adding find input by nft function

CHANGELOG.md

@@ -1,5 +1,7 @@
 # v0.x.y
 
+- Added `input_by_nft` to the find submodule.
+
 # v0.4.5
 
 - Added the `Wallets` type and `to_vks`  to the wallet submodule.

lib/assist/find.ak

@@ -414,3 +414,29 @@ test cant_find_output_datum_by_nft2() fail {
   expect outcome: ByteArray = output_datum_by_nft(outputs, #"fade", #"fade")
   outcome == fake_tx.test_datum
 }
+
+/// Find the first occurance of an inline datum on an output with a value 
+/// that contains a specific nft.
+pub fn input_by_nft(inputs: List<Input>, pid: PolicyId, tkn: AssetName) -> Input {
+  when inputs is {
+    [input, ..rest] ->
+      if values.prove_exact_nft(pid, tkn, input.output.value) {
+        input
+      } else {
+        input_by_nft(rest, pid, tkn)
+      }
+    [] -> fail @"No Input Found In Inputs"
+  }
+}
+
+test cant_find_input_by_nft() fail {
+  let inputs: List<Input> = fake_tx.test_bad_inputs()
+  let input: Input = input_by_nft(inputs, #"acab", #"beef")
+  input == fake_tx.test_one_lovelace_input()
+}
+
+test can_find_input_by_nft() {
+  let inputs: List<Input> = fake_tx.test_bad_inputs()
+  let input: Input = input_by_nft(inputs, #"", #"")
+  input == fake_tx.test_one_lovelace_input()
+}

lib/assist/maths.ak

@@ -5,6 +5,9 @@ use aiken/bytearray
 use aiken/list
 use aiken/math
 
+pub const large_prime: Int =
+  0x1a0111ea397fe69a4b1ba7b6434bacd764774b84f38512bf6730d2a0f6b0f6241eabfffeb153ffffb9feffffffffaaab
+
 /// Calculate `n` to the power of `e` modulo `q` using the exponentiation by 
 /// squaring method. At each multiplication a modulo is calculated, allowing
 /// very large `n` and `e` values.
@@ -50,6 +53,13 @@ test powmod_54_123_1() {
   powmod(54, 123, 1) == 0
 }
 
+test powmod_very_large() {
+  let q =
+    0x1a0111ea397fe69a4b1ba7b6434bacd764774b84f38512bf6730d2a0f6b0f6241eabfffeb153ffffb9feffffffffaaab
+
+  powmod(2, 31565052264044690, q) == 2372285326153189929528332103442483377705667947278803297593729812983050665252776619156384486056106192189240939340047
+}
+
 /// Convert a integer `n` into some base `q`. This method
 /// should scale with any integer and any logical base.
 ///
@@ -89,6 +99,16 @@ test to_base_256() {
   base_q(78237623, 256) == [4, 169, 207, 183]
 }
 
+test to_base_large() {
+  base_q(powmod(2, 15383577435643450949, large_prime), 15) == [
+    12, 9, 14, 13, 5, 2, 11, 13, 5, 13, 10, 8, 5, 11, 10, 4, 7, 5, 11, 0, 10, 8,
+    8, 8, 11, 6, 13, 3, 4, 14, 11, 10, 0, 12, 10, 11, 10, 0, 11, 8, 2, 3, 8, 13,
+    0, 1, 5, 13, 0, 8, 13, 3, 10, 6, 4, 12, 14, 3, 7, 1, 11, 3, 7, 3, 14, 6, 8,
+    4, 14, 3, 2, 7, 10, 14, 13, 10, 6, 8, 1, 7, 6, 13, 11, 10, 9, 12, 2, 13, 4,
+    5, 14, 8, 5, 13, 3, 12, 12,
+  ]
+}
+
 /// Convert a hexadecimal bytearray into its base 10 representation. This
 /// only works with even length bytearrays so arbitrary numbers in hexadecimal
 /// form will not in general work.

lib/assist/tests/fake_tx.ak

@@ -130,6 +130,21 @@ pub fn test_bad_input() -> Input {
   input
 }
 
+pub fn test_one_lovelace_input() -> Input {
+  Input {
+    output_reference: OutputReference {
+      transaction_id: TransactionId { hash: #"" },
+      output_index: 1,
+    },
+    output: Output {
+      address: addresses.create_address(#"face", #""),
+      value: value.from_lovelace(1),
+      datum: NoDatum,
+      reference_script: None,
+    },
+  }
+}
+
 pub fn test_bad_inputs() -> List<Input> {
   [
     Input {
@@ -163,7 +178,7 @@ pub fn test_bad_inputs() -> List<Input> {
       },
       output: Output {
         address: addresses.create_address(#"face", #""),
-        value: value.from_lovelace(5),
+        value: value.from_lovelace(1),
         datum: NoDatum,
         reference_script: None,
       },