/**
 * UTM URL Generator functionality
 * Builds tracking URLs with UTM parameters
 * Client-side only - no data sent to server
 */

document.addEventListener('DOMContentLoaded', function() {
    // DOM Elements
    const baseUrlInput = document.getElementById('baseUrl');
    const utmSourceInput = document.getElementById('utmSource');
    const utmMediumInput = document.getElementById('utmMedium');
    const utmCampaignInput = document.getElementById('utmCampaign');
    const utmTermInput = document.getElementById('utmTerm');
    const utmContentInput = document.getElementById('utmContent');
    const customParamsContainer = document.getElementById('customParams');
    const addParamBtn = document.getElementById('addParamBtn');
    const generatedUrlDiv = document.getElementById('generatedUrl');
    const validationMessage = document.getElementById('validationMessage');
    const copyBtn = document.getElementById('copyBtn');
    const copyFeedback = document.getElementById('copyFeedback');
    const urlBreakdown = document.getElementById('urlBreakdown');
    const breakdownBody = document.getElementById('breakdownBody');

    // Current generated URL
    let currentUrl = '';
    let customParamCount = 0;

    // Debounce timer
    let debounceTimer;

    // Add input listeners to all UTM fields
    const utmInputs = [
        baseUrlInput,
        utmSourceInput,
        utmMediumInput,
        utmCampaignInput,
        utmTermInput,
        utmContentInput
    ];

    utmInputs.forEach(input => {
        input.addEventListener('input', debounceGenerate);
    });

    // Add custom parameter button
    addParamBtn.addEventListener('click', addCustomParam);

    // Copy button
    copyBtn.addEventListener('click', copyToClipboard);

    /**
     * Debounced URL generation
     */
    function debounceGenerate() {
        clearTimeout(debounceTimer);
        debounceTimer = setTimeout(generateUrl, 150);
    }

    /**
     * Add a custom parameter row
     */
    function addCustomParam() {
        customParamCount++;
        const row = document.createElement('div');
        row.className = 'custom-param-row';
        row.id = `customParam${customParamCount}`;
        row.innerHTML = `
            <input type="text" placeholder="Parameter name" class="custom-key" aria-label="Custom parameter name">
            <input type="text" placeholder="Value" class="custom-value" aria-label="Custom parameter value">
            <button type="button" class="btn-remove-param" aria-label="Remove parameter">&times;</button>
        `;

        // Add input listeners
        const keyInput = row.querySelector('.custom-key');
        const valueInput = row.querySelector('.custom-value');
        keyInput.addEventListener('input', debounceGenerate);
        valueInput.addEventListener('input', debounceGenerate);

        // Add remove listener
        const removeBtn = row.querySelector('.btn-remove-param');
        removeBtn.addEventListener('click', function() {
            row.remove();
            debounceGenerate();
        });

        customParamsContainer.appendChild(row);
        keyInput.focus();
    }

    /**
     * Validate URL format
     */
    function isValidUrl(string) {
        try {
            const url = new URL(string);
            return url.protocol === 'http:' || url.protocol === 'https:';
        } catch (_) {
            return false;
        }
    }

    /**
     * Get all custom parameters
     */
    function getCustomParams() {
        const params = [];
        const rows = customParamsContainer.querySelectorAll('.custom-param-row');
        rows.forEach(row => {
            const key = row.querySelector('.custom-key').value.trim();
            const value = row.querySelector('.custom-value').value.trim();
            if (key && value) {
                params.push({ key, value });
            }
        });
        return params;
    }

    /**
     * Generate the UTM URL
     */
    function generateUrl() {
        const baseUrl = baseUrlInput.value.trim();
        const source = utmSourceInput.value.trim();
        const medium = utmMediumInput.value.trim();
        const campaign = utmCampaignInput.value.trim();
        const term = utmTermInput.value.trim();
        const content = utmContentInput.value.trim();
        const customParams = getCustomParams();

        // Clear previous state
        validationMessage.textContent = '';
        validationMessage.className = 'validation-message';
        generatedUrlDiv.className = 'generated-url';

        // Check if we have any input at all
        if (!baseUrl) {
            generatedUrlDiv.textContent = 'Enter a URL to start generating your tracking URL';
            generatedUrlDiv.classList.add('empty');
            copyBtn.disabled = true;
            urlBreakdown.style.display = 'none';
            currentUrl = '';
            return;
        }

        // Validate base URL format
        if (!isValidUrl(baseUrl)) {
            generatedUrlDiv.textContent = baseUrl;
            generatedUrlDiv.classList.add('invalid');
            showValidation('Enter a valid URL (starting with http:// or https://)', 'error');
            copyBtn.disabled = true;
            urlBreakdown.style.display = 'none';
            currentUrl = '';
            return;
        }

        // Build the URL with whatever parameters are filled in
        try {
            const url = new URL(baseUrl);
            
            // Add UTM parameters only if they have values
            if (source) {
                url.searchParams.set('utm_source', source);
            }
            if (medium) {
                url.searchParams.set('utm_medium', medium);
            }
            if (campaign) {
                url.searchParams.set('utm_campaign', campaign);
            }
            if (term) {
                url.searchParams.set('utm_term', term);
            }
            if (content) {
                url.searchParams.set('utm_content', content);
            }

            // Add custom parameters
            customParams.forEach(param => {
                url.searchParams.set(param.key, param.value);
            });

            currentUrl = url.toString();
            generatedUrlDiv.textContent = currentUrl;
            generatedUrlDiv.classList.add('valid');
            copyBtn.disabled = false;

            // Show hint about missing recommended fields
            const missing = [];
            if (!source) missing.push('source');
            if (!medium) missing.push('medium');
            if (!campaign) missing.push('campaign');
            
            if (missing.length > 0) {
                showValidation(`Tip: Add ${missing.join(', ')} for complete tracking`, 'info');
            } else {
                showValidation('URL ready to copy', 'success');
            }

            // Update breakdown
            updateBreakdown(url, customParams);

        } catch (error) {
            showValidation('Error generating URL: ' + error.message, 'error');
            generatedUrlDiv.classList.add('invalid');
            copyBtn.disabled = true;
            urlBreakdown.style.display = 'none';
            currentUrl = '';
        }
    }

    /**
     * Show validation message
     */
    function showValidation(message, type) {
        validationMessage.textContent = message;
        validationMessage.className = `validation-message ${type}`;
    }

    /**
     * Update the URL breakdown table
     */
    function updateBreakdown(url, customParams) {
        urlBreakdown.style.display = 'block';
        
        const rows = [];
        
        // Base URL
        rows.push({ param: 'Base URL', value: url.origin + url.pathname });
        
        // UTM parameters
        const utmParams = ['utm_source', 'utm_medium', 'utm_campaign', 'utm_term', 'utm_content'];
        utmParams.forEach(param => {
            const value = url.searchParams.get(param);
            if (value) {
                rows.push({ param, value });
            }
        });

        // Custom parameters
        customParams.forEach(param => {
            rows.push({ param: param.key, value: param.value });
        });

        breakdownBody.innerHTML = rows.map(row => `
            <tr>
                <th>${escapeHtml(row.param)}</th>
                <td>${escapeHtml(row.value)}</td>
            </tr>
        `).join('');
    }

    /**
     * Escape HTML to prevent XSS
     */
    function escapeHtml(text) {
        const div = document.createElement('div');
        div.textContent = text;
        return div.innerHTML;
    }

    /**
     * Copy URL to clipboard
     */
    async function copyToClipboard() {
        if (!currentUrl) return;

        try {
            await navigator.clipboard.writeText(currentUrl);
            copyFeedback.classList.add('show');
            setTimeout(() => {
                copyFeedback.classList.remove('show');
            }, 2000);
        } catch (err) {
            // Fallback for older browsers
            const textArea = document.createElement('textarea');
            textArea.value = currentUrl;
            textArea.style.position = 'fixed';
            textArea.style.left = '-9999px';
            document.body.appendChild(textArea);
            textArea.select();
            try {
                document.execCommand('copy');
                copyFeedback.classList.add('show');
                setTimeout(() => {
                    copyFeedback.classList.remove('show');
                }, 2000);
            } catch (e) {
                console.error('Failed to copy:', e);
            }
            document.body.removeChild(textArea);
        }
    }
});