/*
   Copyright (c) 2020 gingfrederik
   Copyright (c) 2021 Gonzalo Fernandez-Victorio
   Copyright (c) 2021 Basement Crowd Ltd (https://www.basementcrowd.com)
   Copyright (c) 2023 Fumiama Minamoto (源文雨)

   This program is free software: you can redistribute it and/or modify
   it under the terms of the GNU Affero General Public License as published
   by the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU Affero General Public License for more details.

   You should have received a copy of the GNU Affero General Public License
   along with this program.  If not, see <https://www.gnu.org/licenses/>.
*/

package docx

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 = f.tmplfs.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(_ []byte) (int, 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
}