From e68bc410f770256270a6937f4dd995c1e02143ee Mon Sep 17 00:00:00 2001
From: winebarrel <sugawara@winebarrel.jp>
Date: Sun, 1 Oct 2023 21:48:03 +0900
Subject: [PATCH] Add crongrep

---
 .goreleaser.yml       | 31 +++++++++++++++++++++
 CHANGELOG.md          |  6 ++++
 README.md             | 29 ++++++++++++++++++++
 cmd/crongrep/flags.go | 64 +++++++++++++++++++++++++++++++++++++++++++
 cmd/crongrep/main.go  | 39 ++++++++++++++++++++++++++
 5 files changed, 169 insertions(+)
 create mode 100644 cmd/crongrep/flags.go
 create mode 100644 cmd/crongrep/main.go

diff --git a/.goreleaser.yml b/.goreleaser.yml
index 6e5a4dc..5b3d1c8 100644
--- a/.goreleaser.yml
+++ b/.goreleaser.yml
@@ -23,6 +23,13 @@ builds:
       - -X main.version={{.Version}}
     env:
       - CGO_ENABLED=0
+  - id: crongrep
+    binary: crongrep
+    main: ./cmd/crongrep
+    ldflags:
+      - -X main.version={{.Version}}
+    env:
+      - CGO_ENABLED=0
 checksum:
   name_template: "checksums.txt"
 archives:
@@ -35,6 +42,9 @@ archives:
   - id: cronviz
     builds: [cronviz]
     name_template: "{{ .Binary }}_{{ .Version }}_{{ .Os }}_{{ .Arch }}"
+  - id: crongrep
+    builds: [crongrep]
+    name_template: "{{ .Binary }}_{{ .Version }}_{{ .Os }}_{{ .Arch }}"
 brews:
   - name: cronplan
     ids: [cronplan]
@@ -66,6 +76,16 @@ brews:
     license: MIT
     install: |
       bin.install 'cronviz'
+  - name: crongrep
+    ids: [crongrep]
+    tap:
+      owner: winebarrel
+      name: homebrew-cronplan
+    homepage: https://github.com/winebarrel/cronplan
+    description: crongrep is a tool to grep with cron expression.
+    license: MIT
+    install: |
+      bin.install 'crongrep'
 nfpms:
   - id: cronplan-nfpms
     builds: [cronplan]
@@ -100,3 +120,14 @@ nfpms:
       - deb
       - rpm
     bindir: /usr/bin
+  - id: crongrep-nfpms
+    builds: [crongrep]
+    file_name_template: "{{ .Binary }}_{{ .Version }}_{{ .Arch }}"
+    homepage: https://github.com/winebarrel/cronplan
+    maintainer: Genki Sugawara <sugawara@winebarrel.jp>
+    description: crongrep is a tool to visualize cron schedule.
+    license: MIT
+    formats:
+      - deb
+      - rpm
+    bindir: /usr/bin
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 2330916..c5f8cf9 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,12 @@
 
 N/A
 
+## [1.10.1] - 2023-10-01
+
+### Added
+
+* Add crongrep CLI.
+
 ## [1.10.0] - 2023-10-01
 
 ### Added
diff --git a/README.md b/README.md
index 1f2b919..b50fd6a 100644
--- a/README.md
+++ b/README.md
@@ -215,6 +215,35 @@ $ open output.html
 
 cf. https://raw.githack.com/winebarrel/cronplan/main/_example/timeline.html
 
+# crongrep CLI
+
+CLI to grep with cron expression.
+
+## Installation
+
+```
+brew install winebarrel/cronplan/crongrep
+```
+
+## Usage
+
+```
+Usage: crongrep [OPTION] CRON_EXPR
+  -version
+    	print version and exit
+```
+
+```
+$ for i in {1..5}; do
+LANG=C date
+done | crongrep '0 * * * ? *'
+Sun Oct  1 21:00:00 JST 2023
+Sun Oct  1 21:00:00 JST 2023
+Sun Oct  1 21:00:00 JST 2023
+Sun Oct  1 21:00:00 JST 2023
+Sun Oct  1 21:00:00 JST 2023
+```
+
 ## Related Links
 
 * [Cron expressions reference - Amazon EventBridge](https://docs.aws.amazon.com/eventbridge/latest/userguide/eb-cron-expressions.html)
diff --git a/cmd/crongrep/flags.go b/cmd/crongrep/flags.go
new file mode 100644
index 0000000..ab7eab8
--- /dev/null
+++ b/cmd/crongrep/flags.go
@@ -0,0 +1,64 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+var (
+	version string
+)
+
+type flags struct {
+	expr string
+}
+
+func init() {
+	cmdLine := flag.NewFlagSet(filepath.Base(os.Args[0]), flag.ExitOnError)
+
+	cmdLine.Usage = func() {
+		fmt.Fprintf(cmdLine.Output(), "Usage: %s [OPTION] CRON_EXPR\n", cmdLine.Name())
+		cmdLine.PrintDefaults()
+	}
+
+	flag.CommandLine = cmdLine
+}
+
+func parseFlags() *flags {
+	flags := &flags{}
+	showVersion := flag.Bool("version", false, "print version and exit")
+	flag.Parse()
+
+	if *showVersion {
+		printVersionAndExit()
+	}
+
+	args := flag.Args()
+
+	if len(args) != 1 {
+		printUsageAndExit()
+	}
+
+	flags.expr = strings.TrimSpace(args[0])
+
+	return flags
+}
+
+func printVersionAndExit() {
+	v := version
+
+	if v == "" {
+		v = "<nil>"
+	}
+
+	fmt.Fprintln(flag.CommandLine.Output(), v)
+	os.Exit(0)
+}
+
+func printUsageAndExit() {
+	flag.CommandLine.Usage()
+	os.Exit(0)
+}
diff --git a/cmd/crongrep/main.go b/cmd/crongrep/main.go
new file mode 100644
index 0000000..303f613
--- /dev/null
+++ b/cmd/crongrep/main.go
@@ -0,0 +1,39 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"log"
+	"os"
+
+	"github.com/araddon/dateparse"
+	"github.com/winebarrel/cronplan"
+)
+
+func init() {
+	log.SetFlags(0)
+}
+
+func main() {
+	flags := parseFlags()
+	cron, err := cronplan.Parse(flags.expr)
+
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	scanner := bufio.NewScanner(os.Stdin)
+
+	for scanner.Scan() {
+		line := scanner.Text()
+		t, err := dateparse.ParseAny(line)
+
+		if err != nil {
+			log.Fatal(err)
+		}
+
+		if cron.Match(t) {
+			fmt.Println(line)
+		}
+	}
+}