Added files from the first prototype.

cmd/csaf_provider/extract.go

@@ -0,0 +1,126 @@
+package main
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"errors"
+	"time"
+
+	"github.com/PaesslerAG/gval"
+	"github.com/PaesslerAG/jsonpath"
+
+	"github.com/intevation/csaf_trusted/csaf"
+)
+
+const (
+	idExpr                 = `$.document.tracking.id`
+	titleExpr              = `$.document.title`
+	publisherExpr          = `$.document.publisher`
+	initialReleaseDateExpr = `$.document.tracking.initial_release_date`
+	currentReleaseDateExpr = `$.document.tracking.current_release_date`
+	tlpLabelExpr           = `$.document.distribution.tlp.label`
+	summaryExpr            = `$.document.notes[? @.category=="summary" || @.type=="summary"].text`
+)
+
+type extraction struct {
+	id                 string
+	title              string
+	publisher          *csaf.CSAFPublisher
+	initialReleaseDate time.Time
+	currentReleaseDate time.Time
+	summary            string
+	tlpLabel           string
+}
+
+func newExtraction(content interface{}) (*extraction, error) {
+
+	builder := gval.Full(jsonpath.Language())
+
+	e := new(extraction)
+
+	for _, fn := range []func(*gval.Language, interface{}) error{
+		extractText(idExpr, &e.id),
+		extractText(titleExpr, &e.title),
+		extractTime(currentReleaseDateExpr, &e.currentReleaseDate),
+		extractTime(initialReleaseDateExpr, &e.initialReleaseDate),
+		extractText(summaryExpr, &e.summary),
+		extractText(tlpLabelExpr, &e.tlpLabel),
+		e.extractPublisher,
+	} {
+		if err := fn(&builder, content); err != nil {
+			return nil, err
+		}
+	}
+
+	return e, nil
+}
+
+func extractText(
+	expr string,
+	store *string,
+) func(*gval.Language, interface{}) error {
+	return func(builder *gval.Language, content interface{}) error {
+		eval, err := builder.NewEvaluable(expr)
+		if err != nil {
+			return err
+		}
+		s, err := eval(context.Background(), content)
+		if text, ok := s.(string); ok && err == nil {
+			*store = text
+		}
+		return nil
+	}
+}
+
+func extractTime(
+	expr string,
+	store *time.Time,
+) func(*gval.Language, interface{}) error {
+	return func(builder *gval.Language, content interface{}) error {
+		eval, err := builder.NewEvaluable(expr)
+		if err != nil {
+			return err
+		}
+		s, err := eval(context.Background(), content)
+		if err != nil {
+			return err
+		}
+		text, ok := s.(string)
+		if !ok {
+			return errors.New("not a string")
+		}
+		date, err := time.Parse(dateFormat, text)
+		if err == nil {
+			*store = date.UTC()
+		}
+		return err
+	}
+}
+
+func (e *extraction) extractPublisher(
+	builder *gval.Language,
+	content interface{},
+) error {
+	eval, err := builder.NewEvaluable(publisherExpr)
+	if err != nil {
+		return err
+	}
+	p, err := eval(context.Background(), content)
+	if err != nil {
+		return err
+	}
+
+	// XXX: It's a bit cumbersome to serialize and deserialize
+	// it into our own structure.
+	var buf bytes.Buffer
+	enc := json.NewEncoder(&buf)
+	if err := enc.Encode(p); err != nil {
+		return err
+	}
+	e.publisher = new(csaf.CSAFPublisher)
+	if err := json.Unmarshal(buf.Bytes(), e.publisher); err != nil {
+		return err
+	}
+	return e.publisher.Validate()
+}