/**
 * Rulesets manager (plugin side) — formato v2.
 *
 * Gestisce 5 tipi: logs | forecast_current | forecast_hourly | marine_current | marine_hourly
 *
 * Formato item (v2):
 *   { path, meta: { name, unit, decimals? }, olds: [], enabled: true }
 *
 * Fonti:
 *   1. cache locale (data/rulesets.json)            — sopravvive ai restart
 *   2. GET HTTP {API_URL}/rulesets/<type>/active    — bootstrap o riconciliazione
 *   3. push WS realtime ({_t:'ruleset_update'})     — runtime updates
 *
 * Dopo applyRemote(type, ruleset):
 *   - emette 'update' (type, new, prev)
 *   - emette 'update:<type>' (new, prev)
 *   - invia ack al server (via realtime control message ruleset_ack)
 *
 * I consumer (logs.local, openmeteo) si sottoscrivono per applicare il cambio.
 * Quando arriva un update di tipo 'logs', il consumer triggera un session_reset
 * (cosi' Influx separa storico vecchio da nuovo schema).
 */

const fs = require('fs');
const fsp = require('fs').promises;
const path = require('path');
const EventEmitter = require('events');

const {
    LOG_PATHS,
    FORECAST_CURRENT,
    FORECAST_HOURLY,
    MARINE_CURRENT,
    MARINE_HOURLY
} = require('../rules');

const TYPES = ['logs', 'forecast_current', 'forecast_hourly', 'marine_current', 'marine_hourly'];
const cacheFile = path.join(__dirname, '../../data/rulesets.json');
const emitter = new EventEmitter();

const API_URL = process.env.API_URL;

// state: { type -> { id, version: {major,minor,patch,str}, content: [items], _default } }
let state = {};

// =============== DEFAULTS (fallback iniziale, no DB / no cache) ===============

/** Mapping legacy openmeteo code → SK path */
const LEGACY_SK_MAP = {
    'temperature_2m':            'meb.forecast.temperature',
    'wind_speed_10m':            'meb.forecast.wind.speed',
    'wind_direction_10m':        'meb.forecast.wind.direction',
    'wind_gusts_10m':            'meb.forecast.wind.gusts',
    'precipitation':             'meb.forecast.precipitation',
    'rain':                      'meb.forecast.rain',
    'relative_humidity_2m':      'meb.forecast.humidity',
    'pressure_msl':              'meb.forecast.pressure',
    'precipitation_probability': 'meb.forecast.precipitationProbability',
    'cloud_cover':               'meb.forecast.cloudCover',
    'wave_height':               'meb.waves.height',
    'wave_direction':            'meb.waves.direction',
    'wave_period':               'meb.waves.period',
    'wave_peak_period':          'meb.waves.peakPeriod',
    'ocean_current_velocity':    'meb.waves.currentVelocity',
    'ocean_current_direction':   'meb.waves.currentDirection',
};

function defaultItem(p, meta = {}) {
    return { path: p, meta, olds: [], enabled: true };
}

function buildDefaults() {
    const mk = (items) => ({
        id: null,
        version: { major: 1, minor: 0, patch: 0, str: '1.0.0' },
        description: 'default',
        content: items,
        _default: true,
    });
    return {
        logs: mk(LOG_PATHS.map(p => defaultItem(p, {}))),
        forecast_current: mk(FORECAST_CURRENT.map(c => defaultItem(c, { sk_path: LEGACY_SK_MAP[c] }))),
        forecast_hourly:  mk(FORECAST_HOURLY.map(c => defaultItem(c, { sk_path: LEGACY_SK_MAP[c] }))),
        marine_current:   mk(MARINE_CURRENT.map(c => defaultItem(c, { sk_path: LEGACY_SK_MAP[c] }))),
        marine_hourly:    mk(MARINE_HOURLY.map(c => defaultItem(c, { sk_path: LEGACY_SK_MAP[c] }))),
    };
}

// =============== CACHE I/O ===============

async function ensureDir() {
    try { await fsp.mkdir(path.dirname(cacheFile), { recursive: true }); } catch {}
}

async function loadCache() {
    try {
        const raw = await fsp.readFile(cacheFile, 'utf-8');
        const parsed = JSON.parse(raw);
        if (parsed && typeof parsed === 'object') return parsed;
    } catch {}
    return {};
}

async function saveCache() {
    try { await ensureDir(); await fsp.writeFile(cacheFile, JSON.stringify(state, null, 2)); }
    catch (err) { console.warn('[RULESETS] save cache failed:', err.message); }
}

// =============== INIT + BOOTSTRAP ===============

/**
 * Init: carica cache → applica defaults sui type mancanti. Non emette eventi.
 * Successivamente `bootstrapFromServer()` chiama gli endpoint per riconciliare.
 */
async function init() {
    const cached = await loadCache();
    const defaults = buildDefaults();
    state = {};
    for (const t of TYPES) state[t] = cached[t] || defaults[t];
    console.log('[RULESETS] init:',
        TYPES.map(t => `${t}@v${state[t]?.version?.str || '?'}${state[t]?._default ? '(d)' : ''}`).join(' '));
}

/**
 * Tenta di scaricare la versione attiva di ogni tipo dal server.
 * Se ottenuta e nuova, la applica (emette gli eventi).
 */
async function bootstrapFromServer() {
    if (!API_URL) {
        console.warn('[RULESETS] API_URL non configurato, salto bootstrap');
        return;
    }
    for (const type of TYPES) {
        try {
            const r = await fetch(`${API_URL}/rulesets/${type}/active`, { signal: AbortSignal.timeout(8000) });
            if (!r.ok) { if (r.status !== 404) console.warn(`[RULESETS] ${type} bootstrap ${r.status}`); continue; }
            const remote = await r.json();
            // formato server: { id, type, version:{...,str}, content:[...] }
            await applyRemote(type, remote, { source: 'bootstrap' });
        } catch (err) {
            console.warn(`[RULESETS] bootstrap ${type} err:`, err.message);
        }
    }
}

// =============== ACCESSORS ===============

function get(type) { return state[type] || null; }

function getEnabledItems(type) {
    const rs = state[type];
    if (!rs) return [];
    return (rs.content || []).filter(it => it.enabled !== false);
}

function getEnabledPaths(type) {
    return getEnabledItems(type).map(it => it.path).filter(Boolean);
}

function getPathMap(type) {
    const map = {};
    for (const it of getEnabledItems(type)) {
        if (it.path && it.meta?.sk_path) map[it.path] = it.meta.sk_path;
    }
    return map;
}

function getMetaForPath(type, p) {
    return (state[type]?.content || []).find(it => it.path === p)?.meta || null;
}

function versionStr(type) { return state[type]?.version?.str || null; }
function rulesetId(type) { return state[type]?.id || null; }

// =============== APPLY ===============

/**
 * Applica un ruleset ricevuto. Salva cache, emette update events,
 * e (se non e' bootstrap) manda ack al server.
 *
 * Idempotente per versione: ignora payload con version <= corrente.
 */
async function applyRemote(type, ruleset, { source = 'push' } = {}) {
    if (!TYPES.includes(type)) {
        console.warn(`[RULESETS] tipo sconosciuto: ${type}`);
        return false;
    }
    if (!ruleset || !Array.isArray(ruleset.content)) {
        console.warn(`[RULESETS] ruleset invalido per ${type}`);
        return false;
    }
    const prev = state[type];
    // dedup per id+version: scarta replays
    if (prev && !prev._default && ruleset.id && prev.id === ruleset.id
        && prev.version?.str === ruleset.version?.str) {
        return false;
    }
    state[type] = {
        id: ruleset.id,
        version: ruleset.version,
        description: ruleset.description,
        content: ruleset.content,
        _default: false,
    };
    await saveCache();
    const prevV = prev?.version?.str || '∅';
    const newV  = ruleset.version?.str || '?';
    console.log(`[RULESETS] ${type} ${prevV} → ${newV} (${ruleset.content.length} items, src=${source})`);

    emitter.emit('update', type, state[type], prev);
    emitter.emit(`update:${type}`, state[type], prev);

    // ack al server (skipped on bootstrap to avoid loop)
    if (source !== 'bootstrap' && ruleset.id) {
        try {
            const realtime = require('./realtime/core');
            realtime.sendRaw({
                _t: 'ruleset_ack',
                type,
                ruleset_id: ruleset.id,
                version: ruleset.version?.str || '?',
            });
        } catch (err) {
            console.warn('[RULESETS] ack send failed:', err.message);
        }
    }
    return true;
}

function onUpdate(listener) { emitter.on('update', listener); return () => emitter.off('update', listener); }
function onUpdateOf(type, listener) { emitter.on(`update:${type}`, listener); return () => emitter.off(`update:${type}`, listener); }

module.exports = {
    TYPES,
    init,
    bootstrapFromServer,
    get,
    getEnabledItems,
    getEnabledPaths,
    getPathMap,
    getMetaForPath,
    versionStr,
    rulesetId,
    applyRemote,
    onUpdate,
    onUpdateOf,
};