package backup

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

func TestRestoreFailureRollsBackFiles(t *testing.T) {
	root := t.TempDir()
	current := filepath.Join(root, "debtik")
	network := filepath.Join(root, "network")
	stage := filepath.Join(root, "staged")
	for _, dir := range []string{current, network, filepath.Join(stage, "debtik"), filepath.Join(stage, "network")} {
		if err := os.MkdirAll(dir, 0700); err != nil {
			t.Fatal(err)
		}
	}
	write := func(path, content string) {
		t.Helper()
		if err := os.WriteFile(path, []byte(content), 0600); err != nil {
			t.Fatal(err)
		}
	}
	write(filepath.Join(current, "old.json"), "old config")
	write(filepath.Join(network, "a.cfg"), "old network")
	write(filepath.Join(stage, "debtik", "new.json"), "new config")
	write(filepath.Join(stage, "network", "a.cfg"), "new network")
	write(filepath.Join(stage, "network", "b.cfg"), "new file")
	mgr := NewManager(current, network, filepath.Join(root, "backups"), nil)
	count := 0
	err := mgr.applyStagedRestore(stage, func(step string) error {
		if step == "network" {
			count++
			if count == 2 {
				return errors.New("simulated write failure")
			}
		}
		return nil
	})
	if err == nil || !strings.Contains(err.Error(), "previous files restored") {
		t.Fatalf("unexpected error %v", err)
	}
	for path, want := range map[string]string{filepath.Join(current, "old.json"): "old config", filepath.Join(network, "a.cfg"): "old network"} {
		data, err := os.ReadFile(path)
		if err != nil || string(data) != want {
			t.Fatalf("%s: %q %v", path, data, err)
		}
	}
	for _, path := range []string{filepath.Join(current, "new.json"), filepath.Join(network, "b.cfg")} {
		if _, err := os.Stat(path); !os.IsNotExist(err) {
			t.Fatalf("unexpected remaining %s: %v", path, err)
		}
	}
}

func TestRestoreCrashHelper(t *testing.T) {
	root := os.Getenv("DEBTIK_CRASH_TEST_ROOT")
	if root == "" {
		return
	}
	point := os.Getenv("DEBTIK_CRASH_TEST_POINT")
	mgr := NewManager(filepath.Join(root, "debtik"), filepath.Join(root, "network"), filepath.Join(root, "backups"), nil)
	err := mgr.applyStagedRestore(filepath.Join(root, "stage"), func(step string) error {
		if step == point {
			os.Exit(42)
		}
		return nil
	})
	t.Fatalf("failed to reach %s: %v", point, err)
}

func TestRecoveryAfterProcessCrash(t *testing.T) {
	for _, point := range []string{"old-renamed", "debtik", "network", "committed"} {
		t.Run(point, func(t *testing.T) {
			root := t.TempDir()
			current := filepath.Join(root, "debtik")
			network := filepath.Join(root, "network")
			stage := filepath.Join(root, "stage")
			for _, dir := range []string{current, network, filepath.Join(stage, "debtik"), filepath.Join(stage, "network")} {
				if err := os.MkdirAll(dir, 0700); err != nil {
					t.Fatal(err)
				}
			}
			for path, content := range map[string]string{filepath.Join(current, "config.json"): "old", filepath.Join(network, "a.cfg"): "old network", filepath.Join(stage, "debtik", "config.json"): "new", filepath.Join(stage, "network", "a.cfg"): "new network"} {
				if err := os.WriteFile(path, []byte(content), 0600); err != nil {
					t.Fatal(err)
				}
			}
			cmd := exec.Command(os.Args[0], "-test.run=^TestRestoreCrashHelper$")
			cmd.Env = append(os.Environ(), "DEBTIK_CRASH_TEST_ROOT="+root, "DEBTIK_CRASH_TEST_POINT="+point)
			if err := cmd.Run(); err == nil {
				t.Fatal("expected process to terminate")
			} else if ex, ok := err.(*exec.ExitError); !ok || ex.ExitCode() != 42 {
				t.Fatalf("unexpected subprocess failure: %v", err)
			}
			mgr := NewManager(current, network, filepath.Join(root, "backups"), nil)
			recovered, err := mgr.RecoverInterruptedRestore()
			if err != nil || !recovered {
				t.Fatalf("recover: %v %v", recovered, err)
			}
			config := "old"
			netConfig := "old network"
			if point == "committed" {
				config = "new"
				netConfig = "new network"
			}
			for path, want := range map[string]string{filepath.Join(current, "config.json"): config, filepath.Join(network, "a.cfg"): netConfig} {
				data, err := os.ReadFile(path)
				if err != nil || string(data) != want {
					t.Fatalf("%s: %q %v", path, data, err)
				}
			}
			if again, err := mgr.RecoverInterruptedRestore(); err != nil || again {
				t.Fatalf("recovery not idempotent: %v %v", again, err)
			}
		})
	}
}

func TestRecoveryAfterCrashWithNoPreviousConfig(t *testing.T) {
	root := t.TempDir()
	stage := filepath.Join(root, "stage")
	network := filepath.Join(root, "network")
	if err := os.MkdirAll(filepath.Join(stage, "debtik"), 0700); err != nil {
		t.Fatal(err)
	}
	if err := os.MkdirAll(network, 0700); err != nil {
		t.Fatal(err)
	}
	if err := os.WriteFile(filepath.Join(stage, "debtik", "new.json"), []byte("new"), 0600); err != nil {
		t.Fatal(err)
	}
	cmd := exec.Command(os.Args[0], "-test.run=^TestRestoreCrashHelper$")
	cmd.Env = append(os.Environ(), "DEBTIK_CRASH_TEST_ROOT="+root, "DEBTIK_CRASH_TEST_POINT=debtik")
	if err := cmd.Run(); err == nil {
		t.Fatal("expected process to terminate")
	} else if ex, ok := err.(*exec.ExitError); !ok || ex.ExitCode() != 42 {
		t.Fatal(err)
	}
	mgr := NewManager(filepath.Join(root, "debtik"), network, filepath.Join(root, "backups"), nil)
	if recovered, err := mgr.RecoverInterruptedRestore(); err != nil || !recovered {
		t.Fatalf("recovery: %v %v", recovered, err)
	}
	if _, err := os.Stat(filepath.Join(root, "debtik")); !os.IsNotExist(err) {
		t.Fatalf("new directory still present: %v", err)
	}
}

func TestRecoveryRejectsJournalWithUnrelatedPaths(t *testing.T) {
	root := t.TempDir()
	mgr := NewManager(filepath.Join(root, "debtik"), filepath.Join(root, "network"), filepath.Join(root, "backups"), nil)
	journal := &restoreJournal{DebtikDir: mgr.debtikDir, NetworkDir: mgr.networkDir, Files: []journalFile{{Path: filepath.Join(root, "outside.cfg")}}}
	if err := mgr.writeJournal(journal); err != nil {
		t.Fatal(err)
	}
	if _, err := mgr.RecoverInterruptedRestore(); err == nil {
		t.Fatal("accepted unrelated file")
	}
	if _, err := os.Stat(mgr.journalPath()); err != nil {
		t.Fatalf("journal lost after failed recovery: %v", err)
	}
}

func TestRecoveryRejectsIncompleteJournal(t *testing.T) {
	root := t.TempDir()
	current := filepath.Join(root, "debtik")
	if err := os.MkdirAll(current, 0700); err != nil {
		t.Fatal(err)
	}
	marker := filepath.Join(current, "config")
	if err := os.WriteFile(marker, []byte("preserve"), 0600); err != nil {
		t.Fatal(err)
	}
	mgr := NewManager(current, filepath.Join(root, "network"), filepath.Join(root, "backups"), nil)
	if err := mgr.writeJournal(&restoreJournal{DebtikDir: current, NetworkDir: mgr.networkDir, HasDebtik: true}); err != nil {
		t.Fatal(err)
	}
	if _, err := mgr.RecoverInterruptedRestore(); err == nil {
		t.Fatal("accepted incomplete journal")
	}
	if data, err := os.ReadFile(marker); err != nil || string(data) != "preserve" {
		t.Fatalf("config damaged: %q %v", data, err)
	}
}