package main

import (
	"fmt"
	"io/ioutil"
	"os"
	"sort"

	"gopkg.in/yaml.v2"
)

func loadBangs() (bangs map[string]string) {
	data, err := ioutil.ReadFile("bangs.yml")
	if err != nil {
		panic(fmt.Sprintf("Failed to load bangs.yml: %v", err))
	}

	err = yaml.Unmarshal(data, &bangs)
	if err != nil {
		panic(fmt.Sprintf("Failed to decode bangs: %v", err))
	}

	return
}

func main() {
	bangs := loadBangs()

	// generating sorted keys to have stable generated code
	// this is not optimal, performance-wise but it runs only once at build
	// time, so it doesn’t matter that much)
	bangNames := []string{}
	for bang := range bangs {
		bangNames = append(bangNames, bang)
	}
	sort.Strings(bangNames)

	out, err := os.Create("bangs.go")
	if err != nil {
		panic(fmt.Sprintf("Failed to create bangs.go: %v", err))
	}

	out.Write([]byte("// Code generated from ../bangs.yml DO NOT EDIT.\n"))
	out.Write([]byte("package main \n\nfunc getBang(name string) string {\n\tswitch name {\n"))

	for _, bangName := range bangNames {
		out.Write([]byte("\t\tcase `" + bangName + "`: return `" + bangs[bangName] + "`\n"))
	}
	out.Write([]byte("\t\tdefault: return \"\"\n"))
	out.Write([]byte("\t}\n}\n"))
}