#!/usr/bin/env python3

import argparse
import contextlib
import json
from pathlib import Path
import textwrap
class Sdl3SymbolIterator:
    def __init__(self, sdl3_json, skip_non_partable_symbols=True):
        self.sdl3_json = sdl3_json
        self.next_index = 0
        self.skip_non_partable_symbols = skip_non_partable_symbols

    @property
    def symbols_remaining(self):
        return len(self.sdl3_json) - self.next_index

    def __iter__(self):
        return self

    def __next__(self):
        while True:
            if self.next_index >= len(self.sdl3_json):
                raise StopIteration
            symbol_json = self.sdl3_json[self.next_index]
            self.next_index += 1
            name = symbol_json["name"]
            rettype = symbol_json["retval"]
            parameter_types = symbol_json["parameter"]
            parameter_names = symbol_json["parameter_name"]
            if parameter_types[0] == "void":
                parameter_types = parameter_types[1:]
                parameter_names = parameter_names[1:]
                assert len(parameter_types) == 0
            type_decl = ", ".join(parameter_type.replace("REWRITE_NAME", parameter_name) for parameter_type, parameter_name in zip(parameter_types, parameter_names))

            if self.skip_non_partable_symbols:
                if name.startswith("Vk") or "vulkan" in name.lower():
                    continue
                if "android" in name.lower() or "iOS" in name:
                    continue
                if "XTask" in type_decl or "XUser" in type_decl:
                    continue
                if "SDL_WindowsMessageHook" in type_decl:
                    continue

            return rettype, name, type_decl


@contextlib.contextmanager
def iterate_sdl3_symbols(sdl3_json):
    try:
        yield Sdl3SymbolIterator(sdl3_json)
    finally:
        pass


def main():
    parser = argparse.ArgumentParser(allow_abbrev=False)
    parser.add_argument("--api", required=True, type=Path, help="Path of SDL3 json api (generated by SDL/src/dynapi/gendynapi.py --dump)")
    parser.add_argument("--used", required=True, type=Path, help="Path of used SDL3 symbols as a json file")
    args = parser.parse_args()

    with args.api.open() as f_sdl3:
        sdl3_json = json.load(f_sdl3)

    with args.used.open() as f_used:
        sdl3_used = set(json.load(f_used))

    print("#pragma once")

    print()
    print(f"// This file is auto-generated by {Path(__file__).name}. Do not edit.")

    print()
    print("#ifdef SDL_h_")
    print("#error This file must be included BEFORE SDL3/SDL.h")
    print("#endif")

    print()
    print("#include <SDL3/SDL.h>")
    print("#include <SDL3/SDL_revision.h>")
    print("#ifndef MORTAR_IMPLEMENT_SDL_MAIN")
    print("#define SDL_MAIN_HANDLED")
    print("#endif")
    print("#include <SDL3/SDL_main.h>")
    print("#include <cstdio>")

    print()
    print("#ifdef SDL3_DYNAMIC_LOAD")

    print()
    print("#define FOREACH_SDL3_SYMBOL(X) \\")
    seen_symbols = set()
    with iterate_sdl3_symbols(sdl3_json) as sdl3_symbol_iterator:
        for rettype, name, type_decl in sdl3_symbol_iterator:
            if name in sdl3_used:
                print(f"  X({rettype}, {name}, ({type_decl}))" + ("" if sdl3_symbol_iterator.symbols_remaining == 0 else " \\"))
                seen_symbols.add(name)

    if seen_symbols != sdl3_used:
        missing = sdl3_used - seen_symbols
        parser.error(f"sdl3 api does not provide all required SDL3 symbols (missing={missing})")

    print()
    print("#define X_SDL3_SYMBOL_TYPEDEF(RETTYPE, NAME, TYPES) typedef RETTYPE SDLCALL NAME ## _cbfn TYPES;")
    print("#define X_SDL3_STRUCT_MEMBER(RETTYPE, NAME, TYPES) NAME ## _cbfn *NAME##_symbol;")

    print()
    print("FOREACH_SDL3_SYMBOL(X_SDL3_SYMBOL_TYPEDEF)")
    print("typedef struct SDL3_Symbols {")
    print("  int refcount;")
    print("  void *handle;")
    print("  FOREACH_SDL3_SYMBOL(X_SDL3_STRUCT_MEMBER)")
    print("} SDL3_Symbols;")

    print()
    print("#undef X_SDL3_SYMBOL_TYPEDEF")
    print("#undef X_SDL3_STRUCT_MEMBER")

    print()
    print("extern SDL3_Symbols SDL3;")

    print()
    print("#ifdef IMPLEMENT_DYN_SDL3")

    print()
    print(textwrap.dedent("""\
        #ifdef _WIN32
        static const char * const sdl3_locations[] = {
            "SDL3.dll",
        };
        #elif defined(__APPLE__)
        #define SDL3_LIBNAME "libSDL3.dylib"
        #define SDL3_FRAMEWORK "SDL3.framework/Versions/A/SDL3"
        static const char * const sdl3_locations[] = {
            "@loader_path/" SDL3_LIBNAME, /* MyApp.app/Contents/MacOS/libSDL3_dylib */
            "@loader_path/../Frameworks/" SDL3_FRAMEWORK, /* MyApp.app/Contents/Frameworks/SDL3_framework */
            "@executable_path/" SDL3_LIBNAME, /* MyApp.app/Contents/MacOS/libSDL3_dylib */
            "@executable_path/../Frameworks/" SDL3_FRAMEWORK, /* MyApp.app/Contents/Frameworks/SDL3_framework */
            NULL,  /* /Users/username/Library/Frameworks/SDL3_framework */
            "/Library/Frameworks" SDL3_FRAMEWORK, /* /Library/Frameworks/SDL3_framework */
            SDL3_LIBNAME /* oh well, anywhere the system can see the .dylib (/usr/local/lib or whatever) */
        };
        #undef SDL3_LIBNAME
        #undef SDL3_FRAMEWORK
        #else
        static const char * const sdl3_locations[] = {
            "libSDL3.so.0",
            "libSDL3.so",
        };
        #endif

        #ifdef _WIN32
        #include <windows.h>
        static void *open_object(const char *name) {
            return (void *)LoadLibraryA(name);
        }
        static void close_object(void *obj) {
            FreeLibrary((HMODULE)obj);
        }
        static void *load_symbol(void *obj, const char *name) {
            return (void *)GetProcAddress((HMODULE)obj, name);
        }
        static const char *load_error(void) {
            static char buffer[512];
            DWORD cchMsg = FormatMessageA(FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS,
                NULL,
                GetLastError(),
                MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
                buffer,
                sizeof(buffer)-1,
                NULL);
            if (cchMsg == 0) {
                strncpy(buffer, "GetProcAddress failed", sizeof(buffer));
                buffer[sizeof(buffer)-1] = '\\0';
            }
            return buffer;
        }
        #else
        #include <dlfcn.h>
        static void *open_object(const char *name) {
            return dlopen(name, RTLD_NOW | RTLD_LOCAL);
        }
        static void close_object(void *obj) {
            dlclose(obj);
        }
        static void *load_symbol(void *obj, const char *name) {
            return dlsym(obj, name);
        }
        static const char *load_error(void) {
            return dlerror();
        }
        #endif
    """))

    print()
    print(textwrap.dedent("""\
        #define X_SDL3_LOAD_SYMBOL(RETTYPE, NAME, TYPES) \\
            SDL3.NAME##_symbol = (NAME##_cbfn*)load_symbol(SDL3.handle, #NAME); \\
            if (!SDL3.NAME##_symbol) { \\
                missing_symbol = #NAME; \\
                goto error; \\
            }
        static bool load_sdl3_api() {
            if (SDL3.refcount) {
                SDL3.refcount += 1;
                return true;
            }
            SDL_zero(SDL3);
            for (size_t i = 0; i < SDL_arraysize(sdl3_locations); i++) {
                SDL3.handle = open_object(sdl3_locations[i]);
                if (SDL3.handle != NULL) {
                    break;
                }
            }
            if (!SDL3.handle) {
                fputs("Could not find SDL3 library\\n", stderr);
                return false;
            }
            const char *missing_symbol = NULL;
            FOREACH_SDL3_SYMBOL(X_SDL3_LOAD_SYMBOL)
            SDL3.refcount = 1;
            return true;
        error:
            fprintf(stderr, "Could not find SDL3 symbol: %s\\n", missing_symbol);
            close_object(SDL3.handle);
            SDL_zero(SDL3);
            return false;
        }"""))


    print()
    print(textwrap.dedent("""\
        static void unload_sdl3_api() {
            SDL3.refcount -= 1;
            if (!SDL3.refcount) {
                close_object(SDL3.handle);
                SDL_zero(SDL3.handle);
            }
        }"""))

    print("#endif // IMPLEMENT_DYN_SDL3")
    print()

    slow_symbols = ("SDL_memset", "SDL_memmove", "SDL_memcpy")
    print()
    with iterate_sdl3_symbols(sdl3_json) as sdl3_symbol_iterator:
        for rettype, name, type_decl in sdl3_symbol_iterator:
            if name in slow_symbols:
                print(f"#ifndef SDL_SLOW_{name.removeprefix('SDL_').upper()}")
            print(f"#ifdef {name}")
            print(f"#undef {name}")
            print(f"#endif // {name}")
            if name in sdl3_used:
                print(f"#define {name} SDL3.{name}_symbol")
            else:
                print(f"#define {name} SDL3_symbol_{name}_is_marked_unused")
            if name in slow_symbols:
                print(f"#endif // SDL_SLOW_{name.removeprefix('SDL_').upper()}")

    print()
    print("#else // SDL3_DYNAMIC_LOAD")

    print()
    print("#define load_sdl3_api() true")
    print("#define unload_sdl3_api() do {} while (0)")

    print()
    print("#endif // SDL3_DYNAMIC_LOAD")




if __name__ == "__main__":
    raise SystemExit(main())