From e4f59961284559708725717716323613ca8737ec Mon Sep 17 00:00:00 2001
From: Ray Lin <137183702+ruijialin-avalabs@users.noreply.github.com>
Date: Fri, 13 Dec 2024 10:38:05 -0500
Subject: [PATCH] Update Staking simple flow node sorting and selection logic
 (#2154)

---
 .../app/hooks/earn/useSearchNode.ts           |  2 +
 .../app/services/earn/utils.test.ts           | 42 +++++++++++++++++++
 .../core-mobile/app/services/earn/utils.ts    | 20 +++++++--
 3 files changed, 61 insertions(+), 3 deletions(-)

diff --git a/packages/core-mobile/app/hooks/earn/useSearchNode.ts b/packages/core-mobile/app/hooks/earn/useSearchNode.ts
index 6d7a958d1d..5217f4e0ec 100644
--- a/packages/core-mobile/app/hooks/earn/useSearchNode.ts
+++ b/packages/core-mobile/app/hooks/earn/useSearchNode.ts
@@ -42,8 +42,10 @@ export const useSearchNode = ({
       stakingAmount,
       stakingEndTime,
       minUpTime: 98,
+      maxFee: 4,
       isEndTimeOverOneYear
     })
+
     if (filteredValidators.length === 0) {
       Logger.info(noMatchError.message)
       return { validator: undefined, error: noMatchError }
diff --git a/packages/core-mobile/app/services/earn/utils.test.ts b/packages/core-mobile/app/services/earn/utils.test.ts
index 17f897b027..67d6512a66 100644
--- a/packages/core-mobile/app/services/earn/utils.test.ts
+++ b/packages/core-mobile/app/services/earn/utils.test.ts
@@ -210,6 +210,48 @@ describe('getRandomValidator function', () => {
     const result = getRandomValidator([])
     expect(result).toBe(undefined)
   })
+
+  it('should return first item by end time if staking end time is over one year', () => {
+    const result = getRandomValidator(
+      mockValidators.validators as unknown as NodeValidators,
+      true
+    )
+    expect(result).toBe(mockValidators.validators[0])
+  })
+
+  it('should return first item if only one validator matches the lowest delegation fee', () => {
+    const validators = mockValidators.validators.map((validator, index) => {
+      if (index === 0) {
+        return { ...validator, delegationFee: '1.0000' }
+      }
+      return validator
+    })
+    const result = getRandomValidator(validators as unknown as NodeValidators)
+    expect(result).toBe(validators[0])
+  })
+  it('should return random validator from ones that matches the lowest delegation fee', () => {
+    const validators = mockValidators.validators.map((validator, index) => {
+      if (index <= 1) {
+        return { ...validator, delegationFee: '1.0000' }
+      }
+      return validator
+    })
+    const result = getRandomValidator(validators as unknown as NodeValidators)
+    const nodeIds = validators.map(validator => validator.nodeID)
+    expect(nodeIds.includes(result.nodeID)).toBeTruthy()
+  })
+
+  it('should return random validator from top five of ones that matches the lowest delegation fee', () => {
+    const validators = mockValidators.validators.map((validator, index) => {
+      if (index <= 10) {
+        return { ...validator, delegationFee: '1.0000' }
+      }
+      return validator
+    })
+    const result = getRandomValidator(validators as unknown as NodeValidators)
+    const topFive = validators.slice(0, 5).map(validator => validator.nodeID)
+    expect(topFive.includes(result.nodeID)).toBeTruthy()
+  })
 })
 
 describe('getAdvancedSortedValidators function', () => {
diff --git a/packages/core-mobile/app/services/earn/utils.ts b/packages/core-mobile/app/services/earn/utils.ts
index 78f9d066d9..ab29aca331 100644
--- a/packages/core-mobile/app/services/earn/utils.ts
+++ b/packages/core-mobile/app/services/earn/utils.ts
@@ -237,8 +237,8 @@ export const getSimpleSortedValidators = (
   }
   return [...validators].sort(
     (a, b): number =>
-      Number(b.uptime) - Number(a.uptime) ||
       Number(a.delegationFee) - Number(b.delegationFee) ||
+      Number(b.uptime) - Number(a.uptime) ||
       (peers === undefined
         ? 0
         : comparePeerVersion(
@@ -250,7 +250,7 @@ export const getSimpleSortedValidators = (
 
 /**
  *
- * @param validators input to take random item from,
+ * @param validators input sorted by delegationFee, uptime and node version to take random item from,
  * @param isEndTimeOverOneYear boolean indicating if the stake end time is over one year
  * @returns random item from either top 5 items in the array or all of the items in the array
  */
@@ -262,9 +262,23 @@ export const getRandomValidator = (
     // get the first item in the array sorted by end time
     return validators.at(0) as NodeValidator
   }
-  const endIndex = validators.length >= 5 ? 4 : validators.length - 1
+
+  // get the validators with lowest delegation fee
+  const validatorsWithLowestFee = validators.filter(
+    validator => validator.delegationFee === validators[0]?.delegationFee
+  )
+
+  // if there is only one validator with the lowest fee, return it
+  if (validatorsWithLowestFee.length === 1) {
+    return validatorsWithLowestFee[0] as NodeValidator
+  }
+
+  // if there are more than 2 validators with the lowest fee, return a random one between the 2-5 validators
+  const endIndex =
+    validatorsWithLowestFee.length >= 5 ? 4 : validators.length - 1
   const randomIndex = random(0, endIndex)
   const matchedValidator = validators.at(randomIndex)
+
   return matchedValidator as NodeValidator
 }