go-docx/pack.go

package docxlib

import (
	"archive/zip"
	"bytes"
	"encoding/xml"
	"io"
	"os"
)

// pack receives a zip file writer (word documents are a zip with multiple xml inside)
// and writes the relevant files. Some of them come from the empty_constants file,
// others from the actual in-memory structure
func (f *Docx) pack(zipWriter *zip.Writer) (err error) {
	files := make(map[string]io.Reader, 64)

	if f.template != "" {
		for _, name := range f.tmpfslst {
			files[name], err = TemplateXMLFS.Open("xml/" + f.template + "/" + name)
			if err != nil {
				return
			}
		}
	} else {
		for _, name := range f.tmpfslst {
			files[name], err = f.tmplfs.Open(name)
			if err != nil {
				return
			}
		}
	}

	files["word/_rels/document.xml.rels"] = marshaller{data: &f.docRelation}
	files["word/document.xml"] = marshaller{data: &f.Document}

	for _, m := range f.media {
		files[m.String()] = bytes.NewReader(m.Data)
	}

	for path, r := range files {
		w, err := zipWriter.Create(path)
		if err != nil {
			return err
		}

		_, err = io.Copy(w, r)
		if err != nil {
			return err
		}
	}

	return
}

type marshaller struct {
	data interface{}
	io.Reader
	io.WriterTo
}

// Read is fake and is to trigger io.WriterTo
func (m marshaller) Read(p []byte) (n int, err error) {
	return 0, os.ErrInvalid
}

// WriteTo n is always 0 for we don't care that value
func (m marshaller) WriteTo(w io.Writer) (n int64, err error) {
	_, err = io.WriteString(w, xml.Header)
	if err != nil {
		return
	}
	err = xml.NewEncoder(w).Encode(m.data)
	return
}