import { apiGet, apiPost, apiDelete } from '../api.js';
import { showToast } from '../app.js';
import { isDevTestClientCode, testDataRowClassForClient } from '../test-data.js';

const PAGE_SIZE = 50;

let clientsList = [];
let coachesList = [];
let filterSearch = '';
let filterTestData = '';
let page = 0;

export async function clientsPage() {
    const app = document.getElementById('app');

    app.innerHTML = `
        <div class="page-header">
            <h1>Clients</h1>
            <div class="actions">
                <button class="btn btn-primary" id="showCreateFormBtn">+ Create Client</button>
            </div>
        </div>
        <div id="createClientWrapper" style="display:none"></div>
        <div id="clientsContent"><div class="spinner"></div></div>
    `;

    document.getElementById('showCreateFormBtn').addEventListener('click', () => {
        const wrapper = document.getElementById('createClientWrapper');
        if (wrapper.style.display === 'none') {
            showCreateForm();
        } else {
            hideCreateForm();
        }
    });

    await loadClients();
}

async function loadClients() {
    try {
        const [clientsData, assignData] = await Promise.all([
            apiGet('clients.php'),
            apiGet('assignments.php'),
        ]);
        clientsList = clientsData.clients || [];
        coachesList = assignData.coaches || [];
        renderClients();
    } catch (e) {
        showToast(e.message, 'error');
        document.getElementById('clientsContent').innerHTML =
            `<p class="error-text" style="padding:16px">${esc(e.message)}</p>`;
    }
}

function renderClients() {
    const container = document.getElementById('clientsContent');

    if (!clientsList.length) {
        container.innerHTML = `
            <div class="card">
                <div class="empty-state">
                    <h3>No clients found</h3>
                    <p>Create the first client above.</p>
                </div>
            </div>`;
        return;
    }

    container.innerHTML = `
        <div class="card">
            <div class="filter-bar">
                <input type="search" id="clientListSearch" class="filter-search" placeholder="Search client code…" value="${esc(filterSearch)}">
                <select id="clientTestFilter">
                    <option value="">All clients</option>
                    <option value="test" ${filterTestData === 'test' ? 'selected' : ''}>Test data only</option>
                    <option value="hide-test" ${filterTestData === 'hide-test' ? 'selected' : ''}>Hide test data</option>
                </select>
                <span class="data-toolbar-hint" id="clientListCount"></span>
            </div>
            <div class="table-wrapper">
                <table class="data-table">
                    <thead>
                        <tr>
                            <th>Client Code</th>
                            <th>Current Coach</th>
                            <th>Actions</th>
                        </tr>
                    </thead>
                    <tbody id="clientsTableBody"></tbody>
                </table>
            </div>
            <div class="pagination-bar" id="clientsPagination"></div>
        </div>`;

    document.getElementById('clientListSearch').addEventListener('input', (e) => {
        filterSearch = e.target.value.trim();
        page = 0;
        renderClientTableBody();
    });
    document.getElementById('clientTestFilter').addEventListener('change', (e) => {
        filterTestData = e.target.value;
        page = 0;
        renderClientTableBody();
    });

    renderClientTableBody();
}

function getFilteredClientsList() {
    let list = clientsList;
    if (filterSearch) {
        const q = filterSearch.toLowerCase();
        list = list.filter(c => (c.clientCode || '').toLowerCase().includes(q));
    }
    if (filterTestData === 'test') {
        list = list.filter(c => isDevTestClientCode(c.clientCode));
    } else if (filterTestData === 'hide-test') {
        list = list.filter(c => !isDevTestClientCode(c.clientCode));
    }
    return list;
}

function renderClientTableBody() {
    const body = document.getElementById('clientsTableBody');
    const countEl = document.getElementById('clientListCount');
    const filtered = getFilteredClientsList();
    const totalPages = Math.max(1, Math.ceil(filtered.length / PAGE_SIZE));
    if (page >= totalPages) page = totalPages - 1;
    const slice = filtered.slice(page * PAGE_SIZE, (page + 1) * PAGE_SIZE);

    if (countEl) {
        countEl.textContent = `${filtered.length} client${filtered.length === 1 ? '' : 's'}`;
    }

    if (!slice.length) {
        body.innerHTML = `<tr><td colspan="3" style="text-align:center;color:var(--text-secondary);padding:24px">No clients match</td></tr>`;
    } else {
        body.innerHTML = slice.map(c => clientRowHTML(c)).join('');
        body.querySelectorAll('.delete-client-btn').forEach(btn => {
            btn.addEventListener('click', () => deleteClient(btn.dataset.code));
        });
    }

    const pag = document.getElementById('clientsPagination');
    if (!pag) return;
    if (filtered.length <= PAGE_SIZE) {
        pag.innerHTML = '';
        return;
    }
    const from = page * PAGE_SIZE + 1;
    const to = Math.min((page + 1) * PAGE_SIZE, filtered.length);
    pag.innerHTML = `
        <button type="button" class="btn btn-sm" id="clientsPagePrev" ${page <= 0 ? 'disabled' : ''}>Prev</button>
        <span>Rows ${from}–${to} of ${filtered.length}</span>
        <button type="button" class="btn btn-sm" id="clientsPageNext" ${page >= totalPages - 1 ? 'disabled' : ''}>Next</button>
    `;
    document.getElementById('clientsPagePrev')?.addEventListener('click', () => { page--; renderClientTableBody(); });
    document.getElementById('clientsPageNext')?.addEventListener('click', () => { page++; renderClientTableBody(); });
}

function clientRowHTML(c) {
    const coach = c.coachUsername
        ? `<strong>${esc(c.coachUsername)}</strong>`
        : `<span style="color:var(--text-secondary);font-style:italic">Unassigned</span>`;

    return `
        <tr class="${testDataRowClassForClient(c.clientCode).trim()}">
            <td><strong>${esc(c.clientCode)}</strong></td>
            <td>${coach}</td>
            <td>
                <button class="btn btn-sm btn-danger delete-client-btn" data-code="${esc(c.clientCode)}">Delete</button>
            </td>
        </tr>`;
}

async function deleteClient(clientCode) {
    if (!confirm(`Delete client "${clientCode}"? This will also remove all their answers and results. This cannot be undone.`)) return;
    try {
        await apiDelete('clients.php', { clientCode });
        clientsList = clientsList.filter(c => c.clientCode !== clientCode);
        showToast(`Client "${clientCode}" deleted`, 'success');
        if (!clientsList.length) renderClients();
        else renderClientTableBody();
    } catch (e) {
        showToast(e.message, 'error');
    }
}

function showCreateForm() {
    if (!coachesList.length) {
        showToast('No coaches available. Create a coach first.', 'error');
        return;
    }

    const wrapper = document.getElementById('createClientWrapper');
    wrapper.style.display = '';
    wrapper.innerHTML = `
        <div class="inline-form-card" style="margin-bottom:20px">
            <h4>Create New Client</h4>
            <div class="form-row">
                <div class="form-group" style="flex:2">
                    <label>Client Code</label>
                    <input type="text" id="cc_code" autocomplete="off" placeholder="Enter unique client code">
                </div>
                <div class="form-group" style="flex:2">
                    <label>Assign to Coach</label>
                    <select id="cc_coach">
                        <option value="">— select coach —</option>
                        ${coachesList.map(c =>
                            `<option value="${c.coachID}">${esc(c.username)}${c.supervisorUsername ? ` (${esc(c.supervisorUsername)})` : ''}</option>`
                        ).join('')}
                    </select>
                </div>
            </div>
            <div style="display:flex;gap:8px">
                <button class="btn btn-primary btn-sm" id="cc_submit">Create Client</button>
                <button class="btn btn-sm" id="cc_cancel">Cancel</button>
            </div>
            <p id="cc_error" class="error-text" style="display:none;margin-top:8px"></p>
        </div>
    `;

    const input = document.getElementById('cc_code');
    input.focus();
    wrapper.querySelectorAll('input').forEach(inp => {
        inp.addEventListener('keydown', (e) => {
            if (e.key === 'Enter') submitCreateClient();
            if (e.key === 'Escape') hideCreateForm();
        });
    });

    document.getElementById('cc_submit').addEventListener('click', submitCreateClient);
    document.getElementById('cc_cancel').addEventListener('click', hideCreateForm);
}

function hideCreateForm() {
    const wrapper = document.getElementById('createClientWrapper');
    if (wrapper) { wrapper.style.display = 'none'; wrapper.innerHTML = ''; }
}

async function submitCreateClient() {
    const errEl = document.getElementById('cc_error');
    errEl.style.display = 'none';

    const clientCode = document.getElementById('cc_code').value.trim();
    const coachID    = document.getElementById('cc_coach').value;

    if (!clientCode) { showError(errEl, 'Client code is required'); return; }
    if (!coachID)    { showError(errEl, 'Please select a coach'); return; }

    const btn = document.getElementById('cc_submit');
    btn.disabled = true;
    btn.textContent = 'Creating...';

    try {
        const data = await apiPost('clients.php', { clientCode, coachID });
        const coach = coachesList.find(c => c.coachID === coachID);
        clientsList.push({
            clientCode:   data.clientCode,
            coachID:      coachID,
            coachUsername: coach?.username ?? null,
        });
        showToast(`Client "${data.clientCode}" created`, 'success');
        hideCreateForm();
        renderClients();
    } catch (e) {
        showError(errEl, e.message);
        btn.disabled = false;
        btn.textContent = 'Create Client';
    }
}

function showError(el, msg) {
    el.textContent = msg;
    el.style.display = '';
}

function esc(s) {
    const d = document.createElement('div');
    d.textContent = s ?? '';
    return d.innerHTML;
}