#!/usr/bin/env python3
"""
Printer diagnostic — runs several test prints to identify character width
and font settings on the Epson TM-T88V.
"""
import subprocess, sys, time

PRINTER = "receipt"

ESC = b'\x1b'
GS  = b'\x1d'

INIT      = ESC + b'\x40'        # ESC @ — initialize
FONT_A    = ESC + b'\x4d\x00'   # Font A  (12x24 dots) — expected 42 chars
FONT_B    = ESC + b'\x4d\x01'   # Font B  ( 9x17 dots) — expected 56 chars
SIZE_NORM = GS  + b'\x21\x00'   # GS ! 0  — force 1x1 character size
CUT       = GS  + b'\x56\x00'   # full cut

RULER_42 = "123456789012345678901234567890123456789012"
RULER_56 = "12345678901234567890123456789012345678901234567890123456"

def send(data: bytes):
    r = subprocess.run(["lpr", "-P", PRINTER, "-o", "raw"],
                       input=data, capture_output=True)
    if r.returncode != 0:
        print("lpr error:", r.stderr.decode(), file=sys.stderr)

def test(label, extra_init=b"", font=FONT_A, ruler=RULER_42):
    body = (
        f"\n--- TEST: {label} ---\n"
        f"Font: {'A (expect 42)' if font == FONT_A else 'B (expect 56)'}\n"
        f"{ruler}\n"
        f"ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789!@#$%^\n"
        f"The quick brown fox jumps over the lazy dog\n"
        f"\n"
    ).encode("ascii")
    send(INIT + extra_init + font + body + b"\n\n" + CUT)
    print(f"  Printed: {label}")
    time.sleep(3)

print("Running printer diagnostics -- watch the paper!\n")

print("Test 1: Font A, no GS ! override (baseline -- your current setup)")
test("Font A baseline", extra_init=b"", font=FONT_A, ruler=RULER_42)

print("Test 2: Font A + GS ! 0x00 (force normal 1x1 character size)")
test("Font A + GS!00", extra_init=SIZE_NORM, font=FONT_A, ruler=RULER_42)

print("Test 3: Font B (smaller -- expect 56 chars/line)")
test("Font B baseline", extra_init=b"", font=FONT_B, ruler=RULER_56)

print("Test 4: Font B + GS ! 0x00")
test("Font B + GS!00", extra_init=SIZE_NORM, font=FONT_B, ruler=RULER_56)

print("\nDone. Count where the ruler wraps on each strip.")
print("Report which test gave 42+ chars and we'll lock that in.")