window.Stats = {
    init: function () {
        this.update(History.entries);
    },

    update: function (entries) {
        var stats = this.calculate(entries);
        this.render(stats);
    },

    calculate: function (entries) {
        if (!entries || entries.length === 0) return null;

        var successful = entries.filter(function (e) { return e.status === 'success'; });
        var total = entries.length;

        var durationValues = entries.map(function (e) { return e.duration || 0; });

        // Count pass/fail/inconclusive
        var passCount = successful.filter(function (e) { return e.overallResult === 'pass'; }).length;
        var failCount = successful.filter(function (e) { return e.overallResult === 'fail'; }).length;

        // Collect all field keys seen across results
        var allFieldKeys = {};
        for (var i = 0; i < successful.length; i++) {
            var fields = successful[i].result && successful[i].result.fields ? successful[i].result.fields : {};
            var keys = Object.keys(fields);
            for (var k = 0; k < keys.length; k++) {
                allFieldKeys[keys[k]] = true;
            }
        }

        var fieldRates = {};
        var fieldKeyList = Object.keys(allFieldKeys);
        for (var j = 0; j < fieldKeyList.length; j++) {
            var key = fieldKeyList[j];
            fieldRates[key] = this._rate(successful, function (e) {
                return e.result && e.result.fields && e.result.fields[key] != null && e.result.fields[key] !== '';
            });
        }

        return {
            totalProcessed: total,
            successCount: successful.length,
            errorCount: total - successful.length,
            passCount: passCount,
            failCount: failCount,
            successRate: total > 0 ? successful.length / total : 0,
            avgDuration: this._avg(durationValues),
            fieldRates: fieldRates,
            fieldKeyList: fieldKeyList,
        };
    },

    _avg: function (values) {
        if (!values.length) return 0;
        return values.reduce(function (a, b) { return a + b; }, 0) / values.length;
    },

    _rate: function (entries, predicate) {
        if (!entries.length) return 0;
        return entries.filter(predicate).length / entries.length;
    },

    render: function (stats) {
        var hasStats = stats !== null;
        Utils.$('#stats-empty').classList.toggle('hidden', hasStats);
        Utils.$('#stats-data').classList.toggle('hidden', !hasStats);

        if (!hasStats) return;

        // Stat cards
        var cardsContainer = Utils.$('#stat-cards');
        cardsContainer.innerHTML = '';

        var cards = [
            { value: stats.totalProcessed, label: 'Total Processed' },
            { value: stats.passCount, label: 'Passed' },
            { value: stats.failCount, label: 'Failed' },
            { value: (stats.avgDuration / 1000).toFixed(1) + 's', label: 'Avg Duration' },
        ];

        for (var i = 0; i < cards.length; i++) {
            var card = document.createElement('div');
            card.className = 'stat-card';

            var val = document.createElement('div');
            val.className = 'stat-value';
            val.textContent = cards[i].value;

            var lbl = document.createElement('div');
            lbl.className = 'stat-label';
            lbl.textContent = cards[i].label;

            card.appendChild(val);
            card.appendChild(lbl);
            cardsContainer.appendChild(card);
        }

        // Field extraction rates
        var ratesContainer = Utils.$('#field-rates');
        ratesContainer.innerHTML = '';

        var fieldKeys = stats.fieldKeyList || [];

        for (var j = 0; j < fieldKeys.length; j++) {
            var key = fieldKeys[j];
            var rate = stats.fieldRates[key] || 0;

            var row = document.createElement('div');
            row.className = 'confidence-row';

            var label = document.createElement('span');
            label.className = 'confidence-label';
            label.textContent = Utils.fieldLabel(key);

            var bar = document.createElement('div');
            bar.className = 'confidence-bar';

            var fill = document.createElement('div');
            fill.className = 'confidence-fill ' + Utils.confidenceLevel(rate);
            fill.style.width = Utils.formatConfidence(rate);
            fill.textContent = Utils.formatConfidence(rate);

            bar.appendChild(fill);
            row.appendChild(label);
            row.appendChild(bar);
            ratesContainer.appendChild(row);
        }
    },
};