package main

import (
	"os"
	"os/exec"
	"path/filepath"
	"testing"
)

func TestParseHunkNewRange(t *testing.T) {
	cases := []struct {
		header    string
		wantStart int
		wantCount int
	}{
		{"@@ -1,2 +3,4 @@", 3, 4},
		{"@@ -0,0 +1 @@", 1, 1},                // no ,count on the + side → count 1
		{"@@ -5,0 +6,3 @@ func Foo() {", 6, 3}, // trailing context after @@
		{"@@ -1 +1 @@", 1, 1},
		{"not a hunk", 0, 0},
	}
	for _, c := range cases {
		start, count := parseHunkNewRange(c.header)
		if start != c.wantStart || count != c.wantCount {
			t.Errorf("parseHunkNewRange(%q) = (%d,%d), want (%d,%d)", c.header, start, count, c.wantStart, c.wantCount)
		}
	}
}

func TestParseUnifiedDiffRecordsAddedLines(t *testing.T) {
	diff := "diff --git a/foo.go b/foo.go\n" +
		"--- a/foo.go\n" +
		"+++ b/foo.go\n" +
		"@@ -10,0 +11,2 @@\n" +
		"+added one\n" +
		"+added two\n"
	rd := &repoDiff{changed: map[string]map[int]bool{}, untracked: map[string]bool{}}
	parseUnifiedDiff(diff, rd)

	lines := rd.changed["foo.go"]
	if !lines[11] || !lines[12] {
		t.Fatalf("expected lines 11,12 changed, got %#v", lines)
	}
	if lines[10] || lines[13] {
		t.Fatalf("unexpected extra changed lines: %#v", lines)
	}
}

func TestDiffIndexIsChangedTracksWorkingTreeEdits(t *testing.T) {
	repo := t.TempDir()
	runGit := func(args ...string) {
		t.Helper()
		cmd := exec.Command("git", append([]string{"-C", repo}, args...)...)
		if out, err := cmd.CombinedOutput(); err != nil {
			t.Fatalf("git %v: %v\n%s", args, err, out)
		}
	}
	runGit("init")
	runGit("config", "user.email", "test@example.com")
	runGit("config", "user.name", "test")

	committed := filepath.Join(repo, "committed.go")
	if err := os.WriteFile(committed, []byte("package p\n\nvar a int\nvar b int\n"), 0o644); err != nil {
		t.Fatal(err)
	}
	runGit("add", "committed.go")
	runGit("commit", "-m", "init")

	// Unstaged edit: append a line to the committed file.
	if err := os.WriteFile(committed, []byte("package p\n\nvar a int\nvar b int\nvar c int\n"), 0o644); err != nil {
		t.Fatal(err)
	}
	// Untracked new file.
	untracked := filepath.Join(repo, "new.go")
	if err := os.WriteFile(untracked, []byte("package p\n\nvar d int\n"), 0o644); err != nil {
		t.Fatal(err)
	}

	idx := newDiffIndex()

	if idx.isChanged(committed, 3) {
		t.Errorf("line 3 (unchanged, committed) should not be reported as changed")
	}
	if !idx.isChanged(committed, 5) {
		t.Errorf("line 5 (the unstaged append) should be reported as changed")
	}
	if !idx.isChanged(untracked, 1) || !idx.isChanged(untracked, 3) {
		t.Errorf("all lines of an untracked file should be reported as changed")
	}
}

func TestDiffIndexIsChangedOutsideRepoIsFalse(t *testing.T) {
	dir := t.TempDir() // not a git repo
	f := filepath.Join(dir, "x.go")
	if err := os.WriteFile(f, []byte("package p\n"), 0o644); err != nil {
		t.Fatal(err)
	}
	idx := newDiffIndex()
	if idx.isChanged(f, 1) {
		t.Errorf("files outside any git repo must not be reported as changed")
	}
}