From fcf8a61368e2fdcefff3ef37f191854ffa2ccd49 Mon Sep 17 00:00:00 2001
From: Richard Holland <richard.holland@starstone.co.nz>
Date: Sat, 17 Dec 2022 10:58:33 +0000
Subject: [PATCH] first version of reward_hook, needs more testing

---
 hook/reward_hook.c | 98 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 98 insertions(+)
 create mode 100644 hook/reward_hook.c

diff --git a/hook/reward_hook.c b/hook/reward_hook.c
new file mode 100644
index 000000000..0c7bc9506
--- /dev/null
+++ b/hook/reward_hook.c
@@ -0,0 +1,98 @@
+#include "hookapi.h"
+
+#define ASSERT(x)\
+    if (!(x))\
+        rollback(0,0,__LINE__);
+
+int64_t hook(uint32_t r)
+{
+    etxn_reserve(1);
+    _g(1,1);
+
+    // get the account id
+    uint8_t account_field[20];
+    ASSERT(otxn_field(SBUF(account_field), sfAccount) == 20);
+
+    uint8_t hook_accid[20];
+    hook_account(SBUF(hook_accid));
+
+
+    int equal = 0; BUFFER_EQUAL(equal, hook_accid, account_field, 20);
+    if (equal)
+        accept(0,0,0);
+
+
+    // get the account root keylet
+    uint8_t kl[34];
+    ASSERT(util_keylet(SBUF(kl), KEYLET_ACCOUNT, SBUF(account_field), 0,0,0,0) == 34);
+
+    // slot the account root
+    ASSERT(slot_set(SBUF(kl), 1) == 1);
+
+    
+    int64_t accum_slot = slot_subfield(1, sfRewardAccumulator, 2);
+
+    // this is a first time claim reward has run and will setup these fields
+    if (accum_slot == DOESNT_EXIST)
+        accept(0,0,0);
+
+    // this is an actual claim reward
+    ASSERT(accum_slot == 2);
+    ASSERT(slot_subfield(1, sfRewardLgrFirst, 3) == 3);
+    ASSERT(slot_subfield(1, sfRewardLgrLast, 4) == 4);
+    ASSERT(slot_subfield(1, sfBalance, 5) == 5);
+
+
+    int64_t accumulator = slot(0,0,2);
+    int64_t first = slot(0,0,3);
+    int64_t last = slot(0,0,4);
+    int64_t bal = slot(0,0,5);
+
+    TRACEVAR(accumulator);
+    TRACEVAR(first);
+    TRACEVAR(last);
+
+    ASSERT(accumulator > 0 && first > 0 && last > 0);
+
+    // we need to add the final block ourselves
+
+    int64_t cur = ledger_seq();
+
+    int64_t elapsed = cur - first;
+
+    ASSERT(elapsed > 0);
+
+    int64_t elapsed_since_last = ledger_seq() - last;
+
+    bal &= ~0xE000000000000000ULL;
+    bal /= 1000000;
+
+    TRACEVAR(bal);
+
+    TRACEVAR(accumulator);
+
+    if (bal > 0 && elapsed_since_last > 0)
+        accumulator += bal * elapsed_since_last;
+    
+    TRACEVAR(accumulator);
+
+    int64_t reward = accumulator / elapsed;
+    
+    TRACEVAR(reward);
+
+    int64_t reward_drops = reward * 1000000ULL;
+
+    ASSERT(reward_drops > reward);
+
+    TRACEVAR(reward_drops);
+
+    uint8_t tx[PREPARE_PAYMENT_SIMPLE_SIZE];
+    PREPARE_PAYMENT_SIMPLE(tx, reward_drops, account_field, 0, 0);
+
+    // emit the transaction
+    uint8_t emithash[32];
+    int64_t emit_result = emit(SBUF(emithash), SBUF(tx));
+    TRACEVAR(emit_result);
+
+    accept(0,0,0);
+}