# qh Implementation Status

## What's Been Implemented ✅

### Core Architecture (Phase 1 - COMPLETE)

1. **Transformation Rule System** (`qh/rules.py`)
   - Multi-dimensional rule matching (type, name, function, default value-based)
   - Rule chaining with first-match semantics
   - HTTP location mapping (JSON body, path, query, headers, cookies, etc.)
   - Composable rules with AND/OR logic
   - Built-in fallback rules for Python builtins

2. **Configuration Layer** (`qh/config.py`)
   - Three-tier configuration hierarchy: global → app → function → parameter
   - `AppConfig` for application-wide settings
   - `RouteConfig` for per-function customization
   - Fluent `ConfigBuilder` API for complex scenarios
   - Smart defaults with override capability

3. **Endpoint Creation** (`qh/endpoint.py`)
   - Automatic parameter extraction from HTTP requests
   - Ingress/egress transformation application
   - Required parameter validation
   - Clear error messages with context
   - Support for async and sync functions

4. **Primary API** (`qh/app.py`)
   - Single `mk_app()` entry point
   - Multiple input formats (callable, list, dict)
   - Automatic FastAPI app creation
   - Route introspection (`inspect_routes`, `print_routes`)
   - Docstring → OpenAPI documentation

### Testing

All 12 tests passing:
- Simple function exposure
- Single and multiple functions
- Global and per-function configuration
- Required parameter validation
- Docstring extraction
- Dict and list return values
- Route introspection

### Examples

- `examples/quickstart.py` - Basic usage
- `examples/advanced_config.py` - Advanced configuration patterns

## What Works Right Now

```python
from qh import mk_app

def add(x: int, y: int) -> int:
    """Add two numbers."""
    return x + y

app = mk_app([add])
# That's it! You now have:
# - POST /add endpoint
# - Automatic JSON request/response handling
# - Type validation
# - OpenAPI docs at /docs
# - Error handling with clear messages
```

## What's Next (From the Plan)

### Phase 2: Conventions (Weeks 3-4)

**Not yet implemented but planned:**

1. **Smart Path Generation** (`qh/conventions.py`)
   - Function name parsing (get_user → GET /users/{user_id})
   - RESTful conventions from signatures
   - Verb-based HTTP method inference

2. **Enhanced Store/Object Dispatch**
   - Refactor existing `stores_qh.py` to use new system
   - Generic object method exposure
   - Nested resource patterns

3. **Type Registry** (`qh/types.py`)
   - Automatic serializer/deserializer generation
   - Support for NumPy, Pandas, custom types
   - Registration API for user types

### Phase 3: OpenAPI & Bidirectional (Weeks 5-6)

**Not yet implemented:**

1. **Enhanced OpenAPI Export**
   - Extended metadata (`x-python-signature`, etc.)
   - Python type preservation
   - Examples generation

2. **Client Generation** (`qh/client.py`)
   - Python client from OpenAPI
   - Signature preservation
   - Error handling

3. **JavaScript/TypeScript Support**
   - Client code generation
   - Type definitions

### Phase 4: Polish & Documentation (Weeks 7-8)

**Not yet implemented:**

1. Comprehensive documentation
2. Migration guide from py2http
3. Performance optimization
4. Production hardening

## Current Capabilities vs. Goals

| Feature | Status | Notes |
|---------|--------|-------|
| Function → HTTP endpoint | ✅ DONE | Core functionality working |
| Type-based transformations | ✅ DONE | Rule system in place |
| Parameter extraction | ✅ DONE | From JSON, path, query, headers |
| Configuration layers | ✅ DONE | Global, app, function, parameter |
| Error handling | ✅ DONE | Clear, actionable messages |
| OpenAPI docs | ✅ DONE | Auto-generated from docstrings |
| Convention-based routing | 🔄 TODO | Function name → path inference |
| Type registry | 🔄 TODO | NumPy, Pandas, custom types |
| Store/object dispatch | 🔄 TODO | Refactor existing code |
| Bidirectional transform | 🔄 TODO | HTTP → Python client |
| JS/TS clients | 🔄 TODO | Code generation |

## How to Use (Current State)

### Installation

```bash
# From repo root
export PYTHONPATH=/path/to/qh:$PYTHONPATH
```

### Basic Usage

```python
from qh import mk_app

# Single function
def greet(name: str) -> str:
    return f"Hello, {name}!"

app = mk_app(greet)

# Multiple functions
app = mk_app([func1, func2, func3])

# With configuration
app = mk_app(
    [func1, func2],
    config={'path_prefix': '/api/v1'}
)

# Per-function config
app = mk_app({
    func1: {'path': '/custom', 'methods': ['GET', 'POST']},
    func2: None,  # Use defaults
})
```

### Running

```bash
uvicorn your_module:app --reload
```

## Key Design Decisions

1. **Used `inspect.signature` instead of i2.Sig**: i2.Sig returns params as a list, not dict. For now using standard library, will integrate i2.Wrap more deeply later.

2. **JSON body as default**: All parameters default to JSON body extraction unless rules specify otherwise. This matches most API patterns.

3. **Explicit over implicit for now**: Haven't implemented automatic path inference yet. Better to have explicit, working code first.

4. **FastAPI-native**: No abstraction layer, direct FastAPI usage. Users get full FastAPI capabilities.

## Migration from Old qh

Old code using py2http still works:
```python
from qh.main import mk_http_service_app  # Old API
```

New code uses:
```python
from qh import mk_app  # New API
```

Both can coexist during transition.

## Summary

**Phase 1 is complete!** We have a solid foundation with:
- ✅ Rule-based transformation system
- ✅ Layered configuration
- ✅ Clean, simple API
- ✅ Full test coverage
- ✅ Working examples

Next steps are to add conventions (smart routing) and enhance type support.
