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package pngmeta
import (
"bytes"
"elefant/models"
"encoding/base64"
"encoding/json"
"errors"
"io"
"os"
"path"
"strings"
)
const (
embType = "tEXt"
)
type PngEmbed struct {
Key string
Value string
}
func (c PngEmbed) GetDecodedValue() (*models.CharCardSpec, error) {
data, err := base64.StdEncoding.DecodeString(c.Value)
if err != nil {
return nil, err
}
card := &models.CharCardSpec{}
if err := json.Unmarshal(data, &card); err != nil {
return nil, err
}
return card, nil
}
func extractChar(fname string) (*PngEmbed, error) {
data, err := os.ReadFile(fname)
if err != nil {
return nil, err
}
reader := bytes.NewReader(data)
pr, err := NewPNGStepReader(reader)
if err != nil {
return nil, err
}
for {
step, err := pr.Next()
if err != nil {
if errors.Is(err, io.EOF) {
break
}
}
if step.Type() != embType {
if _, err := io.Copy(io.Discard, step); err != nil {
return nil, err
}
} else {
buf, err := io.ReadAll(step)
if err != nil {
return nil, err
}
dataInstep := string(buf)
values := strings.Split(dataInstep, "\x00")
if len(values) == 2 {
return &PngEmbed{Key: values[0], Value: values[1]}, nil
}
}
if err := step.Close(); err != nil {
return nil, err
}
}
return nil, errors.New("failed to find embedded char in png: " + fname)
}
func ReadCard(fname, uname string) (*models.CharCard, error) {
pe, err := extractChar(fname)
if err != nil {
return nil, err
}
charSpec, err := pe.GetDecodedValue()
if err != nil {
return nil, err
}
return charSpec.Simplify(uname, fname), nil
}
func ReadDirCards(dirname, uname string) ([]*models.CharCard, error) {
files, err := os.ReadDir(dirname)
if err != nil {
return nil, err
}
resp := []*models.CharCard{}
for _, f := range files {
if !strings.HasSuffix(f.Name(), ".png") {
continue
}
fpath := path.Join(dirname, f.Name())
cc, err := ReadCard(fpath, uname)
if err != nil {
// log err
return nil, err
// continue
}
resp = append(resp, cc)
}
return resp, nil
}
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