# deck.pager: Simple text pagination library for T-Deck
# Usage: from deck.pager import print_paged
# Created by Luxferre in 2025, released into public domain

import os
from deck.input import input

# detect terminal size
TERM_ROWS = int(os.getenv('TERM_ROWS', 19))
TERM_COLS = int(os.getenv('TERM_COLS', 53))
try: # if running on CPython
  TERM_COLS, TERM_ROWS = os.get_terminal_size()
except:
  pass

# additional constants
REAL_TERM_COLS = TERM_COLS - 1 # for the line ending character
REAL_TERM_ROWS = TERM_ROWS - 1 # for the "press Enter" message
CONT_MSG = '--- Press Enter ---'

def term_size():
  """Return the detected terminal size (rows, columns)"""
  return (TERM_ROWS, TERM_COLS)

def reflow(text):
  """Split the text into lines not exceeding the terminal width"""
  out = []
  for line in text.split('\n'):
    line = line.rstrip()
    if len(line) == 0: # also handle effectively empty lines
      out.append('')
    else:
      while len(line) > 0:
        out.append(line[0:REAL_TERM_COLS])
        line = line[REAL_TERM_COLS:]
  return out

def print_paged(text):
  """Reflow and print the text in a paginated manner"""
  lines = reflow(text)
  while True:
    chunk = lines[0:REAL_TERM_ROWS]
    for line in chunk: print(line)
    lines = lines[REAL_TERM_ROWS:]
    if len(lines) > 0: input(CONT_MSG)
    else: break