/**
 * Contents Control - Displays document table of contents
 * Implements the Robustness Principle with Fail Fast mode support
 */

class ContentsControl {
    constructor() {
        this.control = Object.create(Control);
        this.control.config = {
            icon: '☰',
            title: 'Contents',
            className: 'contents-control',
            defaultContent: 'Click to view table of contents',
            ariaLabel: 'Contents Control',
            position: 'w'
        };

        // Bind methods to control
        this.control.buildContent = () => {
            const content = this.control.element.querySelector('.control-content');
            const headings = this.extractHeadings();

            content.innerHTML = `
                <div style="padding: 1rem; font-size: 0.8rem;">
                    <h4 style="margin-top: 0;">Table of Contents</h4>
                    <div style="max-height: 250px; overflow-y: auto;">
                        ${headings.length > 0 ?
                            headings.map(heading =>
                                `<div style="margin-bottom: 0.3rem; padding-left: ${(heading.level - 1) * 15}px;">
                                    <a href="#${heading.id}"
                                       style="text-decoration: none; color: #0066cc; font-size: ${0.9 - (heading.level - 1) * 0.05}rem;"
                                       onclick="document.getElementById('${heading.id}')?.scrollIntoView({behavior: 'smooth'})">
                                        ${heading.text}
                                    </a>
                                </div>`
                            ).join('') :
                            '<p>No headings found in document</p>'
                        }
                    </div>
                    <div style="margin-top: 1rem; font-size: 0.7rem; color: #666;">
                        ${headings.length} heading${headings.length !== 1 ? 's' : ''} found
                    </div>
                </div>
            `;
            this.control.isExpanded = true;
        };

        this.control.toggle = () => {
            if (this.control.isExpanded) {
                this.control.element.querySelector('.control-content').style.display = 'none';
                this.control.isExpanded = false;
            } else {
                this.control.buildContent();
                this.control.element.querySelector('.control-content').style.display = 'block';
            }
        };
    }

    extractHeadings() {
        const headings = [];
        const elements = document.querySelectorAll('h1, h2, h3, h4, h5, h6');

        elements.forEach((heading, index) => {
            const level = parseInt(heading.tagName.charAt(1));
            const text = heading.textContent || heading.innerText || '';
            let id = heading.id;

            // Generate ID if not present
            if (!id) {
                id = text.toLowerCase()
                    .replace(/[^\w\s-]/g, '')
                    .replace(/\s+/g, '-')
                    .replace(/-+/g, '-')
                    .replace(/^-|-$/g, '') || `heading-${index}`;
                heading.id = id;
            }

            headings.push({
                level: level,
                text: text.trim(),
                id: id
            });
        });

        return headings;
    }

    createControl() {
        return this.control.createControl();
    }
}

window.ContentsControl = ContentsControl;