auth.py

from passlib.context import CryptContext
from nicegui import ui
from pathlib import Path
import json
from datetime import datetime, timedelta

# Path to persistent users file
USERS_FILE = Path(__file__).with_name('users.json')

# Password hashing setup
pwd_context = CryptContext(schemes=["bcrypt"], deprecated="auto")


def get_default_decks():
    """Generate default Japanese-learning decks: Hiragana, Katakana, and 5 Kanji decks."""
    today = datetime.now()

    def card(front, back, reps=0, interval=0, ef=2.5, delta_days=0):
        return {
            "front": front,
            "back": back,
            "repetitions": reps,
            "interval": interval,
            "ef": ef,
            "due_date": (today + timedelta(days=delta_days)).isoformat()
        }

    # All 46 Hiragana characters
    hiragana_cards = [
        # Basic vowels
        card("あ", "a"), card("い", "i"), card("う", "u"), card("え", "e"), card("お", "o"),
        # K-row
        card("か", "ka"), card("き", "ki"), card("く", "ku"), card("け", "ke"), card("こ", "ko"),
        # S-row
        card("さ", "sa"), card("し", "shi"), card("す", "su"), card("せ", "se"), card("そ", "so"),
        # T-row
        card("た", "ta"), card("ち", "chi"), card("つ", "tsu"), card("て", "te"), card("と", "to"),
        # N-row
        card("な", "na"), card("に", "ni"), card("ぬ", "nu"), card("ね", "ne"), card("の", "no"),
        # H-row
        card("は", "ha"), card("ひ", "hi"), card("ふ", "fu"), card("へ", "he"), card("ほ", "ho"),
        # M-row
        card("ま", "ma"), card("み", "mi"), card("む", "mu"), card("め", "me"), card("も", "mo"),
        # Y-row
        card("や", "ya"), card("ゆ", "yu"), card("よ", "yo"),
        # R-row
        card("ら", "ra"), card("り", "ri"), card("る", "ru"), card("れ", "re"), card("ろ", "ro"),
        # W-row + N
        card("わ", "wa"), card("を", "wo"), card("ん", "n"),
    ]

    # All 46 Katakana characters
    katakana_cards = [
        # Basic vowels
        card("ア", "a"), card("イ", "i"), card("ウ", "u"), card("エ", "e"), card("オ", "o"),
        # K-row
        card("カ", "ka"), card("キ", "ki"), card("ク", "ku"), card("ケ", "ke"), card("コ", "ko"),
        # S-row
        card("サ", "sa"), card("シ", "shi"), card("ス", "su"), card("セ", "se"), card("ソ", "so"),
        # T-row
        card("タ", "ta"), card("チ", "chi"), card("ツ", "tsu"), card("テ", "te"), card("ト", "to"),
        # N-row
        card("ナ", "na"), card("ニ", "ni"), card("ヌ", "nu"), card("ネ", "ne"), card("ノ", "no"),
        # H-row
        card("ハ", "ha"), card("ヒ", "hi"), card("フ", "fu"), card("ヘ", "he"), card("ホ", "ho"),
        # M-row
        card("マ", "ma"), card("ミ", "mi"), card("ム", "mu"), card("メ", "me"), card("モ", "mo"),
        # Y-row
        card("ヤ", "ya"), card("ユ", "yu"), card("ヨ", "yo"),
        # R-row
        card("ラ", "ra"), card("リ", "ri"), card("ル", "ru"), card("レ", "re"), card("ロ", "ro"),
        # W-row + N
        card("ワ", "wa"), card("ヲ", "wo"), card("ン", "n"),
    ]

    # 5 Kanji decks with 15 cards each (75 kanji total)
    kanji_decks = [
        {
            "name": "Kanji: Nature & Elements",
            "cards": [
                card("日", "にち/ひ - sun, day\nEx: 今日(きょう) - today"),
                card("月", "げつ/つき - moon, month\nEx: 今月(こんげつ) - this month"),
                card("火", "か/ひ - fire\nEx: 火山(かざん) - volcano"),
                card("水", "すい/みず - water\nEx: 水曜日(すいようび) - Wednesday"),
                card("木", "もく/き - tree, wood\nEx: 木曜日(もくようび) - Thursday"),
                card("金", "きん/かね - gold, money\nEx: 金曜日(きんようび) - Friday"),
                card("土", "ど/つち - earth, soil\nEx: 土曜日(どようび) - Saturday"),
                card("山", "さん/やま - mountain\nEx: 富士山(ふじさん) - Mt. Fuji"),
                card("川", "かわ - river\nEx: 川口(かわぐち) - Kawaguchi"),
                card("海", "かい/うみ - sea, ocean\nEx: 日本海(にほんかい) - Sea of Japan"),
                card("空", "くう/そら - sky, empty\nEx: 青空(あおぞら) - blue sky"),
                card("雨", "あめ/う - rain\nEx: 雨天(うてん) - rainy weather"),
                card("雪", "ゆき/せつ - snow\nEx: 雪国(ゆきぐに) - snowy country"),
                card("風", "かぜ/ふう - wind\nEx: 台風(たいふう) - typhoon"),
                card("花", "はな/か - flower\nEx: 花火(はなび) - fireworks"),
            ]
        },
        {
            "name": "Kanji: People & Body",
            "cards": [
                card("人", "じん/ひと - person\nEx: 日本人(にほんじん) - Japanese person"),
                card("子", "し/こ - child\nEx: 子供(こども) - child"),
                card("女", "じょ/おんな - woman\nEx: 女の子(おんなのこ) - girl"),
                card("男", "だん/おとこ - man\nEx: 男の子(おとこのこ) - boy"),
                card("目", "もく/め - eye\nEx: 目的(もくてき) - purpose"),
                card("耳", "じ/みみ - ear\nEx: 耳元(みみもと) - close to ear"),
                card("口", "こう/くち - mouth\nEx: 人口(じんこう) - population"),
                card("手", "しゅ/て - hand\nEx: 手紙(てがみ) - letter"),
                card("足", "そく/あし - foot\nEx: 足元(あしもと) - at one's feet"),
                card("心", "しん/こころ - heart, mind\nEx: 心配(しんぱい) - worry"),
                card("父", "ふ/ちち - father\nEx: 父親(ちちおや) - father"),
                card("母", "ぼ/はは - mother\nEx: 母親(ははおや) - mother"),
                card("友", "ゆう/とも - friend\nEx: 友達(ともだち) - friend"),
                card("先", "せん/さき - ahead, previous\nEx: 先生(せんせい) - teacher"),
                card("生", "せい/い(きる) - life, birth\nEx: 学生(がくせい) - student"),
            ]
        },
        {
            "name": "Kanji: Time & Numbers",
            "cards": [
                card("年", "ねん/とし - year\nEx: 今年(ことし) - this year"),
                card("時", "じ/とき - time, hour\nEx: 時間(じかん) - time"),
                card("分", "ふん/わ(ける) - minute, part\nEx: 五分(ごふん) - 5 minutes"),
                card("秒", "びょう - second\nEx: 十秒(じゅうびょう) - 10 seconds"),
                card("間", "かん/あいだ - interval, between\nEx: 時間(じかん) - time"),
                card("朝", "ちょう/あさ - morning\nEx: 朝食(ちょうしょく) - breakfast"),
                card("昼", "ちゅう/ひる - noon, daytime\nEx: 昼食(ちゅうしょく) - lunch"),
                card("夜", "や/よる - night\nEx: 夜中(よなか) - midnight"),
                card("一", "いち - one\nEx: 一つ(ひとつ) - one (thing)"),
                card("二", "に - two\nEx: 二つ(ふたつ) - two (things)"),
                card("三", "さん - three\nEx: 三つ(みっつ) - three (things)"),
                card("四", "し/よん - four\nEx: 四つ(よっつ) - four (things)"),
                card("五", "ご - five\nEx: 五つ(いつつ) - five (things)"),
                card("十", "じゅう/とお - ten\nEx: 十月(じゅうがつ) - October"),
                card("百", "ひゃく - hundred\nEx: 百円(ひゃくえん) - 100 yen"),
            ]
        },
        {
            "name": "Kanji: Places & Directions",
            "cards": [
                card("上", "じょう/うえ - above, up\nEx: 上手(じょうず) - skilled"),
                card("下", "か/した - below, down\nEx: 下手(へた) - unskilled"),
                card("左", "さ/ひだり - left\nEx: 左折(させつ) - left turn"),
                card("右", "う/みぎ - right\nEx: 右折(うせつ) - right turn"),
                card("中", "ちゅう/なか - inside, middle\nEx: 中心(ちゅうしん) - center"),
                card("外", "がい/そと - outside\nEx: 外国(がいこく) - foreign country"),
                card("前", "ぜん/まえ - before, front\nEx: 名前(なまえ) - name"),
                card("後", "ご/あと - after, behind\nEx: 午後(ごご) - afternoon"),
                card("東", "とう/ひがし - east\nEx: 東京(とうきょう) - Tokyo"),
                card("西", "せい/にし - west\nEx: 西洋(せいよう) - the West"),
                card("南", "なん/みなみ - south\nEx: 南極(なんきょく) - Antarctica"),
                card("北", "ほく/きた - north\nEx: 北海道(ほっかいどう) - Hokkaido"),
                card("国", "こく/くに - country\nEx: 中国(ちゅうごく) - China"),
                card("家", "か/いえ - house, home\nEx: 家族(かぞく) - family"),
                card("駅", "えき - station\nEx: 駅前(えきまえ) - in front of station"),
            ]
        },
        {
            "name": "Kanji: Actions & Verbs",
            "cards": [
                card("行", "こう/い(く) - go\nEx: 銀行(ぎんこう) - bank"),
                card("来", "らい/く(る) - come\nEx: 未来(みらい) - future"),
                card("見", "けん/み(る) - see, look\nEx: 意見(いけん) - opinion"),
                card("聞", "ぶん/き(く) - hear, ask\nEx: 新聞(しんぶん) - newspaper"),
                card("話", "わ/はな(す) - speak, talk\nEx: 電話(でんわ) - telephone"),
                card("読", "どく/よ(む) - read\nEx: 読書(どくしょ) - reading"),
                card("書", "しょ/か(く) - write\nEx: 辞書(じしょ) - dictionary"),
                card("食", "しょく/た(べる) - eat\nEx: 食事(しょくじ) - meal"),
                card("飲", "いん/の(む) - drink\nEx: 飲料(いんりょう) - beverage"),
                card("買", "ばい/か(う) - buy\nEx: 買物(かいもの) - shopping"),
                card("売", "ばい/う(る) - sell\nEx: 売店(ばいてん) - shop"),
                card("立", "りつ/た(つ) - stand\nEx: 立食(りっしょく) - stand-up eating"),
                card("休", "きゅう/やす(む) - rest\nEx: 休日(きゅうじつ) - holiday"),
                card("走", "そう/はし(る) - run\nEx: 走者(そうしゃ) - runner"),
                card("泳", "えい/およ(ぐ) - swim\nEx: 水泳(すいえい) - swimming"),
            ]
        },
    ]

    return [
        {
            "name": "Hiragana (All)",
            "description": "Complete hiragana syllabary — 46 characters",
            "cards": hiragana_cards
        },
        {
            "name": "Katakana (All)",
            "description": "Complete katakana syllabary — 46 characters",
            "cards": katakana_cards
        },
    ] + kanji_decks


_default_users = {
    "alice": {
        "password_hash": pwd_context.hash("aliceSecret2025"),
        "full_name": "John Pork",
        "role": "admin",
        "decks": get_default_decks()
    },
    "bob": {
        "password_hash": pwd_context.hash("bob123!letmein"),
        "full_name": "Bob Builder",
        "role": "user",
        "decks": get_default_decks()
    }
}

users = {}


def migrate_user_decks(user_data: dict) -> bool:
    """Migrate user decks to new structure. Returns True if migration occurred."""
    existing_decks = user_data.get('decks', [])
    if not existing_decks:
        return False
    
    # Check if already using new structure
    deck_names = {d.get('name', '') for d in existing_decks}
    if 'Hiragana (All)' in deck_names and 'Katakana (All)' in deck_names:
        return False  # Already migrated
    
    # Check if using old structure
    old_hiragana = {'Hiragana あ行', 'Hiragana か行', 'Hiragana さ行'}
    if old_hiragana.issubset(deck_names):
        # Get new default decks
        new_decks = get_default_decks()
        # Preserve user's progress from old decks if possible
        # For now, replace with new structure
        user_data['decks'] = new_decks
        return True
    
    return False


def load_users():
    global users
    if USERS_FILE.exists():
        try:
            users = json.loads(USERS_FILE.read_text(encoding='utf-8'))
            needs_save = False
            for username in users:
                if 'decks' not in users[username]:
                    users[username]['decks'] = get_default_decks()
                    needs_save = True
                elif migrate_user_decks(users[username]):
                    needs_save = True
            if needs_save:
                save_users()
        except Exception:
            users = _default_users.copy()
    else:
        users = _default_users.copy()


def save_users():
    try:
        USERS_FILE.write_text(json.dumps(users, indent=2), encoding='utf-8')
    except Exception as e:
        ui.notify(f"Failed to save users: {e}", type='negative')


def add_user(username: str, full_name: str, password: str, role: str = 'user') -> bool:
    username = username.strip().lower()
    if not username or username in users:
        return False
    users[username] = {
        'password_hash': pwd_context.hash(password),
        'full_name': full_name,
        'role': role,
        'decks': get_default_decks()
    }
    save_users()
    return True


load_users()

current_user = None
current_username = None


def is_authenticated():
    return current_user is not None


def login_success(username: str):
    global current_user
    global current_username
    current_user = users.get(username)
    current_username = username
    ui.notify(f"Welcome back, {current_user['full_name']}!", type='positive')
    ui.navigate.to('/dashboard')


def login_failed():
    ui.notify("Invalid username or password", type='negative', position='top')


def logout():
    global current_user
    global current_username
    current_user = None
    current_username = None
    ui.navigate.to('/')


# ---------------------------------------------------------------------------
# Dashboard background image
# ---------------------------------------------------------------------------
# The image is stored as a base64 data URL directly in users.json.
# get_bg_css() returns '' when no image is set so callers can skip
# injecting a <style> tag entirely.
# 5 MB raw → ~6.7 MB after base64; acceptable for a desktop single-user app.
# ---------------------------------------------------------------------------

MAX_IMAGE_BYTES = 5 * 1024 * 1024   # 5 MB


def get_bg_css() -> str:
    """Return a full <style> block for the dashboard background, or ''.

    The image is placed on body::before with filter:brightness() applied to
    that pseudo-element alone.  This dims the background without affecting
    the cards, text, or any other page content sitting on top of it.
    """
    if not current_user:
        return ''
    data_url = current_user.get('bg_image', '')
    if not data_url:
        return ''
    brightness = round(float(current_user.get('bg_brightness', 1.0)), 3)
    return (
        'body { margin: 0; }\n'
        'body::before {\n'
        '  content: "";\n'
        '  position: fixed;\n'
        '  inset: 0;\n'
        f' background-image: url("{data_url}");\n'
        '  background-size: cover;\n'
        '  background-position: center;\n'
        '  background-attachment: fixed;\n'
        f' filter: brightness({brightness});\n'
        '  z-index: -1;\n'
        '}\n'
    )


def get_bg_brightness() -> float:
    """Return the stored brightness value (0.0-1.0), defaulting to 1.0."""
    if not current_user:
        return 1.0
    return float(current_user.get('bg_brightness', 1.0))


def set_bg_brightness(value: float) -> None:
    """Persist a brightness value clamped to [0.0, 1.0]."""
    if current_user:
        current_user['bg_brightness'] = round(max(0.0, min(1.0, value)), 3)
        save_users()


def set_bg_image(data_url: str) -> None:
    """Persist a base64 data URL as the custom dashboard background.

    Brightness is always reset to 1.0 on upload so a fresh image starts
    at full brightness regardless of any previously stored value.
    """
    if current_user:
        current_user['bg_image'] = data_url
        current_user['bg_brightness'] = 1.0
        save_users()


def clear_bg_image() -> None:
    """Remove the custom background image."""
    if current_user:
        current_user.pop('bg_image', None)
        save_users()