//**************************************************************************

//** toHTML

//**************************************************************************

/** Converts a Markdown string to an HTML snippet.

public static String toHTML(String markdown){

if (markdown==null) return "";

String[] lines = markdown.split("\n");

StringBuilder html = new StringBuilder();

boolean inCodeBlock = false;

boolean inUl = false;

boolean inOl = false;

boolean inTable = false;

boolean tableHeaderDone = false;

boolean inParagraph = false;

StringBuilder paragraph = new StringBuilder();

for (int i=0; i<lines.length; i++){

String line = lines[i];

//Strip trailing carriage return

if (line.endsWith("\r")) line = line.substring(0, line.length()-1);

//Handle fenced code blocks

if (line.trim().startsWith("```")){

if (!inCodeBlock){

//Close any open block

closeParagraph(html, paragraph, inParagraph);

inParagraph = false;

if (inUl){ html.append("</ul>\n"); inUl = false; }

if (inOl){ html.append("</ol>\n"); inOl = false; }

if (inTable){ html.append("</table>\n"); inTable = false; tableHeaderDone = false; }

//Get optional language

String lang = line.trim().substring(3).trim();

if (lang.isEmpty()){

html.append("<pre>");

}

else{

html.append("<pre class=\"brush: ").append(lang).append(";\">");

}

inCodeBlock = true;

}

else{

html.append("</pre>\n");

inCodeBlock = false;

}

continue;

}

if (inCodeBlock){

html.append(escapeHtml(line)).append("\n");

continue;

}

//Handle headers

if (line.startsWith("#")){

//Close any open block

closeParagraph(html, paragraph, inParagraph);

inParagraph = false;

if (inUl){ html.append("</ul>\n"); inUl = false; }

if (inOl){ html.append("</ol>\n"); inOl = false; }

if (inTable){ html.append("</table>\n"); inTable = false; tableHeaderDone = false; }

int level = 0;

while (level < line.length() && line.charAt(level) == '#') level++;

if (level > 6) level = 6;

String text = line.substring(level).trim();

text = processInline(text);

html.append("<h").append(level).append(">")

.append(text)

.append("</h").append(level).append(">\n");

continue;

}

//Handle unordered list items

if (line.matches("^\\s*[\\-\\*]\\s+.*")){

//Close paragraph or ordered list if open

closeParagraph(html, paragraph, inParagraph);

inParagraph = false;

if (inOl){ html.append("</ol>\n"); inOl = false; }

if (!inUl){

html.append("<ul>\n");

inUl = true;

}

String text = line.replaceFirst("^\\s*[\\-\\*]\\s+", "");

html.append("<li>").append(processInline(text)).append("</li>\n");

continue;

}

//Handle ordered list items

if (line.matches("^\\s*\\d+\\.\\s+.*")){

//Close paragraph or unordered list if open

closeParagraph(html, paragraph, inParagraph);

inParagraph = false;

if (inUl){ html.append("</ul>\n"); inUl = false; }

if (!inOl){

html.append("<ol>\n");

inOl = true;

}

String text = line.replaceFirst("^\\s*\\d+\\.\\s+", "");

html.append("<li>").append(processInline(text)).append("</li>\n");

continue;

}

//Handle list continuation lines (indented text following a list item)

if ((inUl || inOl) && line.length()>0 && (line.charAt(0)==' ' || line.charAt(0)=='\t') && !line.trim().isEmpty()){

// Remove trailing </li>\n from previous item and append continuation

String ending = "</li>\n";

int idx = html.length() - ending.length();

if (idx >= 0 && html.substring(idx).equals(ending)){

html.setLength(idx);

html.append(" ").append(processInline(line.trim())).append("</li>\n");

}

continue;

}

//Handle table rows (lines starting and ending with |)

if (line.trim().startsWith("|") && line.trim().endsWith("|")){

//Close other open blocks

closeParagraph(html, paragraph, inParagraph);

inParagraph = false;

if (inUl){ html.append("</ul>\n"); inUl = false; }

if (inOl){ html.append("</ol>\n"); inOl = false; }

//Skip separator rows (e.g. |---|---|)

if (line.trim().matches("^\\|[\\s\\-:|]+\\|$")){

tableHeaderDone = true;

continue;

}

if (!inTable){

html.append("<table>\n");

inTable = true;

tableHeaderDone = false;

}

//Parse cells

String trimmed = line.trim();

trimmed = trimmed.substring(1, trimmed.length()-1); // strip outer pipes

String[] cells = trimmed.split("\\|");

String cellTag = !tableHeaderDone ? "th" : "td";

html.append("<tr>");

for (String cell : cells){

html.append("<").append(cellTag).append(">")

.append(processInline(cell.trim()))

.append("</").append(cellTag).append(">");

}

html.append("</tr>\n");

continue;

}

//Close table if we're in one and hit a non-table line

if (inTable){

html.append("</table>\n");

inTable = false;

tableHeaderDone = false;

}

//Handle blank lines

if (line.trim().isEmpty()){

closeParagraph(html, paragraph, inParagraph);

inParagraph = false;

if (inUl){ html.append("</ul>\n"); inUl = false; }

if (inOl){ html.append("</ol>\n"); inOl = false; }

continue;

}

//Paragraph text

if (inUl){ html.append("</ul>\n"); inUl = false; }

if (inOl){ html.append("</ol>\n"); inOl = false; }

if (!inParagraph){

inParagraph = true;

paragraph.setLength(0);

}

else{

paragraph.append(" ");

}

paragraph.append(line.trim());

}

//Close any remaining open blocks

closeParagraph(html, paragraph, inParagraph);

if (inUl) html.append("</ul>\n");

if (inOl) html.append("</ol>\n");

if (inTable) html.append("</table>\n");

if (inCodeBlock) html.append("</pre>\n");

return html.toString().trim();

}

//**************************************************************************

//** closeParagraph

//**************************************************************************

private static void closeParagraph(StringBuilder html, StringBuilder paragraph, boolean inParagraph){

if (inParagraph && paragraph.length()>0){

html.append("<p>").append(processInline(paragraph.toString())).append("</p>\n");

paragraph.setLength(0);

}

}

//**************************************************************************

//** processInline

//**************************************************************************

/** Processes inline markdown elements (code, bold, italic, links,

private static String processInline(String text){

//Convert inline code: `text` -> <code>text</code>

//Must come first so content inside backticks is not processed further

StringBuilder code = new StringBuilder();

int cpos = 0;

while (cpos < text.length()){

int start = text.indexOf('`', cpos);

if (start == -1){

code.append(text.substring(cpos));

break;

}

int end = text.indexOf('`', start+1);

if (end == -1){

code.append(text.substring(cpos));

break;

}

code.append(text, cpos, start);

String inner = text.substring(start+1, end);

code.append("<code>").append(escapeHtml(inner)).append("</code>");

cpos = end + 1;

}

text = code.toString();

//Convert bold: **text** -> <b>text</b>

StringBuilder bold = new StringBuilder();

int bpos = 0;

while (bpos < text.length()){

int start = text.indexOf("**", bpos);

if (start == -1){

bold.append(text.substring(bpos));

break;

}

int end = text.indexOf("**", start+2);

if (end == -1){

bold.append(text.substring(bpos));

break;

}

bold.append(text, bpos, start);

bold.append("<b>").append(text, start+2, end).append("</b>");

bpos = end + 2;

}

text = bold.toString();

//Convert italic: *text* -> <i>text</i>

//Must come after bold so ** is consumed first

StringBuilder italic = new StringBuilder();

int ipos = 0;

while (ipos < text.length()){

int start = text.indexOf('*', ipos);

if (start == -1){

italic.append(text.substring(ipos));

break;

}

int end = text.indexOf('*', start+1);

if (end == -1){

italic.append(text.substring(ipos));

break;

}

italic.append(text, ipos, start);

italic.append("<i>").append(text, start+1, end).append("</i>");

ipos = end + 1;

}

text = italic.toString();

//Convert inline images and links:

//  -> <img src="url" alt="alt">

// [text](url) -> <a href="url">text</a>

StringBuilder sb = new StringBuilder();

int pos = 0;

while (pos < text.length()){

int linkStart = text.indexOf('[', pos);

if (linkStart == -1){

sb.append(text.substring(pos));

break;

}

int linkTextEnd = text.indexOf(']', linkStart);

if (linkTextEnd == -1){

sb.append(text.substring(pos));

break;

}

if (linkTextEnd+1 < text.length() && text.charAt(linkTextEnd+1) == '('){

int urlEnd = text.indexOf(')', linkTextEnd+2);

if (urlEnd == -1){

sb.append(text.substring(pos));

break;

}

boolean isImage = (linkStart > 0 && text.charAt(linkStart-1) == '!');

String innerText = text.substring(linkStart+1, linkTextEnd);

String url = text.substring(linkTextEnd+2, urlEnd);

if (isImage){

sb.append(text, pos, linkStart-1); // exclude the '!'

sb.append("<img src=\"").append(url).append("\" alt=\"").append(innerText).append("\">");

}

else{

sb.append(text, pos, linkStart);

sb.append("<a href=\"").append(url).append("\">").append(innerText).append("</a>");

}

pos = urlEnd + 1;

}

else{

sb.append(text, pos, linkTextEnd+1);

pos = linkTextEnd + 1;

}

}

text = sb.toString();

//Convert em-dashes: space--space -> &mdash;

//Also handles -- at start/end of text adjacent to a space

text = text.replace(" -- ", " &mdash; ");

return text;

}

//**************************************************************************

//** escapeHtml

//**************************************************************************

/** Escapes HTML special characters in code blocks.

private static String escapeHtml(String text){

return text.replace("&", "&amp;")

.replace("<", "&lt;")

.replace(">", "&gt;");

}