#!/usr/bin/env python3

from argparse import ArgumentParser
import subprocess
import os
import json

__version__ = "1.0"

ld = os.environ.get("LD", "i586-pc-msdosdjgpp-ld")
strip = os.environ.get("STRIP", "i586-pc-msdosdjgpp-strip")

entity_types = (
    "Player",
    "Snake",
    "Bat",
    "Old",
    "Bones",
    "Time",
    "Bonus",
    "Pickaxe",
    "GoldKey",
    "SilverKey",
)


def get_layer(data, name):
    for layer in data["layers"]:
        if layer["name"] == name:
            return layer
    raise ValueError("Layer %r not found" % name)


def get_prop(data, name, default):
    if "properties" not in data:
        return default
    for prop in data["properties"]:
        if prop["name"] == name:
            return prop["value"]
    return default


def main():
    parser = ArgumentParser(
        description="Tiled JSON Map to .o",
        epilog="Copyright (C) 2023 Juan J Martinez <jjm@usebox.net>",
    )

    parser.add_argument(
        "--version", action="version", version="%(prog)s " + __version__
    )
    parser.add_argument("file_json", help="JSON map to convert")
    parser.add_argument("output", help="object name for the map data")

    args = parser.parse_args()

    with open(args.file_json, "rt") as fd:
        data = json.load(fd)

    if len(data["tilesets"]) != 1:
        parser.error("Unsupported number of tilesets %d" % len(data["tilesets"]))

    tileset = data["tilesets"][0]

    map_layer = get_layer(data, "Map")

    out = list(map(lambda x: (x - tileset["firstgid"]) & 0xFF, map_layer["data"]))

    gold_layer = get_layer(data, "Gold")

    total_gold = 0
    for t in gold_layer["data"]:
        if t != 0:
            total_gold += 1
    if total_gold > 255:
        parser.error("There are more than 255 gold pieces on the screen")

    out.extend(map(lambda x: (x - tileset["firstgid"]) & 0xFF, gold_layer["data"]))

    entity_layer = get_layer(data, "Entities")

    # some entities will never change their y coordinate, so sorting them by y
    # should help the drawing order in the game
    objs_sorted = sorted(entity_layer["objects"], key=lambda o: o["y"])
    for ent in objs_sorted:
        try:
            typ = entity_types.index(ent["name"])
        except ValueError:
            parser.error("Entity in map %r not found in entity types" % ent["name"])

        x = ent["x"] // tileset["tilewidth"]
        y = ent["y"] // tileset["tileheight"]

        flags = 0

        dir = get_prop(ent, "dir", "right")
        if dir not in ("left", "right"):
            parser.error("Invalid value for property dir: %r" % dir)
        if dir == "left":
            flags |= 1

        out.extend([typ, x, y, flags])

        # end of entity list
    out.append(0xFF)

    tmp = args.output.removesuffix(".o")
    with open(tmp, "wb") as fd:
        fd.write(bytearray(out))
        fd.flush()

        # create an object file from the binary
        rc = subprocess.call(
            [
                ld,
                "-r",
                "-b",
                "binary",
                "-o",
                args.output,
                tmp,
            ]
        )
        os.unlink(tmp)
        if rc != 0:
            parser.error("Failed to run %s" % ld)

        # strip unwanted symbols
        rc = subprocess.call([strip, "-w", "-K", "*_%s_*" % tmp, args.output])
        if rc != 0:
            parser.error("Failed to run %s" % ld)


if __name__ == "__main__":
    main()