package recoveryrequest

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

func TestEncodeMatchesRockchipBootloaderMessageLayout(t *testing.T) {
	encoded, err := Encode("fw-0123456789abcdef")
	if err != nil {
		t.Fatal(err)
	}
	if len(encoded) != Size {
		t.Fatalf("size = %d, want %d", len(encoded), Size)
	}
	if got := field(encoded, commandOffset, commandSize); got != Command {
		t.Fatalf("command = %q", got)
	}
	if got := field(encoded, statusOffset, statusSize); got != "" {
		t.Fatalf("status = %q", got)
	}
	if got := field(encoded, recoveryOffset, recoverySize); got != "recovery\n--tera-update\n--operation=fw-0123456789abcdef\n" {
		t.Fatalf("recovery = %q", got)
	}
	if got := field(encoded, stageOffset, stageSize); got != "" {
		t.Fatalf("stage = %q", got)
	}
	message, err := Decode(encoded)
	if err != nil || message.OperationID != "fw-0123456789abcdef" {
		t.Fatalf("Decode = %+v, %v", message, err)
	}
}

func TestWriteAtTouchesOnlyTheBCBAndReadsBack(t *testing.T) {
	device := bytes.NewReader(bytes.Repeat([]byte{0xa5}, int(Offset)+Size+4096))
	buffer := &memoryDevice{data: make([]byte, device.Size())}
	if _, err := device.ReadAt(buffer.data, 0); err != nil {
		t.Fatal(err)
	}
	encoded, _ := Encode("operation-1")
	if err := WriteAt(buffer, encoded); err != nil {
		t.Fatal(err)
	}
	if !bytes.Equal(buffer.data[:Offset], bytes.Repeat([]byte{0xa5}, int(Offset))) {
		t.Fatal("bytes before the BCB changed")
	}
	if !bytes.Equal(buffer.data[Offset+Size:], bytes.Repeat([]byte{0xa5}, len(buffer.data)-int(Offset)-Size)) {
		t.Fatal("bytes after the BCB changed")
	}
	message, err := ReadAt(buffer)
	if err != nil || message.OperationID != "operation-1" {
		t.Fatalf("ReadAt = %+v, %v", message, err)
	}
}

func TestRejectsInvalidOrForeignMessages(t *testing.T) {
	for _, value := range []string{"", " space", "slash/value", string(bytes.Repeat([]byte{'a'}, 65))} {
		if _, err := Encode(value); err == nil {
			t.Fatalf("Encode(%q) succeeded", value)
		}
	}
	foreign := make([]byte, Size)
	copy(foreign, "boot-recovery")
	copy(foreign[recoveryOffset:], "recovery\n--wipe_data\n")
	if _, err := Decode(foreign); err == nil {
		t.Fatal("foreign recovery message was accepted")
	}
	if _, err := Decode(Clear()); err == nil {
		t.Fatal("cleared message was accepted")
	}
}

func TestClearIsExactZeroRecord(t *testing.T) {
	cleared := Clear()
	if len(cleared) != Size {
		t.Fatalf("Clear size = %d, want %d", len(cleared), Size)
	}
	if !bytes.Equal(cleared, make([]byte, Size)) {
		t.Fatal("Clear returned a non-zero BCB byte")
	}
}

func TestWriteRequestFileRequiresClearRecordAndPreservesSurroundingBytes(t *testing.T) {
	path := filepath.Join(t.TempDir(), "misc.img")
	contents := bytes.Repeat([]byte{0xa5}, int(Offset)+Size+4096)
	copy(contents[Offset:Offset+Size], Clear())
	if err := os.WriteFile(path, contents, 0o600); err != nil {
		t.Fatal(err)
	}
	if err := WriteRequestFile(path, "operation-1", true); err != nil {
		t.Fatal(err)
	}
	updated, err := os.ReadFile(path)
	if err != nil {
		t.Fatal(err)
	}
	if !bytes.Equal(updated[:Offset], contents[:Offset]) || !bytes.Equal(updated[Offset+Size:], contents[Offset+Size:]) {
		t.Fatal("WriteRequestFile changed bytes outside the BCB")
	}
	if IsClear(updated[Offset : Offset+Size]) {
		t.Fatal("request remained clear")
	}
	if err := WriteRequestFile(path, "operation-2", true); err == nil {
		t.Fatal("non-cleared recovery request was overwritten")
	}
}

type memoryDevice struct{ data []byte }

func (d *memoryDevice) ReadAt(p []byte, off int64) (int, error) {
	return copy(p, d.data[int(off):]), nil
}

func (d *memoryDevice) WriteAt(p []byte, off int64) (int, error) {
	return copy(d.data[int(off):], p), nil
}