"""Password Cracker, by Al Sweigart.

Displays changing random characters while gradually revealing a hidden phrase.
After holding the completed phrase for five seconds, a new phrase begins.
"""

import os
import random
import time

# Phrases that may be selected at the start of each cracking cycle.
MESSAGES = (
    "It was the best of times, it was the worst of times...",
    "It was a bright cold day in April, and the clocks were striking thirteen.",
    "Too many secrets.",
    "S W O R D F I S H",
    "Common sense is very rare.",
    "I refuse to join any club that would have me as a member.",
    "Speak when you are angry and you will make the best speech you will ever regret.",
    "Experience is simply the name we give our mistakes.",
    "Judge a man by his questions rather than by his answers.",
    "There is no cure for curiosity.",
    "Three may keep a secret, if two of them are dead.",
    "A book must be the axe for the frozen sea within us.”",
    "Freedom is what you do with what’s been done to you.",
    "In a hole in the ground there lived a hobbit.",
    "I am an invisible man.",
    "The sky above the port was the color of television, tuned to a dead channel.",
)

# Pause after each changing row in seconds.
DELAY = 0.01
# Characters randomly displayed in columns that are not locked.
CHARS = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
# Chance from 0 to 1 of locking one more column on each row.
UNLOCK_CHAR_PROBABILITY = 0.04
# Text inserted between the displayed columns. The default keeps characters
# adjacent; phrases such as "S W O R D F I S H" contain their own spaces.
SPACER = ""
# Seconds to hold the completed phrase before beginning again.
FINISHED_PAUSE = 5


def crack_message(message):
    """Animate one phrase until every column has been revealed."""
    locked_columns = [False] * len(message)
    number_locked = 0

    while number_locked < len(message):
        columns = [random.choice(CHARS) for _ in message]

        if random.random() < UNLOCK_CHAR_PROBABILITY:
            unlocked_columns = [
                index for index, is_locked in enumerate(locked_columns)
                if not is_locked
            ]
            column_to_lock = random.choice(unlocked_columns)
            locked_columns[column_to_lock] = True
            number_locked += 1

        for index, is_locked in enumerate(locked_columns):
            if is_locked:
                columns[index] = message[index]

        print(SPACER.join(columns))
        time.sleep(DELAY)

    # Print the completed phrase a few more times before holding it on screen.
    for _ in range(9):
        print(SPACER.join(message))
        time.sleep(DELAY)


def main():
    os.system("cls" if os.name == "nt" else "clear")
    while True:
        crack_message(random.choice(MESSAGES))
        time.sleep(FINISHED_PAUSE)


if __name__ == "__main__":
    try:
        main()
    except KeyboardInterrupt:
        pass