From 27aa85352e91e6eda5adb0e9a1896da8efd1fa21 Mon Sep 17 00:00:00 2001
From: jankun4 <michaljankun@gmail.com>
Date: Sun, 21 Apr 2024 20:18:22 +0200
Subject: [PATCH] [#756] add pagination to drep/list

Signed-off-by: jankun4 <michaljankun@gmail.com>
---
 CHANGELOG.md                         |  1 +
 govtool/backend/src/VVA/API.hs       | 26 ++++++++++++++++----
 govtool/backend/src/VVA/API/Types.hs | 36 ++++++++++++++++++++++++++++
 3 files changed, 59 insertions(+), 4 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 122798219..57824e9fa 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -22,6 +22,7 @@ changes.
 
 ### Added
 
+- added pagination to `drep/list` [Issue 756](https://github.com/IntersectMBO/govtool/issues/756)
 - added search query param to the `drep/getVotes` [Issue 640](https://github.com/IntersectMBO/govtool/issues/640)
 - added filtering and sorting capabilities to the `drep/list` [Issue 722](https://github.com/IntersectMBO/govtool/issues/722)
 - added drepView and txHash to the `ada-holder/get-current-delegation` [Issue 689](https://github.com/IntersectMBO/govtool/issues/689)
diff --git a/govtool/backend/src/VVA/API.hs b/govtool/backend/src/VVA/API.hs
index 08789bbbf..d982c61dd 100644
--- a/govtool/backend/src/VVA/API.hs
+++ b/govtool/backend/src/VVA/API.hs
@@ -47,7 +47,9 @@ type VVAApi =
                 :> QueryParam "search" Text
                 :> QueryParams "status" DRepStatus
                 :> QueryParam "sort" DRepSortMode
-                :> Get '[JSON] [DRep]
+                :> QueryParam "page" Natural
+                :> QueryParam "pageSize" Natural
+                :> Get '[JSON] ListDRepsResponse
     :<|> "drep" :> "get-voting-power" :> Capture "drepId" HexText :> Get '[JSON] Integer
     :<|> "drep" :> "getVotes"
                 :> Capture "drepId" HexText
@@ -120,8 +122,8 @@ delegationToResponse Types.Delegation {..} =
     }
 
 
-drepList :: App m => Maybe Text -> [DRepStatus] -> Maybe DRepSortMode -> m [DRep]
-drepList mSearchQuery statuses mSortMode = do
+drepList :: App m => Maybe Text -> [DRepStatus] -> Maybe DRepSortMode -> Maybe Natural -> Maybe Natural -> m ListDRepsResponse
+drepList mSearchQuery statuses mSortMode mPage mPageSize = do
   CacheEnv {dRepListCache} <- asks vvaCache
   dreps <- cacheRequest dRepListCache () DRep.listDReps
 
@@ -148,7 +150,23 @@ drepList mSearchQuery statuses mSortMode = do
           dRepRegistrationStatus
 
 
-  return $ map drepRegistrationToDrep $ sortDReps $ filterDRepsByQuery $ filterDRepsByStatus dreps
+  let allValidDReps = map drepRegistrationToDrep $ sortDReps $ filterDRepsByQuery $ filterDRepsByStatus dreps
+
+
+  let page = (fromIntegral $ fromMaybe 0 mPage) :: Int
+      pageSize = (fromIntegral $ fromMaybe 10 mPageSize) :: Int
+
+      total = length allValidDReps :: Int
+
+  let elements = take pageSize $ drop (page * pageSize) allValidDReps
+
+  return $ ListDRepsResponse
+    { listDRepsResponsePage = fromIntegral page
+    , listDRepsResponsePageSize = fromIntegral pageSize
+    , listDRepsResponseTotal = fromIntegral total
+    , listDRepsResponseElements = elements
+    }
+
 
 getVotingPower :: App m => HexText -> m Integer
 getVotingPower (unHexText -> dRepId) = do
diff --git a/govtool/backend/src/VVA/API/Types.hs b/govtool/backend/src/VVA/API/Types.hs
index 4462f5a82..e911afa35 100644
--- a/govtool/backend/src/VVA/API/Types.hs
+++ b/govtool/backend/src/VVA/API/Types.hs
@@ -750,6 +750,42 @@ instance ToSchema DRep where
             & example
               ?~ toJSON exampleDrep
 
+
+exampleListDRepsResponse :: Text
+exampleListDRepsResponse =
+   "{ \"page\": 0,"
+  <> "\"pageSize\": 1,"
+  <> "\"total\": 1000,"
+  <> "\"elements\": ["
+  <> exampleDrep <> "]}"
+
+data ListDRepsResponse
+  = ListDRepsResponse
+      { listDRepsResponsePage     :: Integer
+      , listDRepsResponsePageSize :: Integer
+      , listDRepsResponseTotal    :: Integer
+      , listDRepsResponseElements :: [DRep]
+      }
+  deriving (Generic, Show)
+
+deriveJSON (jsonOptions "listDRepsResponse") ''ListDRepsResponse
+
+instance ToSchema ListDRepsResponse where
+  declareNamedSchema proxy = do
+    NamedSchema name_ schema_ <-
+      genericDeclareNamedSchema
+        ( fromAesonOptions $
+            jsonOptions "listDRepsResponse"
+        )
+        proxy
+    return $
+      NamedSchema name_ $
+        schema_
+          & description ?~ "ListProposalsResponse"
+          & example
+            ?~ toJSON exampleListDRepsResponse
+
+
 data DelegationResponse
   = DelegationResponse
       { delegationResponseDRepHash       :: Maybe HexText