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