From 4a48acb8baa864eb2ab83df80a61861d78f41f42 Mon Sep 17 00:00:00 2001
From: AndrejMijic <44673317+AndrejMijic@users.noreply.github.com>
Date: Tue, 4 Aug 2020 18:12:03 +0200
Subject: [PATCH] Add objgroup.txt loader (#677)

---
 d2app/app.go                               |   1 +
 d2common/d2data/d2datadict/object_group.go | 112 +++++++++++++++++++++
 d2common/d2resource/resource_paths.go      |   1 +
 3 files changed, 114 insertions(+)
 create mode 100644 d2common/d2data/d2datadict/object_group.go

diff --git a/d2app/app.go b/d2app/app.go
index 6ace7a1f..def95dd3 100644
--- a/d2app/app.go
+++ b/d2app/app.go
@@ -277,6 +277,7 @@ func (a *App) loadDataDict() error {
 		{d2resource.MonsterSequence, d2datadict.LoadMonsterSequences},
 		{d2resource.PlayerClass, d2datadict.LoadPlayerClasses},
 		{d2resource.MonsterPlacement, d2datadict.LoadMonsterPlacements},
+		{d2resource.ObjectGroup, d2datadict.LoadObjectGroups},
 		{d2resource.CompCode, d2datadict.LoadComponentCodes},
 		{d2resource.MonsterAI, d2datadict.LoadMonsterAI},
 	}
diff --git a/d2common/d2data/d2datadict/object_group.go b/d2common/d2data/d2datadict/object_group.go
new file mode 100644
index 00000000..9125bb83
--- /dev/null
+++ b/d2common/d2data/d2datadict/object_group.go
@@ -0,0 +1,112 @@
+package d2datadict
+
+import (
+	"fmt"
+	"log"
+	"strconv"
+
+	"github.com/OpenDiablo2/OpenDiablo2/d2common"
+)
+
+const (
+	objectsGroupSize     = 7
+	memberDensityMin     = 0
+	memberDensityMax     = 125
+	memberProbabilityMin = 0
+	memberProbabilityMax = 100
+	expansionDataMarker  = "EXPANSION"
+)
+
+// ObjectGroupRecord represents a single line in objgroup.txt.
+// Information has been gathered from [https://d2mods.info/forum/kb/viewarticle?a=394].
+type ObjectGroupRecord struct {
+	// GroupName is the name of the group.
+	GroupName string
+
+	// Offset is the ID of the group, referred to by Levels.txt.
+	Offset int
+
+	// Members are the objects in the group.
+	Members *[objectsGroupSize]ObjectGroupMember
+
+	// Shrines determines whether this is a group of shrines.
+	// Note: for shrine groups, densities must be set to 0.
+	Shrines bool
+
+	// Wells determines whether this is a group of wells.
+	// Note: for wells groups, densities must be set to 0.
+	Wells bool
+}
+
+// ObjectGroupMember represents a member of an object group.
+type ObjectGroupMember struct {
+	// ID is the ID of the object.
+	ID int
+
+	// Density is how densely the level is filled with the object.
+	// Must be below 125.
+	Density int
+
+	// Probability is the probability of this particular object being spawned.
+	// The value is a percentage.
+	Probability int
+}
+
+// ObjectGroups stores the ObjectGroupRecords.
+var ObjectGroups map[int]*ObjectGroupRecord //nolint:gochecknoglobals // Currently global by design.
+
+// LoadObjectGroups loads the ObjectGroupRecords into ObjectGroups.
+func LoadObjectGroups(file []byte) {
+	ObjectGroups = make(map[int]*ObjectGroupRecord)
+	d := d2common.LoadDataDictionary(file)
+
+	for d.Next() {
+		groupName := d.String("GroupName")
+		if groupName == expansionDataMarker {
+			continue
+		}
+
+		shrines, wells := d.Bool("Shrines"), d.Bool("Wells")
+		record := &ObjectGroupRecord{
+			GroupName: groupName,
+			Offset:    d.Number("Offset"),
+			Members:   createMembers(d, shrines || wells),
+			Shrines:   shrines,
+			Wells:     wells,
+		}
+		ObjectGroups[record.Offset] = record
+	}
+
+	if d.Err != nil {
+		panic(d.Err)
+	}
+
+	log.Printf("Loaded %d ObjectGroup records", len(ObjectGroups))
+}
+
+func createMembers(d *d2common.DataDictionary, shrinesOrWells bool) *[objectsGroupSize]ObjectGroupMember {
+	var members [objectsGroupSize]ObjectGroupMember
+
+	for i := 0; i < objectsGroupSize; i++ {
+		suffix := strconv.Itoa(i)
+		members[i].ID = d.Number("ID" + suffix)
+
+		members[i].Density = d.Number("DENSITY" + suffix)
+		if members[i].Density < memberDensityMin || members[i].Density > memberDensityMax {
+			panic(fmt.Sprintf("Invalid object group member density: %v, in group: %v",
+				members[i].Density, d.String("GroupName"))) // Vanilla crashes when density is over 125.
+		}
+
+		if shrinesOrWells && members[i].Density != 0 {
+			panic(fmt.Sprintf("Shrine and well object groups must have densities set to 0, in group: %v", d.String("GroupName")))
+		}
+
+		members[i].Probability = d.Number("PROB" + suffix)
+		if members[i].Probability < memberProbabilityMin || members[i].Probability > memberProbabilityMax {
+			panic(fmt.Sprintf("Invalid object group member probability: %v, in group: %v",
+				members[i].Probability, d.String("GroupName")))
+		}
+	}
+
+	return &members
+}
diff --git a/d2common/d2resource/resource_paths.go b/d2common/d2resource/resource_paths.go
index 3d8295c9..56057dde 100644
--- a/d2common/d2resource/resource_paths.go
+++ b/d2common/d2resource/resource_paths.go
@@ -214,6 +214,7 @@ const (
 	MonsterSound          = "/data/global/excel/monsounds.txt"
 	MonsterSequence       = "/data/global/excel/monseq.txt"
 	PlayerClass           = "/data/global/excel/PlayerClass.txt"
+	ObjectGroup           = "/data/global/excel/objgroup.txt"
 	CompCode              = "/data/global/excel/compcode.txt"
 
 	// --- Animations ---