LibGemini: Implement rendering text/gemini documents to HTML

This also sets Content-Type to whatever 'meta' contains on success, to
allow the browser to pick up what the document contains.

Libraries/LibGemini/Line.cpp

@@ -0,0 +1,143 @@
+/*
+ * Copyright (c) 2020, The SerenityOS developers.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <AK/StringBuilder.h>
+#include <LibGemini/Document.h>
+
+namespace Gemini {
+
+String Text::render_to_html() const
+{
+    StringBuilder builder;
+    builder.append(escape_html_entities(m_text));
+    builder.append("<br>\n");
+    return builder.build();
+}
+
+Text::~Text()
+{
+}
+
+String Heading::render_to_html() const
+{
+    StringBuilder builder;
+    builder.appendf("<h%d>", m_level);
+    builder.append(escape_html_entities(m_text.substring_view(m_level, m_text.length() - m_level)));
+    builder.appendf("</h%d>", m_level);
+    return builder.build();
+}
+Heading::~Heading()
+{
+}
+
+String UnorderedList::render_to_html() const
+{
+    // 1.3.5.4.2 "Advanced clients can take the space of the bullet symbol into account"
+    //           FIXME: The spec is unclear about what the space means, or where it goes
+    //                  somehow figure this out
+    StringBuilder builder;
+    builder.append("<li>");
+    builder.append(escape_html_entities(m_text.substring_view(1, m_text.length() - 1)));
+    builder.append("</li>");
+    return builder.build();
+}
+UnorderedList::~UnorderedList()
+{
+}
+
+String Control::render_to_html() const
+{
+    switch (m_kind) {
+    case Kind::PreformattedEnd:
+        return "</pre>";
+    case Kind::PreformattedStart:
+        return "<pre>";
+    case Kind::UnorderedListStart:
+        return "<ul>";
+    case Kind::UnorderedListEnd:
+        return "</ul>";
+    default:
+        dbg() << "Unknown control kind _" << m_kind << "_";
+        ASSERT_NOT_REACHED();
+        return "";
+    }
+}
+Control::~Control()
+{
+}
+
+Link::Link(String text, const Document& document)
+    : Line(move(text))
+{
+    size_t index = 2;
+    while (index < m_text.length() && (m_text[index] == ' ' || m_text[index] == '\t'))
+        ++index;
+    auto url_string = m_text.substring_view(index, m_text.length() - index);
+    auto space_offset = url_string.find_first_of(" \t");
+    String url = url_string;
+    if (space_offset.has_value()) {
+        url = url_string.substring_view(0, space_offset.value());
+        auto offset = space_offset.value();
+        while (offset < url_string.length() && (url_string[offset] == ' ' || url_string[offset] == '\t'))
+            ++offset;
+        m_name = url_string.substring_view(offset, url_string.length() - offset);
+    }
+    m_url = document.url().complete_url(url);
+    if (m_name.is_null())
+        m_name = m_url.to_string();
+}
+Link::~Link()
+{
+}
+
+String Link::render_to_html() const
+{
+    StringBuilder builder;
+    builder.append("<a href=\"");
+    builder.append(escape_html_entities(m_url.to_string()));
+    builder.append("\">");
+    builder.append(escape_html_entities(m_name));
+    builder.append("</a><br>\n");
+    return builder.build();
+}
+
+String Preformatted::render_to_html() const
+{
+    StringBuilder builder;
+    builder.append(escape_html_entities(m_text.substring_view(3, m_text.length() - 3)));
+    builder.append("\n");
+
+    return builder.build();
+}
+Preformatted::~Preformatted()
+{
+}
+
+Line::~Line()
+{
+}
+
+}