Reorganize and enhance repository with production-ready structure

This commit completely restructures the Book API project following Go best practices and adds comprehensive enhancements:

## Project Structure
- Reorganized code into clean architecture with cmd/, internal/, and pkg/ directories
- Moved main entry point to cmd/api/main.go
- Created organized packages: handlers, models, storage, middleware, config
- Added interface-based storage layer for better testability and extensibility

## New Features
- Health check endpoint (/health) for monitoring
- Comprehensive middleware: logging, CORS, panic recovery
- Configuration management via environment variables
- Enhanced error handling with domain-specific errors
- Input validation for book models
- Thread-safe in-memory storage with proper mutex protection

## Testing
- Added unit tests for models (book validation)
- Added comprehensive storage tests including concurrency tests
- All tests passing with good coverage

## Documentation
- Comprehensive README with API documentation, usage examples, and setup instructions
- CONTRIBUTING.md guide for contributors
- Inline code documentation and godoc comments

## DevOps & Tooling
- Dockerfile with multi-stage build for optimal image size
- docker-compose.yml for easy deployment
- Makefile with common development tasks
- GitHub Actions CI/CD pipeline (test, build, lint)
- golangci-lint configuration for code quality
- Air configuration for hot reload during development
- Example .env file for configuration

## Code Quality
- Go module properly initialized
- Follows Go best practices and conventions
- Clean separation of concerns
- Proper error handling throughout
- Structured logging

The API now provides a solid foundation for a production-ready service with proper structure, testing, documentation, and deployment tooling.

Author: claude

.air.toml

@@ -0,0 +1,47 @@
+# Air configuration file for hot reload during development
+# Install air: go install github.com/cosmtrek/air@latest
+
+root = "."
+testdata_dir = "testdata"
+tmp_dir = "tmp"
+
+[build]
+  args_bin = []
+  bin = "./tmp/main"
+  cmd = "go build -o ./tmp/main ./cmd/api"
+  delay = 1000
+  exclude_dir = ["assets", "tmp", "vendor", "testdata"]
+  exclude_file = []
+  exclude_regex = ["_test.go"]
+  exclude_unchanged = false
+  follow_symlink = false
+  full_bin = ""
+  include_dir = []
+  include_ext = ["go", "tpl", "tmpl", "html"]
+  include_file = []
+  kill_delay = "0s"
+  log = "build-errors.log"
+  poll = false
+  poll_interval = 0
+  rerun = false
+  rerun_delay = 500
+  send_interrupt = false
+  stop_on_error = false
+
+[color]
+  app = ""
+  build = "yellow"
+  main = "magenta"
+  runner = "green"
+  watcher = "cyan"
+
+[log]
+  main_only = false
+  time = false
+
+[misc]
+  clean_on_exit = false
+
+[screen]
+  clear_on_rebuild = false
+  keep_scroll = true

.env.example

@@ -0,0 +1,5 @@
+# Server Configuration
+SERVER_PORT=8080
+
+# Logging Configuration
+LOG_LEVEL=info

.github/workflows/ci.yml

@@ -0,0 +1,87 @@
+name: CI
+
+on:
+  push:
+    branches: [ main, master, develop ]
+  pull_request:
+    branches: [ main, master, develop ]
+
+jobs:
+  test:
+    name: Test
+    runs-on: ubuntu-latest
+
+    steps:
+    - name: Checkout code
+      uses: actions/checkout@v4
+
+    - name: Set up Go
+      uses: actions/setup-go@v5
+      with:
+        go-version: '1.21'
+
+    - name: Cache Go modules
+      uses: actions/cache@v3
+      with:
+        path: ~/go/pkg/mod
+        key: ${{ runner.os }}-go-${{ hashFiles('**/go.sum') }}
+        restore-keys: |
+          ${{ runner.os }}-go-
+
+    - name: Download dependencies
+      run: go mod download
+
+    - name: Verify dependencies
+      run: go mod verify
+
+    - name: Run go vet
+      run: go vet ./...
+
+    - name: Run tests
+      run: go test -v -race -coverprofile=coverage.out -covermode=atomic ./...
+
+    - name: Upload coverage to Codecov
+      uses: codecov/codecov-action@v3
+      with:
+        files: ./coverage.out
+        flags: unittests
+        name: codecov-umbrella
+
+  build:
+    name: Build
+    runs-on: ubuntu-latest
+    needs: test
+
+    steps:
+    - name: Checkout code
+      uses: actions/checkout@v4
+
+    - name: Set up Go
+      uses: actions/setup-go@v5
+      with:
+        go-version: '1.21'
+
+    - name: Build
+      run: go build -v ./cmd/api
+
+    - name: Build Docker image
+      run: docker build -t book-api:latest .
+
+  lint:
+    name: Lint
+    runs-on: ubuntu-latest
+
+    steps:
+    - name: Checkout code
+      uses: actions/checkout@v4
+
+    - name: Set up Go
+      uses: actions/setup-go@v5
+      with:
+        go-version: '1.21'
+
+    - name: Run golangci-lint
+      uses: golangci/golangci-lint-action@v3
+      with:
+        version: latest
+        args: --timeout=5m

.gitignore

@@ -23,3 +23,14 @@ go.work.sum
 
 # env file
 .env
+
+# Build artifacts
+bin/
+tmp/
+
+# Coverage files
+coverage.out
+coverage.html
+
+# Air (live reload) logs
+build-errors.log

.golangci.yml

@@ -0,0 +1,33 @@
+# golangci-lint configuration file
+# See https://golangci-lint.run/usage/configuration/ for more options
+
+run:
+  timeout: 5m
+  tests: true
+  modules-download-mode: readonly
+
+linters:
+  enable:
+    - errcheck
+    - gosimple
+    - govet
+    - ineffassign
+    - staticcheck
+    - unused
+    - gofmt
+    - goimports
+    - misspell
+    - gocritic
+    - revive
+
+linters-settings:
+  govet:
+    check-shadowing: true
+  gofmt:
+    simplify: true
+  goimports:
+    local-prefixes: github.com/codeforgood-org/golang-book-api
+
+issues:
+  exclude-use-default: false
+  max-same-issues: 0

CONTRIBUTING.md

@@ -0,0 +1,193 @@
+# Contributing to Book API
+
+Thank you for your interest in contributing to the Book API project! This document provides guidelines and instructions for contributing.
+
+## Code of Conduct
+
+By participating in this project, you agree to maintain a respectful and inclusive environment for everyone.
+
+## How to Contribute
+
+### Reporting Bugs
+
+If you find a bug, please create an issue with:
+- A clear, descriptive title
+- Steps to reproduce the issue
+- Expected behavior
+- Actual behavior
+- Your environment (OS, Go version, etc.)
+
+### Suggesting Enhancements
+
+Enhancement suggestions are welcome! Please create an issue with:
+- A clear, descriptive title
+- Detailed description of the proposed feature
+- Rationale for why this enhancement would be useful
+- Possible implementation approach (optional)
+
+### Pull Requests
+
+1. **Fork the repository** and create your branch from `main`
+   ```bash
+   git checkout -b feature/amazing-feature
+   ```
+
+2. **Make your changes**
+   - Follow the project's coding style
+   - Write clear, concise commit messages
+   - Add tests for new functionality
+   - Update documentation as needed
+
+3. **Test your changes**
+   ```bash
+   make test
+   make lint
+   ```
+
+4. **Commit your changes**
+   ```bash
+   git commit -m "Add amazing feature"
+   ```
+
+5. **Push to your fork**
+   ```bash
+   git push origin feature/amazing-feature
+   ```
+
+6. **Open a Pull Request**
+   - Provide a clear description of the changes
+   - Reference any related issues
+   - Ensure all tests pass
+   - Wait for review
+
+## Development Setup
+
+### Prerequisites
+
+- Go 1.21 or higher
+- Git
+- Make (optional but recommended)
+
+### Setup Steps
+
+1. Clone your fork:
+   ```bash
+   git clone https://github.com/YOUR_USERNAME/golang-book-api.git
+   cd golang-book-api
+   ```
+
+2. Install dependencies:
+   ```bash
+   go mod download
+   ```
+
+3. Run tests:
+   ```bash
+   make test
+   ```
+
+4. Run the application:
+   ```bash
+   make run
+   ```
+
+## Coding Standards
+
+### Go Style Guide
+
+- Follow the official [Go Code Review Comments](https://github.com/golang/go/wiki/CodeReviewComments)
+- Use `gofmt` to format your code
+- Run `go vet` to check for common mistakes
+- Use meaningful variable and function names
+
+### Project Structure
+
+- **`cmd/`** - Application entry points
+- **`internal/`** - Private application code
+- **`pkg/`** - Public libraries
+- Keep packages focused and cohesive
+- Use interfaces for dependencies
+
+### Testing
+
+- Write unit tests for all new functionality
+- Aim for high test coverage
+- Use table-driven tests where appropriate
+- Mock external dependencies
+
+Example test:
+```go
+func TestBookValidate(t *testing.T) {
+    tests := []struct {
+        name    string
+        book    Book
+        wantErr bool
+    }{
+        // test cases
+    }
+
+    for _, tt := range tests {
+        t.Run(tt.name, func(t *testing.T) {
+            // test implementation
+        })
+    }
+}
+```
+
+### Documentation
+
+- Add godoc comments for public functions and types
+- Update README.md for significant changes
+- Include examples for complex functionality
+
+### Commit Messages
+
+Write clear commit messages:
+- Use present tense ("Add feature" not "Added feature")
+- Keep the first line under 50 characters
+- Add detailed description after a blank line if needed
+
+Good examples:
+```
+Add book validation logic
+
+Implement validation for book title and author fields.
+Returns appropriate error messages for invalid input.
+```
+
+## Testing Guidelines
+
+### Running Tests
+
+```bash
+# Run all tests
+make test
+
+# Run tests with coverage
+make test-cover
+
+# Run specific package tests
+go test ./internal/storage/...
+```
+
+### Writing Tests
+
+- Test public APIs
+- Test edge cases and error conditions
+- Use descriptive test names
+- Keep tests simple and focused
+
+## Review Process
+
+1. All pull requests require review before merging
+2. Address reviewer feedback
+3. Keep discussions professional and constructive
+4. CI checks must pass
+
+## Questions?
+
+If you have questions about contributing, feel free to:
+- Open an issue for discussion
+- Reach out to the maintainers
+
+Thank you for contributing!