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Quest System

Brief

Design a Quest System interface in C++. Design data structures, classes, function signatures, and DB tables supporting a player questing system with the following characteristics.

Quest States:

UNAVAILABLE // unavailable for whatever reason
AVAILABLE   // available but not yet obtained
OBTAINED    // obtained with no objectives completed
IN-PROGRESS // obtained with some objectives completed
COMPLETED   // obtained with all objectives completed

Other Requirements:

Quests can have prerequisites that must be completed to transition to the AVAILABLE state
Quests allow "N of M objectives, N<=M" for transition to the COMPLETED state
Quests in the COMPLETED state can grant achievements

Be sure to explain any assumptions your design makes using code comments.

Assumptions

A1.0 The quest system is for a MMORPG.
- A1.1 Quests can be added to the game.
- A1.2 Quests can be gobally disabled (such as holiday or event-related quests).
- A1.3 Quests can only be updated while the game servers are in maintance mode.
A2.0 All objects in game can have a UUID.
- A2.1 Given a UUID, an object can be created.
- A2.2 Given an object, a UUID can be derived.
- A2.3 UUIDs and objects can be used interchangably.
- A2.4 A UUID exists for every player character.
A3.0 There exists a robust event system.
- A3.1 Events provide an event type (ENEMY_KILLED, ITEM_COLLECTED, VOLUME_ENTERED, et cetera).
- A3.2 Events provide a value referencing a game object (Enraged_Panther, Refined_Ore, Enemy_Base_Entrance, et cetera).
- A3.3 The event system provides an interface for recieving events, IGameEventListener.
- A3.4 The event system provides an interface for sending events, IGameEventDispatcher.
A4.0 Quest objectives are based on discrete, numerical values, such as:
- Bless Pirates 13/20
- Taste Pies 5/8
- Complete Programming Test 0/1
A5.0 There exists a Loot object that can support any possible quest rewards.
A6.0 There exists a robust ORM to handle database I/O.

Design Approach

Class Diagram

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State Diagram

View as PNG

Accepting Quests

When a quest is available, it will appear in-game for the Player. When a player accepts the quest, it will transition to ACCEPTED, and each of the quest objectives will begin to listen for their assigned game events.

Completing Objectives & Quests

Whenever a QuestObjective recieves a matching game event, it will increment currentValue. If currentValue matches or exceeds goalValue, it will alert its associated quest by calling parent.onObjectiveComplete().

Whenever onObjectiveComplete() is called, the Quest it will check isComplete() for each objective in objectives. If all objectives are complete, it will dispatch a game event to notify all quests that it has been completed, update each achievement in achievements and transition to COMPLETE.

Becoming Available

When onPrerequsiteComplete() is triggered from a quest completion event, the quest will check isComplete() for each Quest in prerequsites. If they are all complete and if isAvailable, the quest will transition to AVAILABLE.

Becoming Unavailable

When connecting to the server, the player will query the database. Any quest where !isAvailable will be transitioned to UNAVAILABLE unless COMPLETE.

Global Database

The global database provides all information regarding the global values of the game. It does not contain player information.

Quests

Quests provides the name and description of quests, and allows for turning a quest on or off globally.

Key	Type	Column	Relation
PK	UUID	questId
	VARCHAR	name
	VARCHAR	description
	BOOLEAN	isAvailable
FK1	UUID	reward	`Loot.lootId` (from A5.0)

Prerequsites

Prerequsites provides a mapping of quests to prerequsites.

Key	Type	Column	Relation
PK	UUID	prerequsiteID
FK1	UUID	quest	`Quests.questId`
FK2	UUID	prerequsite	`Quests.questId`

QuestObjectives

QuestObjectives provides the description and details of quest objectives, as well as mapping to their quests.

Key	Type	Column	Relation
PK	UUID	questObjectiveId
FK1	UUID	parent	`Quests.questId`
	VARCHAR	description
FK2	UUID	type	`EventType.eventTypeId` (from A3.1)
FK3	UUID	value	`GameObject.gameObjectId` (from A2.0)
	INTEGER	goal

QuestStates

QuestStates provides all possible states a quest could be in.

Key	Type	Column	Relation
PK	UUID	questStateId
	VARCHAR	name

QuestAchievements

QuestAchievements provides mapping between quests and achievements.

Key	Type	Column	Relation
PK	UUID	questAchievementId
FK1	UUID	quest	`Quests.questId`
FK2	UUID	achievement	`Achievement.achievementId` (from Requirements)

Character Database

The character database provides individual player character progression information.

CharacterQuests

CharacterQuests relates individual progression from characters to quests.

Key	Type	Column	Relation
PK	UUID	characterQuestId
FK1	UUID	character	`Characters.characterId` (from A2.4)
FK2	UUID	quest	`Quests.questId`
FK3	UUID	state	`QuestState.questStateId`

CharacterObjectives

CharacterObjectives relates individual progression from characters to objectives.

Key	Type	Column	Relation
PK	UUID	characterObjectiveId
FK1	UUID	character	`Characters.characterId` (from A2.4)
FK2	UUID	objective	`QuestObjectives.questObjectiveId`
	INTEGER	value

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