package main

import (
	"fmt"
	"os"
	"path/filepath"
	"text/template"
)

func apply(args []string) error {
	if len(args) != 0 {
		return applyFiles(args)
	}
	names, err := getFileNames()
	if err != nil {
		return err
	}
	return applyFiles(names)
}

func applyFiles(names []string) error {
	for _, name := range names {
		fmt.Printf("applying %s\n", name)
		if err := applyFile(name); err != nil {
			return fmt.Errorf("could not apply %s: %v", name, err)
		}
	}
	return nil
}

func applyFile(name string) error {
	src := filepath.Join(base, "templates", name)
	t, err := template.New(filepath.Base(name)).Funcs(buildFuncMap()).ParseFiles(src)
	if err != nil {
		return fmt.Errorf("could not build template: %v", err)
	}
	data, err := getTemplateData()
	if err != nil {
		return err
	}
	d := filepath.Join(dest, name)
	if err = os.MkdirAll(filepath.Dir(d), 0700); err != nil {
		return err
	}
	srcInfo, err := os.Stat(src)
	if err != nil {
		return err
	}
	out, err := os.OpenFile(d, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, srcInfo.Mode())
	if err != nil {
		return err
	}
	defer out.Close()
	if err = t.Execute(out, data); err != nil {
		return fmt.Errorf("could not execute template: %v", err)
	}
	return nil
}

func getFileNames() ([]string, error) {
	var names []string
	d := filepath.Join(base, "templates")
	err := filepath.Walk(d, func(path string, info os.FileInfo, err error) error {
		if err != nil {
			return err
		}
		if info.IsDir() {
			return nil
		}
		name, err := filepath.Rel(d, path)
		if err != nil {
			return err
		}
		names = append(names, name)
		return nil
	})
	if err != nil {
		return nil, err
	}
	return names, nil
}