package hbrtl

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

func TestFCreateWriteReadClose(t *testing.T) {
	_, th := setupVM()
	dir := t.TempDir()
	fpath := filepath.Join(dir, "test.bin")

	// FCREATE
	th.PushString(fpath)
	th.PendingParams2(1)
	FCreate(th)
	h := th.GetRetValue().AsInt()
	if h < 0 {
		t.Fatalf("FCREATE failed: handle=%d", h)
	}

	// FWRITE
	th.PushInt(h)
	th.PushString("Hello Five!")
	th.PendingParams2(2)
	FWrite(th)
	n := th.GetRetValue().AsInt()
	if n != 11 {
		t.Errorf("FWRITE wrote %d bytes, want 11", n)
	}

	// FCLOSE
	th.PushInt(h)
	th.PendingParams2(1)
	FClose(th)
	if !th.GetRetValue().AsBool() {
		t.Error("FCLOSE returned false")
	}

	// FOPEN read
	th.PushString(fpath)
	th.PushInt(0) // read-only
	th.PendingParams2(2)
	FOpen(th)
	h2 := th.GetRetValue().AsInt()
	if h2 < 0 {
		t.Fatalf("FOPEN failed: handle=%d", h2)
	}

	// FREAD
	th.PushInt(h2)
	th.PushNil()  // buffer (not used in our impl)
	th.PushInt(11)
	th.PendingParams2(3)
	FRead(th)
	data := th.GetRetValue().AsString()
	if data != "Hello Five!" {
		t.Errorf("FREAD = %q, want %q", data, "Hello Five!")
	}

	// FCLOSE
	th.PushInt(h2)
	th.PendingParams2(1)
	FClose(th)
}

func TestFSeek(t *testing.T) {
	_, th := setupVM()
	dir := t.TempDir()
	fpath := filepath.Join(dir, "seek.bin")

	// Create and write
	os.WriteFile(fpath, []byte("0123456789"), 0644)

	th.PushString(fpath)
	th.PushInt(0)
	th.PendingParams2(2)
	FOpen(th)
	h := th.GetRetValue().AsInt()

	// Seek to offset 5 from start
	th.PushInt(h)
	th.PushLong(5)
	th.PushInt(0) // from start
	th.PendingParams2(3)
	FSeek(th)
	pos := th.GetRetValue().AsLong()
	if pos != 5 {
		t.Errorf("FSEEK pos = %d, want 5", pos)
	}

	// Read from offset 5
	th.PushInt(h)
	th.PushNil()
	th.PushInt(5)
	th.PendingParams2(3)
	FRead(th)
	if r := th.GetRetValue().AsString(); r != "56789" {
		t.Errorf("FREAD after seek = %q, want %q", r, "56789")
	}

	th.PushInt(h)
	th.PendingParams2(1)
	FClose(th)
}

func TestFEraseRename(t *testing.T) {
	_, th := setupVM()
	dir := t.TempDir()
	fpath := filepath.Join(dir, "todel.txt")
	os.WriteFile(fpath, []byte("x"), 0644)

	// FRENAME
	newPath := filepath.Join(dir, "renamed.txt")
	th.PushString(fpath)
	th.PushString(newPath)
	th.PendingParams2(2)
	FRename(th)
	if r := th.GetRetValue().AsInt(); r != 0 {
		t.Errorf("FRENAME = %d, want 0", r)
	}
	if _, err := os.Stat(newPath); err != nil {
		t.Error("Renamed file not found")
	}

	// FERASE
	th.PushString(newPath)
	th.PendingParams2(1)
	FErase(th)
	if r := th.GetRetValue().AsInt(); r != 0 {
		t.Errorf("FERASE = %d, want 0", r)
	}
	if _, err := os.Stat(newPath); err == nil {
		t.Error("File still exists after FERASE")
	}
}

func TestFWritePartial(t *testing.T) {
	_, th := setupVM()
	dir := t.TempDir()
	fpath := filepath.Join(dir, "partial.bin")

	// Create
	th.PushString(fpath)
	th.PendingParams2(1)
	FCreate(th)
	h := th.GetRetValue().AsInt()

	// Write only 3 bytes of "Hello"
	th.PushInt(h)
	th.PushString("Hello")
	th.PushInt(3)
	th.PendingParams2(3)
	FWrite(th)
	n := th.GetRetValue().AsInt()
	if n != 3 {
		t.Errorf("Partial FWRITE = %d, want 3", n)
	}

	th.PushInt(h)
	th.PendingParams2(1)
	FClose(th)

	// Verify
	data, _ := os.ReadFile(fpath)
	if string(data) != "Hel" {
		t.Errorf("File content = %q, want %q", string(data), "Hel")
	}
}