote} ->
               case Enum.find(quote.plans, &(&1.plan_id == cmd.accepted_plan_id)) do
                 nil -> nil
                 plan -> %{quote: quote, provider: provider_id, plan: plan}
               end
             end) do
          nil ->
            {:error, :plan_not_found}

          result ->
            [
              %QuoteAccepted{
                id: agg.id,
                quote: result.quote,
                plan: result.plan,
                provider: result.provider,
                accepted_by: cmd.accepted_by
              },
              %SolicitationRequestSent{
                id: agg.id,
                plan: result.plan,
                provider_id: result.provider
              }
            ]
        end
      end

      def execute(%__MODULE__{state: :issued}, %RecordPolicyIssued{}),
        do: {:error, :already_issued}

      def execute(%__MODULE__{} = agg, %RecordPolicyIssued{} = cmd) do
        %PolicyIssued{
          id: agg.id,
          provider_policy_number: cmd.provider_policy_number,
          effective_date: cmd.effective_date,
          expiry_date: cmd.expiry_date,
          issued_at: cmd.issued_at || DateTime.utc_now()
        }
      end

      # ── Apply ──────────────────────────────────────────────────────────────

      @impl Commanded.Aggregates.Aggregate
      def apply(%__MODULE__{} = agg, %PolicyApplicationSubmitted{} = e) do
        %__MODULE__{
          agg
          | id: e.id,
            submitted_by: e.submitted_by,
            applicant_info: e.applicant_info,
            policy_details: e.policy_details,
            selected_providers: e.selected_providers,
            quotes: %{},
            state: :awaiting_quotes
        }
      end

      def apply(%__MODULE__{} = agg, %QuoteRequestSent{}), do: agg

      def apply(%__MODULE__{} = agg, %ProviderQuoteReceived{} = e) do
        quote_data = %{
          quote_id: e.quote_id,
          provider_id: e.provider_id,
          valid_until: e.valid_until,
          plans: e.plans || []
        }

        %__MODULE__{agg | quotes: Map.put(agg.quotes, e.provider_id, quote_data)}
      end

      def apply(%__MODULE__{} = agg, %AllQuotesReceived{}) do
        %__MODULE__{agg | state: :quotes_received}
      end

      def apply(%__MODULE__{} = agg, %QuoteAccepted{} = e) do
        %__MODULE__{
          agg
          | accepted_plan_id: e.plan.plan_id,
            accepted_by: e.accepted_by
        }
      end

      def apply(%__MODULE__{} = agg, %SolicitationRequestSent{} = _e) do
        %__MODULE__{
          agg
          | state: :awaiting_policy
        }
      end

      def apply(%__MODULE__{} = agg, %PolicyIssued{} = e) do
        %__MODULE__{
          agg
          | provider_policy_number: e.provider_policy_number,
            effective_date: e.effective_date,
            expiry_date: e.expiry_date,
            state: :issued
        }
      end

      # allow each aggregate to override any callback
      defoverridable execute: 2, apply: 2
    end
  end

  def validate_policy_id(%PolicyService.Aggregates.PolicyId{policy_type: _}), do: :ok
  def validate_policy_id(_), do: {:error, :invalid_policy_id_format}

  def validate_user(id) when is_binary(id) and byte_size(id) > 0, do: :ok
  def validate_user(_), do: {:error, :missing_user_id}

  def validate_applicant(%{"name" => n, "date_of_birth" => _, "document_id" => d})
      when is_binary(n) and is_binary(d) and byte_size(n) > 0 and byte_size(d) > 0,
      do: :ok

  # Match on string keys for Company
  def validate_applicant(%{
        "company_name" => c,
        "ruc" => r,
        "legal_rep_name" => rep,
        "legal_rep_document" => rd
      })
      when is_binary(c) and is_binary(r) and is_binary(rep) and is_binary(rd) and
             byte_size(c) > 0 and byte_size(r) > 0,
      do: :ok

  def validate_applicant(_), do: {:error, :invalid_applicant_info}

  def validate_providers(p) when is_list(p) and length(p) > 0, do: :ok
  def validate_providers(_), do: {:error, :no_providers_selected}

  def find_quote(agg, quote_id) do
    case Enum.find(agg.quotes, fn {_, q} -> q.quote_id == quote_id end) do
      nil -> {:error, :quote_not_found}
      {_, quote} -> {:ok, quote}
    end
  end

  def find_plan(quote, plan_id) do
    case Enum.find(quote.plans || [], fn p ->
           Map.get(p, :plan_id) == plan_id or Map.get(p, "plan_id") == plan_id
         end) do
      nil -> {:error, :plan_not_found}
      plan -> {:ok, plan}
    end
  end

  def find_provider(agg, provider_id) do
    case Enum.find(agg.selected_providers || [], fn p ->
           Map.get(p, :provider_id) == provider_id
         end) do
      nil -> {:error, :provider_not_found}
      provider -> {:ok, provider}
    end
  end
end