multiline: better handle yaml and other text that comes with +/- (#8)

example/example.txt

@@ -27,3 +27,18 @@
                   + node_name                        = (known after apply)
                     restart_policy                   = "Always"
                   + service_account_name             = (known after apply)
+
+# local_file.foo will be created
+  + resource "local_file" "foo" {
+    + content              = <<~EOT
+        can:
+          enter:
+          - yaml
+          - or
+          + anything
+        EOT
+    + directory_permission = "0777"
+    + file_permission      = "0777"
+    + filename             = "./foo.out"
+    + id                   = (known after apply)
+  }

main.go

@@ -12,14 +12,27 @@ import (
 )
 
 func main() {
-	iterateInput(os.Stdin)
+	iterateInput(os.Stdin, os.Stdout)
 }
 
-func iterateInput(input io.Reader) {
+func iterateInput(input io.Reader, out io.Writer) {
+	skipLines := false
+	key := ""
 	scanner := bufio.NewScanner(input)
 	for scanner.Scan() {
 		ln := scanner.Text()
-		processLine(ln, os.Stdout)
+		if strings.TrimSpace(ln) == key {
+			skipLines = false
+		}
+		if skipLines {
+			fmt.Fprintln(out, ln)
+		} else {
+			processLine(ln, out)
+		}
+		if strings.Contains(ln, "<<~") {
+			skipLines = true
+			key = after(ln, "<<~")
+		}
 	}
 	return
 }
@@ -83,3 +96,16 @@ func cleanRawInput(raw string) string {
 	}
 	return nocolor
 }
+
+// Get substring after a string.
+func after(value string, a string) string {
+	pos := strings.LastIndex(value, a)
+	if pos == -1 {
+		return ""
+	}
+	adjustedPos := pos + len(a)
+	if adjustedPos >= len(value) {
+		return ""
+	}
+	return value[adjustedPos:]
+}

main_test.go

@@ -133,3 +133,81 @@ func Test_cleanRawInput(t *testing.T) {
 		})
 	}
 }
+
+func Test_iterateInput(t *testing.T) {
+	tests := []struct {
+		name    string
+		input   string
+		out     *bytes.Buffer
+		wantOut string
+	}{
+		{
+			name:    "empty",
+			input:   "",
+			out:     &bytes.Buffer{},
+			wantOut: ``,
+		},
+		{
+			name: "example",
+			input: `
+  # module.apps.kubernetes_deployment.deployment is tainted, so must be replaced
+-/+ resource "kubernetes_deployment" "deployment" {
+      ~ id               = "some-app" -> (known after apply)
+        wait_for_rollout = true
+
+              ~ spec {
+                  - active_deadline_seconds          = 0 -> null
+`,
+			out: &bytes.Buffer{},
+			wantOut: `
+# module.apps.kubernetes_deployment.deployment is tainted, so must be replaced
+-/+ resource "kubernetes_deployment" "deployment" {
+~       id               = "some-app" -> (known after apply)
+        wait_for_rollout = true
+
+~               spec {
+-                   active_deadline_seconds          = 0 -> null
+`,
+		},
+		{
+			name: "multiline example",
+			input: `
+ # local_file.foo will be created
++ resource "local_file" "foo" {
+    + content              = <<~EOT
+        can:
+          enter:
+          - yaml
+          - or
+          + anything
+        EOT
+    + directory_permission = "0777"
+`,
+			out: &bytes.Buffer{},
+			wantOut: `
+# local_file.foo will be created
++ resource "local_file" "foo" {
++     content              = <<~EOT
+        can:
+          enter:
+          - yaml
+          - or
+          + anything
+        EOT
++     directory_permission = "0777"
+`,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			var stdin bytes.Buffer
+			stdin.Write([]byte(tt.input))
+			iterateInput(&stdin, tt.out)
+			got := tt.out.String()
+			if got != tt.wantOut {
+				t.Errorf("output for %s is now aligned. \nGot:  %v, \nwant: %v", tt.name, got, tt.wantOut)
+				t.Errorf("length  \nGot:  %v, \nwant: %v", len(got), len(tt.wantOut))
+			}
+		})
+	}
+}