Make output file and format configurable (#24)

7 files changed, 195 insertions, 38 deletions

diff --git a/cmd/flyscrape/main.go b/cmd/flyscrape/main.go
index 8b9d430..9772648 100644
--- a/cmd/flyscrape/main.go
+++ b/cmd/flyscrape/main.go
@@ -15,7 +15,9 @@ import (
 	_ "github.com/philippta/flyscrape/modules/depth"
 	_ "github.com/philippta/flyscrape/modules/domainfilter"
 	_ "github.com/philippta/flyscrape/modules/followlinks"
-	_ "github.com/philippta/flyscrape/modules/jsonprint"
+	_ "github.com/philippta/flyscrape/modules/headers"
+	_ "github.com/philippta/flyscrape/modules/output/json"
+	_ "github.com/philippta/flyscrape/modules/output/ndjson"
 	_ "github.com/philippta/flyscrape/modules/proxy"
 	_ "github.com/philippta/flyscrape/modules/ratelimit"
 	_ "github.com/philippta/flyscrape/modules/starturl"
diff --git a/cmd/main.go b/cmd/main.go
index eab3e03..b4f8d1d 100644
--- a/cmd/main.go
+++ b/cmd/main.go
@@ -11,17 +11,6 @@ import (
 	"log"
 	"os"
 	"strings"
-
-	_ "github.com/philippta/flyscrape/modules/cache"
-	_ "github.com/philippta/flyscrape/modules/depth"
-	_ "github.com/philippta/flyscrape/modules/domainfilter"
-	_ "github.com/philippta/flyscrape/modules/followlinks"
-	_ "github.com/philippta/flyscrape/modules/headers"
-	_ "github.com/philippta/flyscrape/modules/jsonprint"
-	_ "github.com/philippta/flyscrape/modules/proxy"
-	_ "github.com/philippta/flyscrape/modules/ratelimit"
-	_ "github.com/philippta/flyscrape/modules/starturl"
-	_ "github.com/philippta/flyscrape/modules/urlfilter"
 )
 
 func main() {
diff --git a/cmd/run.go b/cmd/run.go
index 8c1a39d..a02b2ec 100644
--- a/cmd/run.go
+++ b/cmd/run.go
@@ -53,5 +53,11 @@ Examples:
 
     # Follow paginated links.
     $ flyscrape run example.js --depth 5 --follow ".next-button > a"
+
+    # Set the output format to ndjson.
+    $ flyscrape run example.js --output.format ndjson
+
+    # Write the output to a file.
+    $ flyscrape run example.js --output.file results.json
 `[1:])
 }
diff --git a/modules/output/json/json.go b/modules/output/json/json.go
new file mode 100644
index 0000000..5b4e9d0
--- /dev/null
+++ b/modules/output/json/json.go
@@ -0,0 +1,130 @@
+// 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 json
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"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"`
+
+	once bool
+	w    io.WriteCloser
+}
+
+func (Module) ModuleInfo() flyscrape.ModuleInfo {
+	return flyscrape.ModuleInfo{
+		ID:  "output.json",
+		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
+	}
+
+	if !m.once {
+		fmt.Fprintln(m.w, "[")
+		m.once = true
+	} else {
+		fmt.Fprintln(m.w, ",")
+	}
+
+	o := output{
+		URL:       resp.Request.URL,
+		Data:      resp.Data,
+		Timestamp: time.Now(),
+	}
+	if resp.Error != nil {
+		o.Error = resp.Error.Error()
+	}
+
+	var buf bytes.Buffer
+	enc := json.NewEncoder(&buf)
+	enc.SetEscapeHTML(false)
+	enc.SetIndent("  ", "  ")
+	enc.Encode(o)
+
+	fmt.Fprint(m.w, "  ")
+	fmt.Fprint(m.w, buf.String()[:buf.Len()-1])
+}
+
+func (m *Module) Finalize() {
+	if m.disabled() {
+		return
+	}
+	if m.once {
+		fmt.Fprintln(m.w, "\n]")
+	}
+	m.w.Close()
+}
+
+func (m *Module) disabled() bool {
+	return m.Output.Format != "json" && m.Output.Format != ""
+}
+
+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)
+)
diff --git a/modules/jsonprint/jsonprint.go b/modules/output/ndjson/ndjson.go
index c40a8b9..956b2ed 100644
--- a/modules/jsonprint/jsonprint.go
+++ b/modules/output/ndjson/ndjson.go
@@ -2,10 +2,13 @@
 // 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 jsonprint
+package ndjson
 
 import (
-	"fmt"
+	"encoding/json"
+	"io"
+	"log"
+	"os"
 	"time"
 
 	"github.com/philippta/flyscrape"
@@ -16,26 +19,46 @@ func init() {
 }
 
 type Module struct {
-	once bool
+	Output struct {
+		Format string `json:"format"`
+		File   string `json:"file"`
+	} `json:"output"`
+
+	w io.WriteCloser
 }
 
 func (Module) ModuleInfo() flyscrape.ModuleInfo {
 	return flyscrape.ModuleInfo{
-		ID:  "jsonprint",
+		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 resp.Error == nil && resp.Data == nil {
+	if m.disabled() {
 		return
 	}
 
-	if !m.once {
-		fmt.Println("[")
-		m.once = true
-	} else {
-		fmt.Println(",")
+	if resp.Error == nil && resp.Data == nil {
+		return
 	}
 
 	o := output{
@@ -47,13 +70,20 @@ func (m *Module) ReceiveResponse(resp *flyscrape.Response) {
 		o.Error = resp.Error.Error()
 	}
 
-	fmt.Print(flyscrape.Prettify(o, "  "))
+	enc := json.NewEncoder(m.w)
+	enc.SetEscapeHTML(false)
+	enc.Encode(o)
 }
 
 func (m *Module) Finalize() {
-	if m.once {
-		fmt.Println("\n]")
+	if m.disabled() {
+		return
 	}
+	m.w.Close()
+}
+
+func (m *Module) disabled() bool {
+	return m.Output.Format != "ndjson"
 }
 
 type output struct {
@@ -63,7 +93,20 @@ type output struct {
 	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)
 )
diff --git a/scrape.go b/scrape.go
index 4de36d8..3e38e46 100644
--- a/scrape.go
+++ b/scrape.go
@@ -14,8 +14,6 @@ import (
 	"github.com/cornelk/hashmap"
 )
 
-type FetchFunc func(url string) (string, error)
-
 type Context interface {
 	ScriptName() string
 	Visit(url string)
diff --git a/utils.go b/utils.go
index f26dc6c..eda38d5 100644
--- a/utils.go
+++ b/utils.go
@@ -5,8 +5,6 @@
 package flyscrape
 
 import (
-	"bytes"
-	"encoding/json"
 	"fmt"
 	"io"
 	"net/http"
@@ -15,15 +13,6 @@ import (
 
 const HeaderBypassCache = "X-Flyscrape-Bypass-Cache"
 
-func Prettify(v any, prefix string) string {
-	var buf bytes.Buffer
-	enc := json.NewEncoder(&buf)
-	enc.SetEscapeHTML(false)
-	enc.SetIndent(prefix, "  ")
-	enc.Encode(v)
-	return prefix + strings.TrimSuffix(buf.String(), "\n")
-}
-
 type RoundTripFunc func(*http.Request) (*http.Response, error)
 
 func (f RoundTripFunc) RoundTrip(r *http.Request) (*http.Response, error) {