#!/usr/bin/env python3

import logging

import xml.etree.ElementTree as ET
import re

###############################################################################
def camel_to_snake(name):
    name = re.sub('([a-z])([A-Z])', r'\1_\2', name)
    return name.lower()


def remove_namespace(name):
    name = re.sub('^VK_', '', name)
    name = re.sub('^[vV][kK]', '', name)
    return name


###############################################################################
def rename(name):
    return name
    name = remove_namespace(name)
    name = camel_to_snake(name)
    return name


##-----------------------------------------------------------------------------
def rename_enum(type, value):
    return value
    value = rename(value)
    value = re.sub("^%s_" % type, '', value)
    return value


###############################################################################
class type(object):
    def __init__(self, name):
        self.name = name

    def depends(self):
        return []

    def declare(self):
        return ""

    def define(self,types):
        return ""


##-----------------------------------------------------------------------------
class basetype(type):
    def __init__(self, node):
        assert(node.tag == 'type')
        assert(node.attrib['category'] == 'basetype')

        super().__init__(node.find('name').text)
        self._type = node.find('type').text

    def depends(self):
        return [self._type]

    def define(self, types):
        return "using %(name)s = %(type)s;" % {
            'name': rename(self.name),
            'type': self._type
        }


##-----------------------------------------------------------------------------
class handle(type):
    def __init__(self, node):
        assert (node.tag == "type")
        assert (node.attrib['category'] == 'handle')

        super().__init__(node.find('name').text)

    def declare(self):
        return "using %(name)s = struct _%(name)s*;" % {
            'name': rename(self.name)
        }


##-----------------------------------------------------------------------------
class constant(type):
    def __init__(self,node):
        assert(node.tag == 'enum')

        super().__init__(node.attrib['name'])

        self._value = node.attrib['value']

    def define(self, types):
        return "constexpr auto %(name)s = %(value)s;" % {
            'name': self.name,
            'value': self._value
        }


##-----------------------------------------------------------------------------
# a high level 'bitmask' enum that doesn't necessarily define anything.
# inherits the values from something else instead. super fucking weird..
class bitmask(type):
    def __init__(self, node):
        assert(node.tag == 'type')
        assert(node.attrib['category'] == 'bitmask')

        super().__init__(node.find('name').text)

        self._requires = node.attrib.get('requires', None)
        self._type = node.find('type').text

    def depends(self):
        if self._requires:
            return [self._type, self._requires]
        else:
            return [self._type]

    def declare(self):
        return ""

    def define(self, types):
        if not self._requires:
            return "using %(name)s = %(type)s;" % {
                'name': rename(self.name),
                'type': rename(self._type)
            }

        return "using %(name)s = %(requires)s;" % {
            'name': rename(self.name),
            'requires': rename(self._requires)
        }

        members = types[self._requires].values

        return "enum class %(name)s : %(type)s { %(members)s };" % {
            'name': rename(self.name),
            'type': rename(self._type),
            'members': "\n".join("%(name)s = %(value)s," % x for x in members)
        }


##-----------------------------------------------------------------------------
# an enum with bit values that will be used by a bitmask enum. weirdly...
class bitflag(type):
    def __init__(self, node):
        assert(node.tag == "enums")
        assert(node.attrib['type'] == 'bitmask')

        name = node.attrib['name']
        super ().__init__(name)

        self._depends = node.attrib.get('requires', None)

        self.values = []
        for v in node.findall("./enum"):
            if 'value' in v.attrib:
                self.add(v.attrib['name'], v.attrib['value'])
            elif 'bitpos' in v.attrib:
                self.add(v.attrib['name'], '1 << %s' % v.attrib['bitpos'])
            else:
                assert False, "unhandled bitmask type"

    def add(self, name, value=None):
        self.values.append({'name': name, 'value': value})

    def values(self):
        return self.values

    def depends(self):
        if self._depends:
            return ['VkFlags',self._depends]
        else:
            return ['VkFlags']

    def declare(self):
        return ""

    def define(self,types):
        values = []
        for v in self.values:
            if 'value' in v:
                values.append(
                    "%(name)s = %(value)s" % {
                        'name': rename(v['name']),
                        'value': v['value']
                    }
                )
            else:
                values.append(rename(v['name']))

        return """
            enum %(name)s : %(vkflags)s { %(members)s };
            """ % {
                'name': rename(self.name),
                'vkflags': rename('VkFlags'),
                'members': ", ".join(values)
        }


##-----------------------------------------------------------------------------
class enum(type):
    def __init__(self, node):
        assert(node.tag == "enums")

        name = node.attrib['name']
        super().__init__(name)

        self.values = list(map(
            lambda x: {
                'name' : x.attrib['name'],
                'value': x.attrib['value']
            },
            node.findall('./enum')
        ))

    def add(self,name,value=None):
        self.values.append({'name': name, 'value': value})

    def declare(self):
        return ""

    def define(self,types):
        values = []
        for v in self.values:
            if v['value']:
                values.append(
                    "%(name)s = %(value)s" % {
                        'name': rename(v['name']),
                        'value': v['value']
                    }
                )
            else:
                values.append(rename(v['name']))

        attribute = '[[nodiscard]]' if self.name == 'VkResult' else ''

        return "enum %(attribute)s %(name)s : int32_t { %(values)s };" % ({
            'name': rename(self.name),
            'attribute': attribute,
            'values': ", ".join(values),
        })


##-----------------------------------------------------------------------------
class funcpointer(type):
    def __init__(self, node):
        assert(node.tag == 'type')
        assert(node.attrib['category'] == "funcpointer")

        name = node.find('name').text
        super().__init__(name)
        self.params = list(map(lambda x: x.text, node.findall('./type')))
        self.text = "".join(node.itertext())

    def depends(self):
        return ['VkBool32'] + self.params

    def declare(self):
        return self.text

    def define(self,types):
        return "";


##-----------------------------------------------------------------------------
class pod(type):
    def __init__(self,node):
        assert(node.tag == 'type')
        assert(node.attrib['category'] in ['struct', 'union'])

        super().__init__(node.attrib['name'])
        self._node = node
        self._category = node.attrib['category']

        # sometimes there are enums hiding in the member fields being used as array sizes
        self._depends  = []
        self._depends += list(e.text for e in node.findall('.//enum'))
        self._depends += list(t.text for t in node.findall('.//type'))

        self._members = []

        for member in node.findall('./member'):
            type = member.find('type').text
            name = member.find('name').text

            comment = member.find('comment')
            if not comment is None:
                member.remove(comment)
            code = " ".join(member.itertext())

            #code = member.iter()
            #code = filter(lambda x: x.tag != 'comment', code)
            #code = map(lambda x: x.itertext(), code)
            #code = map(lambda x: "".join(x), code)
            #code = "".join(code)

            self._members.append({'code': code, 'type': type, 'name': name})

    def depends(self):
        return self._depends

    def declare(self):
        return "%(category)s %(name)s;" % {
            'category': self._category,
            'name': rename(self.name)
        }

    def define(self,types):
        return "%(category)s %(name)s {\n%(members)s\n};" % {
            'category': self._category,
            'name': rename(self.name),
            'members': "\n".join(m['code'] + ';' for m in self._members)
        }


##-----------------------------------------------------------------------------
class struct(pod):
    def __init__(self,node):
        super().__init__(node)


##-----------------------------------------------------------------------------
class union(pod):
    def __init__(self,node):
        super().__init__(node)


###############################################################################
def parse_types(nodes):
    types = []

    for n in nodes:
        # we need to parse too much unstructured text to actually do anything
        # useful with these declarations
        for t in n.findall("./type[@category='handle']"):
            types.append(handle(t))

        for t in n.findall('./type[@category="bitmask"]'):
            types.append(bitmask(t))

        for t in n.findall('./type[@category="basetype"]'):
            types.append(basetype(t))

        for t in n.findall("./type[@category='funcpointer']"):
            types.append(funcpointer(t))

        for t in n.findall("./type[@category='union']"):
            types.append(union(t))

        for t in n.findall("./type[@category='struct']"):
            types.append(struct(t))

        return types


###############################################################################
def parse_enums(nodes):
    enums = []

    for n in nodes:
        if n.attrib['name'] == "API Constants":
            for c in n.findall('./enum'):
                enums.append(constant(c))
        elif n.attrib['type'] == 'bitmask':
            enums.append(bitflag(n))
        elif n.attrib['type'] == 'enum':
            enums.append(enum(n))
        else:
            assert False, "unhandled enum type"

    return enums


###############################################################################
class command(type):
    def __init__(self, node):
        assert(node.tag == "command")
        proto = node.find('proto')
        super().__init__(proto.find('name').text)

        self._result = proto.find('type').text
        self._params = []
        self._depends = []
        for p in node.findall('./param'):
            self._depends.append(p.find('type').text)
            self._params.append("".join(p.itertext()))

    def depends(self):
        return [self._result] + self._depends

    def declare(self):
        return "%(result)s %(name)s (%(params)s) noexcept;" % {
            'name': rename(self.name),
            'result': self._result,
            'params': ", ".join(self._params)
        }


##-----------------------------------------------------------------------------
def parse_commands(nodes):
    commands = []

    for n in nodes:
        for c in n.findall('./command'):
            commands.append(command(c))

    return commands


###############################################################################
def parse_extension(types, node):
    r = node.find('require')

    for enum in r.findall('./enum'):
        if 'extends' in enum.attrib:
            types[enum.attrib['extends']].add(name=enum.attrib['name'])
    for command in r.findall('./command'):
        if not command.attrib['name'] in types:
            raise "unknown command"


###############################################################################
def write_type(dst, all, pending, t):
    logging.info("writing: %s", t.name)

    for d in t.depends():
        if d in pending:
            write_type(dst, all, pending, pending[d])

    if t.name in pending:
        dst.write(t.declare())
        dst.write('\n')
        dst.write(t.define(all))
        dst.write('\n')
        del pending[t.name]


##-----------------------------------------------------------------------------
import copy
def write_types(dst, types):
    all = types
    pending = copy.deepcopy(types)
    keys = list(types.keys())

    for k in keys:
        if k in types:
            write_type(dst, all, pending, types[k])


##-----------------------------------------------------------------------------
def write_root(dst, node):
    dst.write ("""
        #ifndef __VK_HPP
        #define __VK_HPP
        #include <type_traits>

        template <typename T>
        struct enable_bitops : public std::false_type { };

        #include <cstdint>
        #include <cstddef>

        #if defined(__cplusplus)
        extern "C" {
        #endif

        struct Display;
        struct VisualID;
        using Window = unsigned long;

        struct ANativeWindow;

        struct MirConnection;
        struct MirSurface;

        struct wl_display;
        struct wl_surface;

        using HANDLE = void*;
        using HINSTANCE = HANDLE;
        using HWND = HANDLE;

        using SECURITY_ATTRIBUTES = HANDLE;
        using DWORD = uint32_t;
        using LPCWSTR = char16_t*;

        struct xcb_connection_t;
        struct xcb_visualid_t;
        using xcb_window_t = uint32_t;
        using XID = unsigned long;
        using RROutput = XID;

        #define VKAPI_PTR /*VKAPI_PTR*/

        // because, in its wisdom, the spec doesn't actually allow us to
        // extract the value for VK_NULL_HANDLE from the XML we'll just
        // hard code it here.
        #define VK_NULL_HANDLE nullptr

        // TODO: make this correspond to a required version
        #define VK_VERSION_1_0
    """)

    types = []
    types += parse_types(node.findall('./types'))
    types += parse_enums(node.findall('./enums'))
    types += parse_commands(node.findall('./commands'))

    types = dict((t.name,t) for t in types)

    for n in node.findall('./extensions/extension'):
        parse_extension(types, n)

    write_types(dst, types)

    #dst.writelines("\n".join(map(lambda x: x.declare(), types)))
    #dst.writelines("\n".join(map(lambda x: x.define(), types)))
    #dst.writelines("\n".join(map(lambda x: x.declare(), commands)))

    dst.write ("""
        #if defined(__cplusplus)
        }
        #endif
    """)

    for x in types.values():
        if isinstance(x,bitflag):
            dst.write("""
                template <>
                struct enable_bitops<%(name)s> :
                    public std::true_type
                { };
                """ % { 'name': x.name }
            )

    dst.write("""
    template <typename T>
    std::enable_if_t<enable_bitops<T>::value, T>
    operator| (T a, T b)
    {
        return T (
            static_cast<std::underlying_type_t<T>> (a) |
            static_cast<std::underlying_type_t<T>> (b)
        );
    }

    #endif
    """)


###############################################################################
import argparse


##-----------------------------------------------------------------------------
if __name__ == '__main__':
    #logging.getLogger().setLevel(logging.INFO)

    parser = argparse.ArgumentParser(description='Transform XML API specification into C++ headers')
    parser.add_argument('src', type=str, help='the path to the XML file to transform')
    parser.add_argument('dst', type=str, help='the output path for the result')

    args = parser.parse_args()

    src = open(args.src, 'r')
    dst = open(args.dst, 'w')

    tree = ET.parse(src)
    root = tree.getroot()

    write_root(dst, root)