"""
Урок 12. Цикл while — весь код примеров одним файлом.

Источник: subjects/python-fundamentals/course/lessons/12-while-loop/examples.html
Файл собран автоматически (tools/build_lesson_examples.py): правьте страницу урока.
Запуск: python lesson-12.py
"""



# ====================================================================
# Пример 1. Счётчик от 1 до 5
# ====================================================================
i = 1
while i <= 5:
    print(i)
    i += 1
# 1
# 2
# 3
# 4
# 5


# ====================================================================
# Пример 2. Накопление результата: сумма и список за один проход
# ====================================================================
values = [4, -2, 9, 0, 5, -7, 3]
i = 0
total = 0
positives = []

while i < len(values):
    if values[i] > 0:
        total += values[i]
        positives.append(values[i])
    i += 1

print("Total of positives:", total)
print("Positives list:", positives)
# Total of positives: 21
# Positives list: [4, 9, 5, 3]


# ====================================================================
# Пример 3. Ловушка бесконечного цикла — забыли изменить переменную
# ====================================================================
i = 0
attempts = 0
MAX_ITERATIONS = 5  # защитный лимит — в реальной ловушке i += 1 отсутствует,
                     # поэтому i < 3 никогда не станет ложным

while i < 3:
    print("iteration", attempts)
    attempts += 1
    if attempts >= MAX_ITERATIONS:
        print("Forgot to update i! Breaking out after", attempts, "iterations to avoid a real infinite loop.")
        break
    # i += 1  # <- без этой строки i никогда не достигнет 3 само по себе

# iteration 0
# iteration 1
# iteration 2
# iteration 3
# iteration 4
# Forgot to update i! Breaking out after 5 iterations to avoid a real infinite loop.


# ====================================================================
# Пример 4. break: досрочный выход по сигналу
# ====================================================================
inputs = iter(["10", "25", "stop", "999"])

total = 0
while True:
    value = next(inputs)
    if value == "stop":
        print("Stopped by user command.")
        break
    total += int(value)

print("Sum before stop:", total)
# Stopped by user command.
# Sum before stop: 35


# ====================================================================
# Пример 5. continue: пропуск одной итерации
# ====================================================================
numbers = [5, -3, 8, -1, 2]
i = 0
total = 0

while i < len(numbers):
    n = numbers[i]
    i += 1
    if n < 0:
        continue
    total += n

print("Sum of non-negative numbers:", total)
# Sum of non-negative numbers: 15


# ====================================================================
# Пример 6. while ... else: когда выполняется, а когда нет
# ====================================================================
values = [1, 2, 3, 4, 5]

target = 4
i = 0
while i < len(values):
    if values[i] == target:
        print(f"Found {target} at index {i}")
        break
    i += 1
else:
    print(f"{target} was not found")
# Found 4 at index 3

target2 = 9
i = 0
while i < len(values):
    if values[i] == target2:
        print(f"Found {target2} at index {i}")
        break
    i += 1
else:
    print(f"{target2} was not found")
# 9 was not found


# ====================================================================
# Пример 7. while и for: когда что уместнее
# ====================================================================
# for: число шагов известно заранее — три дня, и точка
for day in range(1, 4):
    print(f"Day {day}: watering the plant")
# Day 1: watering the plant
# Day 2: watering the plant
# Day 3: watering the plant

# while: продолжаем, пока не выполнится условие — число шагов заранее не известно
water_level = 10
day = 0
while water_level > 0:
    day += 1
    water_level -= 3
    print(f"Day {day}: water level = {water_level}")
# Day 1: water level = 7
# Day 2: water level = 4
# Day 3: water level = 1
# Day 4: water level = -2


# ====================================================================
# Пример 8. Валидация ввода: цикл до получения корректного значения
# ====================================================================
fake_inputs = iter(["abc", "-5", "42"])  # смоделированная последовательность вводов

while True:
    raw = next(fake_inputs)
    if not raw.lstrip("-").isdigit():
        print(f"'{raw}' is not a number, try again")
        continue
    number = int(raw)
    if number < 0:
        print(f"{number} is negative, try again")
        continue
    break

print("Accepted number:", number)
# 'abc' is not a number, try again
# -5 is negative, try again
# Accepted number: 42


# ====================================================================
# Пример 9. Реальная защита от бесконечного цикла: лимит попыток в игре «Угадай число»
# ====================================================================
import random

random.seed(7)
secret = random.randint(1, 10)
guesses = iter([3, 8, 6])  # смоделированные попытки игрока
max_attempts = 3
attempts_used = 0

while attempts_used < max_attempts:
    guess = next(guesses)
    attempts_used += 1
    if guess == secret:
        print(f"Guessed correctly in {attempts_used} attempts!")
        break
    hint = "greater" if guess < secret else "less"
    print(f"Attempt {attempts_used}: the secret number is {hint}")
else:
    print(f"Out of attempts. The secret number was {secret}.")
# Attempt 1: the secret number is greater
# Attempt 2: the secret number is less
# Guessed correctly in 3 attempts!


# ====================================================================
# Пример 10. Модуль random: случайные числа для игр и симуляций
# ====================================================================
import random

random.seed(42)
print("Random float:", random.random())
print("Dice roll:", random.randint(1, 6))
print("Random step:", random.randrange(0, 101, 10))
# Random float: 0.6394267984578837
# Dice roll: 1
# Random step: 40