/**
 * invoice-modal.js — Invoice create/edit modal
 * Uses shared item-editor for accordion items
 * 
 * Features:
 * - Auto-sets tax-exempt based on customer's taxable flag
 * - Recurring invoice support (monthly/yearly)
 */
import { addItem, getItems, resetItemCounter } from '../utils/item-editor.js';
import { setDefaultDate, showSpinner, hideSpinner } from '../utils/helpers.js';
import '../utils/api.js';

let currentInvoiceId = null;
let qboLaborRate = null;
let workerList = [];

export async function loadWorkers() {
    try {
        const result = await window.API.settings.get('invoice_workers');
        if (result && result.value) {
            workerList = result.value.split(',').map(w => w.trim()).filter(Boolean);
        } else {
            workerList = [];
        }
        populateWorkerDropdown();
        console.log(`👷 ${workerList.length} Bearbeiter geladen`);
    } catch (e) {
        console.log('Worker-Liste konnte nicht geladen werden.');
    }
}

function populateWorkerDropdown() {
    const sel = document.getElementById('invoice-worker');
    if (!sel) return;
    const current = sel.value;
    sel.innerHTML = `<option value="">— None —</option>` +
        workerList.map(w => `<option value="${w}">${w}</option>`).join('');
    if (current) sel.value = current;
}

export async function loadLaborRate() {
    try {
        const response = await fetch('/api/qbo/labor-rate');
        const data = await response.json();
        if (data.rate) {
            qboLaborRate = data.rate;
            console.log(`💰 Labor Rate geladen: $${qboLaborRate}`);
        }
    } catch (e) {
        console.log('Labor Rate konnte nicht geladen werden.');
    }
}

export function getLaborRate() { return qboLaborRate; }

/**
 * Auto-set tax exempt based on customer's taxable flag
 */
function applyCustomerTaxStatus(customerId) {
    const allCust = window.getCustomers ? window.getCustomers() : (window.customers || []);
    const customer = allCust.find(c => c.id === parseInt(customerId));
    if (customer) {
        const cb = document.getElementById('invoice-tax-exempt');
        if (cb) {
            cb.checked = (customer.taxable === false);
            updateInvoiceTotals();
        }
    }
}

// ────────────────────────────────────────────────────────────────────
// Customer Credit
//
// Das Guthaben selbst wird in QBO gefuehrt (negativer A/R-Saldo). Die App
// merkt sich nur, welcher Betrag auf DIESER Rechnung ausgewiesen wird, damit
// der Kunde den Endbetrag nachvollziehen kann. Subtotal, Tax und Total bleiben
// unberuehrt — ein Guthaben ist eine Zahlungsverrechnung, kein Rabatt.
// ────────────────────────────────────────────────────────────────────

/** Guthaben des aktuell gewaehlten Kunden laut QBO (null = noch nicht geprueft). */
let availableCredit = null;

function creditEls() {
    return {
        banner:  document.getElementById('invoice-credit-banner'),
        text:    document.getElementById('invoice-credit-available-text'),
        fields:  document.getElementById('invoice-credit-fields'),
        amount:  document.getElementById('invoice-credit-applied'),
        memo:    document.getElementById('invoice-credit-memo'),
        balance: document.getElementById('invoice-balance-due')
    };
}

/** Betrag im Guthabenfeld — 0, wenn leer oder ungueltig. */
function appliedCredit() {
    const el = document.getElementById('invoice-credit-applied');
    const n = parseFloat(el?.value);
    return isFinite(n) && n > 0 ? n : 0;
}

function resetCreditUi() {
    availableCredit = null;
    const e = creditEls();
    if (e.banner) e.banner.classList.add('hidden');
    if (e.fields) e.fields.style.display = 'none';
    if (e.amount) e.amount.value = '0';
    if (e.memo)   e.memo.value = '';
}

/**
 * Fragt QBO nach Guthaben des gewaehlten Kunden. Fehler bleiben stumm: ein
 * nicht erreichbares QBO darf das Anlegen einer Rechnung nicht blockieren.
 */
async function checkCustomerCredit(customerId) {
    availableCredit = null;
    const e = creditEls();
    if (e.banner) e.banner.classList.add('hidden');
    if (!customerId) return;

    try {
        const credits = await window.API.accounting.getCustomerCredits();
        if (!Array.isArray(credits)) return;
        const match = credits.find(c => c.customerId === parseInt(customerId));
        if (!match || !(match.credit > 0)) return;

        availableCredit = match.credit;
        if (e.text) e.text.textContent =
            `${match.name} has a credit of $${match.credit.toFixed(2)} on account.`;
        if (e.banner) e.banner.classList.remove('hidden');
    } catch (err) {
        console.log('Customer credit check skipped:', err.message);
    }
}

/** Uebernimmt das Guthaben in die Rechnung — gedeckelt auf das Rechnungstotal. */
export function applyCustomerCredit() {
    if (!(availableCredit > 0)) return;
    const e = creditEls();
    const total = currentInvoiceTotal();
    const value = Math.min(availableCredit, total);

    if (value <= 0) {
        alert('Please add items first — a credit can only be applied to an invoice amount.');
        return;
    }
    if (e.fields) e.fields.style.display = 'block';
    if (e.amount) e.amount.value = value.toFixed(2);
    if (e.memo && !e.memo.value) e.memo.value = 'Credit on account';
    if (value < availableCredit) {
        alert(`Only $${value.toFixed(2)} of the $${availableCredit.toFixed(2)} credit fits on this invoice. `
            + 'The remainder stays on account in QBO.');
    }
    updateInvoiceTotals();
}

export function clearCustomerCredit() {
    const e = creditEls();
    if (e.amount) e.amount.value = '0';
    if (e.memo)   e.memo.value = '';
    if (e.fields) e.fields.style.display = 'none';
    updateInvoiceTotals();
}

function currentInvoiceTotal() {
    const items = getItems('invoice-items');
    const taxExempt = document.getElementById('invoice-tax-exempt')?.checked;
    let subtotal = 0;
    items.forEach(item => {
        subtotal += parseFloat(String(item.amount).replace(/[$,]/g, '')) || 0;
    });
    return subtotal + (taxExempt ? 0 : subtotal * 8.25 / 100);
}

function updateRecurringChildUi(invoice = null) {
    const recurringCb = document.getElementById('invoice-recurring');
    if (!recurringCb) return;

    const recurringWrapper = recurringCb.closest('label') || recurringCb.parentElement;
    if (!recurringWrapper) return;

    let labelText = document.getElementById('invoice-recurring-label-text');
    let childBadge = document.getElementById('invoice-recurring-child-badge');
    let childNote = document.getElementById('invoice-recurring-child-note');

    // Find or create a stable label span
    if (!labelText) {
        // Prefer an existing span/text element containing "Recurring"
        const existingTextElement = Array.from(recurringWrapper.children).find(el =>
            el !== recurringCb &&
            el.id !== 'invoice-recurring-child-badge' &&
            el.textContent &&
            el.textContent.trim() === 'Recurring'
        );

        if (existingTextElement) {
            existingTextElement.id = 'invoice-recurring-label-text';
            labelText = existingTextElement;
        } else {
            // Fallback: try to replace a raw text node
            const textNode = Array.from(recurringWrapper.childNodes).find(node =>
                node.nodeType === Node.TEXT_NODE &&
                node.textContent.trim().includes('Recurring')
            );

            if (textNode) {
                const span = document.createElement('span');
                span.id = 'invoice-recurring-label-text';
                span.textContent = 'Recurring';
                recurringWrapper.replaceChild(span, textNode);
                labelText = span;
            } else {
                // Final fallback: create label text after checkbox
                labelText = document.createElement('span');
                labelText.id = 'invoice-recurring-label-text';
                labelText.textContent = 'Recurring';
                labelText.className = 'ml-2';

                if (recurringCb.nextSibling) {
                    recurringWrapper.insertBefore(labelText, recurringCb.nextSibling);
                } else {
                    recurringWrapper.appendChild(labelText);
                }
            }
        }
    }

    if (!childBadge) {
        childBadge = document.createElement('span');
        childBadge.id = 'invoice-recurring-child-badge';
        childBadge.className = 'ml-2 inline-flex items-center px-2 py-0.5 rounded-full text-xs font-semibold bg-yellow-100 text-yellow-800 hidden';
        childBadge.textContent = 'Child invoice';
        recurringWrapper.appendChild(childBadge);
    }

    if (!childNote) {
        childNote = document.createElement('div');
        childNote.id = 'invoice-recurring-child-note';
        childNote.className = 'mt-1 ml-8 text-xs text-gray-500 hidden';

        const parent = recurringWrapper.parentElement || recurringWrapper;
        parent.appendChild(childNote);
    }

    const isChild = !!invoice?.recurring_source_id;

    if (isChild) {
        labelText.textContent = 'Recurring child invoice';
        childBadge.classList.remove('hidden');

        const sourceNumber =
            invoice.recurring_source_invoice_number ||
            invoice.source_invoice_number ||
            invoice.recurring_source_id;

        childNote.textContent =
            `This invoice was generated from recurring invoice #${sourceNumber} and will not create further recurring invoices.`;

        childNote.classList.remove('hidden');
    } else {
        labelText.textContent = 'Recurring';
        childBadge.classList.add('hidden');
        childNote.classList.add('hidden');
        childNote.textContent = '';
    }
}

export async function openInvoiceModal(invoiceId = null) {
    currentInvoiceId = invoiceId;
    if (invoiceId) {
        await loadInvoiceForEdit(invoiceId);
    } else {
        prepareNewInvoice();
    }
    document.getElementById('invoice-modal').classList.add('active');
}

export function closeInvoiceModal() {
    document.getElementById('invoice-modal').classList.remove('active');
    currentInvoiceId = null;
}

async function loadInvoiceForEdit(invoiceId) {
    document.getElementById('invoice-modal-title').textContent = 'Edit Invoice';
    const response = await fetch(`/api/invoices/${invoiceId}`);
    const data = await response.json();

    // Set customer in Alpine component
    const allCust = window.getCustomers ? window.getCustomers() : (window.customers || []);
    const customer = allCust.find(c => c.id === data.invoice.customer_id);
    if (customer) {
        const customerInput = document.querySelector('#invoice-modal input[placeholder="Search customer..."]');
        if (customerInput) {
            customerInput.value = customer.name;
            customerInput.dispatchEvent(new Event('input'));
            const alpineData = Alpine.$data(customerInput.closest('[x-data]'));
            if (alpineData) {
                alpineData.search = customer.name;
                alpineData.selectedId = customer.id;
                alpineData.selectedName = customer.name;
            }
        }
    }

    document.getElementById('invoice-number').value = data.invoice.invoice_number || '';
    document.getElementById('invoice-customer').value = data.invoice.customer_id;
    document.getElementById('invoice-date').value = data.invoice.invoice_date.split('T')[0];
    document.getElementById('invoice-terms').value = data.invoice.terms;
    document.getElementById('invoice-authorization').value = data.invoice.auth_code || '';
    document.getElementById('invoice-tax-exempt').checked = data.invoice.tax_exempt;
    document.getElementById('invoice-bill-to-name').value = data.invoice.bill_to_name || '';

    // Guthaben einer bestehenden Rechnung wiederherstellen
    resetCreditUi();
    const savedCredit = parseFloat(data.invoice.credit_applied) || 0;
    if (savedCredit > 0) {
        const ce = creditEls();
        if (ce.fields) ce.fields.style.display = 'block';
        if (ce.amount) ce.amount.value = savedCredit.toFixed(2);
        if (ce.memo)   ce.memo.value = data.invoice.credit_memo || '';
    }
    checkCustomerCredit(data.invoice.customer_id);
    
    // Worker
    populateWorkerDropdown();
    const workerEl = document.getElementById('invoice-worker');
    if (workerEl) workerEl.value = data.invoice.worker || '';

    const sendDateEl = document.getElementById('invoice-send-date');
    if (sendDateEl) {
        sendDateEl.value = data.invoice.scheduled_send_date
            ? data.invoice.scheduled_send_date.split('T')[0] : '';
    }

    // Recurring fields
    const recurringCb = document.getElementById('invoice-recurring');
    const recurringInterval = document.getElementById('invoice-recurring-interval');
    const recurringGroup = document.getElementById('invoice-recurring-group');
    if (recurringCb) {
        const isGeneratedRecurringChild = !!data.invoice.recurring_source_id;
        const canBeRecurringMaster = !isGeneratedRecurringChild;

        recurringCb.checked = canBeRecurringMaster && (data.invoice.is_recurring || false);
        recurringCb.disabled = !canBeRecurringMaster;

        if (recurringInterval) {
            recurringInterval.value = data.invoice.recurring_interval || 'monthly';
            recurringInterval.disabled = !canBeRecurringMaster;
        }

        if (recurringGroup) {
            recurringGroup.style.display = recurringCb.checked ? 'block' : 'none';
        }

        // Make recurring child invoices obvious in the UI
        updateRecurringChildUi(data.invoice);
    }

    // Load items
    document.getElementById('invoice-items').innerHTML = '';
    resetItemCounter();
    data.items.forEach(item => {
        addItem('invoice-items', { item, type: 'invoice', laborRate: qboLaborRate, onUpdate: updateInvoiceTotals });
    });
    updateInvoiceTotals();
}

function prepareNewInvoice() {
    document.getElementById('invoice-modal-title').textContent = 'New Invoice';
    document.getElementById('invoice-form').reset();
    document.getElementById('invoice-items').innerHTML = '';
    resetCreditUi();
    document.getElementById('invoice-terms').value = 'Net 14';
    document.getElementById('invoice-number').value = '';
    document.getElementById('invoice-send-date').value = '';
    
    // Worker zurücksetzen
    populateWorkerDropdown();
    const workerEl = document.getElementById('invoice-worker');
    if (workerEl) workerEl.value = '';
    
    // Reset recurring
    const recurringCb = document.getElementById('invoice-recurring');
    const recurringGroup = document.getElementById('invoice-recurring-group');
    if (recurringCb) recurringCb.checked = false;
    if (recurringGroup) recurringGroup.style.display = 'none';
    
    const recurringInterval = document.getElementById('invoice-recurring-interval');
    if (recurringCb) recurringCb.disabled = false;
    if (recurringInterval) recurringInterval.disabled = false;
    updateRecurringChildUi(null);

    resetItemCounter();
    setDefaultDate();
    addItem('invoice-items', { type: 'invoice', laborRate: qboLaborRate, onUpdate: updateInvoiceTotals });
}

export function addInvoiceItem(item = null) {
    addItem('invoice-items', { item, type: 'invoice', laborRate: qboLaborRate, onUpdate: updateInvoiceTotals });
}

export function updateInvoiceTotals() {
    const items = getItems('invoice-items');
    const taxExempt = document.getElementById('invoice-tax-exempt').checked;
    let subtotal = 0;
    items.forEach(item => {
        const amount = parseFloat(item.amount.replace(/[$,]/g, '')) || 0;
        subtotal += amount;
    });
    const taxAmount = taxExempt ? 0 : (subtotal * 8.25 / 100);
    const total = subtotal + taxAmount;
    document.getElementById('invoice-subtotal').textContent = `$${subtotal.toFixed(2)}`;
    document.getElementById('invoice-tax').textContent = taxExempt ? '$0.00' : `$${taxAmount.toFixed(2)}`;
    document.getElementById('invoice-total').textContent = `$${total.toFixed(2)}`;
    document.getElementById('invoice-tax-row').style.display = taxExempt ? 'none' : 'block';

    // Guthabenzeile: Betrag nie ueber dem Total, sonst waere die Balance Due negativ.
    const credit = appliedCredit();
    const e = creditEls();
    if (credit > 0) {
        if (credit > total && e.amount) e.amount.value = total.toFixed(2);
        const applied = Math.min(credit, total);
        if (e.fields) e.fields.style.display = 'block';
        if (e.balance) e.balance.textContent = `$${(total - applied).toFixed(2)}`;
    } else if (e.fields) {
        e.fields.style.display = 'none';
    }
}

export async function handleInvoiceSubmit(e) {
    e.preventDefault();
    const isRecurring = document.getElementById('invoice-recurring')?.checked || false;
    const recurringInterval = isRecurring
        ? (document.getElementById('invoice-recurring-interval')?.value || 'monthly') : null;

    const data = {
        invoice_number: document.getElementById('invoice-number').value || null,
        customer_id: document.getElementById('invoice-customer').value,
        invoice_date: document.getElementById('invoice-date').value,
        terms: document.getElementById('invoice-terms').value,
        auth_code: document.getElementById('invoice-authorization').value,
        tax_exempt: document.getElementById('invoice-tax-exempt').checked,
        scheduled_send_date: document.getElementById('invoice-send-date')?.value || null,
        bill_to_name: document.getElementById('invoice-bill-to-name')?.value || null,
        worker: document.getElementById('invoice-worker')?.value || null,
        is_recurring: isRecurring,
        recurring_interval: recurringInterval,
        credit_applied: appliedCredit(),
        credit_memo: document.getElementById('invoice-credit-memo')?.value?.trim() || null,
        items: getItems('invoice-items')
    };

    if (!data.customer_id) { alert('Please select a customer.'); return; }
    if (!data.items || data.items.length === 0) { alert('Please add at least one item.'); return; }

    const invoiceId = currentInvoiceId;
    const url = invoiceId ? `/api/invoices/${invoiceId}` : '/api/invoices';
    const method = invoiceId ? 'PUT' : 'POST';
    showSpinner(invoiceId ? 'Saving invoice & syncing QBO...' : 'Creating invoice & exporting to QBO...');

    try {
        const response = await fetch(url, { method, headers: { 'Content-Type': 'application/json' }, body: JSON.stringify(data) });
        const result = await response.json();
        if (response.ok) {
            closeInvoiceModal();
            if (result.qbo_doc_number) console.log(`✅ Invoice saved & exported to QBO: #${result.qbo_doc_number}`);
            else if (result.qbo_synced) console.log('✅ Invoice saved & synced to QBO');
            else console.log('✅ Invoice saved locally (QBO sync pending)');
            if (window.invoiceView) window.invoiceView.loadInvoices();
        } else {
            alert(`Error: ${result.error}`);
        }
    } catch (error) {
        console.error('Error:', error);
        alert('Error saving invoice');
    } finally {
        hideSpinner();
    }
}

export function initInvoiceModal() {
    const form = document.getElementById('invoice-form');
    if (form) form.addEventListener('submit', handleInvoiceSubmit);
    
    loadWorkers();   // Bearbeiterliste laden
    
    const taxExempt = document.getElementById('invoice-tax-exempt');
    if (taxExempt) taxExempt.addEventListener('change', updateInvoiceTotals);

    const creditAmount = document.getElementById('invoice-credit-applied');
    if (creditAmount) creditAmount.addEventListener('input', updateInvoiceTotals);

    // Recurring toggle
    const recurringCb = document.getElementById('invoice-recurring');
    const recurringGroup = document.getElementById('invoice-recurring-group');
    if (recurringCb && recurringGroup) {
        recurringCb.addEventListener('change', () => {
            recurringGroup.style.display = recurringCb.checked ? 'block' : 'none';
        });
    }

    // Watch for customer selection → auto-set tax exempt (only for new invoices)
    const customerHidden = document.getElementById('invoice-customer');
    if (customerHidden) {
        const observer = new MutationObserver(() => {
            // Only auto-apply when creating new (not editing existing)
            if (!currentInvoiceId && customerHidden.value) {
                applyCustomerTaxStatus(customerHidden.value);
                checkCustomerCredit(customerHidden.value);
            }
        });
        observer.observe(customerHidden, { attributes: true, attributeFilter: ['value'] });
    }
}

window.invoiceModal = {
    applyCustomerCredit,
    clearCustomerCredit
};
window.openInvoiceModal = openInvoiceModal;
window.closeInvoiceModal = closeInvoiceModal;
window.addInvoiceItem = addInvoiceItem;
window.reloadInvoiceWorkers = loadWorkers;