import os
import subprocess
import tempfile
import platform
from pathlib import Path

def get_bgcode_binary():
    """Returns the path to the correct bgcode binary for the current platform."""
    addon_dir = os.path.dirname(os.path.dirname(os.path.dirname(__file__)))
    os_name = platform.system()
    
    if os_name == "Windows":
        bin_name = "bgcode.exe"
    elif os_name == "Darwin":  # macOS
        bin_name = "bgcode_mac"
    else:  # Linux/Other
        bin_name = "bgcode"
        
    bin_path = os.path.join(addon_dir, "infra", "bin", bin_name)
    
    # Fallback to just "bgcode" if platform-specific one isn't found
    if not os.path.exists(bin_path):
        fallback_path = os.path.join(addon_dir, "infra", "bin", "bgcode")
        if os.path.exists(fallback_path):
            return fallback_path
            
    return bin_path

def convert_to_bgcode(gcode: str, name_part: str, compress: bool = True) -> bytes:
    """
    Converts a G-code string to binary BGCode using the internal bgcode tool.
    Returns the binary content of the converted file.
    """
    bgcode_bin = get_bgcode_binary()
    
    if not os.path.exists(bgcode_bin):
        raise FileNotFoundError(f"bgcode binary not found at {bgcode_bin}")

    with tempfile.TemporaryDirectory() as tmpdir:
        tmp_gcode = Path(tmpdir) / (name_part + ".gcode")
        tmp_gcode.write_text(gcode, encoding="utf-8")
        
        # Run conversion: bgcode <input>
        cmd = [bgcode_bin, str(tmp_gcode)]
        if compress:
            # Recommended settings for true binary bgcode
            cmd.extend([
                "--slicer_metadata_compression=1",
                "--gcode_compression=3", 
                "--gcode_encoding=2"
            ])

        res = subprocess.run(cmd, capture_output=True, text=True)
        if res.returncode != 0:
            err_msg = res.stderr.strip() or res.stdout.strip() or "Unknown error"
            raise RuntimeError(f"bgcode conversion failed: {err_msg}")
        
        tmp_bgcode = tmp_gcode.with_suffix(".bgcode")
        if tmp_bgcode.exists():
            return tmp_bgcode.read_bytes()
        else:
            raise FileNotFoundError("Failed to find generated .bgcode file")