import { Rule } from './rule-interface';
/**
* MD045: Images should have alternate text (alt text)
*
* This rule is triggered when an image is missing alternate text (alt text).
* Alternate text is important for accessibility and should always be provided
* for images.
*/
export const name = 'MD045';
export const description = 'Images should have alternate text (alt text)';
/**
* Regular expression to find image references
* Both inline images  and reference images ![alt][ref] are included
*/
const imageRegex = /!\[(.*?)\](?:\((.*?)\)|\[(.*?)\])/g;
/**
* Fix images that are missing alternate text by adding empty alt text
* @param lines Array of string lines to fix
* @returns Fixed lines array with proper alt text for images
*/
export function fix(lines: string[]): string[] {
return lines.map(line => {
// Find all image references in the line
let result = line;
let match;
let offset = 0;
// Reset the regex lastIndex
imageRegex.lastIndex = 0;
// Process each image reference in the line
while ((match = imageRegex.exec(line)) !== null) {
const [fullMatch, altText, inlineUrl, referenceId] = match;
// If the alt text is empty, add an empty pair of brackets
if (!altText || altText.trim() === '') {
const newText = fullMatch.replace('![]', '![ ]');
// Replace at the correct position with the offset applied
const startPos = match.index + offset;
const endPos = startPos + fullMatch.length;
// Update the result string
result = result.substring(0, startPos) + newText + result.substring(endPos);
// Update the offset for subsequent replacements
offset += newText.length - fullMatch.length;
// Update the lastIndex to account for the change in string length
imageRegex.lastIndex += newText.length - fullMatch.length;
}
}
return result;
});
}
/**
* Rule implementation for MD045
*/
export const rule: Rule = {
name,
description,
fix
};
export default rule;
