import struct
from io import BytesIO
import json
from os.path import splitext


def read_u32(f):
    return struct.unpack('<I', f.read(4))[0]


def read_cstring(f):
    chars = []
    while True:
        c = f.read(1)
        if c == b'\x00' or c == b'':
            break
        chars.append(c)
    return b''.join(chars)


def rotate_left(val, rshift):
    return ((val << rshift) & 0xFF) | (val >> (8 - rshift))


def decrypt(data: bytes) -> BytesIO:
    pos = 0x10
    shift = 4
    decrypted = bytearray(data)
    while pos + 4 <= len(decrypted):
        data = decrypted[pos:pos+4]
        data[0] = rotate_left(data[0], shift)
        shift = (shift + 1) % 8
        data = struct.unpack('<I', data)[0]
        data ^= 0x084DF873 ^ 0xFF987DEE
        decrypted[pos:pos+4] = struct.pack('<I', data)
        pos += 4
    return BytesIO(decrypted)


def load_text_data(f, e):
    f.read(12)  # Skip header
    count = read_u32(f)
    first_idx = read_u32(f)
    if first_idx != 0:
        f.seek(0)
        f = decrypt(f.read())
        f.read(16)
        first_idx = read_u32(f)
    f.seek(16)
    table = {}
    for j in range(count):
        cur = read_u32(f)
        s = read_cstring(f).decode(e)
        table[cur] = s
    return table


if __name__ == '__main__':
    import sys

    if len(sys.argv) < 2:
        print("Usage: python unpack_softpal_text_dat.py <file> [<output>] [<encoding>]")
        sys.exit(1)

    filename = sys.argv[1]
    output = sys.argv[2] if len(sys.argv) > 2 else splitext(filename)[0] + '.json'
    encoding = sys.argv[3] if len(sys.argv) > 3 else 'cp932'

    with open(filename, 'rb') as f:
        table = load_text_data(f, encoding)
    with open(output, 'w', encoding='utf-8') as f:
        json.dump(table, f, ensure_ascii=False, indent=4)