From 8dd4bc80ec4fbaa73202935ef93367b29a1cfec2 Mon Sep 17 00:00:00 2001
From: Kelsi <kelsihates2fa@gmail.com>
Date: Tue, 10 Mar 2026 01:20:41 -0700
Subject: [PATCH] game: fix Classic 1.12 SMSG_TRAINER_LIST per-spell field
 layout
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Classic 1.12 trainer list entries lack the profDialog and profButton
uint32 fields (8 bytes) that TBC/WotLK added before reqLevel. Instead,
reqLevel immediately follows spellCost, and a trailing unk uint32 appears
at the end of each entry. Parsing the WotLK format for Classic caused
misalignment from the third field onward, corrupting state, cost, level,
skill, and chain data for all trainer spells.

- TrainerListParser::parse() gains a isClassic bool parameter (default false)
- Classic path: cost(4) → reqLevel(1) → reqSkill... → chainNode3 → unk(4)
- WotLK/TBC path: cost(4) → profDialog(4) → profButton(4) → reqLevel(1) → reqSkill...
- handleTrainerList() passes isClassicLikeExpansion() as the flag
---
 include/game/world_packets.hpp |  4 +++-
 src/game/game_handler.cpp      |  3 ++-
 src/game/world_packets.cpp     | 40 ++++++++++++++++++++++++----------
 3 files changed, 33 insertions(+), 14 deletions(-)

diff --git a/include/game/world_packets.hpp b/include/game/world_packets.hpp
index 0809ac43..4d308028 100644
--- a/include/game/world_packets.hpp
+++ b/include/game/world_packets.hpp
@@ -2231,7 +2231,9 @@ struct TrainerListData {
 
 class TrainerListParser {
 public:
-    static bool parse(network::Packet& packet, TrainerListData& data);
+    // isClassic: Classic 1.12 per-spell layout has no profDialog/profButton fields
+    // (reqLevel immediately follows cost), plus a trailing unk uint32 per entry.
+    static bool parse(network::Packet& packet, TrainerListData& data, bool isClassic = false);
 };
 
 class TrainerBuySpellPacket {
diff --git a/src/game/game_handler.cpp b/src/game/game_handler.cpp
index a22aa7c2..01679430 100644
--- a/src/game/game_handler.cpp
+++ b/src/game/game_handler.cpp
@@ -15012,7 +15012,8 @@ void GameHandler::handleListInventory(network::Packet& packet) {
 // ============================================================
 
 void GameHandler::handleTrainerList(network::Packet& packet) {
-    if (!TrainerListParser::parse(packet, currentTrainerList_)) return;
+    const bool isClassic = isClassicLikeExpansion();
+    if (!TrainerListParser::parse(packet, currentTrainerList_, isClassic)) return;
     trainerWindowOpen_ = true;
     gossipWindowOpen = false;
 
diff --git a/src/game/world_packets.cpp b/src/game/world_packets.cpp
index 275ad5b8..c88f3750 100644
--- a/src/game/world_packets.cpp
+++ b/src/game/world_packets.cpp
@@ -3833,7 +3833,11 @@ bool ListInventoryParser::parse(network::Packet& packet, ListInventoryData& data
 // Trainer
 // ============================================================
 
-bool TrainerListParser::parse(network::Packet& packet, TrainerListData& data) {
+bool TrainerListParser::parse(network::Packet& packet, TrainerListData& data, bool isClassic) {
+    // WotLK per-entry: spellId(4) + state(1) + cost(4) + profDialog(4) + profButton(4) +
+    //                  reqLevel(1) + reqSkill(4) + reqSkillValue(4) + chain×3(12) = 38 bytes
+    // Classic per-entry: spellId(4) + state(1) + cost(4) + reqLevel(1) +
+    //                    reqSkill(4) + reqSkillValue(4) + chain×3(12) + unk(4) = 34 bytes
     data = TrainerListData{};
     data.trainerGuid = packet.readUInt64();
     data.trainerType = packet.readUInt32();
@@ -3847,23 +3851,35 @@ bool TrainerListParser::parse(network::Packet& packet, TrainerListData& data) {
     data.spells.reserve(spellCount);
     for (uint32_t i = 0; i < spellCount; ++i) {
         TrainerSpell spell;
-        spell.spellId    = packet.readUInt32();
-        spell.state      = packet.readUInt8();
-        spell.spellCost  = packet.readUInt32();
-        spell.profDialog = packet.readUInt32();
-        spell.profButton = packet.readUInt32();
-        spell.reqLevel   = packet.readUInt8();
-        spell.reqSkill   = packet.readUInt32();
+        spell.spellId   = packet.readUInt32();
+        spell.state     = packet.readUInt8();
+        spell.spellCost = packet.readUInt32();
+        if (isClassic) {
+            // Classic 1.12: reqLevel immediately after cost; no profDialog/profButton
+            spell.profDialog = 0;
+            spell.profButton = 0;
+            spell.reqLevel   = packet.readUInt8();
+        } else {
+            // TBC / WotLK: profDialog + profButton before reqLevel
+            spell.profDialog = packet.readUInt32();
+            spell.profButton = packet.readUInt32();
+            spell.reqLevel   = packet.readUInt8();
+        }
+        spell.reqSkill      = packet.readUInt32();
         spell.reqSkillValue = packet.readUInt32();
-        spell.chainNode1 = packet.readUInt32();
-        spell.chainNode2 = packet.readUInt32();
-        spell.chainNode3 = packet.readUInt32();
+        spell.chainNode1    = packet.readUInt32();
+        spell.chainNode2    = packet.readUInt32();
+        spell.chainNode3    = packet.readUInt32();
+        if (isClassic) {
+            packet.readUInt32(); // trailing unk / sort index
+        }
         data.spells.push_back(spell);
     }
 
     data.greeting = packet.readString();
 
-    LOG_INFO("Trainer list: ", spellCount, " spells, type=", data.trainerType,
+    LOG_INFO("Trainer list (", isClassic ? "Classic" : "TBC/WotLK", "): ",
+             spellCount, " spells, type=", data.trainerType,
              ", greeting=\"", data.greeting, "\"");
     return true;
 }