FF-59: respect withdrawal provider's terms (#58)

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* FF-59: respect withdrawal provider's terms
* fix test to proof code validity

apps/ff_cth/src/ct_domain.erl

@@ -44,7 +44,7 @@ withdrawal_provider(Ref, ProxyRef, IdentityID, C) ->
             proxy = #domain_Proxy{ref = ProxyRef, additional = #{}},
             identity = IdentityID,
             withdrawal_terms = #domain_WithdrawalProvisionTerms{
-                currencies = {value, ?ordset([])},
+                currencies = {value, ?ordset([?cur(<<"RUB">>)])},
                 payout_methods = {value, ?ordset([])},
                 cash_limit = {value, ?cashrng(
                     {inclusive, ?cash(       0, <<"RUB">>)},

apps/ff_transfer/src/ff_withdrawal.erl

@@ -240,11 +240,27 @@ create_route(Withdrawal) ->
         DestinationMachine = unwrap(destination, ff_destination:get_machine(DestinationID)),
         Destination = ff_destination:get(DestinationMachine),
         VS = unwrap(collect_varset(Body, Wallet, Destination)),
-        ProviderID = unwrap(ff_payment_institution:compute_withdrawal_provider(PaymentInstitution, VS)),
+        Providers = unwrap(ff_payment_institution:compute_withdrawal_providers(PaymentInstitution, VS)),
+        ProviderID = unwrap(choose_provider(Providers, VS)),
         {continue, [{route_changed, #{provider_id => ProviderID}}]}
     end).
 
+choose_provider(Providers, VS) ->
+    case lists:filter(fun(P) -> validate_withdrawals_terms(P, VS) end, Providers) of
+        [ProviderID | _] ->
+            {ok, ProviderID};
+        [] ->
+            {error, route_not_found}
+    end.
 
+validate_withdrawals_terms(ID, VS) ->
+    Provider = unwrap(ff_payouts_provider:get(ID)),
+    case ff_payouts_provider:validate_terms(Provider, VS) of
+        {ok, valid} ->
+            true;
+        {error, _Error} ->
+            false
+    end.
 
 -spec create_p_transfer(withdrawal()) ->
     {ok, process_result()} |

apps/fistful/src/ff_payment_institution.erl

@@ -28,7 +28,7 @@
 
 -export([ref/1]).
 -export([get/1]).
--export([compute_withdrawal_provider/2]).
+-export([compute_withdrawal_providers/2]).
 -export([compute_system_accounts/2]).
 
 %% Pipeline
@@ -59,16 +59,16 @@ get(ID) ->
         decode(ID, PaymentInstitution)
     end).
 
--spec compute_withdrawal_provider(payment_institution(), hg_selector:varset()) ->
-    {ok, ff_payouts_provider:id()} | {error, term()}.
+-spec compute_withdrawal_providers(payment_institution(), hg_selector:varset()) ->
+    {ok, [ff_payouts_provider:id()]} | {error, term()}.
 
-compute_withdrawal_provider(#{providers := ProviderSelector}, VS) ->
-    do(fun() ->
-        Providers = unwrap(hg_selector:reduce_to_value(ProviderSelector, VS)),
-        %% TODO choose wizely one of them
-        [#domain_WithdrawalProviderRef{id = ProviderID} | _] = Providers,
-        ProviderID
-    end).
+compute_withdrawal_providers(#{providers := ProviderSelector}, VS) ->
+    case hg_selector:reduce_to_value(ProviderSelector, VS) of
+        {ok, Providers} ->
+            {ok, [ProviderID || #domain_WithdrawalProviderRef{id = ProviderID} <- Providers]};
+        Error ->
+            Error
+    end.
 
 -spec compute_system_accounts(payment_institution(), hg_selector:varset()) ->
     {ok, system_accounts()} | {error, term()}.

apps/fistful/src/ff_payouts_provider.erl

@@ -27,6 +27,7 @@
 -export([ref/1]).
 -export([get/1]).
 -export([compute_fees/2]).
+-export([validate_terms/2]).
 
 %% Pipeline
 
@@ -77,8 +78,47 @@ compute_fees(#{withdrawal_terms := WithdrawalTerms}, VS) ->
         postings => ff_cash_flow:decode_domain_postings(CashFlow)
     }.
 
+-spec validate_terms(withdrawal_provider(), hg_selector:varset()) ->
+    {ok, valid} |
+    {error, Error :: term()}.
+
+validate_terms(#{withdrawal_terms := WithdrawalTerms}, VS) ->
+    #domain_WithdrawalProvisionTerms{
+        currencies = CurrenciesSelector,
+        payout_methods = PayoutMethodsSelector,
+        cash_limit = CashLimitSelector
+    } = WithdrawalTerms,
+    do(fun () ->
+        valid = unwrap(validate_currencies(CurrenciesSelector, VS)),
+        valid = unwrap(validate_payout_methods(PayoutMethodsSelector, VS)),
+        valid = unwrap(validate_cash_limit(CashLimitSelector, VS))
+    end).
+
 %%
 
+validate_currencies(CurrenciesSelector, #{currency := CurrencyRef} = VS) ->
+    Currencies = unwrap(hg_selector:reduce_to_value(CurrenciesSelector, VS)),
+    case ordsets:is_element(CurrencyRef, Currencies) of
+        true ->
+            {ok, valid};
+        false ->
+            {error, {terms_violation, {not_allowed_currency, {CurrencyRef, Currencies}}}}
+    end.
+
+validate_payout_methods(_, _) ->
+    %% PayoutMethodsSelector is useless for withdrawals
+    %% so we can just ignore it
+    {ok, valid}.
+
+validate_cash_limit(CashLimitSelector, #{cost := Cash} = VS) ->
+    CashRange = unwrap(hg_selector:reduce_to_value(CashLimitSelector, VS)),
+    case hg_cash_range:is_inside(Cash, CashRange) of
+        within ->
+            {ok, valid};
+        _NotInRange  ->
+            {error, {terms_violation, {cash_range, {Cash, CashRange}}}}
+    end.
+
 decode(ID, #domain_WithdrawalProvider{
     proxy = Proxy,
     identity = Identity,