package host

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

	"golang.org/x/sys/unix"
)

func plan14RootFixture(t *testing.T) bool {
	t.Helper()
	if os.Getenv("PLAN14_ROOT_FIXTURE") == t.Name() {
		root := os.Getenv("PLAN14_ROOT_DIR")
		if err := unix.Mount("/proc", filepath.Join(root, "proc"), "", unix.MS_BIND|unix.MS_REC, ""); err != nil {
			t.Fatal(err)
		}
		source := "/usr/bin/true"
		if os.Getenv("PLAN14_REAL_ROOT") == "1" {
			source = filepath.Join(root, "foreign-source")
		}
		if err := unix.Mount(source, filepath.Join(root, "foreign"), "", unix.MS_BIND, ""); err != nil {
			t.Fatal(err)
		}
		if err := unix.Mount("/usr", filepath.Join(root, "foreign-dir"), "", unix.MS_BIND, ""); err != nil {
			t.Fatal(err)
		}
		if err := unix.Chroot(root); err != nil {
			t.Fatal(err)
		}
		if err := os.Chdir("/"); err != nil {
			t.Fatal(err)
		}
		if err := os.Chmod("/", 0755); err != nil {
			t.Fatal(err)
		}
		t.Setenv("TMPDIR", "/scratch")
		return true
	}
	root := t.TempDir()
	if err := os.Mkdir(filepath.Join(root, "scratch"), 0755); err != nil {
		t.Fatal(err)
	}
	if err := os.Mkdir(filepath.Join(root, "proc"), 0755); err != nil {
		t.Fatal(err)
	}
	if err := os.WriteFile(filepath.Join(root, "foreign"), nil, 0644); err != nil {
		t.Fatal(err)
	}
	if err := os.Mkdir(filepath.Join(root, "foreign-dir"), 0755); err != nil {
		t.Fatal(err)
	}
	binary, err := os.Executable()
	if err != nil {
		t.Fatal(err)
	}
	probe := exec.Command("unshare", "--user", "--map-root-user", "--mount", "true")
	if out, err := probe.CombinedOutput(); err != nil {
		t.Skipf("user namespace unavailable: %v %s", err, out)
	}
	cmd := exec.Command("unshare", "--user", "--map-root-user", "--mount", binary, "-test.run=^"+t.Name()+"$", "-test.v")
	cmd.Env = append(os.Environ(), "PLAN14_ROOT_FIXTURE="+t.Name(), "PLAN14_ROOT_DIR="+root)
	if os.Geteuid() == 0 {
		raw, err := os.ReadFile("/usr/bin/true")
		if err != nil {
			t.Fatal(err)
		}
		source := filepath.Join(root, "foreign-source")
		if err := os.WriteFile(source, raw, 0644); err != nil {
			t.Fatal(err)
		}
		if err := os.Chown(source, 65534, 65534); err != nil {
			t.Fatal(err)
		}
		cmd.Env = append(cmd.Env, "PLAN14_REAL_ROOT=1")
	}
	if out, err := cmd.CombinedOutput(); err != nil {
		t.Fatalf("isolated root fixture: %v\n%s", err, out)
	} else {
		t.Log(string(out))
	}
	return false
}

func makeProofAncestorsPublic(t *testing.T, path string) {
	t.Helper()
	for dir := filepath.Dir(path); dir != "/"; dir = filepath.Dir(dir) {
		if err := os.Chmod(dir, 0755); err != nil {
			t.Fatal(err)
		}
	}
}