llmgw/internal/kb/extract/odf.go

package extract

import (
	"errors"
	"fmt"
	"strconv"
)

// odfText reads an OpenDocument file (LibreOffice's ODT, ODS, ODP): its
// content.xml.
func odfText(b []byte) (string, error) {
	zr, err := openZip(b)
	if err != nil {
		return "", err
	}
	content, err := member(zr, "content.xml")
	if err != nil {
		return "", err
	}
	if content == nil {
		return "", errors.New("not an OpenDocument file: no content.xml")
	}
	return odfXML(content)
}

// flatODFText reads the single-file XML form (.fodt, .fods, .fodp).
func flatODFText(b []byte) (string, error) { return odfXML(b) }

// odfXML reads OpenDocument's text model, which all three kinds share:
// text:h with an outline level is a heading, text:p a paragraph, list items,
// table rows and cells, slides (draw:page) and sheets (table:table) named as
// headings.
func odfXML(b []byte) (string, error) {
	var o out
	skip, slide := 0, 0
	// Paragraphs inside a cell or a list item do not end the row or the list.
	inCell, inItem := 0, 0
	err := walkXML(b, func(e xmlEvent) {
		switch {
		case e.start:
			switch e.name {
			case "tracked-changes", "notes-configuration", "annotation", "frame-name":
				skip++
			case "h":
				lvl, _ := strconv.Atoi(e.get("outline-level"))
				o.heading(max(lvl, 1))
			case "list-item":
				inItem++
				o.item()
			case "table-cell":
				inCell++
			case "tab":
				o.raw("\t")
			case "s":
				n, _ := strconv.Atoi(e.get("c"))
				for range max(n, 1) {
					o.raw(" ")
				}
			case "line-break":
				o.newline()
			case "page":
				slide++
				o.heading(2)
				name := e.get("name")
				if name == "" || isDefaultPageName(name) {
					name = fmt.Sprintf("Slide %d", slide)
				}
				o.text(name)
				o.para()
			case "table":
				if n := e.get("name"); n != "" {
					o.heading(2)
					o.text(n)
					o.para()
				}
			}
		case e.end:
			switch e.name {
			case "tracked-changes", "notes-configuration", "annotation", "frame-name":
				skip--
			case "h", "p":
				switch {
				case inCell > 0:
					o.text(" ")
				case inItem > 0:
					o.newline()
				default:
					o.para()
				}
			case "list-item":
				inItem--
				o.newline()
			case "table-cell":
				inCell--
				o.tab()
			case "table-row":
				o.newline()
			case "table", "page":
				o.para()
			}
		default:
			if skip == 0 {
				o.raw(e.text)
			}
		}
	})
	return o.String(), err
}

// isDefaultPageName is LibreOffice's own name for an unnamed slide, "page1".
func isDefaultPageName(s string) bool {
	if len(s) < 5 || s[:4] != "page" {
		return false
	}
	_, err := strconv.Atoi(s[4:])
	return err == nil
}