package services

import "testing"

func TestCountDiffLines(t *testing.T) {
	tests := []struct {
		name  string
		patch string
		want  int
	}{
		{
			name: "standard diff with additions and deletions",
			patch: `--- a/file.go
+++ b/file.go
@@ -1,5 +1,6 @@
 package main
+import "fmt"
+import "os"
-func old() {}
+func new() {}
 func keep() {}`,
			want: 4, // +import, +import, -func, +func
		},
		{
			name:  "only additions",
			patch: "+++ b/file.go\n@@ -0,0 +1,3 @@\n+line1\n+line2\n+line3",
			want:  3,
		},
		{
			name:  "only deletions",
			patch: "--- a/file.go\n@@ -1,3 +0,0 @@\n-line1\n-line2\n-line3",
			want:  3,
		},
		{
			name:  "empty patch",
			patch: "",
			want:  0,
		},
		{
			name: "context only lines (no +/- prefix)",
			patch: `@@ -1,3 +1,3 @@
 func unchanged() {}
 	return nil
 }`,
			want: 0,
		},
		{
			name: "header lines excluded",
			patch: `--- a/old.go
+++ b/new.go
@@ -1 +1 @@
-old
+new`,
			want: 2, // -old and +new (headers excluded)
		},
		{
			name:  "mixed content with no changes",
			patch: "just some\nplain text\nlines",
			want:  0,
		},
		{
			name:  "single addition",
			patch: "+added line",
			want:  1,
		},
		{
			name:  "single deletion",
			patch: "-removed line",
			want:  1,
		},
		{
			name:  "line starting with plus in content context",
			patch: " +not a change, just context\n+actual addition",
			want:  1, // only the line starting with + at position 0
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			got := countDiffLines(tt.patch)
			if got != tt.want {
				t.Errorf("countDiffLines() = %d, want %d", got, tt.want)
			}
		})
	}
}

func TestCountDiffLines_MultiFileDiff(t *testing.T) {
	patch := `--- a/file1.go
+++ b/file1.go
@@ -1,3 +1,4 @@
 package main
+import "fmt"
 func main() {
+	fmt.Println("hello")
 }
--- a/file2.go
+++ b/file2.go
@@ -1,2 +1,2 @@
-old line
+new line`
	got := countDiffLines(patch)
	want := 4 // +import, +fmt.Println, -old line, +new line
	if got != want {
		t.Errorf("countDiffLines() = %d, want %d", got, want)
	}
}