import json
from dataclasses import dataclass
from typing import List, Dict, Any
from pathlib import Path


@dataclass
class XICInstruction:
    op: str
    args: List[Any]


@dataclass
class XICProgram:
    magic: str
    version: int
    model: str
    entrypoint: str
    symbols: Dict[str, int]
    instructions: List[XICInstruction]


class XICLoadError(Exception):
    pass


def load_xic(path: str) -> XICProgram:
    """Load and validate an XIC program from JSON."""
    try:
        p = Path(path)
        if not p.exists():
            raise XICLoadError(f"File not found: {path}")

        with open(p) as f:
            data = json.load(f)

        # Validate magic and version
        magic = data.get("magic")
        if magic != "GXIC1":
            raise XICLoadError(f"Invalid magic: {magic} (expected GXIC1)")

        version = data.get("version")
        if version != 1:
            raise XICLoadError(f"Unsupported version: {version}")

        # Parse instructions
        instructions = []
        for instr in data.get("instructions", []):
            instructions.append(XICInstruction(
                op=instr["op"],
                args=instr.get("args", [])
            ))

        return XICProgram(
            magic=magic,
            version=version,
            model=data.get("model", ""),
            entrypoint=data.get("entrypoint", "main"),
            symbols=data.get("symbols", {}),
            instructions=instructions
        )

    except json.JSONDecodeError as e:
        raise XICLoadError(f"Invalid JSON: {e}")
    except Exception as e:
        raise XICLoadError(f"Load failed: {e}")