#!/usr/bin/env python3
# vim:set tabstop=4 shiftwidth=4 expandtab smarttab

from sys import argv, exit, stderr
from struct import unpack, calcsize
from enum import Enum

class nodetype(Enum):
    REPT = 0
    FILE = 1
    MACRO = 2

class symtype(Enum):
    LOCAL = 0
    IMPORT = 1
    EXPORT = 2

class sectype(Enum):
    WRAM0 = 0
    VRAM = 1
    ROMX = 2
    ROM0 = 3
    HRAM = 4
    WRAMX = 5
    SRAM = 6
    OAM = 7

class patchtype(Enum):
    BYTE = 0
    WORD = 1
    LONG = 2
    JR = 3

class asserttype(Enum):
    WARN = 0
    ERROR = 1
    FAIL = 2

def unpack_file(fmt, file):
    size = calcsize(fmt)
    return unpack(fmt, file.read(size))

def read_string(file):
    buf = bytearray()
    while True:
        b = file.read(1)
        if b is None or b == b'\0':
            return buf.decode()
        else:
            buf += b

def parse_object(filename):
    file = open(filename, "rb")

    obj = {
        "nodes": [],
        "symbols": [],
        "sections": [],
        "assertions": [],
    }

    magic = unpack_file("4s", file)[0]
    if magic == b'RGB6':
        obj_ver = 6
    elif magic == b'RGB9':
        obj_ver = 10 + unpack_file("<I", file)[0]
    else:
        print("Error: File '%s' is of an unknown format." % filename, file=stderr)
        return None

    if obj_ver not in [6, 10, 11, 13, 14, 16]:
        print("Error: File '%s' is of an unknown format: %d" % (filename, obj_ver), file=stderr)
        return None

    obj["version"] = obj_ver

    num_symbols, num_sections = unpack_file("<II", file)

    num_nodes = 0
    if obj_ver >= 16:
        num_nodes = unpack_file("<I", file)[0]

    for x in range(num_nodes):
        node = {}

        node["parent_id"], node["parent_line"] = unpack_file("<II", file)
        node["type"] = nodetype(unpack_file("<B", file)[0])
        if node["type"] != nodetype.REPT:
            node["name"] = read_string(file)
        else:
            depth = unpack_file("<I", file)[0]
            node["depth"] = [unpack_file("<I", file) for x in range(depth)]
        obj["nodes"].append(node)

    for x in range(num_symbols):
        symbol = {}

        symbol["name"] = read_string(file)
        symbol["type"] = symtype(unpack_file("<B", file)[0])
        if symbol["type"] != symtype.IMPORT:
            if obj_ver >= 16:
                node = unpack_file("<I", file)[0]
                symbol["node"] = node
            else:
                symbol["filename"] = read_string(file)
            symbol["line_num"], symbol["section"], symbol["value"] = unpack_file("<III", file)

        obj["symbols"].append(symbol)

    for x in range(num_sections):
        section = {}

        section["name"] = read_string(file)
        size, type, section["org"], section["bank"] = unpack_file("<IBII", file)
        section["type"] = sectype(type)

        if obj_ver >= 14:
            section["align"], section["offset"] = unpack_file("<BI", file)
        else:
            section["align"] = unpack_file("<I", file)[0]

        if section["type"] == sectype.ROMX or section["type"] == sectype.ROM0:
            section["data"] = file.read(size)

            section["patches"] = []
            num_patches = unpack_file("<I", file)[0]
            for x in range(num_patches):
                patch = {}

                if obj_ver >= 16:
                    node = unpack_file("<I", file)[0]
                    patch["node"] = node
                else:
                    patch["filename"] = read_string(file)
                if obj_ver < 11 or obj_ver >= 16:
                    patch["line"] = unpack_file("<I", file)[0]
                patch["offset"] = unpack_file("<I", file)[0]
                if obj_ver >= 14:
                    patch["pcsectionid"], patch["pcoffset"] = unpack_file("<II", file)
                type, rpn_size = unpack_file("<BI", file)
                patch["type"] = patchtype(type)
                patch["rpn"] = file.read(rpn_size)

                section["patches"].append(patch)

        obj["sections"].append(section)

    num_assertions = 0
    if obj_ver >= 13:
        num_assertions = unpack_file("<I", file)[0]

    for x in range(num_assertions):
        assertion = {}

        if obj_ver >= 16:
            node = unpack_file("<I", file)[0]
            assertion["node"] = node
            assertion["line"] = unpack_file("<I", file)[0]
        else:
            assertion["filename"] = read_string(file)
        assertion["offset"] = unpack_file("<I", file)[0]
        if obj_ver >= 14:
            assertion["section"], assertion["pcoffset"] = unpack_file("<II")
        type, rpn_size = unpack_file("<BI", file)
        assertion["type"] = asserttype(type)
        assertion["rpn"] = file.read(rpn_size)
        assertion["message"] = read_string(file)

        obj["assertions"].append(assertion)

    return obj


if len(argv) <= 1:
    print("Usage: %s [-D] <objects.o...>" % argv[0], file=stderr)
    exit(1)

argi = 1

just_dump = False
if argv[argi] == "-D":
    just_dump = True
    argi += 1
if argv[argi] == "--":
    argi += 1

globalsyms = {}

for filename in argv[argi:]:
    print(filename, file=stderr)

    obj = parse_object(filename)
    if obj is None:
        exit(1)

    if just_dump:
        for symbol in obj["symbols"]:
            print(symbol["name"])
        continue

    localsyms = {}

    imports = 0
    exports = 0
    for symbol in obj["symbols"]:
        if symbol["type"] == symtype.LOCAL:
            if symbol["name"] not in localsyms:
                localsyms[symbol["name"]] = 0
        elif symbol["type"] == symtype.IMPORT:
            imports += 1
            if symbol["name"] not in globalsyms:
                globalsyms[symbol["name"]] = 0
        elif symbol["type"] == symtype.EXPORT:
            exports += 1
            if symbol["name"] not in globalsyms:
                globalsyms[symbol["name"]] = 0

    print("Locals:", len(localsyms), file=stderr)
    print("Imports:", imports, file=stderr)
    print("Exports:", exports, file=stderr)

    def parse_rpn(rpn):
        pos = 0
        while pos < len(rpn):
            if rpn[pos] == 0x51:
                pos += 1
                while rpn[pos] != 0:
                    pos += 1
                pos += 1
            elif rpn[pos] == 0x80:
                pos += 5
            elif rpn[pos] == 0x50 or rpn[pos] == 0x81:
                symbol_id = unpack("<I", rpn[pos + 1:pos + 5])[0]
                if symbol_id != 0xffffffff:
                    symbol = obj["symbols"][symbol_id]
                    if symbol["type"] == symtype.LOCAL:
                        localsyms[symbol["name"]] += 1
                    else:
                        globalsyms[symbol["name"]] += 1
                pos += 5
            else:
                pos += 1

    for section in obj["sections"]:
        if section["type"] == sectype.ROMX or section["type"] == sectype.ROM0:
            for patch in section["patches"]:
                parse_rpn(patch["rpn"])
    for assertion in obj["assertions"]:
        parse_rpn(assertion["rpn"])

    print(file=stderr)

if just_dump:
    exit()

print("Unreferenced globals:", file=stderr)
for symbol in globalsyms:
    if globalsyms[symbol] == 0:
        print(symbol)