package main

import (
	"flag"
	"fmt"
	"os"
	"path/filepath"
	"strings"
)

func main() {
	flag.Parse()
	args := flag.Args()

	if len(args) != 1 {
		fmt.Println("Usage: just-go <project-name>")
		os.Exit(1)
	}

	projectName := args[0]
	if strings.Contains(projectName, "/") || strings.Contains(projectName, "\\") {
		die(fmt.Errorf("keep it flat. no nested paths allowed"))
	}

	if err := os.Mkdir(projectName, 0755); err != nil {
		die(err)
	}

	createFile(projectName, "go.mod", fmt.Sprintf("module %s\n\ngo 1.23\n", projectName))
	
	createFile(projectName, "main.go", `package main

import "fmt"

func main() {
	if err := run(); err != nil {
		fmt.Println(err)
		os.Exit(1)
	}
}

func run() error {
	fmt.Println("Hello, world")
	return nil
}
`)

	createFile(projectName, "main_test.go", `package main

import "testing"

func TestSanity(t *testing.T) {
	// Standard library testing only.
	// If you need an assertion library, you are writing too much code.
	if 1+1 != 2 {
		t.Fatal("math is broken")
	}
}
`)

	createFile(projectName, "README.md", fmt.Sprintf("# %s\n\nGenerated by just-go. Keep it flat.\n", projectName))

	createFile(projectName, "Makefile", `.PHONY: run build test clean

run:
	go run main.go

build:
	go build -o bin/app main.go

test:
	go test -v ./...

clean:
	rm -rf bin
`)

	createFile(projectName, ".gitignore", "bin/\n*.exe\n*.test\n")

	fmt.Printf("Created %s. No subdirectories. Pure Go.\n", projectName)
}

func createFile(dir, name, content string) {
	path := filepath.Join(dir, name)
	if err := os.WriteFile(path, []byte(content), 0644); err != nil {
		die(err)
	}
}

func die(err error) {
	fmt.Fprintf(os.Stderr, "Error: %v\n", err)
	os.Exit(1)
}