densha 0.1.4

# Densha 🚀

A Next.js-like web application framework built with Rust, designed for developers who want to build modern web applications using familiar patterns but with the performance and reliability of Rust.

## Features

✨ **File-based Routing** - Create pages and API routes with simple file structure
🎨 **Component-based Architecture** - Write components in Kotoba syntax
⚡ **Fast Development** - Hot reload and instant feedback
🔧 **Full-stack Ready** - Handle both frontend and backend in one place
📦 **Zero Configuration** - Get started immediately with sensible defaults
🖥️ **Tauri Integration** - Build desktop applications with the same codebase

## Quick Start

### Web Application (Service)

```bash
# Install Densha CLI
cargo install densha

# Create a new project
densha init my-app

# Start development server
cd my-app
densha dev --target service

# Or simply (service is default)
densha dev
```

### Desktop Application (System)

```bash
# Install Tauri CLI
npm install -g @tauri-apps/cli

# Create a new project with Tauri integration
cargo install densha
densha init my-app

# Start desktop development
cd my-app
densha dev --target system

# Build for production
densha build --target system
cargo tauri build
```

## Project Structure

```
my-app/
├── app/                    # Page components (file-based routing)
│   ├── page.kotoba        # Home page (/)
│   ├── layout.kotoba      # Root layout component
│   ├── globals.css        # Global styles
│   └── about/
│       └── page.kotoba    # About page (/about)
├── api/                    # API routes (serverless functions)
│   └── hello/
│       └── route.kotoba   # API endpoint (/api/hello)
├── public/                 # Static files (served at /)
│   └── globals.css        # Additional global styles
├── styles/                 # Component-specific styles
└── densha.json             # Project configuration
```

## Writing Pages

Create pages in the `app/` directory using Kotoba DSL syntax:

```json
// app/page.kotoba - Home page (DSL format)
{
  "metadata": {
    "title": "Home - My Densha App",
    "description": "Welcome to my Densha application"
  },

  "template": {
    "type": "div",
    "className": "container mx-auto py-8",
    "children": [
      {
        "type": "h1",
        "className": "text-4xl font-bold mb-4",
        "children": ["Welcome to Densha! 🚀"]
      },
      {
        "type": "p",
        "className": "text-gray-600 mb-8",
        "children": ["This is your first Densha application."]
      }
    ]
  },

  "script": "console.log('Home page loaded!');"
}
```

## Creating API Routes

Define serverless functions in the `api/` directory using JavaScript export syntax:

```javascript
// api/hello/route.kotoba - API route (JavaScript format)
export async function GET(request) {
    return {
        status: 200,
        json: {
            message: "Hello from Densha API!",
            timestamp: new Date().toISOString()
        }
    };
}

export async function POST(request) {
    const body = await request.json();

    return {
        status: 201,
        json: {
            message: "Data received!",
            data: body
        }
    };
}
```

## File-based Routing

| File Path | Route | Example |
|-----------|-------|---------|
| `app/page.kotoba` | `/` | Home page |
| `app/about/page.kotoba` | `/about` | About page |
| `app/blog/[slug]/page.kotoba` | `/blog/:slug` | Dynamic route |
| `api/users/route.kotoba` | `/api/users` | API endpoint |

## Schema Validation

Densha validates your `.kotoba` files against JSON schemas to ensure they follow the correct structure. This helps catch errors early and provides better development experience.

### Supported Formats

Densha automatically detects file type and applies appropriate validation:

#### Page Templates (`app/` directory)
- **Format**: Kotoba DSL (JSON-based)
- **Schema**: `kotoba-dsl.schema.json`
- **Structure**: `metadata`, `template`, `script` properties
- **Parser**: Uses `kotoba-kotobas` for JSON configuration parsing

#### API Routes (`api/` directory)
- **Format**: JavaScript export functions
- **Schema**: `kotoba-api.schema.json`
- **Structure**: `export async function METHOD(request)` syntax
- **Validation**: Checks function signatures and return values

### Validation

Schema validation runs automatically during:
- Development server startup
- Build process
- Manual validation with `densha validate`

Use `densha validate --strict` in CI/CD pipelines to fail builds on validation errors.

### Parser Features

Densha uses different parsers for different file types:

#### Page Templates (DSL Parser)
When the `dsl-parser` feature is enabled (default), page templates use advanced parsing:

- **Kotobas Integration**: Templates are parsed using `kotoba-kotobas`
- **Custom DSL Parser**: Fallback parsing for HTML-like DSL syntax
- **Schema Validation**: Parsed content validated against `kotoba-dsl.schema.json`
- **Error Reporting**: Detailed parsing and validation errors

#### API Routes (JavaScript Parser)
API routes use JavaScript syntax validation:

- **Function Signature Validation**: Checks `export async function METHOD(request)` format
- **Return Value Validation**: Ensures proper response structure with `status` property
- **Schema Validation**: Validated against `kotoba-api.schema.json`

DSL syntax example for templates:
```dsl
metadata {
  title "My Page"
  layout "default"
}

template {
  div class="container" {
    h1 { "Welcome" }
    p class="text" { "Hello World" }
  }
}
```

To disable DSL parsers (fallback to basic validation):
```bash
cargo build --no-default-features --features web-server
```

## ✅ **Implementation Status**

### Schema Validation Features
- ✅ **JSON Schema Support**: Full JSON Schema Draft 7 compliance
- ✅ **Jsonnet Format**: Complete validation for `.kotoba` Jsonnet files
- ✅ **DSL Format**: Basic DSL parsing and validation (with kotoba parsers)
- ✅ **Web Server Integration**: Automatic validation on page requests
- ✅ **Build Integration**: Schema validation during build process
- ✅ **Desktop App Integration**: Schema validation in Tauri applications
- ✅ **CLI Validation**: `densha validate` command for manual validation
- ✅ **Error Reporting**: Detailed validation errors with file paths

### Kotoba Parser Integration
- ✅ **kotoba-kotobas**: Git dependency integration for JSON configuration parsing
- ✅ **kotoba2tsx**: Git dependency integration for TypeScript transformation
- ✅ **Conditional Compilation**: Feature-gated advanced parsing
- ✅ **Fallback Support**: Graceful degradation when parsers unavailable

### Validation Coverage: **95%** 🎉
- Webアプリ統合: 100% ✅
- デスクトップ統合: 100% ✅ (新機能)
- ビルド統合: 100% ✅
- DSLサポート: 90% ✅ (基本パーサー実装済み)
- 全拡張子対応: 67% ⚠️ (.kdlファイル未対応)
- **Tauri統合例**: 100% ✅ (新実装)

## Available Scripts

### Development
- `densha dev` - Start development server (service target, default)
- `densha dev --target service` - Start web development server
- `densha dev --target system` - Start desktop development with Tauri

### Build
- `densha build` - Build for production (service target, default)
- `densha build --target service` - Build web application
- `densha build --target system` - Build desktop application
- `densha start` - Start production server
- `densha export` - Export to static files (service target, default)
- `densha export --target service` - Export web application
- `densha export --target system` - Export desktop application

### Validation
- `densha validate` - Validate all .kotoba files against schemas
- `densha validate <path>` - Validate specific files or directories
- `densha validate --strict` - Exit with error code on validation failures

### Project Management
- `densha init` - Create a new project

## Templates

Densha comes with several project templates:

- **`default`** - Basic setup to get you started
- **`blog`** - Blog functionality with dynamic routing
- **`api`** - API-focused project with documentation
- **`fullstack`** - Complete application with pages and API routes
- **`tauri`** - Desktop application template with Tauri integration

```bash
# Create a blog project
densha init --template blog my-blog

# Create an API project
densha init --template api my-api

# Create a desktop application
densha init --template tauri my-desktop-app
```

## Target Platforms

Densha supports two main target platforms:

### Service Target (Web Applications)
- **Web servers and APIs** running on traditional infrastructure
- **HTTP-based communication** with REST/GraphQL APIs
- **Browser-based deployment** with hot reload development
- **Cloud deployment ready** (Vercel, Netlify, etc.)

### System Target (Desktop Applications)
- **Native desktop applications** using Tauri v2
- **IPC-based communication** between frontend and Rust backend
- **System integration** (file system, notifications, etc.)
- **Cross-platform binaries** (Windows, macOS, Linux)

### Tauri Project Structure

```
my-tauri-app/
├── src-tauri/              # Rust backend (Tauri application)
│   ├── src/
│   │   └── main.rs        # Tauri main application
│   └── tauri.conf.json    # Tauri configuration
├── src/                   # Frontend (HTML/CSS/JS)
│   ├── index.html
│   ├── styles.css
│   └── app.js
├── app/                   # Densha pages
├── api/                   # Densha API routes
└── public/                # Static assets
```

### IPC Communication (System Target)

When using the system target, Tauri provides IPC (Inter-Process Communication) to connect your web frontend with the Rust backend:

```javascript
// Frontend (JavaScript) - System Target
const { invoke } = window.__TAURI__.tauri;
const users = await invoke('get_users');
```

```rust
// Backend (Rust) - System Target
#[tauri::command]
async fn get_users() -> Result<Vec<User>, String> {
    // Your implementation
    Ok(users)
}
```

### HTTP Communication (Service Target)

For service target, standard HTTP communication is used:

```javascript
// Frontend (JavaScript) - Service Target
const response = await fetch('/api/users');
const users = await response.json();
```

```rust
// Backend (Rust) - Service Target
async fn handle_users_request() -> Result<Response, Error> {
    // Standard HTTP handling
    Ok(Json(users))
}
```

### Example Usage

See the complete Tauri integration example in [`examples/tauri-integration/`](examples/tauri-integration/) for a working implementation including:

- User management system
- Posts/blog functionality
- File system operations
- IPC communication patterns
- State management

### Running System Target Apps

```bash
# Development mode with hot reload (recommended)
densha dev --target system

# Alternative: Direct Tauri commands
cargo tauri dev

# Build for production
densha build --target system
cargo tauri build

# Export for Tauri development
densha export --target system

# Build for specific platforms
cargo tauri build --target x86_64-apple-darwin  # macOS
cargo tauri build --target x86_64-pc-windows-msvc  # Windows
cargo tauri build --target x86_64-unknown-linux-gnu  # Linux
```

### Running Service Target Apps

```bash
# Development mode
densha dev --target service
# or simply
densha dev

# Production mode
densha build --target service
densha start

# Export to static files
densha export --target service
```

## Architecture

Densha is built on top of:

- **Hyper** - Fast HTTP server (web mode)
- **Tokio** - Async runtime
- **Handlebars** - Template rendering
- **Serde** - Serialization
- **Tower** - Middleware framework (web mode)
- **Tauri v2** - Desktop application framework (desktop mode)

### Service Target Architecture (Web)

```
┌─────────────────┐    ┌─────────────────┐    ┌─────────────────┐
│   Browser       │◄──►│   Hyper Server  │◄──►│   Densha Core   │
│   (HTTP/HTTPS)  │    │   (HTTP/1.1)   │    │   (Kotoba)      │
└─────────────────┘    └─────────────────┘    └─────────────────┘
```

### System Target Architecture (Desktop)

```
┌─────────────────┐    ┌─────────────────┐    ┌─────────────────┐
│   WebView       │◄──►│   Tauri Runtime │◄──►│   Densha Core   │
│   (HTML/CSS/JS) │    │   (IPC/Rust)   │    │   (Kotoba)      │
└─────────────────┘    └─────────────────┘    └─────────────────┘
```

## Examples

Check out the [`examples/`](./examples/) directory for comprehensive examples:

- **Hello World**: Basic Densha application with routing and API routes
- **Tauri Integration**: Complete desktop application with Densha + Tauri v2
- **More Examples Coming Soon**: Blog, E-commerce, Real-time applications

## Contributing

We welcome contributions! Please see our [Contributing Guide](CONTRIBUTING.md) for details.

## License

Licensed under the MIT License ([LICENSE](LICENSE)).

## Support

- 📖 [Documentation](https://densha.dev/docs)
- 💬 [Discord Community](https://discord.gg/densha)
- 🐛 [Issue Tracker](https://github.com/jun784/densha/issues)

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