From 99e244fa925e396309c438582ebac66f928ef1a5 Mon Sep 17 00:00:00 2001
From: Sasha Koshka <sashakoshka@tebibyte.media>
Date: Wed, 11 Dec 2024 21:44:34 -0500
Subject: [PATCH] providers: Add validation functions

---
 providers/all.go               |  4 +--
 providers/validate/strings.go  |  7 +++++
 providers/validate/validate.go | 47 ++++++++++++++++++++++++++++++++++
 3 files changed, 56 insertions(+), 2 deletions(-)
 create mode 100644 providers/validate/strings.go
 create mode 100644 providers/validate/validate.go

diff --git a/providers/all.go b/providers/all.go
index 8d528ea..774c21c 100644
--- a/providers/all.go
+++ b/providers/all.go
@@ -5,9 +5,9 @@ import fpos       "git.tebibyte.media/sashakoshka/step/providers/os"
 import fphttp     "git.tebibyte.media/sashakoshka/step/providers/http"
 import fppath     "git.tebibyte.media/sashakoshka/step/providers/path"
 import fpmime     "git.tebibyte.media/sashakoshka/step/providers/mime"
-import fpslice    "git.tebibyte.media/sashakoshka/step/providers/slice"
 import fpsprig    "git.tebibyte.media/sashakoshka/step/providers/sprig"
 import fpimport   "git.tebibyte.media/sashakoshka/step/providers/import"
+import fpvalidate "git.tebibyte.media/sashakoshka/step/providers/validate"
 import fpmarkdown "git.tebibyte.media/sashakoshka/step/providers/markdown"
 
 // All returns a slice of all providers defined in sub-packages.
@@ -17,9 +17,9 @@ func All () []step.Provider {
 		new(fphttp.Provider),
 		new(fppath.Provider),
 		new(fpmime.Provider),
-		new(fpslice.Provider),
 		new(fpsprig.Provider),
 		new(fpimport.Provider),
+		new(fpvalidate.Provider),
 		fpmarkdown.Default(),
 	}
 }
diff --git a/providers/validate/strings.go b/providers/validate/strings.go
new file mode 100644
index 0000000..c74e38d
--- /dev/null
+++ b/providers/validate/strings.go
@@ -0,0 +1,7 @@
+package validate
+
+import "regexp"
+
+// see:
+// https://stackoverflow.com/questions/201323/how-can-i-validate-an-email-address-using-a-regular-expression
+var defaultEmailRegexp = regexp.MustCompile("(?:[a-z0-9!#$%&'*+/=?^_`{|}~-]+(?:\\.[a-z0-9!#$%&'*+/=?^_`{|}~-]+)*|\"(?:[\\x01-\\x08\\x0b\\x0c\\x0e-\\x1f\\x21\\x23-\\x5b\\x5d-\\x7f]|\\\\[\\x01-\\x09\\x0b\\x0c\\x0e-\\x7f])*\")@(?:(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?|\\[(?:(?:(2(5[0-5]|[0-4][0-9])|1[0-9][0-9]|[1-9]?[0-9]))\\.){3}(?:(2(5[0-5]|[0-4][0-9])|1[0-9][0-9]|[1-9]?[0-9])|[a-z0-9-]*[a-z0-9]:(?:[\\x01-\\x08\\x0b\\x0c\\x0e-\\x1f\\x21-\\x5a\\x53-\\x7f]|\\\\[\\x01-\\x09\\x0b\\x0c\\x0e-\\x7f])+)\\])")
diff --git a/providers/validate/validate.go b/providers/validate/validate.go
new file mode 100644
index 0000000..3cc9994
--- /dev/null
+++ b/providers/validate/validate.go
@@ -0,0 +1,47 @@
+package validate
+
+import "regexp"
+import "html/template"
+import "git.tebibyte.media/sashakoshka/step"
+
+var _ step.FuncProvider = new(Provider)
+var _ step.Configurable = new(Provider)
+
+// Provider provides validation functions.
+type Provider struct {
+	emailRegexp *regexp.Regexp
+}
+
+// Package fulfills the step.Provider interface.
+func (this *Provider) Package () string {
+	return "validate"
+}
+
+func (this *Provider) Configure (config step.Meta) error {
+	emailRegexpText := config.Get("validate.email-regexp")
+	this.emailRegexp = nil
+	if emailRegexpText != "" {
+		emailRegexp, err := regexp.Compile(emailRegexpText)
+		if err != nil { return err }
+		this.emailRegexp = emailRegexp
+	}
+	return nil
+}
+
+// FuncMap fulfills the step.FuncProvider interface.
+func (this *Provider) FuncMap () template.FuncMap {
+	return template.FuncMap {
+		"isEmail": this.funcIsEmail,
+		"inRange": this.funcInRange,
+	}
+}
+
+func (this *Provider) funcIsEmail (input string) bool {
+	emailRegexp := this.emailRegexp
+	if emailRegexp == nil { emailRegexp = defaultEmailRegexp }
+	return emailRegexp.Match([]byte(input))
+}
+
+func (this *Provider) funcInRange (min, max, value int) bool {
+	return value >= min && value <= max
+}