package staros

import (
	"errors"
	"os"
	"path/filepath"
	"runtime"
	"testing"
	"time"
)

func Test_FileLock(t *testing.T) {
	filename := filepath.Join(t.TempDir(), "test.file")
	lock := NewFileLock(filename)
	lock2 := NewFileLock(filename)
	if err := lock.LockNoBlocking(false); err != nil {
		t.Fatal(err)
	}
	if err := lock2.LockNoBlocking(false); err != nil {
		t.Fatal(err)
	}
	if err := lock.Unlock(); err != nil {
		t.Fatal(err)
	}
	if err := lock2.Unlock(); err != nil {
		t.Fatal(err)
	}
	if err := lock2.LockNoBlocking(true); err != nil {
		t.Fatal(err)
	}
	if err := lock2.Unlock(); err != nil {
		t.Fatal(err)
	}
	_ = os.Remove(filename)
}

func TestFileLockExclusiveConflictTimeout(t *testing.T) {
	filename := filepath.Join(t.TempDir(), "timeout.file")
	lock := NewFileLock(filename)
	contender := NewFileLock(filename)
	if err := lock.Lock(true); err != nil {
		t.Fatal(err)
	}
	defer lock.Unlock()

	if err := contender.LockNoBlocking(true); !errors.Is(err, ERR_ALREADY_LOCKED) {
		if err == nil {
			_ = contender.Unlock()
		}
		t.Fatalf("expected non-blocking exclusive lock conflict, got %v", err)
	}

	start := time.Now()
	if err := contender.LockWithTimeout(50*time.Millisecond, true); !errors.Is(err, ERR_TIMEOUT) {
		if err == nil {
			_ = contender.Unlock()
		}
		t.Fatalf("expected exclusive lock timeout, got %v", err)
	}
	if elapsed := time.Since(start); elapsed > time.Second {
		t.Fatalf("lock timeout took too long: %s", elapsed)
	}

	if err := lock.Unlock(); err != nil {
		t.Fatal(err)
	}
	if err := contender.LockWithTimeout(time.Second, true); err != nil {
		t.Fatalf("expected lock after owner unlock, got %v", err)
	}
	if err := contender.Unlock(); err != nil {
		t.Fatal(err)
	}
}

func TestFileLockUnlockWithoutSuccessfulLock(t *testing.T) {
	filename := filepath.Join(t.TempDir(), "unlock-state.file")
	lock := NewFileLock(filename)
	if err := lock.Unlock(); !errors.Is(err, errFileLockNotLocked) {
		t.Fatalf("expected unlock without lock error, got %v", err)
	}

	owner := NewFileLock(filename)
	contender := NewFileLock(filename)
	if err := owner.Lock(true); err != nil {
		t.Fatal(err)
	}
	defer owner.Unlock()
	if err := contender.LockNoBlocking(true); !errors.Is(err, ERR_ALREADY_LOCKED) {
		if err == nil {
			_ = contender.Unlock()
		}
		t.Fatalf("expected lock conflict, got %v", err)
	}
	if err := contender.Unlock(); !errors.Is(err, errFileLockNotLocked) {
		t.Fatalf("failed lock attempt should not be unlockable, got %v", err)
	}
	if err := owner.Unlock(); err != nil {
		t.Fatal(err)
	}
}

func TestFileLockRejectsSecondLockOnSameObject(t *testing.T) {
	filename := filepath.Join(t.TempDir(), "same-object.file")
	lock := NewFileLock(filename)
	if err := lock.Lock(true); err != nil {
		t.Fatal(err)
	}
	defer lock.Unlock()

	for name, fn := range map[string]func() error{
		"Lock":            func() error { return lock.Lock(true) },
		"LockNoBlocking":  func() error { return lock.LockNoBlocking(true) },
		"LockWithTimeout": func() error { return lock.LockWithTimeout(time.Second, true) },
	} {
		if err := fn(); !errors.Is(err, ERR_ALREADY_LOCKED) {
			if err == nil {
				_ = lock.Unlock()
			}
			t.Fatalf("expected %s on same lock object to reject second lock, got %v", name, err)
		}
	}
}

func TestGetFileCreationTimeLinuxUnavailable(t *testing.T) {
	if runtime.GOOS != "linux" {
		t.Skip("linux-only creation time fallback")
	}
	filename := filepath.Join(t.TempDir(), "creation-time.file")
	if err := os.WriteFile(filename, []byte("demo"), 0o644); err != nil {
		t.Fatal(err)
	}
	info, err := os.Stat(filename)
	if err != nil {
		t.Fatal(err)
	}
	if got := GetFileCreationTime(info); !got.IsZero() {
		t.Fatalf("linux FileInfo should not report synthetic creation time, got %s", got)
	}
}