"""Small input-prompting and formatting helpers shared by the menu screens."""

import datetime
import re

GUID_RE = re.compile(r"^\d{12}$")
PHONE_RE = re.compile(r"^\d{10}$")


def pause():
	input("\nPress Enter to continue...")


def clear_hint():
	print("\n" + "-" * 60 + "\n")


def prompt_str(label, max_len=None, required=True, allow_blank_skip=False):
	"""Prompt for a string. allow_blank_skip=True returns None on empty input (for 'leave unchanged')."""
	while True:
		suffix = f" (max {max_len} chars)" if max_len else ""
		val = input(f"{label}{suffix}: ").strip()
		if not val:
			if allow_blank_skip:
				return None
			if required:
				print("  This field is required.")
				continue
			return ""
		if max_len and len(val) > max_len:
			print(f"  Too long — max {max_len} characters.")
			continue
		return val


def prompt_int(label, max_digits=None, allow_blank_skip=False):
	while True:
		val = input(f"{label}: ").strip()
		if not val:
			if allow_blank_skip:
				return None
			print("  This field is required.")
			continue
		if not val.isdigit():
			print("  Please enter a whole number.")
			continue
		if max_digits and len(val) > max_digits:
			print(f"  Too many digits — max {max_digits}.")
			continue
		return int(val)


def prompt_guid(label="Guardian ID / GUID (12-digit Aadhaar number)", allow_blank_skip=False):
	while True:
		val = input(f"{label}: ").strip()
		if not val:
			if allow_blank_skip:
				return None
			print("  This field is required.")
			continue
		if not GUID_RE.match(val):
			print("  GUID must be exactly 12 digits.")
			continue
		return val


def prompt_phone(label="Guardian phone (10 digits, optional)", allow_blank_skip=True):
	while True:
		val = input(f"{label}: ").strip()
		if not val:
			return None  # NULL is allowed for GPhone
		if not PHONE_RE.match(val):
			print("  Phone must be exactly 10 digits (or leave blank).")
			continue
		return val


def prompt_date(label, allow_blank_skip=False):
	while True:
		val = input(f"{label} (YYYY-MM-DD): ").strip()
		if not val:
			if allow_blank_skip:
				return None
			print("  This field is required.")
			continue
		try:
			return datetime.datetime.strptime(val, "%Y-%m-%d").date()
		except ValueError:
			print("  Invalid date — use format YYYY-MM-DD, e.g. 2015-08-21.")


def prompt_attendance_status(label="Status (P=present, A=absent)"):
	while True:
		val = input(f"{label}: ").strip().upper()
		if val in ("P", "A"):
			return val
		print("  Please enter 'P' or 'A'.")


def print_table(rows, columns=None):
	"""Pretty-print a list of dict rows as a simple aligned table."""
	if not rows:
		print("  (no records found)")
		return

	if columns is None:
		columns = list(rows[0].keys())

	widths = {}
	for col in columns:
		widths[col] = max(len(str(col)), *(len(str(r.get(col, ""))) for r in rows))

	header = "  " + " | ".join(str(col).ljust(widths[col]) for col in columns)
	print(header)
	print("  " + "-+-".join("-" * widths[col] for col in columns))
	for r in rows:
		print("  " + " | ".join(str(r.get(col, "")).ljust(widths[col]) for col in columns))
	print(f"\n  ({len(rows)} record{'s' if len(rows) != 1 else ''})")