package fs

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

	"github.com/spf13/afero"
	"opslag.de/schobers/zntg"
	"opslag.de/schobers/zntg/ui"
)

type aferoResources struct {
	dir  string
	fs   afero.Fs
	copy *zntg.Dir
}

var _ ui.Resources = &aferoResources{}

// NewAferoResources provides resources from a afero file system. The prefix is used as a prefix of the temporary directory.
func NewAferoResources(fs afero.Fs, prefix string) (ui.Resources, error) {
	return NewAferoFallbackResources("", fs, prefix)
}

// NewAferoFallbackResources provides resources from the directory first and uses afero file system as a fallback if the resource in the directory doesn't exist. The prefix is used as a prefix of the temporary directory.
func NewAferoFallbackResources(dir string, fs afero.Fs, prefix string) (ui.Resources, error) {
	copy, err := zntg.NewTempDir(prefix)
	if err != nil {
		return nil, err
	}
	return &aferoResources{dir, fs, copy}, nil
}

func (r *aferoResources) fetchAferoResource(name string) (string, error) {
	path := r.copy.FilePath(name)
	if !zntg.FileExists(path) {
		src, err := r.fs.Open(name)
		if err != nil {
			return "", err
		}
		defer src.Close()

		err = r.copy.Write(name, src)
		if err != nil {
			return "", err
		}
	}
	return path, nil
}

func (r *aferoResources) openAferoResource(name string) (io.ReadCloser, error) { return r.fs.Open(name) }

func (r *aferoResources) Destroy() error { return r.copy.Destroy() }

func (r *aferoResources) FetchResource(name string) (string, error) {
	if r.dir == "" {
		return r.fetchAferoResource(name)
	}
	path := filepath.Join(r.dir, name)
	if zntg.FileExists(path) {
		return path, nil
	}
	return r.fetchAferoResource(name)
}

func (r *aferoResources) OpenResource(name string) (io.ReadCloser, error) {
	if r.dir == "" {
		return r.openAferoResource(name)
	}
	path := filepath.Join(r.dir, name)
	if zntg.FileExists(path) {
		return os.Open(path)
	}
	return r.openAferoResource(name)
}