const MIN_CONFIDENCE_VALUE = 50

function normalizeFieldName(fieldType) {
    //Placeholder normalization for now. 
    return fieldType;
}

const standardizedFieldsnames = {
    actual_cost: "actual_cost",
    actual_price: "actual_price",
    line_desc: "line_desc",
    quantity: "quantity",
    part_no: "part_no",
    ro_number: "ro_number",
}

function normalizeLabelName(labelText) {
    if (!labelText) return '';

    // Convert to lowercase and trim whitespace
    let normalized = labelText.toLowerCase().trim();

    // Remove special characters and replace spaces with underscores
    normalized = normalized.replace(/[^a-z0-9\s]/g, '').replace(/\s+/g, '_');


    // Common label normalizations
    const labelMap = {
        'qty': standardizedFieldsnames.quantity,
        'qnty': standardizedFieldsnames.quantity,
        'sale_qty': standardizedFieldsnames.quantity,
        'invoiced_qty': standardizedFieldsnames.quantity,
        'qty_shipped': standardizedFieldsnames.quantity,
        'quantity': standardizedFieldsnames.quantity,
        'filled': standardizedFieldsnames.quantity,
        'count': standardizedFieldsnames.quantity,
        'quant': standardizedFieldsnames.quantity,
        'desc': standardizedFieldsnames.line_desc,
        'description': standardizedFieldsnames.line_desc,
        'item': standardizedFieldsnames.line_desc,
        'part': standardizedFieldsnames.part_no,
        'part_no': standardizedFieldsnames.part_no,
        'part_num': standardizedFieldsnames.part_no,
        'part_number': standardizedFieldsnames.part_no,
        'item_no': standardizedFieldsnames.part_no,
        'price': standardizedFieldsnames.actual_price,
        //'amount': standardizedFieldsnames.actual_price,
        'list_price': standardizedFieldsnames.actual_price,
        'unit_price': standardizedFieldsnames.actual_price,
        'list': standardizedFieldsnames.actual_price,
        'retail_price': standardizedFieldsnames.actual_price,
        'retail': standardizedFieldsnames.actual_price,
        'net': standardizedFieldsnames.actual_cost,
        'selling_price': standardizedFieldsnames.actual_cost,
        'net_price': standardizedFieldsnames.actual_cost,
        'net_cost': standardizedFieldsnames.actual_cost,
        'total': standardizedFieldsnames.actual_cost,
        'po_no': standardizedFieldsnames.ro_number,
        'customer_po_no': standardizedFieldsnames.ro_number,
        'customer_po_no_': standardizedFieldsnames.ro_number

    };

    return labelMap[normalized] || `NOT_MAPPED => ${normalized}`; // TODO: Should we monitor unmapped labels?
}

function processScanData(invoiceData) {
    // Process and clean the extracted data
    const processed = {
        summary: {},
        lineItems: []
    };

    // Clean summary fields
    for (const [key, value] of Object.entries(invoiceData.summary)) {
        if (value.confidence > MIN_CONFIDENCE_VALUE) { // Only include fields with > 50% confidence
            processed.summary[key] = {
                value: value.value,
                label: value.label,
                normalizedLabel: value.normalizedLabel,
                confidence: value.confidence
            };
        }
    }

    // Process line items
    processed.lineItems = invoiceData.lineItems
        .map(item => {
            const processedItem = {};

            for (const [key, value] of Object.entries(item)) {
                if (value.confidence > MIN_CONFIDENCE_VALUE) { // Only include fields with > 50% confidence
                    let cleanValue = value.value;

                    // Parse numbers for quantity and price fields
                    if (key === 'quantity') {
                        cleanValue = parseFloat(cleanValue) || 0;
                    } else if (key === 'retail_price' || key === 'actual_price') {
                        // Remove currency symbols and parse
                        cleanValue = parseFloat(cleanValue.replace(/[^0-9.-]/g, '')) || 0;
                    }

                    processedItem[key] = {
                        value: cleanValue,
                        label: value.label,
                        normalizedLabel: value.normalizedLabel,
                        confidence: value.confidence
                    };
                }
            }

            return processedItem;
        })

    return processed;
}

function extractInvoiceData(textractResponse) {
    const invoiceData = {
        summary: {},
        lineItems: []
    };

    if (!textractResponse.ExpenseDocuments || textractResponse.ExpenseDocuments.length === 0) {
        return invoiceData;
    }

    // Process each page of the invoice
    textractResponse.ExpenseDocuments.forEach(expenseDoc => {
        // Extract summary fields (vendor, invoice number, date, total, etc.)
        if (expenseDoc.SummaryFields) {
            expenseDoc.SummaryFields.forEach(field => {
                const fieldType = field.Type?.Text || '';
                const fieldValue = field.ValueDetection?.Text || '';
                const fieldLabel = field.LabelDetection?.Text || '';
                const confidence = field.ValueDetection?.Confidence || 0;

                // Map common invoice fields
                if (fieldType && fieldValue) {
                    invoiceData.summary[fieldType] = {
                        value: fieldValue,
                        label: fieldLabel,
                        normalizedLabel: normalizeLabelName(fieldLabel),
                        confidence: confidence
                    };
                }
            });
        }

        // Extract line items
        if (expenseDoc.LineItemGroups) {
            expenseDoc.LineItemGroups.forEach(lineItemGroup => {
                if (lineItemGroup.LineItems) {
                    lineItemGroup.LineItems.forEach(lineItem => {
                        const item = {};
                        const fieldNameCounts = {}; // Track field name occurrences

                        if (lineItem.LineItemExpenseFields) {
                            lineItem.LineItemExpenseFields.forEach(field => {
                                const fieldType = field.Type?.Text || '';
                                const fieldValue = field.ValueDetection?.Text || '';
                                const fieldLabel = field.LabelDetection?.Text || '';
                                const confidence = field.ValueDetection?.Confidence || 0;

                                if (fieldType && fieldValue) {
                                    // Normalize field names
                                    let normalizedField = normalizeFieldName(fieldType);

                                    // Ensure uniqueness by appending a counter if the field already exists
                                    if (Object.prototype.hasOwnProperty.call(item, normalizedField)) {
                                        fieldNameCounts[normalizedField] = (fieldNameCounts[normalizedField] || 1) + 1;
                                        normalizedField = `${normalizedField}_${fieldNameCounts[normalizedField]}`;
                                    }

                                    item[normalizedField] = {
                                        value: fieldValue,
                                        label: fieldLabel,
                                        normalizedLabel: normalizeLabelName(fieldLabel),
                                        confidence: confidence
                                    };
                                }
                            });
                        }

                        if (Object.keys(item).length > 0) {
                            invoiceData.lineItems.push(item);
                        }
                    });
                }
            });
        }
    });

    return invoiceData;
}

module.exports = {
    extractInvoiceData,
    processScanData,
    standardizedFieldsnames
}