snapshot of https://github.com/cortezaproject/corteza.git (2024.9.x, 2026-09-18; blobs > 131072B omitted)

server/pkg/envoy/csv/decoder.go

@@ -0,0 +1,123 @@
+package csv
+
+import (
+	"context"
+	"encoding/csv"
+	"io"
+	"strings"
+
+	"github.com/cortezaproject/corteza/server/pkg/envoy"
+	"github.com/cortezaproject/corteza/server/pkg/envoy/resource"
+	"github.com/gabriel-vasile/mimetype"
+)
+
+type (
+	// wrapper struct for csv related methods
+	decoder struct{}
+
+	// csv decoder wrapper for additional bits
+	reader struct {
+		header []string
+		count  uint64
+
+		cache      []map[string]string
+		cacheIndex int
+	}
+)
+
+// Decoder initializes and returns a fresh CSV decoder
+func Decoder() *decoder {
+	return &decoder{}
+}
+
+// CanDecodeFile determines if the file can be determined by this decoder
+func (y *decoder) CanDecodeFile(f io.Reader) bool {
+	m, err := mimetype.DetectReader(f)
+	if err != nil {
+		return false
+	}
+
+	return y.CanDecodeExt(m.Extension())
+}
+
+func (y *decoder) CanDecodeMime(m string) bool {
+	return m == "text/csv"
+}
+
+func (y *decoder) CanDecodeExt(ext string) bool {
+	pt := strings.Split(ext, ".")
+	return strings.TrimSpace(pt[len(pt)-1]) == "csv"
+}
+
+// Decode decodes the given io.Reader into a generic resource dataset
+func (c *decoder) Decode(ctx context.Context, r io.Reader, do *envoy.DecoderOpts) ([]resource.Interface, error) {
+	cr := &reader{
+		cacheIndex: 0,
+		cache:      make([]map[string]string, 0, 1000),
+	}
+
+	err := cr.prepare(r)
+	if err != nil {
+		return nil, err
+	}
+
+	return []resource.Interface{resource.NewResourceDataset(do.Name, cr)}, nil
+}
+
+// The prepare step caches all of the rows into a cache array that will be used
+// to access already visited CSV rows.
+//
+// @todo implement FS cache file for larger files
+func (cr *reader) prepare(r io.Reader) (err error) {
+	cReader := csv.NewReader(r)
+
+	// Header
+	cr.header, err = cReader.Read()
+	if err != nil {
+		return err
+	}
+
+	for {
+		aux := make(map[string]string)
+		rr, err := cReader.Read()
+		if err == io.EOF {
+			return nil
+		} else if err != nil {
+			return err
+		}
+
+		// Entry count
+		cr.count++
+
+		// Cache entry
+		for i, h := range cr.header {
+			aux[h] = rr[i]
+		}
+		cr.cache = append(cr.cache, aux)
+	}
+}
+
+// Fields returns every available field in this dataset
+func (cr *reader) Fields() []string {
+	return cr.header
+}
+
+func (cr *reader) Reset() error {
+	cr.cacheIndex = 0
+	return nil
+}
+
+// Next returns the field: value mapping for the next row
+func (cr *reader) Next() (map[string]string, error) {
+	if cr.cacheIndex >= len(cr.cache) {
+		return nil, nil
+	}
+
+	mr := cr.cache[cr.cacheIndex]
+	cr.cacheIndex++
+	return mr, nil
+}
+
+func (cr *reader) Count() uint64 {
+	return cr.count
+}