#!/usr/bin/env python3

import yaml
import sys

class ObjectGeneratorException(Exception):
    pass

class OGAttributeSwitch:
    def __init__(self, attr, mandatory, **kwargs):
        if "default" in kwargs:
            self._default = kwargs["default"]
        else:
            self._default = None

        if not mandatory and self._default is None:
            raise ObjectGeneratorException("Switch must be either mandatory or with a default value supplied")

        self.attr = attr
        self._return = kwargs["return"]
        self._format = kwargs["format"]
        self.mandatory = mandatory

    def write_header(self, _file):
        _file.write(f"{self._return} {self.attr.obj.prefix}{self.attr.name}({self.attr.obj.key});\n")

    def write_body(self, _file, data):
        _file.write("\n".join([
            f"{self._return} {self.attr.obj.prefix}{self.attr.name}({self.attr.obj.key} key)",
            "{",
            "  switch (key)",
            "  {",
            ""]))

        for k in data:
            if self.attr.name in data[k]:
                _file.write(f"    case {k}: return {self._format.format(data=data[k][self.attr.name])};\n")
            elif self.mandatory:
                raise ObjectGeneratorException("No value for mandatory attribute {self.attr.name} in key {k}")

        if self.mandatory:
            _file.write(f'    default: bug("Garbled value of {self.attr.obj.key} in {self.attr.obj.prefix}{self.attr.name}: %d", key);\n')
        else:
            _file.write(f'    default: return {self._default};\n')
        _file.write("  }\n}\n\n")


class OGAttribute:
    def __init__(self, obj, name, mandatory=False, switch=None):
        self.obj = obj
        self.name = name
        self.mandatory = mandatory

        if switch is not None:
            self.resolver = OGAttributeSwitch(attr=self, name=name, mandatory=mandatory, **switch)

        if self.resolver is None:
            raise ObjectGeneratorException("No resolver specified")

    def write_header(self, _file):
        self.resolver.write_header(_file)

    def write_body(self, _file, data):
        self.resolver.write_body(_file, data)

class OGObject:
    def __init__(self, og, _def, _data):
        self.og = og
        self.attributes = { k: OGAttribute(name=k, obj=self, **_def["attributes"][k]) for k in _def["attributes"] }
        self.data = _data
        self.prefix = _def["prefix"]
        self.key = _def["key"]

    def write_header(self, _file):
        _file.write(f"{self.key} " + "{\n")
        for k in self.data:
            if "_value" in self.data[k]:
                _file.write(f"  {k} = {self.data[k]['_value']},\n")
            else:
                _file.write(f"  {k},\n")
        _file.write("};\n\n")

        for name,a in self.attributes.items():
            a.write_header(_file)

    def write_body(self, _file):
        for name, a in self.attributes.items():
            a.write_body(_file, self.data)


class ObjectGenerator:
    def __init__(self, _meta, _keys, **data):
        try:
            self.objects = { k: OGObject(og=self, _def=_keys[k], _data=data[k]) for k in data }
        except Exception as e:
            raise ObjectGeneratorException(f"Failed to map data and _keys") from e

        self._meta = _meta

    def write_out(self, _file):
        self._write_header(_file)
        self._write_body(_file)

    def _write_header(self, _file):
        _file.write(f"""/* File generated by ObjectGenerator */
#ifndef {self._meta["header_guard"]}
#define {self._meta["header_guard"]}

""")
        if "include" in self._meta:
            for i in self._meta["include"]:
                _file.write(f"#include {i}\n")

        for k, o in self.objects.items():
            header = f"/* Headers for {k} */"
            _file.write(header + "\n")
            _file.write("/" + ("*"*(len(header)-2)) + "/\n")
            o.write_header(_file)
            _file.write("\n")

        _file.write(f"#endif /* {self._meta['header_guard']} */\n\n\n")

    def _write_body(self, _file):
        _file.write(f"""/* Build with -DOG_BUILD_BODY=1 */
#ifdef OG_BUILD_BODY
""")
        
        for k, o in self.objects.items():
            header = f"/* Body for {k} */"
            _file.write(header + "\n")
            _file.write("/" + ("*"*(len(header)-2)) + "/\n")
            o.write_body(_file)
            _file.write("\n")

        _file.write(f"#endif /* OG_BUILD_BODY */\n")


with open(sys.argv[1], "r") as f:
    t = ObjectGenerator(**dict(yaml.safe_load(f).items()))

with open(sys.argv[2], "w") as f:
    t.write_out(f)