package git

import (
	"context"
	"errors"
	"os"
	"os/exec"
	"path/filepath"
	"strings"
	"testing"
	"time"
)

func TestDiscoverRepositoryRoot(t *testing.T) {
	repo := newRemoteFixture(t)
	child := filepath.Join(repo.work, "child")
	if err := os.Mkdir(child, 0755); err != nil {
		t.Fatal(err)
	}
	alias := filepath.Join(t.TempDir(), "alias")
	if err := os.Symlink(repo.work, alias); err != nil {
		t.Fatal(err)
	}
	worktree := filepath.Join(t.TempDir(), "worktree")
	gitRun(t, repo.work, "worktree", "add", "--detach", worktree)
	for _, tc := range []struct{ dir, want string }{{repo.work, repo.work}, {child, repo.work}, {alias, repo.work}, {worktree, worktree}} {
		root, found, err := DiscoverRepositoryRoot(context.Background(), tc.dir)
		want, e := filepath.EvalSymlinks(tc.want)
		if e != nil {
			t.Fatal(e)
		}
		if err != nil || !found || root != want {
			t.Fatalf("Discover(%s) = %q, %t, %v; want %q", tc.dir, root, found, err, want)
		}
	}
	standalone := t.TempDir()
	if root, found, err := DiscoverRepositoryRoot(context.Background(), standalone); err != nil || found || root != "" {
		t.Fatalf("standalone = %q, %t, %v", root, found, err)
	}
	if _, err := RepositoryRoot(context.Background(), standalone); err == nil {
		t.Fatal("strict lookup accepted standalone")
	}
	if _, found, err := DiscoverRepositoryRoot(context.Background(), repo.bare); err == nil || found {
		t.Fatalf("bare repository: found %t, error %v", found, err)
	}
	broken := t.TempDir()
	if err := os.WriteFile(filepath.Join(broken, ".git"), []byte("gitdir: missing\n"), 0600); err != nil {
		t.Fatal(err)
	}
	if _, found, err := DiscoverRepositoryRoot(context.Background(), broken); err == nil || found {
		t.Fatalf("broken marker: found %t, error %v", found, err)
	}
	if _, found, err := DiscoverRepositoryRoot(context.Background(), filepath.Join(standalone, "missing")); err == nil || found {
		t.Fatalf("missing directory: found %t, error %v", found, err)
	}
}

func TestNoRepositoryBoundary(t *testing.T) {
	for _, tc := range []struct {
		message string
		want    bool
	}{
		{"fatal: not a git repository (or any of the parent directories): .git\n", true},
		{"fatal: not a git repository (or any parent up to mount point /some path)\nStopping at filesystem boundary (GIT_DISCOVERY_ACROSS_FILESYSTEM not set).\n", true},
		{"fatal: not a git repository: '/bad'", false},
		{"fatal: detected dubious ownership in repository", false},
	} {
		if _, got := noRepositoryBoundary(tc.message); got != tc.want {
			t.Errorf("diagnostic %q = %t", tc.message, got)
		}
	}
}

func TestDiscoverRepositoryRootHonorsDiscoveryBoundaries(t *testing.T) {
	repo := newRemoteFixture(t)
	child := filepath.Join(repo.work, "child")
	if err := os.Mkdir(child, 0o755); err != nil {
		t.Fatal(err)
	}
	alias := filepath.Join(t.TempDir(), "alias")
	if err := os.Symlink(repo.work, alias); err != nil {
		t.Fatal(err)
	}
	if err := os.Remove(filepath.Join(repo.work, ".git", "HEAD")); err != nil {
		t.Fatal(err)
	}
	for _, tc := range []struct {
		name, directory, ceiling string
		standalone               bool
	}{
		{"damaged ancestor", child, "", false},
		{"excluded ancestor", child, repo.work, true},
		{"physical ceiling alias", child, alias, true},
		{"literal ceiling alias", child, string(os.PathListSeparator) + alias, false},
		{"ceiling includes current directory", repo.work, repo.work, false},
	} {
		t.Run(tc.name, func(t *testing.T) {
			t.Setenv("GIT_CEILING_DIRECTORIES", tc.ceiling)
			_, found, err := DiscoverRepositoryRoot(t.Context(), tc.directory)
			if tc.standalone {
				if err != nil || found {
					t.Fatalf("excluded checkout: found %t, error %v", found, err)
				}
			} else {
				var exitErr *exec.ExitError
				if found || !errors.As(err, &exitErr) || exitErr.ExitCode() != 128 {
					t.Fatalf("damaged checkout: found %t, error %v", found, err)
				}
			}
		})
	}
	bin := t.TempDir()
	script := "#!/bin/sh\nprintf 'fatal: not a git repository (or any parent up to mount point %s)\\nStopping at filesystem boundary (GIT_DISCOVERY_ACROSS_FILESYSTEM not set).\\n' \"$DISCOVERY_BOUNDARY\" >&2\nexit 128\n"
	if err := os.WriteFile(filepath.Join(bin, "git"), []byte(script), 0o755); err != nil {
		t.Fatal(err)
	}
	t.Setenv("PATH", bin)
	t.Setenv("GIT_CEILING_DIRECTORIES", "")
	t.Setenv("DISCOVERY_BOUNDARY", repo.work)
	if _, found, err := DiscoverRepositoryRoot(t.Context(), child); err != nil || found {
		t.Fatalf("filesystem boundary: found %t, error %v", found, err)
	}
}

func TestDiscoverRepositoryRootFailures(t *testing.T) {
	dir := t.TempDir()
	bin := t.TempDir()
	script := "#!/bin/sh\nprintf '%s\\n' 'fatal: detected dubious ownership in repository' >&2\nexit 128\n"
	if err := os.WriteFile(filepath.Join(bin, "git"), []byte(script), 0755); err != nil {
		t.Fatal(err)
	}
	t.Setenv("PATH", bin)
	_, found, err := DiscoverRepositoryRoot(context.Background(), dir)
	var exitErr *exec.ExitError
	if found || !errors.As(err, &exitErr) || exitErr.ExitCode() != 128 || !strings.Contains(err.Error(), "dubious ownership") {
		t.Fatalf("found %t, error %v", found, err)
	}
	if err := os.WriteFile(filepath.Join(bin, "git"), []byte("#!/bin/sh\nprintf '%s\\n' 'fatal: permission denied' >&2\nexit 128\n"), 0o755); err != nil {
		t.Fatal(err)
	}
	_, found, err = DiscoverRepositoryRoot(context.Background(), dir)
	if found || !errors.As(err, &exitErr) || exitErr.ExitCode() != 128 || !strings.Contains(err.Error(), "permission denied") {
		t.Fatalf("found %t, error %v", found, err)
	}
	ctx, cancel := context.WithCancel(context.Background())
	cancel()
	if _, _, err := DiscoverRepositoryRoot(ctx, dir); !errors.Is(err, context.Canceled) {
		t.Fatalf("cancellation = %v", err)
	}
}

func TestDiscoverRepositoryRootInterruptedGit(t *testing.T) {
	dir := t.TempDir()
	bin := t.TempDir()
	ready := filepath.Join(t.TempDir(), "ready")
	script := "#!/bin/sh\n[ \"$LC_ALL\" = C ] || exit 42\n: > \"$DISCOVERY_READY\"\nexec /bin/sleep 60\n"
	if err := os.WriteFile(filepath.Join(bin, "git"), []byte(script), 0o755); err != nil {
		t.Fatal(err)
	}
	t.Setenv("PATH", bin)
	t.Setenv("DISCOVERY_READY", ready)
	t.Setenv("LC_ALL", "different-locale")
	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()
	done := make(chan error, 1)
	go func() { _, _, err := DiscoverRepositoryRoot(ctx, dir); done <- err }()
	timer := time.NewTimer(5 * time.Second)
	defer timer.Stop()
	ticker := time.NewTicker(10 * time.Millisecond)
	defer ticker.Stop()
	for {
		if _, err := os.Stat(ready); err == nil {
			break
		}
		select {
		case err := <-done:
			t.Fatalf("Git ended before readiness: %v", err)
		case <-timer.C:
			cancel()
			err := <-done
			t.Fatalf("Git did not become ready: %v", err)
		case <-ticker.C:
		}
	}
	cancel()
	if err := <-done; !errors.Is(err, context.Canceled) {
		t.Fatalf("cancellation = %v", err)
	}
	if got := os.Getenv("LC_ALL"); got != "different-locale" {
		t.Fatalf("parent locale changed to %q", got)
	}
}

func TestDiscoverRepositoryRootWithoutGit(t *testing.T) {
	repo := newRemoteFixture(t)
	standalone := t.TempDir()
	t.Setenv("PATH", t.TempDir())
	if _, found, err := DiscoverRepositoryRoot(context.Background(), standalone); found || err != nil {
		t.Fatalf("standalone: found %t, error %v", found, err)
	}
	if _, found, err := DiscoverRepositoryRoot(context.Background(), repo.work); found || !errors.Is(err, exec.ErrNotFound) {
		t.Fatalf("checkout: found %t, error %v", found, err)
	}
	broken := t.TempDir()
	if err := os.WriteFile(filepath.Join(broken, ".git"), []byte("broken"), 0600); err != nil {
		t.Fatal(err)
	}
	if _, found, err := DiscoverRepositoryRoot(context.Background(), broken); found || !errors.Is(err, exec.ErrNotFound) {
		t.Fatalf("broken marker: found %t, error %v", found, err)
	}
	t.Setenv("GIT_DIR", "invalid")
	if _, found, err := DiscoverRepositoryRoot(context.Background(), standalone); found || !errors.Is(err, exec.ErrNotFound) {
		t.Fatalf("explicit context: found %t, error %v", found, err)
	}
}