import { renderMainMenu } from './screens/mainMenu.js';
import { renderTypingGame } from './screens/typingGame.js';
import { renderEndScreen } from './screens/endScreen.js';
import { renderPassiveMode } from './screens/passiveMode.js';
import { renderStatsScreen } from './screens/statsScreen.js';
import { renderPlaceholderScreen } from './screens/placeholderScreen.js';
import { renderAccountScreen } from './screens/accountScreen.js';
import { renderLeaderboardScreen } from './screens/leaderboardScreen.js';
import { renderFriendsScreen } from './screens/friendsScreen.js';
import { renderMultiplayerScreen } from './screens/multiplayerScreen.js';
import { renderLyricsScreen } from './screens/lyricsScreen.js';
import { renderPublicProfileScreen } from './screens/publicProfileScreen.js';
import { renderStoreScreen } from './screens/storeScreen.js';
import { renderContributeScreen } from './screens/contributeScreen.js';
import { createGame, freeGame } from './game.js';
import { api } from './api.js';
import { saveDocument, setPosition, getDocument, listDocuments, removeDocument } from './customLibrary.js';
import { getSettings } from './settings.js';
import { generateWordStream, generateWeakKeyStream, wordCountForDuration } from './wordGenerator.js';
import { getWeakChars } from './keyStats.js';
import { mountTopAdBanner, mountSideAdRails } from './adSlot.js';

const FALLBACK_TEXT = { category: 'general', content: 'The quick brown fox jumps over the lazy dog.', attribution: 'Traditional pangram' };

function uniqueCategories(items) {
    const set = new Set();
    for (const t of items) if (t.category) set.add(t.category);
    return Array.from(set).sort();
}

function pickRandom(arr) {
    return arr[Math.floor(Math.random() * arr.length)];
}

// A test that ends in twelve seconds measures nothing. The dataset holds a
// lot of single-sentence entries - a 22 character quote, a 17 character
// shell command - and picking one at random produced exactly that.
const MIN_TEST_CHARS = 120;

// Packs where several entries in a row make a better exercise than one. A
// drill of three commands is how these are actually used, and each keeps its
// own explanation.
const CHAINED_CATEGORIES = new Set(['shell', 'sysadmin', 'programming', 'hacking']);

// Enough long entries in a pack to insist on one. Below this the pack simply
// has not got the material, and a short passage beats no passage.
const ENOUGH_LONG = 5;

function getRandomTextItem(items, category) {
    const pool = category && category !== 'random' ? items.filter(t => t.category === category) : items;
    if (!pool.length) return FALLBACK_TEXT;

    if (CHAINED_CATEGORIES.has(category)) return chainShortItems(pool);

    // Prefer a passage worth timing, but only where the pack has enough of
    // them that the same few would not come up every session.
    const long = pool.filter(t => (t.content || '').length >= MIN_TEST_CHARS);
    return pickRandom(long.length >= ENOUGH_LONG ? long : pool);
}

/// Joins consecutive entries from a pack until the result is long enough to
/// be worth timing. Attributions and explanations are collected so the
/// results screen can still say what each line was.
function chainShortItems(pool) {
    const first = pickRandom(pool);
    if ((first.content || '').length >= MIN_TEST_CHARS) return first;

    const chosen = [first];
    const remaining = pool.filter(t => t !== first);
    let total = (first.content || '').length;
    while (total < MIN_TEST_CHARS && remaining.length) {
        const next = remaining.splice(Math.floor(Math.random() * remaining.length), 1)[0];
        chosen.push(next);
        total += (next.content || '').length + 1;
    }

    const attributions = [...new Set(chosen.map(t => t.attribution).filter(Boolean))];
    const explanations = chosen
        .map(t => (t.explanation ? `${t.attribution || ''}${t.attribution ? ': ' : ''}${t.explanation}` : null))
        .filter(Boolean);
    return {
        category: first.category,
        // One line, because the typing input is one line. A space between
        // commands keeps each one readable and typable as written.
        content: chosen.map(t => t.content).join(' '),
        attribution: attributions.join(', ') || 'Unknown',
        language: first.language,
        explanation: explanations.join('\n\n') || undefined,
    };
}

export function startApp(root, localTexts) {
    let allTexts = localTexts;
    let categories = uniqueCategories(localTexts);
    let selectedCategory = localStorage.getItem('typerpunk:last_mode') || 'time';
    let customText = null; // { name, chunks: [{content, time}], language, timed }
    let session = { type: 'random', customIndex: 0 };
    let game = null;
    let cleanupScreen = null;
    const adBanner = mountTopAdBanner();
    const adRails = mountSideAdRails();

    // Approved community submissions, merged on top of the bundled dataset.
    // Best-effort: the app is fully usable on the packs it ships with, so a
    // server that is down or unreachable must not delay or break startup.
    api.get('/api/texts')
        .then(items => {
            if (!Array.isArray(items) || items.length === 0) return;
            allTexts = allTexts.concat(items.map(t => ({
                category: t.category,
                content: t.content,
                attribution: t.attribution || undefined,
                language: t.language || undefined,
            })));
            categories = uniqueCategories(allTexts);
        })
        .catch(() => {});

    const onlineUrl = window.TYPERPUNK_TEXTS_URL;
    if (onlineUrl) {
        fetch(onlineUrl, { cache: 'no-store' })
            .then(res => (res.ok ? res.json() : null))
            .then(data => {
                if (Array.isArray(data)) {
                    allTexts = data;
                    categories = uniqueCategories(data);
                }
            })
            .catch(() => {});
    }

    function teardown() {
        if (cleanupScreen) {
            cleanupScreen();
            cleanupScreen = null;
        }
    }

    // Which screen is showing, and whether leaving it costs the user
    // something. Escape is a global "get me out of here", but walking out of a
    // live race drops you from it for everyone else in the room too, so that
    // one case asks first.
    let currentScreenName = 'menu';
    let escapeIsCostly = () => false;

    function setScreen(name, costly = () => false) {
        currentScreenName = name;
        escapeIsCostly = costly;
        adBanner.setScreen(name);
        adRails.setScreen(name);
    }

    function handleGlobalEscape(e) {
        if (e.key !== 'Escape') return;
        // Let an open popover close itself first - one Escape should not both
        // dismiss a menu and navigate away from the screen behind it.
        const openPopover = document.querySelector(
            '.mode-popover:not([hidden]), .rail-settings-panel:not([hidden]), .settings-panel:not([hidden]), '
            + '.custom-panel:not([hidden]), .lang-popover:not([hidden]), .theme-gallery-popover:not([hidden])');
        if (openPopover) {
            openPopover.hidden = true;
            return;
        }
        if (currentScreenName === 'menu') return;
        if (escapeIsCostly() && !window.confirm('Leave the race? Your opponents will see you drop out.')) return;
        showMainMenu();
    }
    document.addEventListener('keydown', handleGlobalEscape);

    function showMainMenu() {
        teardown();
        freeGame(game);
        game = null;
        setScreen('menu');
        cleanupScreen = renderMainMenu(root, {
            onStartGame: () => { session = { type: 'random', customIndex: 0 }; startGame(); },
            categories,
            selectedCategory,
            onSelectCategory: cat => {
                selectedCategory = cat;
                try { localStorage.setItem('typerpunk:last_mode', cat); } catch {}
                showMainMenu();
            },
            // Picking a mode from the Single Player menu starts that mode --
            // choosing what to type and starting it are one action now, not a
            // selection followed by a second click on the same button.
            onPickAndStart: cat => {
                selectedCategory = cat;
                try { localStorage.setItem('typerpunk:last_mode', cat); } catch {}
                session = { type: 'random', customIndex: 0 };
                startGame();
            },
            customText,
            // Documents are kept so a set of notes survives a reload - see
            // customLibrary.js. Purely local; nothing is uploaded.
            onOpenDocument: id => {
                const doc = getDocument(id);
                if (!doc) return;
                const parsed = parseCustomContent(doc.raw, doc.name);
                customText = { name: doc.name, docId: doc.id, ...parsed };
                session = { type: 'custom', customIndex: Math.min(doc.position || 0, parsed.chunks.length - 1) };
                startGame();
            },
            documents: listDocuments(),
            onRemoveDocument: id => { removeDocument(id); showMainMenu(); },
            onLoadCustom: loaded => {
                const doc = saveDocument({
                    name: loaded.name,
                    raw: loaded.raw ?? '',
                    chunkCount: loaded.chunks.length,
                });
                customText = { ...loaded, docId: doc.id };
                showMainMenu();
            },
            onClearCustom: () => {
                customText = null;
                showMainMenu();
            },
            onStartCustom: () => {
                session = { type: 'custom', customIndex: 0 };
                startGame();
            },
            onStartPassive: startPassive,
            onShowStats: showStats,
            onShowPlaceholder: showPlaceholder,
            onShowAccount: showAccount,
            onShowLeaderboard: showLeaderboard,
            onShowFriends: showFriends,
            onShowMultiplayer: showMultiplayer,
            onShowStore: showStore,
            onShowLyrics: showLyrics,
            onShowPrivacy: showPrivacy,
            onShowContribute: showContribute,
            onSimulateTest: simulateTest,
        });
    }

    // Dev-only shortcut: jumps straight to the end screen with synthetic
    // results, no actual typing needed - for iterating on the end screen's
    // design without retyping a full passage every time.
    function simulateTest() {
        teardown();
        const text = 'The quick brown fox jumps over the lazy dog while typing very quickly today, right now, in this exact moment.';
        const wpm = 70 + Math.random() * 90;
        const accuracy = 85 + Math.random() * 15;
        const time = 8 + Math.random() * 15;
        const charTimings = [];
        const keypressHistory = [];
        for (let i = 0; i < text.length; i++) {
            const t = (i / text.length) * time;
            const isCorrect = Math.random() * 100 < accuracy;
            charTimings.push({ time: t, isCorrect, index: i });
            keypressHistory.push({ time: t, isCorrect, index: i });
        }
        const incorrectChars = charTimings.filter(c => !c.isCorrect).length;
        const stats = {
            wpm, rawWpm: wpm * 1.08, accuracy, time,
            correctChars: text.length - incorrectChars, incorrectChars, totalChars: text.length,
            currentStreak: 0, bestStreak: Math.floor(text.length / 3),
        };
        showEndScreen({ stats, text, userInput: text, charTimings, keypressHistory, modeKey: null });
    }

    function showStats() {
        teardown();
        setScreen('stats');
        cleanupScreen = renderStatsScreen(root, { onBack: showMainMenu, onShowPlaceholder: showPlaceholder, onShowAccount: showAccount, onShowLeaderboard: showLeaderboard, onShowFriends: showFriends, onShowMultiplayer: showMultiplayer, onShowStore: showStore });
    }

    // Written from what the code actually does, not from a template: this app
    // has no analytics, no third-party scripts and no npm runtime dependencies,
    // so there is genuinely very little to disclose.
    function showContribute() {
        teardown();
        setScreen('contribute');
        cleanupScreen = renderContributeScreen(root, { onBack: showMainMenu, onShowStats: showStats, onShowPlaceholder: showPlaceholder, onShowAccount: showAccount, onShowLeaderboard: showLeaderboard, onShowFriends: showFriends, onShowMultiplayer: showMultiplayer, onShowStore: showStore });
    }

    function showPrivacy() {
        showPlaceholder('Privacy', [
            'On this device, in your browser: your theme, typing settings, personal bests, lifetime stats and per-key accuracy. Clearing site data removes all of it. Nothing here is sent anywhere unless you sign in.',
            '',
            'On the server, only if you create an account: your username, a hash of your password (never the password), your completed results, your friendships, and anything you equip from the store. Sessions expire. If you connect Spotify, its access token is stored so Lyrics mode can read what is playing.',
            '',
            'Multiplayer sends the name you race under, your live progress and your final result to the other people in your room, for as long as the race lasts.',
            '',
            'There are no analytics, no advertising and no third-party scripts - the site loads no code it does not ship itself. Nothing is sold or shared.',
        ].join('\n'));
    }

    function showPlaceholder(title, description) {
        teardown();
        setScreen('placeholder');
        cleanupScreen = renderPlaceholderScreen(root, { title, description, onBack: showMainMenu, onShowStats: showStats, onShowPlaceholder: showPlaceholder, onShowAccount: showAccount, onShowLeaderboard: showLeaderboard, onShowFriends: showFriends, onShowMultiplayer: showMultiplayer, onShowStore: showStore });
    }

    function showAccount() {
        teardown();
        setScreen('account');
        cleanupScreen = renderAccountScreen(root, { onBack: showMainMenu, onShowStats: showStats, onShowPlaceholder: showPlaceholder, onShowLeaderboard: showLeaderboard, onShowFriends: showFriends, onShowMultiplayer: showMultiplayer, onShowStore: showStore });
    }

    function showLeaderboard() {
        teardown();
        setScreen('leaderboard');
        cleanupScreen = renderLeaderboardScreen(root, { onBack: showMainMenu, onShowPublicProfile: showPublicProfile, onShowStats: showStats, onShowPlaceholder: showPlaceholder, onShowAccount: showAccount, onShowFriends: showFriends, onShowMultiplayer: showMultiplayer, onShowStore: showStore });
    }

    function showPublicProfile(username) {
        teardown();
        setScreen('profile');
        cleanupScreen = renderPublicProfileScreen(root, { username, onBack: showLeaderboard, onShowStats: showStats, onShowPlaceholder: showPlaceholder, onShowAccount: showAccount, onShowLeaderboard: showLeaderboard, onShowFriends: showFriends, onShowMultiplayer: showMultiplayer, onShowStore: showStore });
    }

    function showFriends() {
        teardown();
        setScreen('friends');
        cleanupScreen = renderFriendsScreen(root, { onBack: showMainMenu, onShowStats: showStats, onShowPlaceholder: showPlaceholder, onShowAccount: showAccount, onShowLeaderboard: showLeaderboard, onShowMultiplayer: showMultiplayer, onShowStore: showStore });
    }

    function showMultiplayer() {
        teardown();
        setScreen('multiplayer', () => !!document.querySelector('.mp-opponents'));
        cleanupScreen = renderMultiplayerScreen(root, { onBack: showMainMenu, onFinish: showEndScreen, onShowStats: showStats, onShowPlaceholder: showPlaceholder, onShowAccount: showAccount, onShowLeaderboard: showLeaderboard, onShowFriends: showFriends, onShowStore: showStore });
    }

    function showStore() {
        teardown();
        setScreen('store');
        cleanupScreen = renderStoreScreen(root, { onBack: showMainMenu, onShowStats: showStats, onShowPlaceholder: showPlaceholder, onShowAccount: showAccount, onShowLeaderboard: showLeaderboard, onShowFriends: showFriends, onShowMultiplayer: showMultiplayer });
    }

    function showLyrics() {
        teardown();
        setScreen('lyrics');
        cleanupScreen = renderLyricsScreen(root, {
            onBack: showMainMenu,
            onLyricsReady: loaded => {
                customText = loaded;
                session = { type: 'custom', customIndex: 0 };
                startGame();
            },
            onShowStats: showStats,
            onShowPlaceholder: showPlaceholder,
            onShowAccount: showAccount,
            onShowLeaderboard: showLeaderboard,
            onShowFriends: showFriends,
            onShowMultiplayer: showMultiplayer,
            onShowStore: showStore,
        });
    }

    async function startGame() {
        teardown();
        let content;
        let attribution;
        let category;
        let explanation;
        let language;
        let progress;
        let timeLimit;
        // Custom text has no stable, repeatable challenge to compare against,
        // so it's excluded from personal-best tracking (stays undefined).
        let modeKey;

        if (session.type === 'custom' && customText) {
            const chunk = customText.chunks[session.customIndex];
            content = chunk.content;
            attribution = customText.name;
            language = customText.language;
            progress = `${customText.name} · segment ${session.customIndex + 1}/${customText.chunks.length}`;
        } else if (selectedCategory === 'words') {
            const s = getSettings();
            content = generateWordStream(s.wordCount || 25, { punctuation: s.wordsPunctuation, numbers: s.wordsNumbers, tier: s.wordListTier, language: s.language });
            modeKey = `words-${s.wordCount || 25}`;
        } else if (selectedCategory === 'time') {
            const s = getSettings();
            timeLimit = s.timeDuration || 30;
            content = generateWordStream(wordCountForDuration(timeLimit), { punctuation: s.wordsPunctuation, numbers: s.wordsNumbers, tier: s.wordListTier, language: s.language });
            modeKey = `time-${timeLimit}`;
        } else if (selectedCategory === 'zen') {
            // No timer, no fixed length - type until you choose to stop (the
            // visible Finish button in the typing screen). No modeKey: like
            // custom text, there's no fixed-length challenge to compare a
            // "personal best" against since every session covers a different
            // amount of text.
            const s = getSettings();
            content = generateWordStream(800, { punctuation: s.wordsPunctuation, numbers: s.wordsNumbers, tier: s.wordListTier, language: s.language });
        } else if (selectedCategory === 'practice') {
            // Adaptive, personal, and different every time by nature - no
            // modeKey, same reasoning as Zen/Custom: there's no fixed
            // challenge here to compare a "personal best" against.
            const s = getSettings();
            const weakChars = getWeakChars();
            content = generateWeakKeyStream(wordCountForDuration(30), weakChars, { punctuation: s.wordsPunctuation, numbers: s.wordsNumbers });
        } else {
            const item = getRandomTextItem(allTexts, selectedCategory);
            content = item.content;
            attribution = item.attribution;
            // Shown under the passage when it has no attribution of its own,
            // so the results always say where the text came from.
            category = item.category;
            // Code snippets highlight themselves; prose packs have no language
            // and fall through as plain text.
            language = item.language || undefined;
            explanation = item.explanation || undefined;
            modeKey = `quote-${selectedCategory || 'random'}`;
        }

        try {
            game = await createGame();
            game.set_text(content);
        } catch (err) {
            console.error('Failed to start game:', err);
            showMainMenu();
            return;
        }
        setScreen('typing');
        cleanupScreen = renderTypingGame(root, {
            game,
            text: content,
            attribution,
            category,
            explanation,
            language,
            progress,
            timeLimit,
            modeKey,
            zenMode: selectedCategory === 'zen' && !(session.type === 'custom' && customText),
            onFinish: showEndScreen,
            onMainMenu: showMainMenu,
            onRestart: startGame,
            onShowStats: showStats,
            onShowPlaceholder: showPlaceholder,
            onShowAccount: showAccount,
            onShowLeaderboard: showLeaderboard,
            onShowFriends: showFriends,
            onShowMultiplayer: showMultiplayer,
            onShowStore: showStore,
            onShowPrivacy: showPrivacy,
        });
    }

    function playAgain() {
        if (session.type === 'custom' && customText) {
            if (session.customIndex + 1 < customText.chunks.length) {
                session.customIndex += 1;
                if (customText.docId) setPosition(customText.docId, session.customIndex);
            } else {
                showMainMenu();
                return;
            }
        }
        startGame();
    }

    function showEndScreen(result) {
        // Record the segment as done as soon as it is finished, not when the
        // next one is started. Closing the tab after finishing a segment
        // otherwise lost it, and returning to a set of notes at the segment
        // you had already typed is exactly the thing this is meant to avoid.
        if (session.type === 'custom' && customText?.docId) {
            setPosition(customText.docId, Math.min(session.customIndex + 1, customText.chunks.length));
        }
        teardown();
        setScreen('end');
        // A race carries standings; a solo run does not. Play Again used to
        // call startGame() either way, so finishing a race and asking to play
        // again dropped you into a single player test on your own. Going back
        // through showMultiplayer queues for another race. The end screen's
        // own cleanup calls onLeaveRace, so the old room is left before the
        // next one is joined.
        const wasRace = Array.isArray(result.standings) && result.standings.length > 0;
        cleanupScreen = renderEndScreen(root, {
            ...result,
            onPlayAgain: wasRace ? showMultiplayer : playAgain,
            onMainMenu: showMainMenu,
            onShowStats: showStats,
            onShowPlaceholder: showPlaceholder,
            onShowAccount: showAccount,
            onShowLeaderboard: showLeaderboard,
            onShowFriends: showFriends,
            onShowMultiplayer: showMultiplayer,
            onShowStore: showStore,
        });
    }

    function startPassive() {
        teardown();
        if (!customText) {
            showMainMenu();
            return;
        }
        setScreen('passive');
        cleanupScreen = renderPassiveMode(root, {
            name: customText.name,
            chunks: customText.chunks,
            onExit: showMainMenu,
        });
    }

    const { skipMenu, favoriteMode } = getSettings();
    const bootMode = favoriteMode || selectedCategory;
    if (skipMenu && bootMode !== 'custom') {
        selectedCategory = bootMode;
        try { localStorage.setItem('typerpunk:last_mode', bootMode); } catch {}
        session = { type: 'random', customIndex: 0 };
        startGame();
    } else {
        showMainMenu();
    }
}