const form = document.getElementById('device-settings-form');
const saveButton = document.getElementById('device-settings-save');
const message = document.getElementById('device-settings-message');
const configVersion = document.getElementById('config-version');
const avatarPreview = document.getElementById('avatar-preview');
const previewCaption = document.getElementById('preview-caption');

const fields = {
    owner_name: document.getElementById('owner_name'),
    car_model: document.getElementById('car_model'),
    device_name: document.getElementById('device_name'),
    avatar_path: document.getElementById('avatar_path'),
};

let initialState = null;

function showMessage(text, kind) {
    message.className = `alert alert-${kind}`;
    message.textContent = text;
    message.hidden = false;
}

function hideMessage() {
    message.hidden = true;
}

function currentState() {
    return {
        owner_name: fields.owner_name.value.trim(),
        car_model: fields.car_model.value.trim(),
        device_name: fields.device_name.value.trim(),
        avatar_path: fields.avatar_path.value.trim(),
    };
}

function avatarUrl(path) {
    if (!path) return '/static/img/yaris.png';
    if (/^https?:\/\//.test(path)) return path;
    return `/static/${path.replace(/^\/+/, '')}`;
}

function updatePreview() {
    const state = currentState();
    avatarPreview.src = avatarUrl(state.avatar_path);
    previewCaption.textContent = state.owner_name && state.car_model
        ? `${state.owner_name} • ${state.car_model}`
        : 'Preview updates as you type.';
}

function updateDirtyState() {
    if (!initialState) {
        saveButton.disabled = true;
        return;
    }
    saveButton.disabled = JSON.stringify(currentState()) === JSON.stringify(initialState);
}

function populate(config) {
    fields.owner_name.value = config.owner_name || '';
    fields.car_model.value = config.car_model || '';
    fields.device_name.value = config.device_name || '';
    fields.avatar_path.value = config.avatar_path || '';
    configVersion.textContent = config.config_version ?? '—';
    initialState = currentState();
    updatePreview();
    updateDirtyState();
}

async function loadConfig() {
    try {
        const response = await fetch('/api/v1/portal/device-config');
        const payload = await response.json();
        if (!response.ok) {
            throw new Error(payload.error || 'Could not load device config.');
        }
        populate(payload);
    } catch (error) {
        showMessage(error.message, 'danger');
    }
}

async function saveConfig(event) {
    event.preventDefault();
    hideMessage();
    saveButton.disabled = true;

    try {
        const response = await fetch('/api/device-config', {
            method: 'POST',
            headers: { 'Content-Type': 'application/json' },
            body: JSON.stringify(currentState()),
        });
        const payload = await response.json();
        if (!response.ok) {
            const detail = payload.fields
                ? Object.values(payload.fields).join(' ')
                : (payload.error || 'Could not save device config.');
            throw new Error(detail);
        }
        populate(payload);
        showMessage('Device settings saved. The Pi will pick them up on its next sync.', 'success');
    } catch (error) {
        showMessage(error.message, 'danger');
        updateDirtyState();
    }
}

for (const field of Object.values(fields)) {
    field.addEventListener('input', () => {
        hideMessage();
        updatePreview();
        updateDirtyState();
    });
}

avatarPreview.addEventListener('error', () => {
    previewCaption.textContent = 'Preview image not found on the server static path.';
});

form.addEventListener('submit', saveConfig);
loadConfig();