# AGENTS.md - File Server Project

## Project Overview

This is a FastAPI-based file server that serves files from a directory or ZIP archive using hashed paths. The server indexes files and serves them via random access or by hash lookup.

## Language & Runtime

- **Language**: Python 3.13
- **Framework**: FastAPI 0.128.0+
- **Server**: Uvicorn 0.40.0+

## Build, Lint, and Test Commands

### Running the Server

```bash
# Run with a directory
python main.py /path/to/files

# Run with a ZIP archive
python main.py /path/to/archive.zip
```

### Testing

No test framework is currently configured. To add tests, install pytest:

```bash
pip install pytest
```

Run all tests:
```bash
pytest
```

Run a single test:
```bash
pytest path/to/test_file.py::TestClass::test_method
pytest -k "test_name_pattern"
```

### Linting

No linting tool is currently configured. Recommended tools:

```bash
# Install ruff (fast linter/formatter)
pip install ruff

# Run linting
ruff check .

# Auto-fix issues
ruff check --fix .

# Format code
ruff format .
```

Alternatively, using pylint:
```bash
pip install pylint
pylint main.py
```

### Type Checking

```bash
# Install mypy
pip install mypy

# Run type checking
mypy main.py
```

## Code Style Guidelines

### Imports

- Standard library imports first, then third-party, then local
- Group imports by type: stdlib, third-party, local
- Use absolute imports for local modules
- Example:
  ```python
  import os
  import sys
  from pathlib import Path
  
  from fastapi import FastAPI, HTTPException
  from fastapi.responses import FileResponse, StreamingResponse
  
  from mymodule import MyClass
  ```

### Formatting

- Use 4 spaces for indentation (no tabs)
- Maximum line length: 100 characters
- Use blank lines to separate logical sections (2 blank lines between top-level definitions)
- One blank line between method definitions within a class

### Types

- Use type hints for all function arguments and return values
- Use Python 3.13+ typing features where appropriate
- Example:
  ```python
  def process_file(path: str) -> bytes:
      ...
  
  class FileIndexer:
      def __init__(self, path: str) -> None:
          ...
  ```

### Naming Conventions

- **Classes**: `PascalCase` (e.g., `FileIndexer`, `ZipFileIndexer`)
- **Functions/variables**: `snake_case` (e.g., `get_file_by_hash`, `file_mapping`)
- **Constants**: `UPPER_SNAKE_CASE` (e.g., `INDEXER_MAP`)
- **Private methods/attributes**: Prefix with underscore (e.g., `_index`, `_salt`)
- Use descriptive, full words for names (avoid abbreviations except well-known ones)

### Error Handling

- Use exceptions for exceptional cases, not flow control
- Raise `HTTPException` for HTTP-level errors in FastAPI endpoints
- Provide meaningful error messages
- Example:
  ```python
  if not indexer.file_mapping:
      raise HTTPException(status_code=404, detail="No files indexed")
  
  if file_hash not in self.file_mapping:
      return None
  ```

### Async/Await

- Use `async def` for FastAPI endpoint handlers
- Use regular functions for synchronous operations (file I/O, hashing)
- Do not mix sync and async improperly

### File Operations

- Use `pathlib.Path` for path manipulations
- Use context managers (`with` statements) for file operations
- Handle both directory and archive (ZIP) file sources

### Documentation

- Use docstrings for public classes and functions
- Follow Google-style docstring format:
  ```python
  def get_file_by_hash(file_hash: str) -> str | None:
      """Get filename by hash.
      
      Args:
          file_hash: The hash identifier for the file.
      
      Returns:
          The filename if found, None otherwise.
      """
  ```

### Best Practices

- Keep functions small and focused (single responsibility)
- Use properties for computed attributes with caching
- Avoid global state where possible; use dependency injection
- Use dataclasses or attrs for simple data containers
- Follow PEP 8 style guidelines

## Project Structure

```
/projects/file_server/
├── main.py           # Main application entry point
├── pyproject.toml   # Project configuration
├── .python-version  # Python version specification
└── README.md        # Project documentation (currently empty)
```

## Common Tasks

### Adding a New Endpoint

1. Add the route handler in `main.py`
2. Use appropriate HTTP method decorator (`@app.get`, `@app.post`, etc.)
3. Add type hints and docstrings
4. Handle errors with `HTTPException`

### Adding a New File Indexer

1. Create a new class inheriting from `FileIndexer`
2. Override the `_index` method to populate `self.file_mapping`
3. Implement `get_file_by_hash` and `get_filename_by_hash`
4. Register in `INDEXER_MAP` dictionary

### Running the Server in Development

```bash
python -m uvicorn main:app --reload --host 0.0.0.0 --port 8000
```