injection-engine.js

// Advanced injection engine for HTML, CSS, and JavaScript
class InjectionEngine {
    constructor() {
        this.injections = {
            html: [],      // HTML snippets to inject
            css: [],       // CSS styles to inject
            js: [],        // JavaScript to inject
            head: [],      // Raw head content
            bodyStart: [], // Content at start of body
            bodyEnd: []    // Content at end of body
        };
        this.assets = new Map(); // Virtual file system for plugin assets
    }

    // Register HTML injection
    injectHTML(position, html, id = null) {
        const injection = { html, id, timestamp: Date.now() };
        if (['head', 'bodyStart', 'bodyEnd'].includes(position)) {
            this.injections[position].push(injection);
        } else {
            this.injections.html.push({ ...injection, position });
        }
        return this;
    }

    // Register CSS injection
    injectCSS(css, id = null, important = false) {
        this.injections.css.push({ css, id, important, timestamp: Date.now() });
        return this;
    }

    // Register JavaScript injection
    injectJS(js, id = null, position = 'bodyEnd') {
        this.injections.js.push({ js, id, position, timestamp: Date.now() });
        return this;
    }

    // Register external script URL
    injectScript(url, id = null, async = true, position = 'head') {
        const script = `<script src="${url}"${async ? ' async' : ''}></script>`;
        this.injections[position].push({ html: script, id, timestamp: Date.now() });
        return this;
    }

    // Register external stylesheet
    injectStylesheet(url, id = null) {
        const link = `<link rel="stylesheet" href="${url}">`;
        this.injections.head.push({ html: link, id, timestamp: Date.now() });
        return this;
    }

    // Add virtual asset (served at /_plugins/assets/:id)
    addAsset(id, content, contentType = 'text/plain') {
        this.assets.set(id, { content, contentType });
        return this;
    }

    // Get asset for serving
    getAsset(id) {
        return this.assets.get(id);
    }

    // List all assets
    listAssets() {
        return Array.from(this.assets.keys());
    }

    // Remove injection by ID
    removeById(id) {
        for (const key of Object.keys(this.injections)) {
            this.injections[key] = this.injections[key].filter(i => i.id !== id);
        }
        this.assets.delete(id);
        return this;
    }

    // Process HTML response and apply all injections
    processHTML(body) {
        // Inject CSS into head
        if (this.injections.css.length > 0) {
            const cssContent = this.injections.css
                .map(c => c.css)
                .join('\n');
            const styleTag = `<style data-injected="true">\n${cssContent}\n</style>`;
            body = this.injectAtPosition(body, 'head', styleTag, 'end');
        }

        // Inject head content
        for (const injection of this.injections.head) {
            body = this.injectAtPosition(body, 'head', injection.html, 'end');
        }

        // Inject bodyStart content
        for (const injection of this.injections.bodyStart) {
            body = this.injectAtPosition(body, 'body', injection.html, 'start');
        }

        // Inject JS modules
        if (this.injections.js.length > 0) {
            const jsContent = this.injections.js
                .map(j => j.js)
                .join('\n;\n');
            const scriptTag = `<script data-injected="true">\n(function(){\n${jsContent}\n})();\n</script>`;
            body = this.injectAtPosition(body, 'body', scriptTag, 'end');
        }

        // Inject bodyEnd content
        for (const injection of this.injections.bodyEnd) {
            body = this.injectAtPosition(body, 'body', injection.html, 'end');
        }

        // Generic HTML injections at specific positions
        for (const injection of this.injections.html) {
            const { position, html } = injection;
            if (position.includes('before:')) {
                const selector = position.replace('before:', '');
                body = body.replace(new RegExp(`(<${selector}[^>]*>)`, 'i'), `${html}$1`);
            } else if (position.includes('after:')) {
                const selector = position.replace('after:', '');
                body = body.replace(new RegExp(`(</${selector}>)`, 'i'), `$1${html}`);
            }
        }

        return body;
    }

    injectAtPosition(body, tag, content, position) {
        const tagRegex = new RegExp(`(<${tag}[^>]*>)`, 'i');
        const closeTagRegex = new RegExp(`(</${tag}>)`, 'i');

        if (position === 'start' && tagRegex.test(body)) {
            return body.replace(tagRegex, `$1${content}`);
        } else if (position === 'end' && closeTagRegex.test(body)) {
            return body.replace(closeTagRegex, `${content}$1`);
        }
        return body;
    }

    // Get current injection stats
    getStats() {
        return {
            html: this.injections.html.length,
            css: this.injections.css.length,
            js: this.injections.js.length,
            head: this.injections.head.length,
            bodyStart: this.injections.bodyStart.length,
            bodyEnd: this.injections.bodyEnd.length,
            assets: this.assets.size
        };
    }
}

module.exports = InjectionEngine;