"""
Урок 23. Summary session 6 — весь код примеров одним файлом.

Источник: subjects/python-fundamentals/course/lessons/23-summary-session-6/examples.html
Файл собран автоматически (tools/build_lesson_examples.py): правьте страницу урока.
Запуск: python lesson-23.py
"""



# ====================================================================
# Пример 1. Строки неизменяемы: методы возвращают новую строку
# ====================================================================
text = "  Python Summary  "
upper_text = text.upper()

print(repr(text))         # '  Python Summary  ' — исходная строка не изменилась
print(repr(upper_text))   # '  PYTHON SUMMARY  '

result = text.strip().lower().replace("python", "language")
print(repr(result))       # 'language summary'


# ====================================================================
# Пример 2. Предикаты: классификация текста
# ====================================================================
def classify_token(token):
    if token.isdigit():
        return "число"
    if token.isalpha():
        return "слово"
    if token.isspace():
        return "пробел"
    return "смешанный текст"


tokens = ["2026", "Python", "   ", "py3.14"]
for token in tokens:
    print(repr(token), "->", classify_token(token))
# '2026' -> число
# 'Python' -> слово
# '   ' -> пробел
# 'py3.14' -> смешанный текст

print("Hello".startswith("He"), "Hello".endswith("lo"))  # True True
print("Hello World".istitle(), "hello world".istitle())  # True False


# ====================================================================
# Пример 3. isdecimal(), isdigit(), isnumeric() — не одно и то же
# ====================================================================
print("123".isdecimal(), "123".isdigit(), "123".isnumeric())  # True True True
print("²".isdecimal(), "²".isdigit(), "²".isnumeric())  # False True True  (надстрочная цифра ²)
print("Ⅷ".isdecimal(), "Ⅷ".isdigit(), "Ⅷ".isnumeric())  # False False True (римская цифра Ⅷ)

print("total_2026".isidentifier(), "2026_total".isidentifier())  # True False
print("Python".isascii(), "Питон".isascii())                     # True False
print("line1\nline2".isprintable())                              # False


# ====================================================================
# Пример 4. Поиск подстроки: безопасный и «падающий» варианты
# ====================================================================
text = "Python is awesome. Python is dynamic."
print(text.find("Python"), text.rfind("Python"))  # 0 19
print(text.find("Java"))                           # -1
print(text.count("Python"))                         # 2

try:
    text.index("Java")
except ValueError as error:
    print("ValueError:", error)  # ValueError: substring not found


# ====================================================================
# Пример 5. Изменение регистра: шесть методов и одна ловушка
# ====================================================================
text = "Hello, worlD! it's a TEST"
print(text.upper())       # HELLO, WORLD! IT'S A TEST
print(text.lower())       # hello, world! it's a test
print(text.capitalize())  # Hello, world! it's a test
print(text.title())       # Hello, World! It'S A Test
print(text.swapcase())    # hELLO, WORLd! IT'S A test

print("Straße".casefold(), "Straße".lower())  # strasse straße


# ====================================================================
# Пример 6. Разделение и объединение: split(), rsplit(), splitlines(), join()
# ====================================================================
data = "2026-08-13T10:30:00"
print(data.split("-"))       # ['2026', '08', '13T10:30:00']
print(data.split("-", 1))    # ['2026', '08-13T10:30:00']
print(data.rsplit("-", 1))   # ['2026-08', '13T10:30:00']

log = "line one\nline two\r\nline three"
print(log.splitlines())      # ['line one', 'line two', 'line three']

fruits = "apple, banana,  cherry"
print([f.strip() for f in fruits.split(",")])  # ['apple', 'banana', 'cherry']
print(" | ".join(["a", "b", "c"]))              # a | b | c


# ====================================================================
# Пример 7. Очистка краёв: strip(), lstrip(), rstrip()
# ====================================================================
raw = "   ***Python 2026***   "
print(f"[{raw.strip()}]")              # [***Python 2026***]
print(f"[{raw.strip().strip('*')}]")   # [Python 2026]
print(f"[{raw.lstrip()}]")             # [***Python 2026***   ]
print(f"[{raw.rstrip()}]")             # [   ***Python 2026***]

filename = "###important_notes###"
print(filename.strip("#"))             # important_notes


# ====================================================================
# Пример 8. Выравнивание и заполнение: center(), ljust(), rjust(), zfill()
# ====================================================================
rows = [("Alice", 92), ("Bob", 7), ("Carol", 105)]
for row_name, score in rows:
    print(row_name.ljust(10, ".") + str(score).rjust(5))
# Alice.....   92
# Bob.......    7
# Carol.....  105

print("42".zfill(5))          # 00042
print("-42".zfill(5))         # -0042
print("hi".center(10, "*"))   # ****hi****

# то же самое через спецификаторы f-строк
label = "hi"
print(f"{label:*^10}")  # ****hi****
print(f"{label:*<10}")  # hi********
print(f"{label:*>10}")  # ********hi


# ====================================================================
# Пример 9. removeprefix() и removesuffix() против ручной вырезки (Python 3.9+)
# ====================================================================
filename = "test_report.txt"

# современный способ
name = filename.removeprefix("test_").removesuffix(".txt")
print(name)  # report

# старый способ (Python < 3.9)
old_name = filename
if old_name.startswith("test_"):
    old_name = old_name[len("test_"):]
if old_name.endswith(".txt"):
    old_name = old_name[:-len(".txt")]
print(old_name)  # report

# безопасность: префикса нет — строка не меняется, ошибки не будет
print("report.txt".removeprefix("test_"))  # report.txt


# ====================================================================
# Пример 10. Три способа форматирования рядом
# ====================================================================
name, age, balance = "Alice", 30, 1234.5

print("Name: %s, Age: %d, Balance: %.2f" % (name, age, balance))
print("Name: {}, Age: {}, Balance: {:.2f}".format(name, age, balance))
print(f"Name: {name}, Age: {age}, Balance: {balance:.2f}")
# Name: Alice, Age: 30, Balance: 1234.50   -- все три строки одинаковы

# format() умеет переиспользовать и именовать аргументы
print("{0} is {1} years old, {0} again".format(name, age))  # Alice is 30 years old, Alice again
print("{n} is {a} years old".format(n=name, a=age))          # Alice is 30 years old

# f-string вычисляет выражения и вызывает методы прямо внутри {}
print(f"{name.upper()} turns {age + 1} next year")  # ALICE turns 31 next year


# ====================================================================
# Пример 11. Форматирование чисел: точность, разделители, знак, проценты
# ====================================================================
prices = {"Book": 12.5, "Pen": 1.234, "Laptop": 1234.567}
for item, price in prices.items():
    print(f"{item:<10}{price:>10,.2f}")
# Book           12.50
# Pen             1.23
# Laptop      1,234.57

pi = 3.14159265
print(f"{pi:.2f}")      # 3.14
print(f"{pi:+.2f}")     # +3.14   -- явный знак
print(f"{1234567:,}")   # 1,234,567
print(f"{42:05d}")      # 00042
print(f"{0.256:.1%}")   # 25.6%


# ====================================================================
# Пример 12. Собираем приёмы вместе: проверка на панграмму
# ====================================================================
import string

def is_pangram(text):
    letters_used = {char for char in text.lower() if char.isalpha()}
    return letters_used >= set(string.ascii_lowercase)

phrase = "The quick brown fox jumps over the lazy dog"
print(is_pangram(phrase))          # True
print(is_pangram("Hello world"))   # False

# вариант без множеств, через all() -- ближе к тому, что видно в уроке
def is_pangram_v2(text):
    text_lower = text.lower()
    return all(letter in text_lower for letter in string.ascii_lowercase)

print(is_pangram_v2(phrase))  # True