/**
 * GoingsOn - "What's New" after-update dialog
 *
 * After an OTA update applies and the app relaunches on the new version, this
 * surfaces the matching CHANGELOG.md section once, so beta testers see what
 * changed at the moment they hit the update. Shown at most once per version;
 * the first-ever launch is owned by the welcome flow, not this dialog.
 */
(function() {
    'use strict';

    const LAST_VERSION_KEY = 'go-last-version';

    /**
     * Pull the body of a single version's section out of a Keep a Changelog
     * document. Matches the `## [<version>]` header and collects every line up
     * to the next `## [` header. Returns '' when the version isn't present.
     */
    function extractSection(markdown, version) {
        const lines = String(markdown).split('\n');
        const body = [];
        let inSection = false;
        for (const line of lines) {
            const header = line.match(/^##\s+\[([^\]]+)\]/);
            if (header) {
                if (inSection) break;            // next version reached
                if (header[1] === version) { inSection = true; }
                continue;                        // skip the header line itself
            }
            if (inSection) body.push(line);
        }
        return body.join('\n').trim();
    }

    /**
     * Render a changelog section (Keep a Changelog format) to safe HTML.
     * Everything is HTML-escaped; only the structural markup is ours.
     */
    function renderSection(section) {
        const esc = GoingsOn.utils.escapeHtml;
        const out = [];
        let listOpen = false;
        const closeList = () => { if (listOpen) { out.push('</ul>'); listOpen = false; } };
        for (const raw of section.split('\n')) {
            const line = raw.trim();
            if (!line) continue;
            const heading = line.match(/^###\s+(.*)$/);
            const bullet = line.match(/^[-*]\s+(.*)$/);
            if (heading) {
                closeList();
                out.push(`<h3 class="whats-new-group">${esc(heading[1])}</h3>`);
            } else if (bullet) {
                if (!listOpen) { out.push('<ul class="whats-new-list">'); listOpen = true; }
                out.push(`<li>${esc(bullet[1])}</li>`);
            } else {
                closeList();
                out.push(`<p class="whats-new-text">${esc(line)}</p>`);
            }
        }
        closeList();
        return out.join('');
    }

    function show(version, section) {
        const content = `
            <div class="whats-new-panel">
                ${renderSection(section)}
            </div>
            <div class="form-actions">
                <button class="btn btn-primary" onclick="GoingsOn.ui.closeModal()">Got It</button>
            </div>
        `;
        GoingsOn.ui.openModal(`What's New in v${version}`, content);
    }

    /**
     * Decide whether to show the dialog and, if so, show it. Safe to call on
     * every startup: it no-ops when nothing changed, and records the current
     * version so the dialog shows only once per update.
     */
    async function maybeShow() {
        if (!window.__TAURI__) return;

        let current;
        try {
            current = await window.__TAURI__.app.getVersion();
        } catch (_) {
            return;
        }

        const last = localStorage.getItem(LAST_VERSION_KEY);

        // First launch on this profile: let the welcome flow own first
        // impressions; just remember where we are.
        if (!last) {
            localStorage.setItem(LAST_VERSION_KEY, current);
            return;
        }

        if (last === current) return;

        // An update landed since the last run. Record the new version up front
        // so a missing/empty changelog section never re-triggers next launch.
        localStorage.setItem(LAST_VERSION_KEY, current);

        let markdown;
        try {
            markdown = await GoingsOn.api.app.getChangelog();
        } catch (_) {
            return;
        }

        const section = extractSection(markdown, current);
        if (!section) return;    // no notes for this version — don't show an empty dialog

        show(current, section);
    }

    GoingsOn.whatsNew = { maybeShow, extractSection, renderSection };

})();