feat: list payment_methods with the required fields in each method (#1310)

Co-authored-by: Sangamesh Kulkarni <59434228+Sangamesh26@users.noreply.github.com>
Co-authored-by: Prasunna Soppa <prasunna.soppa@juspay.in>

crates/api_models/src/enums.rs

@@ -974,6 +974,26 @@ pub struct UnresolvedResponseReason {
     pub message: String,
 }
 
+/// Possible field type of required fields in payment_method_data
+#[derive(
+    Clone,
+    Debug,
+    Eq,
+    PartialEq,
+    serde::Deserialize,
+    serde::Serialize,
+    strum::Display,
+    strum::EnumString,
+    ToSchema,
+    Hash,
+)]
+#[serde(rename_all = "snake_case")]
+#[strum(serialize_all = "snake_case")]
+pub enum FieldType {
+    Text,
+    DropDown { options: Vec<String> },
+}
+
 #[derive(
     Debug,
     serde::Deserialize,

crates/api_models/src/payment_methods.rs

@@ -1,3 +1,5 @@
+use std::collections::HashSet;
+
 use cards::CardNumber;
 use common_utils::{crypto::OptionalEncryptableName, pii};
 use serde::de;
@@ -214,6 +216,23 @@ pub struct ResponsePaymentMethodTypes {
     pub bank_debits: Option<BankDebitTypes>,
     /// The Bank transfer payment method information, if applicable for a payment method type.
     pub bank_transfers: Option<BankTransferTypes>,
+
+    /// Required fields for the payment_method_type.
+    pub required_fields: Option<HashSet<RequiredFieldInfo>>,
+}
+
+/// Required fields info used while listing the payment_method_data
+#[derive(Debug, serde::Deserialize, serde::Serialize, Clone, PartialEq, Eq, ToSchema, Hash)]
+pub struct RequiredFieldInfo {
+    /// Required field for a payment_method through a payment_method_type
+    pub required_field: String,
+
+    /// Display name of the required field in the front-end
+    pub display_name: String,
+
+    /// Possible field type of required field
+    #[schema(value_type = FieldType)]
+    pub field_type: api_enums::FieldType,
 }
 
 #[derive(Debug, Clone, serde::Deserialize, serde::Serialize, ToSchema)]