# backend/serializer.py
import pcbnew

class Serializer:
    @staticmethod
    def serialize(item):
        """
        Returns (sexpr_string, error_message).
        """
        if not item: return None, "Item is None"
        
        last_error = ""
        
        # Method 1: PCB_IO_KICAD_SEXPR (Robust, KiCad 6+)
        try:
            sf = pcbnew.STRING_FORMATTER()
            plugin = pcbnew.PCB_IO_KICAD_SEXPR()
            plugin.SetOutputFormatter(sf)
            plugin.Format(item)
            res = sf.GetString()
            if res and len(res) > 0:
                return res, None
            else:
                last_error = "Format returned empty string"
        except Exception as e:
            last_error = str(e)
        
        # Method 2: Fallback to direct Serialize
        try:
            sf = pcbnew.STRING_FORMATTER()
            if hasattr(item, 'Serialize'):
                item.Serialize(sf)
                res = sf.GetString()
                if res and len(res) > 0:
                    return res, None
        except Exception as e:
            last_error = f"{last_error} | Fallback: {str(e)}"
            
        return None, last_error

    @staticmethod
    def deserialize(data, board):
        """
        Returns (item, error_message).
        """
        if not data: return None, "No data provided"
        cls_name = data.get('class')
        sexpr = data.get('sexpr')
        if not cls_name or not sexpr: return None, "Missing class or sexpr"
        
        try:
            if not hasattr(pcbnew, cls_name):
                return None, f"Class {cls_name} not found in pcbnew"
            
            cls = getattr(pcbnew, cls_name)
            item = None
            
            # Instantiate item
            try:
                item = cls(board)
            except:
                try:
                    item = cls()
                except Exception as e:
                    return None, f"Constructor failed for {cls_name}: {e}"
            
            # Deserialize with KiCad version compatibility
            # KiCad 9+ requires (data, source_name), older versions take (data)
            try:
                lr = pcbnew.STRING_LINE_READER(sexpr, "restore")
            except:
                try:
                    lr = pcbnew.STRING_LINE_READER(sexpr)
                except Exception as e:
                    return None, f"STRING_LINE_READER init failed: {e}"
                
            item.Deserialize(lr)
            return item, None
        except Exception as e:
            return None, f"Deserialization error for {cls_name}: {e}"