# Text-to-Cypher Library Implementation Summary

## Overview

This implementation enables text-to-cypher to be used as a Rust library, not just as a REST API server. Users can now integrate text-to-cypher directly into their Rust applications without the overhead of REST API dependencies.

## Key Changes

### 1. Cargo.toml Configuration

**Added metadata for crates.io:**
- `readme`, `authors`, `homepage` fields
- Updated description to reflect library + API capabilities

**Feature-based dependency management:**
- Created `server` feature (enabled by default)
- Made REST API dependencies optional:
  - actix-web, actix-multipart, actix-web-lab
  - utoipa, utoipa-swagger-ui
  - dashmap, tokio-stream
  - rust-mcp-sdk, dotenvy, moka

**Binary configuration:**
- Added `required-features = ["server"]` to both binaries
- Prevents build errors when using `--no-default-features`

### 2. Public API (src/lib.rs)

**Created `TextToCypherClient` for high-level usage:**
```rust
let client = TextToCypherClient::new(
    "gpt-4o-mini",
    "your-api-key",
    "falkor://localhost:6379"
);

let response = client.text_to_cypher("graph_name", request).await?;
```

**Methods provided:**
- `text_to_cypher()` - Full processing: schema → query → execute → answer
- `cypher_only()` - Generate query only, no execution
- `discover_schema()` - Get graph schema as JSON

**Re-exported commonly used types:**
- `ChatRequest`, `ChatMessage`, `ChatRole`
- `TextToCypherRequest`, `TextToCypherResponse`
- `ErrorResponse`

**Added comprehensive documentation:**
- Module-level docs with examples
- Method-level docs with examples
- Usage patterns for different scenarios

### 3. Conditional Compilation

Made server-specific features conditional with `#[cfg(feature = "server")]`:

**Files updated:**
- `src/chat.rs` - Made `ToSchema` derive conditional
- `src/error.rs` - Made actix-web and utoipa imports conditional
- `src/schema/attribute.rs` - Made `ToSchema` derive conditional
- `src/schema/entity.rs` - Made `ToSchema` derive conditional
- `src/schema/relation.rs` - Made `ToSchema` derive conditional
- `src/schema/discovery.rs` - Made utoipa import conditional
- `src/lib.rs` - Made server modules conditional

**Pattern used:**
```rust
#[cfg(feature = "server")]
use utoipa::ToSchema;

#[derive(Serialize, Deserialize, Debug)]
#[cfg_attr(feature = "server", derive(ToSchema))]
pub struct MyStruct { ... }
```

### 4. Response Type Improvements

**Added helper methods to `TextToCypherResponse`:**
- `is_success()` - Check if response is successful
- `is_error()` - Check if response is an error

**Added TODOs for future improvements:**
- Consider using enum for status instead of String
- Consider creating specific error type instead of Box<dyn Error>

### 5. Example Code

**Created `examples/library_usage.rs` demonstrating:**
1. High-level `TextToCypherClient` usage
2. Using core functions directly for more control
3. Generating Cypher queries without execution

### 6. Documentation

**Updated README.md:**
- Added library usage quick start section
- Documented two usage modes (library vs server)
- Added publishing to crates.io instructions

**Created docs/LIBRARY_API.md:**
- Comprehensive API reference
- Detailed method documentation
- Usage examples for all scenarios
- Best practices and troubleshooting

## Usage Modes

### Library-Only Mode (Minimal Dependencies)

```toml
[dependencies]
text-to-cypher = { version = "0.1", default-features = false }
```

**Includes:**
- Core text-to-cypher functionality
- Schema discovery
- Query generation and execution
- Minimal dependencies (serde, tokio, genai, falkordb, etc.)

**Excludes:**
- REST API server
- Swagger/OpenAPI documentation
- MCP server
- Server-specific dependencies

### Full Server Mode (Default)

```toml
[dependencies]
text-to-cypher = "0.1"
```

**Includes everything from library mode plus:**
- REST API with actix-web
- Swagger UI documentation
- MCP server support
- All server infrastructure

## Build Verification

All build modes verified:
- ✓ Library-only: `cargo build --lib --no-default-features`
- ✓ Full server: `cargo build`
- ✓ Example: `cargo build --example library_usage --no-default-features`
- ✓ Clippy: No warnings
- ✓ Formatting: All code properly formatted

## Backward Compatibility

**100% backward compatible:**
- Default build includes all previous functionality
- REST API unchanged
- MCP server unchanged
- Docker deployments unchanged
- All existing configurations work as before

## Publishing to crates.io

**Ready for publishing:**
1. All required metadata present in Cargo.toml
2. Documentation complete
3. Examples provided
4. Tests pass
5. Code properly formatted

**To publish:**
```bash
cargo publish
```

## File Manifest

**Modified files:**
- `Cargo.toml` - Feature configuration and metadata
- `src/lib.rs` - Public API and client
- `src/chat.rs` - Conditional compilation
- `src/error.rs` - Conditional compilation
- `src/processor.rs` - Response helper methods
- `src/schema/attribute.rs` - Conditional compilation
- `src/schema/entity.rs` - Conditional compilation
- `src/schema/relation.rs` - Conditional compilation
- `src/schema/discovery.rs` - Conditional compilation
- `readme.md` - Library usage documentation

**New files:**
- `examples/library_usage.rs` - Usage examples
- `docs/LIBRARY_API.md` - API documentation

## Benefits

1. **Flexible Integration**: Use as a library or REST API
2. **Reduced Dependencies**: Library mode has minimal dependencies
3. **Type Safety**: Strong Rust type system throughout
4. **Performance**: Direct function calls without HTTP overhead
5. **Ease of Use**: High-level client for common use cases
6. **Fine-Grained Control**: Core functions available for advanced users
7. **Well Documented**: Comprehensive docs and examples
8. **Production Ready**: Error handling, validation, and logging included

## Next Steps

**For maintainers:**
1. Review and merge this PR
2. Publish to crates.io: `cargo publish`
3. Announce library availability

**For users:**
1. Add to Cargo.toml
2. See examples/library_usage.rs for usage patterns
3. Read docs/LIBRARY_API.md for full API reference

## Issue Resolution

This implementation fully addresses the requirements from the issue:

- ✅ Can be used from a Rust application (not just REST API)
- ✅ Ready to be published on crates.io
- ✅ Maintains backward compatibility with REST API mode
- ✅ Comprehensive documentation and examples
- ✅ Clean, well-documented public API
