// Package pdftest builds small PDFs for the jz.bm tests. Only tests import
// it.
package pdftest

import (
	"bytes"
	"fmt"
	"strings"
)

// OnePage is a one-page PDF that shows text in the base-14 Helvetica font,
// so pdftotext extracts it without any embedded font. text must be ASCII
// and hold no parentheses or backslashes. The xref offsets are computed from
// the objects as written.
func OnePage(text string) []byte {
	if strings.ContainsAny(text, "()\\") {
		panic("pdftest: text holds a parenthesis or a backslash")
	}
	stream := "BT /F1 24 Tf 72 700 Td (" + text + ") Tj ET"
	objects := []string{
		"<< /Type /Catalog /Pages 2 0 R >>",
		"<< /Type /Pages /Kids [3 0 R] /Count 1 >>",
		"<< /Type /Page /Parent 2 0 R /MediaBox [0 0 612 792] /Contents 4 0 R /Resources << /Font << /F1 5 0 R >> >> >>",
		fmt.Sprintf("<< /Length %d >>\nstream\n%s\nendstream", len(stream), stream),
		"<< /Type /Font /Subtype /Type1 /BaseFont /Helvetica >>",
	}
	var b bytes.Buffer
	b.WriteString("%PDF-1.4\n")
	offsets := make([]int, len(objects))
	for i, obj := range objects {
		offsets[i] = b.Len()
		fmt.Fprintf(&b, "%d 0 obj\n%s\nendobj\n", i+1, obj)
	}
	xref := b.Len()
	fmt.Fprintf(&b, "xref\n0 %d\n", len(objects)+1)
	b.WriteString("0000000000 65535 f \n")
	for _, off := range offsets {
		fmt.Fprintf(&b, "%010d 00000 n \n", off)
	}
	fmt.Fprintf(&b, "trailer\n<< /Size %d /Root 1 0 R >>\nstartxref\n%d\n%%%%EOF\n", len(objects)+1, xref)
	return b.Bytes()
}