feat: lower discount level thresholds (#638)

Author: renauter

docs/architecture/0008-discount-levels-changed.md

@@ -0,0 +1,36 @@
+# 8. Lower discount level threshold
+
+Date: 2023-03-10
+
+## Status
+
+Accepted
+
+## Context
+
+See [here](https://github.com/threefoldtech/tfchain/issues/637) for more details.
+
+## Decision
+
+We decided to lower the discount level thresholds by reduzing them by half.
+In consequence, a grid user get faster access to a better discount level
+
+Before:
+
+ | discount level | pricing discount | nr months staking |
+ | -------------- | -----------------| ----------------- |
+ | none           | - 0%             | 0 month           |
+ | default        | - 20%            | 3 months          |
+ | bronze         | - 30%            | 6 months          |
+ | silver         | - 40%            | 12 months         |
+ | gold           | - 60%            | 36 months         |
+
+Now:
+
+ | discount level | pricing discount | nr months staking |
+ | -------------- | -----------------| ----------------- |
+ | none           | - 0%             | 0 month           |
+ | default        | - 20%            | 1.5 months        |
+ | bronze         | - 30%            | 3 months          |
+ | silver         | - 40%            | 6 months          |
+ | gold           | - 60%            | 18 months         |

substrate-node/pallets/pallet-smart-contract/src/cost.rs

@@ -258,12 +258,12 @@ pub fn calculate_discount<T: Config>(
     let discount_level = U64F64::from_num(balance_as_u128) / U64F64::from_num(amount_due_monthly);
 
     // predefined discount levels
-    // https://wiki.threefold.io/#/threefold__grid_pricing
-    let discount_received = match discount_level.floor().to_num::<u64>() {
-        d if d >= 3 && d < 6 => types::DiscountLevel::Default,
-        d if d >= 6 && d < 12 => types::DiscountLevel::Bronze,
-        d if d >= 12 && d < 36 => types::DiscountLevel::Silver,
-        d if d >= 36 => types::DiscountLevel::Gold,
+    // https://library.threefold.me/info/manual/#/threefold__pricing?id=discount-levels
+    let discount_received = match discount_level {
+        d if d >= 1.5 && d < 3 => types::DiscountLevel::Default,
+        d if d >= 3 && d < 6 => types::DiscountLevel::Bronze,
+        d if d >= 6 && d < 18 => types::DiscountLevel::Silver,
+        d if d >= 18 => types::DiscountLevel::Gold,
         _ => types::DiscountLevel::None,
     };
 

substrate-node/pallets/pallet-smart-contract/src/tests.rs

@@ -3233,12 +3233,12 @@ macro_rules! test_calculate_discount {
             let amount_due = 1000;
             let seconds_elapsed = SECS_PER_HOUR; // amount due is relative to 1h
             // Give just enough balance for targeted number of months at the rate of 1000 per hour
-            let balance = (amount_due * 24 * 30) * number_of_months;
+            let balance = U64F64::from_num(amount_due * 24 * 30) * U64F64::from_num(number_of_months);
 
             let result = cost::calculate_discount::<TestRuntime>(
                 amount_due,
                 seconds_elapsed,
-                balance,
+                balance.to_num::<u64>(),
                 NodeCertification::Diy,
             );
 
@@ -3259,10 +3259,10 @@ macro_rules! test_calculate_discount {
 // Confirm expected discount level given a number of month of balance autonomy
 test_calculate_discount! {
     test_calculate_discount_none_works: (1, types::DiscountLevel::None),
-    test_calculate_discount_default_works: (3, types::DiscountLevel::Default),
-    test_calculate_discount_bronze_works: (6, types::DiscountLevel::Bronze),
-    test_calculate_discount_silver_works: (12, types::DiscountLevel::Silver),
-    test_calculate_gold_discount_gold_works: (36, types::DiscountLevel::Gold),
+    test_calculate_discount_default_works: (1.5, types::DiscountLevel::Default),
+    test_calculate_discount_bronze_works: (3, types::DiscountLevel::Bronze),
+    test_calculate_discount_silver_works: (6, types::DiscountLevel::Silver),
+    test_calculate_gold_discount_gold_works: (18, types::DiscountLevel::Gold),
 }
 
 // ***** HELPER FUNCTIONS ***** //