# Epic 0: Implementation Summary

## Overview

Epic 0 establishes the foundation of the Go Platform project with core infrastructure components that enable all future development. This epic includes project initialization, configuration management, structured logging, CI/CD pipeline, and dependency injection setup.

## Completed Stories

### ✅ 0.1 Project Initialization
- Go module initialized with proper module path
- Complete directory structure following Clean Architecture
- `.gitignore` configured for Go projects
- Comprehensive README with project overview

### ✅ 0.2 Configuration Management System
- `ConfigProvider` interface in `pkg/config/`
- Viper-based implementation in `internal/config/`
- YAML configuration files in `config/` directory
- Environment variable support with automatic mapping
- Type-safe configuration access methods

### ✅ 0.3 Structured Logging System
- `Logger` interface in `pkg/logger/`
- Zap-based implementation in `internal/logger/`
- JSON and console output formats
- Configurable log levels
- Request ID and context-aware logging support

### ✅ 0.4 CI/CD Pipeline
- GitHub Actions workflow for automated testing and linting
- Comprehensive Makefile with common development tasks
- Automated build and test execution

### ✅ 0.5 Dependency Injection and Bootstrap
- DI container using Uber FX in `internal/di/`
- Provider functions for core services
- Application entry point in `cmd/platform/main.go`
- Lifecycle management with graceful shutdown

## Verification Instructions

### Prerequisites
- Go 1.24 or later installed
- Make installed (optional, for using Makefile commands)

### 1. Verify Project Structure

```bash
# Check Go module
go mod verify

# Check directory structure
ls -la
# Should see: cmd/, internal/, pkg/, config/, docs/, etc.
```

### 2. Verify Configuration System

```bash
# Build the application
go build ./cmd/platform

# Check if config files exist
ls -la config/
# Should see: default.yaml, development.yaml, production.yaml

# Test config loading (will fail without database, but config should load)
# This will be tested in Epic 1 when database is available
```

### 3. Verify Logging System

```bash
# Run tests for logging
go test ./internal/logger/...

# Expected output: Tests should pass
```

### 4. Verify CI/CD Pipeline

```bash
# Run linting (if golangci-lint is installed)
make lint

# Run tests
make test

# Build the application
make build
# Binary should be created in bin/platform

# Run all checks
make check
```

### 5. Verify Dependency Injection

```bash
# Build the application
go build ./cmd/platform

# Check if DI container compiles
go build ./internal/di/...

# Run the application (will fail without database in Epic 1)
# go run ./cmd/platform/main.go
```

### 6. Verify Application Bootstrap

```bash
# Build the application
make build

# Check if binary exists
ls -la bin/platform

# The application should be ready to run (database connection will be tested in Epic 1)
```

## Testing Configuration

The configuration system can be tested by:

1. **Modifying config files**: Edit `config/default.yaml` and verify changes are loaded
2. **Environment variables**: Set `ENVIRONMENT=production` and verify production config is loaded
3. **Type safety**: Configuration access methods (`GetString`, `GetInt`, etc.) provide compile-time safety

## Testing Logging

The logging system can be tested by:

1. **Unit tests**: Run `go test ./internal/logger/...`
2. **Integration**: Logging will be tested in Epic 1 when HTTP server is available
3. **Format switching**: Change `logging.format` in config to switch between JSON and console output

## Common Issues and Solutions

### Issue: `go mod verify` fails
**Solution**: Run `go mod tidy` to update dependencies

### Issue: Build fails
**Solution**: Ensure Go 1.24+ is installed and all dependencies are downloaded (`go mod download`)

### Issue: Config not loading
**Solution**: Ensure `config/default.yaml` exists and is in the correct location relative to the binary

## Next Steps

After verifying Epic 0, proceed to [Epic 1](../epic1/SUMMARY.md) to set up the database and HTTP server, which will enable full end-to-end testing of the configuration and logging systems.