/**
 * BIST Predictor — API İletişim Modülü
 * Backend REST API ve SSE stream yönetimi.
 */

const API = {
    BASE_URL: window.location.origin,
    
    /** SSE event source instance */
    _eventSource: null,
    _sseListeners: [],
    
    // ─── HTTP İstekleri ─────────────────────────────────────────────────────
    
    async _fetch(endpoint, options = {}) {
        try {
            const url = `${this.BASE_URL}/api${endpoint}`;
            const response = await fetch(url, {
                headers: { 'Content-Type': 'application/json' },
                ...options,
            });
            
            if (!response.ok) {
                const error = await response.json().catch(() => ({ detail: response.statusText }));
                throw new Error(error.detail || `HTTP ${response.status}`);
            }
            
            return await response.json();
        } catch (error) {
            console.error(`API Error [${endpoint}]:`, error);
            throw error;
        }
    },
    
    async get(endpoint) {
        return this._fetch(endpoint);
    },
    
    async post(endpoint, data = null) {
        const options = { method: 'POST' };
        if (data) options.body = JSON.stringify(data);
        return this._fetch(endpoint, options);
    },
    
    // ─── Dashboard ──────────────────────────────────────────────────────────
    
    async getDashboard(horizon = 10) {
        return this.get(`/dashboard?horizon=${horizon}`);
    },
    
    async getStocks() {
        return this.get('/stocks');
    },
    
    async getStockDetail(symbol, horizon = 10) {
        return this.get(`/stock/${symbol}?horizon=${horizon}`);
    },
    
    // ─── Tahminler ──────────────────────────────────────────────────────────
    
    async getPredictions(symbol, horizon = 10) {
        return this.get(`/predictions/${symbol}?horizon=${horizon}`);
    },
    
    async triggerPrediction(symbol, horizons = '10') {
        return this.post(`/predict/${symbol}?horizons=${horizons}`);
    },
    
    async triggerAllPredictions() {
        return this.post('/predict-all');
    },
    
    // ─── Güven Puanı ────────────────────────────────────────────────────────
    
    async getConfidence(symbol, horizon = 10) {
        return this.get(`/confidence/${symbol}?horizon=${horizon}`);
    },
    
    async getConfidenceRanking(horizon = 10) {
        return this.get(`/confidence-ranking?horizon=${horizon}`);
    },
    
    // ─── Karşılaştırma ──────────────────────────────────────────────────────
    
    async getComparison(symbol, horizon = 10) {
        return this.get(`/comparison/${symbol}?horizon=${horizon}`);
    },
    
    // ─── Veri Yönetimi ──────────────────────────────────────────────────────
    
    async loadInitialData() {
        return this.post('/data/load');
    },
    
    async updateStockData(symbol) {
        return this.post(`/data/update/${symbol}`);
    },
    
    async triggerComparison() {
        return this.post('/data/compare');
    },
    
    // ─── Sistem ─────────────────────────────────────────────────────────────
    
    async getSystemStatus() {
        return this.get('/system/status');
    },
    
    async getSystemLogs(limit = 50) {
        return this.get(`/system/logs?limit=${limit}`);
    },
    
    // ─── SSE (Server-Sent Events) ────────────────────────────────────────────
    
    connectSSE() {
        if (this._eventSource) {
            this._eventSource.close();
        }
        
        this._eventSource = new EventSource(`${this.BASE_URL}/api/stream`);
        
        this._eventSource.onopen = () => {
            console.log('SSE bağlantısı kuruldu');
            this._notifyListeners('connected', {});
        };
        
        this._eventSource.onmessage = (event) => {
            try {
                const parsed = JSON.parse(event.data);
                const { type, data, timestamp } = parsed;
                this._notifyListeners(type, data, timestamp);
            } catch (e) {
                console.warn('SSE parse hatası:', e);
            }
        };
        
        this._eventSource.onerror = (error) => {
            console.warn('SSE bağlantı hatası, yeniden bağlanılıyor...');
            this._notifyListeners('disconnected', {});
            
            // Otomatik yeniden bağlanma (EventSource bunu otomatik yapar)
        };
    },
    
    disconnectSSE() {
        if (this._eventSource) {
            this._eventSource.close();
            this._eventSource = null;
        }
    },
    
    onSSE(callback) {
        this._sseListeners.push(callback);
    },
    
    offSSE(callback) {
        this._sseListeners = this._sseListeners.filter(cb => cb !== callback);
    },
    
    _notifyListeners(type, data, timestamp) {
        for (const listener of this._sseListeners) {
            try {
                listener(type, data, timestamp);
            } catch (e) {
                console.error('SSE listener hatası:', e);
            }
        }
    },
};