add GetUserNameFromText

name.go

@@ -0,0 +1,70 @@
+package igslim
+
+import (
+	"regexp"
+	"strings"
+)
+
+const (
+	reUserNameStr = `[A-Za-z0-9_][A-Za-z0-9_.]{0,28}[A-Za-z0-9_]`
+)
+
+var (
+	reIg         = regexp.MustCompile(`(?i)(?:^|[^\w])(ig|instagram|insta|ins)(?:[^\w]|$)`)
+	reUserNameOn = regexp.MustCompile(`(?i)(^|[^\w])(@?)(` + reUserNameStr + `)(\s+on\s+)$`)
+	reUserNameAt = regexp.MustCompile(`(?:^|[^\w])@(` + reUserNameStr + `)`)
+	reUserName   = regexp.MustCompile(reUserNameStr)
+)
+
+// GetUserNameFromText extracts Instagram user name from "text" (usually the
+// biography of a social media account) using regular expressions. Because of
+// too many edge cases, this function does not guarantee the accuracy of the
+// extracted user names. The "username" argument is returned if Instagram is
+// mentioned but no user name is found. Empty string is returned if no user
+// name is found.
+func GetUserNameFromText(text, username string) string {
+	loc := reIg.FindStringSubmatchIndex(text)
+	if len(loc) < 4 {
+		return ""
+	}
+
+	// follow * on Instagram
+	if m := reUserNameOn.FindStringSubmatch(text[:loc[2]]); len(m) > 0 {
+		// CAN'T DECIDE: this is very likely an English word instead of
+		// username if it does not start with @ and its length is less than 8
+		if m[2] == "@" || len(m[3]) >= 8 {
+			if m[1] != "@" {
+				return m[3]
+			}
+		}
+	}
+
+	text = text[loc[3]:]
+
+	var hasColon bool
+	if i := strings.IndexAny(text, ":-=：>👉"); i > -1 {
+		text = text[i:]
+		hasColon = true
+	}
+
+	if m := reUserNameAt.FindStringSubmatch(text); len(m) > 0 {
+		return m[1]
+	}
+
+	if hasColon {
+		loc := reUserName.FindStringIndex(text)
+		if len(loc) == 2 {
+			if loc[1]+1 <= len(text) && text[loc[1]:loc[1]+1] == "@" {
+				// more like an email address
+				return username
+			}
+			// CAN'T DECIDE: this is very likely an English word instead of
+			// username if it does not start with @ and its length is less than 8
+			if name := text[loc[0]:loc[1]]; len(name) >= 8 {
+				return name
+			}
+		}
+	}
+
+	return username
+}

name_test.go

@@ -0,0 +1,47 @@
+package igslim
+
+import "testing"
+
+const originalUserName = "original"
+
+var testcases = map[string]string{
+	"Follow Me On IG - @example":                  "example",
+	"Follow the IG: EXAMPLE_01":                   "EXAMPLE_01",
+	"follow my insta >username_ business":         "username_",
+	"INSTA=example__official example@example.com": "example__official",
+	"IG: @foo_bar foo@bar.com":                    "foo_bar",
+	"Instagram: loremipsum YouTube:LoremIpsum":    "loremipsum",
+	"Insta:Some_name":                             "Some_name",
+	"IG: hello_world yes":                         "hello_world",
+	"Follow our Twitter @ourtwitter":              "",
+	"Follow us on Instagram and YouTube":          originalUserName,
+	"Insta/YouTube: James002":                     "James002",
+	"Insta / YouTube: foobar123":                  "foobar123",
+	"Instagram:@example email: example@gmail.com": "example",
+	"Get my IG to 100K @foobar!":                  "foobar",
+	"Insta • Youtube • Blog":                      originalUserName,
+	"alright":                                     "",
+	"BIG":                                         "",
+	"IG":                                          originalUserName,
+	"Insta ↓ Thank you":                           originalUserName,
+	"Follow me on Instagram: example@gmail.com":   originalUserName,
+	"Follow me on Instagram: example@":            originalUserName,
+	"Follow me on Instagram: example003":          "example003",
+	"Why not follow helloworld on Instagram?":     "helloworld",
+	"Why not follow @example on IG?":              "example",
+	"leaked face on IG":                           originalUserName,
+	"face reveal on instagram":                    originalUserName,
+	"Why not follow foo@example.com on IG?":       originalUserName,
+	"helloworld ON IG":                            "helloworld",
+	"insta👉hello_world":                           "hello_world",
+	"insta -15%":                                  originalUserName,
+}
+
+func TestGetUserNameFromText(t *testing.T) {
+	for text, expected := range testcases {
+		actual := GetUserNameFromText(text, originalUserName)
+		if actual != expected {
+			t.Errorf("GetUserNameFromText(%s) should return %s instead of %s", text, expected, actual)
+		}
+	}
+}