package extract

import (
	"bytes"
	"html"

	"io"
	"os"
	"text/template"
)

type BSQWriter struct {
	filepath string
	fio      *os.File
	w        io.Writer
	content  *EnviHdr
}

var HDRTemplate = `ENVI
description = {
  File Imported into ENVI.}
samples = {{.Samples}}
lines = {{.Lines}}
bands = {{.Bands}}
header offset = 0
file type = ENVI Standard
data type = 12
interleave = bsq
sensor type = Unknown
byte order = 0
wavelength units = Unknown`

// https://www.nv5geospatialsoftware.com/docs/ENVIHeaderFiles.html
type EnviHdr struct {
	Samples int // samples (pixels) each line
	Lines   int
	Bands   int
}

func (h *EnviHdr) String() string {
	var t *template.Template
	t = template.New("template")
	t, err := t.Parse(HDRTemplate)
	if err != nil {
		return ""
	}
	buf := new(bytes.Buffer)
	t.Execute(buf, h)
	buf = bytes.NewBufferString(html.UnescapeString(buf.String()))

	return buf.String()
}

func NewBSQWriter(filepath string, content *EnviHdr) (*BSQWriter, error) {
	fio, err := os.Create(filepath)
	if err != nil {
		return nil, err
	}
	w := fio
	return &BSQWriter{filepath, fio, w, content}, nil
}

func (w *BSQWriter) Write(data []byte) (int, error) {
	return w.w.Write(data)
}

func (w *BSQWriter) Close() error {
	return w.fio.Close()
}