const {addCreateDocumentOption} = require('../render-utils/add-create-document-option');
const {renderWithVisibility} = require('../render-utils/visibility');
const {wrapReplacementStrings} = require('../render-utils/replacement-strings');
const {html} = require('../render-utils/tagged-template-fns');

function renderTransistorNode(node, options = {}) {
    addCreateDocumentOption(options);
    const document = options.createDocument();

    if (options.target === 'email') {
        return emailTemplate(node, document, options);
    }
    return frontendTemplate(node, document, options);
}

function setIframeAttributes(iframe) {
    iframe.setAttribute('width', '100%');
    iframe.setAttribute('height', '370');
    iframe.setAttribute('frameborder', 'no');
    iframe.setAttribute('scrolling', 'no');
    iframe.setAttribute('seamless', '');
}

function frontendTemplate(node, document, options) {
    const figure = document.createElement('figure');
    figure.setAttribute('class', 'kg-card kg-transistor-card');

    // Use {uuid} placeholder - content.js will substitute with member UUID at request time
    const embedUrl = new URL(`https://partner.transistor.fm/ghost/embed/{uuid}`);

    if (options.siteUuid) {
        embedUrl.searchParams.set('ctx', options.siteUuid);
    }

    const iframe = document.createElement('iframe');
    setIframeAttributes(iframe);
    iframe.setAttribute('title', 'Transistor podcasts');
    iframe.setAttribute('data-src', embedUrl.toString());
    iframe.setAttribute('data-kg-transistor-embed', '');
    figure.appendChild(iframe);

    // Use innerHTML to inject script - jsdom's createElement('script') doesn't serialize textContent in outerHTML
    // Matches implementation from kg-default-nodes set-src-background-from-parent.js
    figure.insertAdjacentHTML('beforeend', buildEmbedScript());

    // noscript fallback with src (not data-src) so the iframe loads without JS
    const noscript = document.createElement('noscript');
    const fallbackIframe = document.createElement('iframe');
    setIframeAttributes(fallbackIframe);
    fallbackIframe.setAttribute('src', embedUrl.toString());
    noscript.appendChild(fallbackIframe);
    figure.appendChild(noscript);

    return renderWithVisibility({element: figure, type: 'inner'}, node.visibility, options);
}

function emailTemplate(node, document, options) {
    // Use the site accent color from the newsletter/email design settings
    const accentColor = options.design?.accentColor || '#15171A';

    // Use {uuid} replacement string - wrapReplacementStrings converts this to %%{uuid}%%
    // which gets replaced with actual member UUID when email is sent to each recipient
    const transistorUrl = 'https://partner.transistor.fm/ghost/{uuid}';

    const cardHtml = html`
        <table class="kg-card kg-transistor-card" cellspacing="0" cellpadding="0" border="0" width="100%">
            <tr>
                <td style="padding: 24px; text-align: center;">
                    <table cellspacing="0" cellpadding="0" border="0" width="100%" style="text-align: center;">
                        <tr>
                            <td style="text-align: center; padding-bottom: 12px;">
                                <a href="${transistorUrl}" style="display: inline-block; width: 72px; height: 72px; padding-top: 4px; padding-right: 4px; padding-bottom: 4px; padding-left: 4px; border-radius: 8px; background-color: ${accentColor}">
                                    <img src="https://static.ghost.org/v6.0.0/images/transistor-logo-ondark.png"
                                        width="40" height="40"
                                        alt="Transistor"
                                        style="width: 40px; height: 40px; padding: 16px;">
                                </a>
                            </td>
                        </tr>
                        <tr>
                            <td style="text-align: center;">
                                <a href="${transistorUrl}" class="kg-transistor-title">
                                    Listen to your podcasts
                                </a>
                                <a href="${transistorUrl}"  class="kg-transistor-description">
                                    Subscribe and listen to your personal podcast feed in your favorite app.
                                </a>
                            </td>
                        </tr>
                    </table>
                </td>
            </tr>
        </table>
    `;

    const wrappedHtml = wrapReplacementStrings(cardHtml);

    const container = document.createElement('div');
    container.innerHTML = wrappedHtml;

    return renderWithVisibility({element: container.firstElementChild}, node.visibility, options);
}

function buildEmbedScript() {
    /* eslint-disable no-undef */
    // This function is serialized via .toString() and runs in the browser, not Node
    function initTransistorEmbed() {
        const script = document.currentScript;
        if (!script) {
            return;
        }

        const el = script.parentElement.querySelector('iframe[data-src]');
        if (!el) {
            return;
        }

        // Set src with background color detection
        const baseSrc = el.getAttribute('data-src');

        function colorToRgb(color) {
            const canvas = document.createElement('canvas');
            canvas.width = 1;
            canvas.height = 1;
            const ctx = canvas.getContext('2d');
            ctx.fillStyle = color;
            ctx.fillRect(0, 0, 1, 1);
            const [r, g, b, a] = ctx.getImageData(0, 0, 1, 1).data;
            return {r, g, b, a};
        }

        let node = el.parentElement;
        let bg;
        while (node) {
            bg = window.getComputedStyle(node).backgroundColor;
            if (bg && bg !== 'transparent') {
                const {a} = colorToRgb(bg);
                if (a > 0) {
                    break;
                }
            }
            node = node.parentElement;
        }

        if (!node || !bg || bg === 'transparent') {
            el.src = baseSrc;
        } else {
            const {r, g, b, a} = colorToRgb(bg);
            if (a === 0) {
                el.src = baseSrc;
            } else {
                const hex = [r, g, b].map(c => c.toString(16).padStart(2, '0')).join('');
                const u = new URL(baseSrc);
                u.searchParams.set('background', hex);
                el.src = u.toString();
            }
        }

        // Listen for resize messages from the Transistor iframe
        window.addEventListener('message', (event) => {
            const isMessageFromValidSource = (
                event.source === el.contentWindow &&
                event.origin === 'https://partner.transistor.fm'
            );
            if (!isMessageFromValidSource) {
                return;
            }

            const isDataValid = (
                !!event.data &&
                typeof event.data === 'object' &&
                !Array.isArray(event.data) &&
                'type' in event.data &&
                event.data.type === 'resize' &&
                'height' in event.data &&
                typeof event.data.height === 'number' &&
                Number.isSafeInteger(event.data.height) &&
                event.data.height >= 1
            );
            if (!isDataValid) {
                return;
            }

            el.style.height = event.data.height + 'px';
        });
    }
    /* eslint-enable no-undef */

    return `<script>(${initTransistorEmbed.toString()})()</script>`;
}

module.exports = renderTransistorNode;
