The collections system provides comprehensive achievement-based item collection functionality for EverQuest II server emulation, converted from the original C++ EQ2EMu implementation.

Overview

The collections system allows players to find specific items scattered throughout the game world and combine them into collections for rewards. When players complete a collection by finding all required items, they receive rewards such as experience, coins, items, or a choice of selectable items.

Architecture

Core Components

Collection - Individual collection with required items, rewards, and completion tracking
MasterCollectionList - Registry of all available collections in the game
PlayerCollectionList - Per-player collection progress and completion tracking
CollectionManager - High-level collection system coordinator
CollectionService - Service layer for game integration and client communication

Key Features

Item-Based Collections: Players find specific items to complete collections
Multiple Reward Types: Coins, experience points, fixed items, and selectable items
Progress Tracking: Real-time tracking of collection completion progress
Category Organization: Collections organized by categories for easy browsing
Level Restrictions: Collections appropriate for different player levels
Thread Safety: All operations use proper Go concurrency patterns
Database Persistence: Player progress saved automatically

Collection Structure

Collection Data

ID: Unique collection identifier
Name: Display name for the collection
Category: Organizational category (e.g., "Artifacts", "Shinies")
Level: Recommended level for the collection
Items: List of required items with index positions
Rewards: Coins, XP, items, and selectable items

Item States

Not Found (0): Player hasn't found this item yet
Found (1): Player has found and added this item to the collection

Collection States

Incomplete: Not all required items have been found
Ready to Turn In: All items found but not yet completed
Completed: Collection has been turned in and rewards claimed

Database Schema

Collections Table

CREATE TABLE collections (
    id INTEGER PRIMARY KEY,
    collection_name TEXT NOT NULL,
    collection_category TEXT NOT NULL DEFAULT '',
    level INTEGER NOT NULL DEFAULT 0,
    created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
    updated_at DATETIME DEFAULT CURRENT_TIMESTAMP
);

Collection Details Table

CREATE TABLE collection_details (
    collection_id INTEGER NOT NULL,
    item_id INTEGER NOT NULL,
    item_index INTEGER NOT NULL DEFAULT 0,
    PRIMARY KEY (collection_id, item_id),
    FOREIGN KEY (collection_id) REFERENCES collections(id) ON DELETE CASCADE
);

Collection Rewards Table

CREATE TABLE collection_rewards (
    id INTEGER PRIMARY KEY AUTOINCREMENT,
    collection_id INTEGER NOT NULL,
    reward_type TEXT NOT NULL,  -- 'Item', 'Selectable', 'Coin', 'XP'
    reward_value TEXT NOT NULL,
    reward_quantity INTEGER NOT NULL DEFAULT 1,
    FOREIGN KEY (collection_id) REFERENCES collections(id) ON DELETE CASCADE
);

Player Collections Table

CREATE TABLE character_collections (
    char_id INTEGER NOT NULL,
    collection_id INTEGER NOT NULL,
    completed INTEGER NOT NULL DEFAULT 0,
    created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
    updated_at DATETIME DEFAULT CURRENT_TIMESTAMP,
    PRIMARY KEY (char_id, collection_id),
    FOREIGN KEY (collection_id) REFERENCES collections(id) ON DELETE CASCADE
);

Player Collection Items Table

CREATE TABLE character_collection_items (
    char_id INTEGER NOT NULL,
    collection_id INTEGER NOT NULL,
    collection_item_id INTEGER NOT NULL,
    found_at DATETIME DEFAULT CURRENT_TIMESTAMP,
    PRIMARY KEY (char_id, collection_id, collection_item_id),
    FOREIGN KEY (char_id, collection_id) REFERENCES character_collections(char_id, collection_id) ON DELETE CASCADE
);

Usage Examples

System Initialization

// Initialize collection service
database := NewDatabaseCollectionManager(db)
itemLookup := NewItemLookupService()
clientManager := NewClientManager()

service := NewCollectionService(database, itemLookup, clientManager)
err := service.Initialize(ctx)

Player Operations

// Load player collections when they log in
err := service.LoadPlayerCollections(ctx, characterID)

// Process when player finds an item
err := service.ProcessItemFound(characterID, itemID)

// Complete a collection
rewardProvider := NewRewardProvider()
err := service.CompleteCollection(characterID, collectionID, rewardProvider)

// Get player's collection progress
progress, err := service.GetPlayerCollectionProgress(characterID)

// Unload when player logs out
err := service.UnloadPlayerCollections(ctx, characterID)

Collection Management

// Get all collections in a category
collections := manager.GetCollectionsByCategory("Artifacts")

// Search collections by name
collections := manager.SearchCollections("Ancient")

// Get collections appropriate for player level
collections := manager.GetAvailableCollections(playerLevel)

// Check if item is needed by any collection
needed := masterList.NeedsItem(itemID)

Reward System

Reward Types

Coin Rewards

collection.SetRewardCoin(50000) // 5 gold

Experience Rewards

collection.SetRewardXP(10000) // 10,000 XP

Item Rewards (automatically given)

collection.AddRewardItem(CollectionRewardItem{
    ItemID:   12345,
    Quantity: 1,
})

Selectable Rewards (player chooses one)

collection.AddSelectableRewardItem(CollectionRewardItem{
    ItemID:   12346,
    Quantity: 1,
})

Integration Interfaces

ItemLookup

Provides item information and validation for collections.

ClientManager

Handles client communication for collection updates and lists.

RewardProvider

Manages distribution of collection rewards to players.

CollectionEventHandler

Handles collection-related events for logging and notifications.

Thread Safety

All operations are thread-safe using:

sync.RWMutex for collection and list operations
Atomic updates for collection progress
Database transactions for consistency
Proper locking hierarchies to prevent deadlocks

Performance Features

Efficient Lookups: Hash-based collection and item lookups
Lazy Loading: Player collections loaded only when needed
Batch Operations: Multiple items and collections processed together
Connection Pooling: Efficient database connection management
Caching: Master collections cached in memory

Event System

The collections system provides comprehensive event handling:

// Item found event
OnItemFound(characterID, collectionID, itemID int32)

// Collection completed event
OnCollectionCompleted(characterID, collectionID int32)

// Rewards claimed event
OnRewardClaimed(characterID, collectionID int32, rewards []CollectionRewardItem, coin, xp int64)

Statistics and Monitoring

System Statistics

Total collections available
Collections per category
Total items across all collections
Reward distribution statistics

Player Statistics

Collections completed
Collections in progress
Items found
Progress percentages

Error Handling

Comprehensive error handling covers:

Database connection failures
Invalid collection or item IDs
Reward distribution failures
Concurrent access issues
Data validation errors

Future Enhancements

Areas marked for future implementation:

Collection discovery mechanics
Rare item collection bonuses
Collection sharing and trading
Achievement integration
Collection leaderboards
Seasonal collections

File Structure

internal/collections/
├── README.md              # This documentation
├── constants.go           # Collection constants and limits
├── types.go              # Core data structures
├── interfaces.go         # Integration interfaces
├── collections.go        # Collection implementation
├── master_list.go        # Master collection registry
├── player_list.go        # Player collection tracking
├── database.go           # Database operations
└── manager.go            # High-level collection services

Dependencies

eq2emu/internal/database - Database wrapper
Standard library: context, sync, fmt, strings, time

Testing

The collections system is designed for comprehensive testing:

Mock interfaces for all dependencies
Unit tests for collection logic
Integration tests with database
Concurrent operation testing
Performance benchmarking

Migration from C++

Key changes from the C++ implementation:

Go interfaces for better modularity
Context-based operations for cancellation
Proper error handling with wrapped errors
Thread-safe operations using sync primitives
Database connection pooling
Event-driven architecture for notifications

Integration Notes

When integrating with the game server:

Initialize the collection service at server startup
Load player collections on character login
Process item finds during gameplay
Handle collection completion through UI interactions
Save collections on logout or periodic intervals
Clean up resources during server shutdown