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+.idea
+build/
+test/

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+module git.sophuwu.com/qrstr
+
+go 1.24.2
+
+require github.com/boombuler/barcode v1.0.2

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+github.com/boombuler/barcode v1.0.2 h1:79yrbttoZrLGkL/oOI8hBrUKucwOL0oOjUgEguGMcJ4=
+github.com/boombuler/barcode v1.0.2/go.mod h1:paBWMcWSl3LHKBqUq+rly7CNSldXjb2rDl3JlRe0mD8=

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+package qrstr
+
+/*
+ * This file is to turn strings into unicode or html qr codes.
+ * Author: sophuwu <sophie@skisiel.com>
+ * Feel free to use this code in any way you want.
+ * Just call QR("string", header bool, html bool) to get a qr code.
+ * The header will display the string above the qr code.
+ */
+
+import (
+	"fmt"
+	"github.com/boombuler/barcode/qr"
+	"image"
+	"image/color"
+	"slices"
+	"strings"
+)
+
+// utf8r aliases rune
+type utf8r rune
+
+// String returns the plain text or html representation of the rune
+func (u utf8r) String(html bool) string {
+	if html {
+		return fmt.Sprintf("<td>&#x%x;</td>", u)
+	}
+	return string(u)
+}
+
+const blank rune = ' '
+const upper rune = '▀'
+const lower rune = '▄'
+const whole rune = '█'
+
+// pad returns a string with the given length
+func pad(n int, r ...rune) string {
+	if n == 0 {
+		return ""
+	}
+	if n < 0 {
+		n = 1
+	}
+	if len(r) == 0 {
+		return strings.Repeat(string(whole), n)
+	}
+	return strings.Repeat(string(r[0]), n)
+}
+
+type runeCol []rune
+
+func (c *runeCol) getRune(top, bot color.Color) rune {
+	return (*c)[func() int {
+		i := 0
+		if top == color.Black {
+			i |= 1
+		}
+		if bot == color.Black {
+			i |= 2
+		}
+		return i
+	}()]
+}
+
+func (c *runeCol) addRune(s *string, top, bot color.Color) {
+	*s += string(c.getRune(top, bot))
+}
+
+var lightMode = runeCol{blank, upper, lower, whole}
+var darkMode = runeCol{whole, lower, upper, blank}
+
+// wrap wraps text around a newline, hard wrapping at the given width
+// but trying to soft wrap if possible
+func wrap(w int, s ...string) []string {
+	var line = ""
+	var lines, b []string
+	var v string
+	var i, j int
+	w--
+	for _, l := range s {
+		if len(l) < w {
+			lines = append(lines, l)
+			continue
+		}
+
+		b = strings.Split(l, " ")
+		for i, v = range b {
+			if len(v) > w {
+				for j = 0; j < len(v); j += w {
+					if j+w < len(v) {
+						lines = append(lines, v[j:j+w]+"-")
+					} else {
+						line = v[j:] + " "
+					}
+				}
+				continue
+			}
+			if len(line)+len(v) < w {
+				line += v + " "
+			} else {
+				lines = append(lines, strings.TrimSuffix(line, " "))
+				line = ""
+				continue
+			}
+			if i == len(b)-1 {
+				lines = append(lines, strings.TrimSuffix(line, " "))
+				line = ""
+				continue
+			}
+		}
+	}
+
+	return slices.Clip(lines)
+}
+
+type qrEncoder struct {
+	strFunc func(rc *runeCol, code *image.Image, headers *[]string) (string, error)
+	rc      *runeCol
+	errCorr errorCorrectionLevel
+}
+
+func (q *qrEncoder) Encode(data string, header ...string) (string, error) {
+	strFunc := q.strFunc
+	if strFunc == nil {
+		return "", fmt.Errorf("encoder misconfigured, use NewEncoder when creating it")
+	}
+	var code image.Image
+	var err error
+	code, err = qr.Encode(data, qr.ErrorCorrectionLevel((*q).errCorr), qr.Auto)
+	if err != nil {
+		return "", err
+	}
+	return strFunc(q.rc, &code, &header)
+}
+
+func text(rc *runeCol, code *image.Image, headers *[]string) (string, error) {
+	if rc == nil || code == nil {
+		return "", fmt.Errorf("encoder misconfigured, use NewEncoder when creating it")
+	}
+	var output = ""
+	dx := (*code).Bounds().Dx()
+	dy := (*code).Bounds().Dy()
+	wr := rc.getRune(color.White, color.White)
+	prefix := ""
+	suffix := "\n"
+
+	hashead := headers != nil && len(*headers) > 0
+
+	if hashead {
+		output += fmt.Sprintln(string(whole) + pad(dx+2, upper) + string(whole))
+		for _, v := range wrap(dx, *headers...) {
+			v = v + pad(dx-len(v)+1, blank) + string(whole)
+			v = string(whole) + string(blank) + v
+			output += v + "\n"
+		}
+
+		output += string(whole) + pad(dx+2, lower) + string(whole) + "\n" + string(whole) + pad(dx+2, wr) + string(whole) + "\n"
+		prefix = string(whole) + string(wr)
+		suffix = string(wr) + string(whole) + "\n"
+	}
+
+	output += prefix
+	prefix = suffix + prefix
+
+	var y, x int
+	for y = 0; y < dy-dy%2; y += 2 {
+		for x = 0; x < dx; x++ {
+			rc.addRune(&output, (*code).At(x, y), (*code).At(x, y+1))
+		}
+		output += prefix
+	}
+	if dy%2 == 1 {
+		for x = 0; x < dx; x++ {
+			rc.addRune(&output, (*code).At(x, y), color.White)
+		}
+		output += suffix
+	} else {
+		output = strings.TrimSuffix(output, prefix) + suffix
+	}
+
+	if hashead {
+		output += string(whole) + pad(dx+2, lower) + string(whole) + "\n"
+	}
+
+	return output, nil
+}
+
+func html(rc *runeCol, code *image.Image, headers *[]string) (string, error) {
+	var output = ""
+	return output, nil
+}
+
+type encoderType int
+type errorCorrectionLevel qr.ErrorCorrectionLevel
+
+const (
+	// TextDarkMode makes qr codes for printing on dark backgrounds with white text,
+	// like a terminal or a screen with dark/night mode enabled.
+	// MUST BE PRINTED/DISPLAYED USING A MONOSPACE FONT.
+	TextDarkMode encoderType = 0
+	// TextLightMode makes qr codes for printing on light backgrounds with black text,
+	// like paper or a screen with light mode.
+	// MUST BE PRINTED/DISPLAYED USING A MONOSPACE FONT.
+	TextLightMode encoderType = 1
+	// HTMLMode makes qr codes for embedding in HTML documents or web pages.
+	// Generates a table using HTML tags, does not require a monospace font.
+	HTMLMode encoderType = 2
+
+	// ErrorCorrection7Percent indicates 7% of lost data can be recovered, makes the qr code smaller
+	ErrorCorrection7Percent errorCorrectionLevel = 0
+	// ErrorCorrection15Percent indicates 15% of lost data can be recovered, default
+	ErrorCorrection15Percent errorCorrectionLevel = 1
+	// ErrorCorrection25Percent indicates 25% of lost data can be recovered, makes the qr code bigger
+	ErrorCorrection25Percent errorCorrectionLevel = 2
+	// ErrorCorrection30Percent indicates 30% of lost data can be recovered, makes the qr code very big
+	ErrorCorrection30Percent errorCorrectionLevel = 3
+)
+
+// NewEncoder returns a new qrEncoder code with the given data and headers
+func NewEncoder(encoderType encoderType, errorCorrectionLevel errorCorrectionLevel) (*qrEncoder, error) {
+	var q qrEncoder
+	switch encoderType {
+	case TextDarkMode:
+		q.rc = &darkMode
+		q.strFunc = text
+		break
+	case TextLightMode:
+		q.rc = &lightMode
+		q.strFunc = text
+		break
+	case HTMLMode:
+		q.strFunc = html
+		break
+	default:
+		return nil, fmt.Errorf("invalid encoder type: %d", encoderType)
+	}
+	if errorCorrectionLevel < 0 || errorCorrectionLevel > 3 {
+		return nil, fmt.Errorf("invalid error correction level: %d", errorCorrectionLevel)
+	}
+	q.errCorr = errorCorrectionLevel
+	return &q, nil
+}