package main

import (
	"io/ioutil"
	"os"
	"path/filepath"
)

type Index struct {
	Files map[string][]byte
	Dirs  map[string][]string
}

func NewIndex() *Index {
	return &Index{
		Files: map[string][]byte{},
		Dirs:  map[string][]string{},
	}
}

// ReadDir reads a directory and indexes the files and directories within it.
func (index *Index) ReadDir(srcDir string, dstDir string) error {
	entries, err := ioutil.ReadDir(srcDir)
	if err != nil {
		return err
	}

	for _, entry := range entries {
		name := entry.Name()
		srcPath := filepath.Join(srcDir, name)
		dstPath := filepath.Join(dstDir, name)

		if entry.IsDir() {
			index.Dirs[dstPath] = []string{}
			index.ReadDir(srcPath, dstPath)
		} else {
			content, err := ioutil.ReadFile(srcPath)
			if err != nil {
				return err
			}

			index.Files[dstPath] = content
			index.Dirs[dstDir] = append(index.Dirs[dstDir], dstPath)
		}
	}
	return nil
}

// Write writes the contents of the Index to the provided destination directory.
func (index *Index) Write(dstDir string) error {
	// Empty the destination directory
	if err := os.RemoveAll(dstDir); err != nil {
		return err
	}
	if err := os.MkdirAll(dstDir, 0755); err != nil {
		return err
	}

	for path := range index.Files {
		// Create any parent directories
		if dir := filepath.Dir(path); dir != "." {
			dstPath := filepath.Join(dstDir, dir)
			if err := os.MkdirAll(dstPath, 0755); err != nil {
				return err
			}
		}

		// Write the file
		dstPath := filepath.Join(dstDir, path)
		f, err := os.Create(dstPath)
		if err != nil {
			return err
		}
		data := index.Files[path]
		if _, err := f.Write(data); err != nil {
			return err
		}
	}
	return nil
}