🏗️ Architecture Overview

leetrs is designed as a modular, asynchronous Rust crate focused on performance, clean separation of concerns, and robust error handling.

---

📦 Workspace & Crate Structure

leetrs is structured as a Cargo workspace with distinct crates for separation of concerns:

Member	Directory	Purpose
leetrs	src/	Main CLI binary and interactive Ratatui TUI application
cookie-extract	crates/cookie-extract	Standalone, lightweight browser cookie extraction & cURL parsing library (completely replaces the deprecated rookie crate)
xtask	xtask/	Developer and CI task runner for cross-platform linting, testing, and formatting

---

🧱 Module Structure

The application codebase (src/) is organized into dedicated modules:

Module	Source File	Description
auth	src/auth.rs	Encapsulates browser cookie extraction (cookie-extract) and credential persistence
client	src/client.rs	Authenticated HTTP client managing LeetCode REST and GraphQL API queries
models	src/models/	Serde-compatible data models (ProblemSummary, Question, Submission, Language)
picker	src/picker.rs	Main workflow orchestrator connecting client, caching, disk I/O, and editor launching
tui	src/tui/	Ratatui rendering engine, screen state management, and custom widget components
services	src/services/	Polling and submission handling logic
cache	src/cache.rs	Disk caching service for problem list metadata (data.json)
config	src/config.rs	Global configuration manager backed by OnceLock<Config>
format	src/format.rs	Terminal colorizing and result formatting utilities
error	src/error.rs	Custom error types implemented with thiserror (EngineError)

---

🔄 Core Execution Pipeline

sequenceDiagram
    autonumber
    actor User
    participant CLI as main.rs / commands.rs
    participant Auth as auth.rs
    participant Config as config.rs
    participant Picker as picker.rs
    participant Client as client.rs
    participant Editor as Neovim Process

    User->>CLI: leetrs pick 1
    CLI->>Auth: LeetCodeCredentials::load()
    Auth-->>CLI: Credentials
    CLI->>Config: CONFIG.get()
    Config-->>CLI: Config Options
    CLI->>Picker: Picker::new(client).pick(1)
    Picker->>Client: get_question_by_id(1)
    Client-->>Picker: Question Details & Code Snippets
    Picker->>Picker: Write two_sum.md & two_sum.rs to disk
    Picker->>Editor: Launch nvim two_sum.md -c "vsplit two_sum.rs"
    Editor-->>User: Side-by-side terminal split