ChatStorage is a C++ framework designed for local storage, processing, and analysis of chat data from multiple sources. It enables importing chat logs, media files, and user information, persisting them in a structured way, and providing a clean, consistent API for querying and manipulating chat histories. The framework is suitable for applications such as chat analytics, migration, or building custom chat-based interfaces.

• C++17 or later: Core language features and standard library usage.
• SQLite3: Lightweight database backend for persistence.
• Meson build system: For building the project across platforms.
• C++ compiler: Must support C++17 features.
• Optional dependencies: standard C++ libraries for file I/O, logging, and string utilities.

1. Import Layer: Chat logs are ingested via format-specific parsers that implement a common abstract interface. Parsers transform raw files into normalized internal representations of chats, messages, users, and media.
2. Persistence Layer: Data is stored in SQLite databases through a repository pattern. Each entity type (Chat, Message, User, Media) has a dedicated repository managing CRUD operations and ensuring consistency.
3. Core API: Provides structured access to chat data. Applications interact with ChatStorage and ChatContext objects, which expose chats, messages, users, and media. The core handles caching, object lifecycle, and orchestrates import and persistence operations.
4. Utilities: Common helper classes provide logging, file handling, platform abstractions, and string utilities to ensure cross-platform consistency and maintainable code.

ChatStorage follows a layered architecture designed for separation of concerns:

• Public API Stable interfaces for external consumption: ChatStorage, ChatContext, Chat, Message, User, Media, ChatSource. These define the operations clients can perform without exposing implementation details.

• Core Domain Implements the business logic for chat storage, retrieval, and manipulation. Handles orchestration between importers and persistence, caching, and API object management.

• Importer Layer Contains parsers for different chat formats. Each parser implements a common interface, allowing the framework to support multiple input formats seamlessly. Includes ImportManager for coordinating parsing, and ChatImportContext for maintaining state during imports.

• Database / Persistence Layer Repositories (ChatRepository, MessageRepository, UserRepository, MediaRepository) handle SQLite storage. PersistenceManager coordinates transactions and database connections. Statement classes encapsulate prepared SQL statements.

• Common / Infrastructure Cross-cutting utilities: logging (Logger), file operations (FileUtil), string processing (StringUtil), platform abstraction (Platform), and command-line option parsing (OptionParser). Ensures maintainability and consistency across all layers.

See docs/ChatStorage_HighLevel_Architecture.puml for a high-level UML diagram of the architecture. This diagram illustrates the dependencies and flow between the Public API, Core Domain, Importer, Persistence, and Common layers.