import os
import sys

# Add src to path
sys.path.append(os.path.join(os.getcwd(), 'src'))

from teletext.models import Packet, Page
from teletext.io import load_t42, save_t42

def create_dummy_t42(filename):
    # Create a 42-byte packet
    # Byte 0: Mag 1, Row 0. 
    # M=1 (001), R=0 (00000)
    # Encoded:
    # B1: M1 M2 M3 R1 -> 1 0 0 0. With Hamming: P1, D1(1), P2, D2(0), P3, D3(0), P4, D4(0)
    # D1=1 -> P1=1 (1,3,5,7 parity). 
    # Actually let's use a simpler way or pre-calculated bytes for testing.
    # Magazine 1, Row 0 is often: 0x15 0x15 (example guess, need real hamming)
    
    # Let's simple write 42 zero bytes, then set some manually to test "parsing" robustness
    # or just trust the load/save loop for raw data conservation.
    
    # We'll create a "Header" packet (Row 0) and a "Content" packet (Row 1).
    
    # Packet 1: Row 0.
    # We need to construct bytes that pass our minimal decoder.
    # decode_common: returns D1..D4 for bits 1,3,5,7.
    # Mag=1 => 001. R=0 => 00000.
    # B1 (Low row bits + Mag): M1, M2, M3, R1 -> 1, 0, 0, 0
    # D1=1, D2=0, D3=0, D4=0.
    # Byte value: x1x0x0x0. 
    # B2 (High row bits): R2, R3, R4, R5 -> 0, 0, 0, 0
    # Byte value: x0x0x0x0.
    
    # Let's arbitrarily set parity bits to 0 for this test as my decoder ignores them (it only reads D bits).
    # B1: 0 1 0 0 0 0 0 0 -> 0x02
    # B2: 0 0 0 0 0 0 0 0 -> 0x00
    
    p1_data = bytearray(42)
    p1_data[0] = 0x02
    p1_data[1] = 0x00
    # Add some text in the rest
    p1_data[2:] = b'Header Packet' + b'\x00' * (40 - 13)
    
    # Packet 2: Row 1.
    # M=1, R=1.
    # B1: M1 M2 M3 R1 -> 1 0 0 1
    # D1=1, D2=0, D3=0, D4=1.
    # Byte: x1x0x0x1 -> 0x82 (if bit 7 is D4). 
    # Position: 0(P1) 1(D1-b0) 2(P2) 3(D2-b1) 4(P3) 5(D3-b2) 6(P4) 7(D4-b3)
    # My decoder keys off D1(bit1), D2(bit3), D3(bit5), D4(bit7).
    # So we want bits 1 and 7 set. 0x82 = 1000 0010. Correct.
    
    p2_data = bytearray(42)
    p2_data[0] = 0x82
    p2_data[1] = 0x00 # Row high bits 0
    p2_data[2:] = b'Content Row 1' + b'\x00' * (40 - 13)
    
    with open(filename, 'wb') as f:
        f.write(p1_data)
        f.write(p2_data)
        
    print(f"Created {filename}")

def test_load_save():
    fname = "test.t42"
    out_fname = "test_out.t42"
    
    create_dummy_t42(fname)
    
    service = load_t42(fname)
    print(f"Loaded {len(service.all_packets)} packets")
    print(f"Loaded {len(service.pages)} pages")
    
    if len(service.pages) > 0:
        p = service.pages[0]
        print(f"Page 0: Mag {p.magazine} Num {p.page_number}")
        print(f"Packets in page: {len(p.packets)}")
        
    save_t42(out_fname, service)
    
    # Verify binary identity
    with open(fname, 'rb') as f1, open(out_fname, 'rb') as f2:
        b1 = f1.read()
        b2 = f2.read()
        if b1 == b2:
            print("SUCCESS: Output matches input")
        else:
            print("FAILURE: Output differs")
            print(f"In: {len(b1)}, Out: {len(b2)}")

if __name__ == "__main__":
    test_load_save()