Make output file and format configurable (#24)

1 files changed, 112 insertions, 0 deletions

diff --git a/modules/output/ndjson/ndjson.go b/modules/output/ndjson/ndjson.go
new file mode 100644
index 0000000..956b2ed
--- /dev/null
+++ b/modules/output/ndjson/ndjson.go
@@ -0,0 +1,112 @@
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+package ndjson
+
+import (
+	"encoding/json"
+	"io"
+	"log"
+	"os"
+	"time"
+
+	"github.com/philippta/flyscrape"
+)
+
+func init() {
+	flyscrape.RegisterModule(Module{})
+}
+
+type Module struct {
+	Output struct {
+		Format string `json:"format"`
+		File   string `json:"file"`
+	} `json:"output"`
+
+	w io.WriteCloser
+}
+
+func (Module) ModuleInfo() flyscrape.ModuleInfo {
+	return flyscrape.ModuleInfo{
+		ID:  "output.ndjson",
+		New: func() flyscrape.Module { return new(Module) },
+	}
+}
+
+func (m *Module) Provision(ctx flyscrape.Context) {
+	if m.disabled() {
+		return
+	}
+
+	if m.Output.File == "" {
+		m.w = nopCloser{os.Stdout}
+		return
+	}
+
+	f, err := os.Create(m.Output.File)
+	if err != nil {
+		log.Printf("failed to create file %q: %v", m.Output.File, err)
+		os.Exit(1)
+	}
+	m.w = f
+}
+
+func (m *Module) ReceiveResponse(resp *flyscrape.Response) {
+	if m.disabled() {
+		return
+	}
+
+	if resp.Error == nil && resp.Data == nil {
+		return
+	}
+
+	o := output{
+		URL:       resp.Request.URL,
+		Data:      resp.Data,
+		Timestamp: time.Now(),
+	}
+	if resp.Error != nil {
+		o.Error = resp.Error.Error()
+	}
+
+	enc := json.NewEncoder(m.w)
+	enc.SetEscapeHTML(false)
+	enc.Encode(o)
+}
+
+func (m *Module) Finalize() {
+	if m.disabled() {
+		return
+	}
+	m.w.Close()
+}
+
+func (m *Module) disabled() bool {
+	return m.Output.Format != "ndjson"
+}
+
+type output struct {
+	URL       string    `json:"url,omitempty"`
+	Data      any       `json:"data,omitempty"`
+	Error     string    `json:"error,omitempty"`
+	Timestamp time.Time `json:"timestamp,omitempty"`
+}
+
+type nopCloser struct {
+	io.Writer
+}
+
+func (c nopCloser) Write(p []byte) (n int, err error) {
+	return c.Writer.Write(p)
+}
+
+func (c nopCloser) Close() error {
+	return nil
+}
+
+var (
+	_ flyscrape.Provisioner      = (*Module)(nil)
+	_ flyscrape.ResponseReceiver = (*Module)(nil)
+	_ flyscrape.Finalizer        = (*Module)(nil)
+)