import streamlit as st
import random
from faker import Faker
from datetime import datetime, timedelta

fake = Faker()

# ---------------- UI CONFIG ----------------
st.set_page_config(
    page_title="Credit Card Generator",
    layout="centered",
    initial_sidebar_state="collapsed"
)

# ---- Dark Mode Styling ----
st.markdown("""
<style>
body {
    background-color: #0e1117;
    color: #ffffff;
}
.stButton>button {
    background-color: #4CAF50;
    color: white;
    border-radius: 8px;
    height: 3em;
    width: 100%;
}
.card-box {
    background: linear-gradient(135deg, #1f2937, #111827);
    padding: 20px;
    border-radius: 12px;
    color: white;
    font-family: monospace;
}
.copy-btn {
    margin-top: 10px;
}
</style>
""", unsafe_allow_html=True)

st.title("💳 Credit Card Generator")

st.caption("Generate **test credit card details** for development and QA use only.")

# ---------------- INPUT ----------------
card_type = st.selectbox("Select Card Type", ["VISA", "MASTERCARD"])
generate = st.button("Generate Card")

# ---------------- CORE LOGIC ----------------

def luhn_generate(prefix, length):
    number = prefix
    while len(number) < length - 1:
        number += str(random.randint(0, 9))

    digits = [int(d) for d in number]

    for i in range(len(digits) - 1, -1, -2):
        digits[i] *= 2
        if digits[i] > 9:
            digits[i] -= 9

    checksum = (10 - (sum(digits) % 10)) % 10
    return number + str(checksum)

def format_card(number):
    return " ".join([number[i:i+4] for i in range(0, len(number), 4)])

def generate_expiry():
    future_date = datetime.now() + timedelta(days=random.randint(365, 1825))
    return future_date.strftime("%m/%y")

def generate_cvv():
    return str(random.randint(100, 999))

def detect_country(bin_prefix):
    bin_map = {
        "4": "USA / International (VISA)",
        "51": "USA (MasterCard)",
        "52": "Canada",
        "53": "UK",
        "54": "Germany",
        "55": "France"
    }
    return bin_map.get(bin_prefix[:2], "Unknown")

def generate_card(card_type):
    if card_type == "VISA":
        prefix = "4"
        length = 16
    else:
        prefix = str(random.choice(range(51, 56)))
        length = 16

    number = luhn_generate(prefix, length)

    return {
        "number": number,
        "formatted": format_card(number),
        "name": fake.name(),
        "zip": fake.zipcode(),
        "expiry": generate_expiry(),
        "cvv": generate_cvv(),
        "country": detect_country(prefix)
    }

# ---------------- OUTPUT ----------------

if generate:
    card = generate_card(card_type)

    st.success("Card Generated")

    st.markdown(f"""
    <div class="card-box">
        <h3>{card_type}</h3>
        <p style="font-size:20px;">{card['formatted']}</p>
        <p>{card['name']}</p>
        <p>EXP: {card['expiry']} | CVV: {card['cvv']}</p>
    </div>
    """, unsafe_allow_html=True)

    st.write(f"**ZIP Code:** {card['zip']}")
    st.write(f"**Country (BIN):** {card['country']}")

    # -------- Copy Buttons --------
    st.subheader("Copy Details")

    st.code(card["number"], language="text")
    st.code(card["formatted"], language="text")
    st.code(card["cvv"], language="text")

    st.info("⚠️ These are fake/generated details for testing only. Not usable for real transactions.")