Align Go project structure and add Mage targets

Amp-Thread-ID: https://ampcode.com/threads/T-019c7f3b-1326-767b-94d5-366b91eaf712
Co-authored-by: Amp <amp@ampcode.com>

4 files changed, 90 insertions, 32 deletions

diff --git a/Magefile.go b/Magefile.go
new file mode 100644
index 0000000..7f63a22
--- /dev/null
+++ b/Magefile.go
@@ -0,0 +1,52 @@
+//go:build mage
+
+// Magefile for ior targets: build, test, install.
+package main
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+
+	"github.com/magefile/mage/mg"
+	"github.com/magefile/mage/sh"
+)
+
+const binaryName = "ior"
+
+// Default builds the project.
+func Default() {
+	mg.Deps(Build)
+}
+
+// Build compiles the binary.
+func Build() error {
+	return sh.RunV("go", "build", "-o", binaryName, "./cmd/ior")
+}
+
+// Test runs the full test suite.
+func Test() error {
+	return sh.RunV("go", "test", "./...")
+}
+
+// Install copies the binary into GOPATH/bin.
+func Install() error {
+	mg.Deps(Build)
+
+	goPath := os.Getenv("GOPATH")
+	if goPath == "" {
+		home, err := os.UserHomeDir()
+		if err != nil {
+			return fmt.Errorf("resolve home directory: %w", err)
+		}
+		goPath = filepath.Join(home, "go")
+	}
+
+	binDir := filepath.Join(goPath, "bin")
+	if err := os.MkdirAll(binDir, 0o755); err != nil {
+		return fmt.Errorf("ensure %s: %w", binDir, err)
+	}
+
+	dest := filepath.Join(binDir, binaryName)
+	return sh.RunV("cp", "-v", binaryName, dest)
+}
diff --git a/cmd/ior/main.go b/cmd/ior/main.go
index 0f3b38e..595f8f6 100644
--- a/cmd/ior/main.go
+++ b/cmd/ior/main.go
@@ -2,10 +2,11 @@ package main
 
 import (
 	"fmt"
-	"ior/internal"
-	"ior/internal/flags"
 	"os"
 	"runtime"
+
+	"ior/internal"
+	"ior/internal/flags"
 )
 
 // main is the entry point for the application. It checks if the OS is Linux,
diff --git a/internal/flags/flags.go b/internal/flags/flags.go
index 512697c..de0e74f 100644
--- a/internal/flags/flags.go
+++ b/internal/flags/flags.go
@@ -17,25 +17,25 @@ var (
 	once      sync.Once
 )
 
-var validCollapsedFields = []string{
-	"path",
-	"comm",
-	"tracepoint",
-	"pid",
-	"tid",
-	"flags",
-}
+const flamegraphToolDefault = "$HOME/git/FlameGraph/flamegraph.pl"
 
-var validCollapsedCounts = []string{
-	"count",
-	"duration",
-	"durationToPrev",
-	"bytes",
-}
+var (
+	validCollapsedFields = []string{
+		"path",
+		"comm",
+		"tracepoint",
+		"pid",
+		"tid",
+		"flags",
+	}
 
-func Get() Flags {
-	return singleton
-}
+	validCollapsedCounts = []string{
+		"count",
+		"duration",
+		"durationToPrev",
+		"bytes",
+	}
+)
 
 type Flags struct {
 	PidFilter    int
@@ -63,6 +63,10 @@ type Flags struct {
 	FlamegraphTool string
 }
 
+func Get() Flags {
+	return singleton
+}
+
 func Parse() {
 	once.Do(func() {
 		parse()
@@ -70,8 +74,6 @@ func Parse() {
 }
 
 func parse() {
-	version := flag.Bool("version", false, "Print version")
-
 	flag.IntVar(&singleton.PidFilter, "pid", -1, "Filter for processes ID")
 	flag.IntVar(&singleton.TidFilter, "tid", -1, "Filter for thread ID")
 	flag.IntVar(&singleton.EventMapSize, "mapSize", 4096*16, "BPF FD event ring buffer map size")
@@ -96,12 +98,11 @@ func parse() {
 
 	// https://github.com/brendangregg/FlameGraph
 	flag.StringVar(&singleton.FlamegraphTool, "flamegraphTool",
-		os.Getenv("HOME")+"/git/FlameGraph/flamegraph.pl", "Path to the flamegraph tool (e.g. flamegraph.pl or inferno-flamegraph)")
+		"", "Path to the flamegraph tool (e.g. flamegraph.pl or inferno-flamegraph)")
 	flag.Parse()
 
-	if *version {
-		PrintVersion()
-		os.Exit(0)
+	if singleton.FlamegraphTool == "" {
+		singleton.FlamegraphTool = flamegraphToolDefault
 	}
 
 	singleton.TracepointsToAttach = extractTracepointFlags(*tracepointsToAttach)
diff --git a/internal/flags/version.go b/internal/flags/version.go
index 1cb2dfd..7e6c50e 100644
--- a/internal/flags/version.go
+++ b/internal/flags/version.go
@@ -1,13 +1,17 @@
 package flags
 
-const version = `v0.0.0`
+import "fmt"
 
-const asciiBanner = ` ___   _____    ___ _     _   
-|_ _| / / _ \  | _ (_)___| |_ 
- | | / / (_) | |   / / _ \  _|
-|___/_/ \___/  |_|_\_\___/\__| NG
-               ` + version
+// Version is the current application version.
+const Version = "v0.0.0"
 
+const asciiBannerTemplate = ` ___   _____    ___ _     _
+|_ _| / / _ \  | _ (_)___| |_ 
+ | | / / (_) | |   / / _ \  _|
+|___/_/ \___/  |_|_\_\___/\__| NG
+               %s`
+
+// PrintVersion prints the banner with the current version.
 func PrintVersion() {
-	println(asciiBanner)
+	fmt.Printf(asciiBannerTemplate+"\n", Version)
 }