From a252681b26c22d29e760dde1a4555109d0f46ac8 Mon Sep 17 00:00:00 2001
From: Andrey Shcherbinin <jynweythek223@gmail.com>
Date: Fri, 4 Jun 2021 08:50:12 +0000
Subject: [PATCH] Fix logger config and parser bugs; use scanner instead of
 reading request body at once

---
 .gitignore                      |  1 +
 internal/application/fetcher.go |  7 ++-----
 internal/application/parser.go  | 32 +++++++++++++++++++-------------
 internal/logger/logger.go       |  4 ++++
 4 files changed, 26 insertions(+), 18 deletions(-)

diff --git a/.gitignore b/.gitignore
index 476f2a0..e37f082 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,4 @@
 ._bin
 .vscode
 metricator.yaml
+.idea
diff --git a/internal/application/fetcher.go b/internal/application/fetcher.go
index 207c2c8..0a81013 100644
--- a/internal/application/fetcher.go
+++ b/internal/application/fetcher.go
@@ -1,7 +1,6 @@
 package application
 
 import (
-	"io/ioutil"
 	"net/http"
 	"time"
 )
@@ -44,15 +43,13 @@ func (a *Application) fetch() {
 
 	defer resp.Body.Close()
 
-	body, err := ioutil.ReadAll(resp.Body)
+	data, err := a.parse(resp.Body)
 	if err != nil {
-		a.logger.Infoln("Failed to read response body for", a.name, "metrics:", err.Error())
+		a.logger.Infoln("Failed to parse response body for", a.name, "metrics:", err.Error())
 
 		return
 	}
 
-	data := a.parse(string(body))
-
 	a.storage.Put(data)
 
 	a.fetchIsRunningMutex.Lock()
diff --git a/internal/application/parser.go b/internal/application/parser.go
index 3b631db..4a615f2 100644
--- a/internal/application/parser.go
+++ b/internal/application/parser.go
@@ -1,19 +1,27 @@
 package application
 
 import (
+	"bufio"
+	"fmt"
+	"io"
 	"strings"
 
 	"go.dev.pztrn.name/metricator/pkg/schema"
 )
 
-// Parses passed body and returns a map suitable for pushing into storage.
-func (a *Application) parse(body string) map[string]schema.Metric {
+// Parses io.Reader passed and returns a map suitable for pushing into storage.
+func (a *Application) parse(r io.Reader) (map[string]schema.Metric, error) {
 	data := make(map[string]schema.Metric)
 
-	// ToDo: switch to bytes buffer and maybe do not read body in caller?
-	splittedBody := strings.Split(body, "\n")
+	scanner := bufio.NewScanner(r)
+	for scanner.Scan() {
+		line := scanner.Text()
+
+		// Skip empty lines.
+		if line == "" {
+			continue
+		}
 
-	for _, line := range splittedBody {
 		// Prometheus line contains metric name and metric parameters defined
 		// in "{}".
 		var (
@@ -21,11 +29,6 @@ func (a *Application) parse(body string) map[string]schema.Metric {
 			params []string
 		)
 
-		// Skip empty lines.
-		if line == "" {
-			continue
-		}
-
 		a.logger.Debugln("Analyzing line:", line)
 
 		name = a.getMetricName(line)
@@ -80,19 +83,22 @@ func (a *Application) parse(body string) map[string]schema.Metric {
 			newMetric.Params = params
 
 			metric = newMetric
-			data[metric.Name] = metric
 		}
 
 		metric.Value = a.getMetricValue(line)
 
 		a.logger.Debugf("Got metric: %+v\n", metric)
 
-		data[name] = metric
+		data[metric.Name] = metric
+	}
+
+	if err := scanner.Err(); err != nil {
+		return nil, fmt.Errorf("wasn't able to scan input: %w", err)
 	}
 
 	a.logger.Debugf("Data parsed: %+v\n", data)
 
-	return data
+	return data, nil
 }
 
 // Gets metric description from passed line.
diff --git a/internal/logger/logger.go b/internal/logger/logger.go
index a12306e..a09ae84 100644
--- a/internal/logger/logger.go
+++ b/internal/logger/logger.go
@@ -9,6 +9,10 @@ type Logger struct {
 
 // NewLogger creates new logging wrapper and returns it to caller.
 func NewLogger(config *Config) *Logger {
+	if config == nil {
+		config = &Config{Debug: false}
+	}
+
 	l := &Logger{config: config}
 
 	return l