package org.simantics.scl.compiler.markdown.html;
import java.io.IOException;
import java.io.InputStream;
import java.io.StringReader;
import java.nio.charset.Charset;
import java.util.Arrays;
import java.util.List;

import org.simantics.scl.compiler.errors.Failable;
import org.simantics.scl.compiler.markdown.internal.MarkdownParser;
import org.simantics.scl.compiler.markdown.nodes.HeaderNode;
import org.simantics.scl.compiler.markdown.nodes.Node;
import org.simantics.scl.compiler.module.Module;
import org.simantics.scl.compiler.module.repository.ModuleRepository;

public class HtmlDocumentationGeneration {
    
    private static String STYLESHEET;
    static {
        try {
            InputStream stream = HtmlDocumentationGeneration.class.getResourceAsStream("SclDoc.css");
            try {
                byte[] buffer = new byte[2048];
                int pos = 0;
                while(true) {
                    int count = stream.read(buffer, pos, buffer.length-pos);
                    if(count <= 0)
                        break;
                    pos += count;
                    if(pos == buffer.length)
                        buffer = Arrays.copyOf(buffer, 2*buffer.length);
                }
                STYLESHEET = new String(buffer, Charset.forName("UTF-8"));
            } finally {
                stream.close();
            }
        } catch(IOException e) {
            e.printStackTrace();
        }
    }
    
    public static String generate(ModuleRepository moduleRepository, String documentationName, String navigation) {
        String documentation = moduleRepository.getDocumentation(documentationName);
        if(documentation == null || documentation.isEmpty()) {
            Failable<Module> module = moduleRepository.getModule(documentationName);
            if(!module.didSucceed())
                return "Didn't find documentation or module for " + documentationName + ".";
            documentation = "# Module "+documentationName+"\n\nThis module is undocumented. This is a list of its definitions.\n\n::undocumented[]";
        }
        MarkdownParser parser = new MarkdownParser();
        try {
            Node result = parser.parseDocument(new StringReader(documentation));
            result.processExtensionNodes(new SCLDocumentationExtensionNodeHandler(moduleRepository, documentationName));
            
            StringBuilder b = new StringBuilder();
            addHTMLHeader(b);

            if(navigation != null) {
                b.append("<table class=\"pagestructure\"><tr><td class=\"navi\">\n");
                b.append(navigation);
                b.append("</td><td class=\"content\">\n");
            }
            addContentsTree(b, result);
            result.toHtml(HtmlGenerationContext.DEFAULT, b);
            if(navigation != null)
                b.append("</td></tr></table>\n");
            
            addHTMLFooter(b);
            
            return b.toString();
        } catch (IOException e) {
            e.printStackTrace();
            return "";
        }
    }
    
    private static void addContentsTree(StringBuilder b, Node node) {
        List<HeaderNode> headers = node.extractHeaders();
        if(headers.size() > 1) {
            int minLevel=Integer.MAX_VALUE, minLevelCount=0;
            for(HeaderNode header : headers) {
                if(header.level == minLevel)
                    ++minLevelCount;
                else if(header.level < minLevel) {
                    minLevel = header.level;
                    minLevelCount = 1;
                }
            }
            if(minLevelCount == 1)
                ++minLevel;
            
            b.append("<div id=\"contentspanel\">");
            b.append("<h2>Contents</h2>\n");
            int level = minLevel-1;
            for(HeaderNode header : headers) {
                if(header.level < minLevel)
                    continue;
                while(header.level != level) {
                    if(header.level > level) {
                        b.append("<ul>\n");
                        ++level;
                    }
                    else {
                        b.append("</ul>\n");
                        --level;
                    }
                }
                 
                b.append("<li><a href=\"#");
                header.toPlainText(b);
                b.append("\">");
                header.toPlainText(b);
                b.append("</a></li>\n");
            }
            while(level >= minLevel) {
                b.append("</ul>\n");
                --level;
            }
            b.append("</div>");
        }
    }

    private static void addHTMLHeader(StringBuilder b) {
        b.append("<!DOCTYPE html>\n");
        b.append("<html>\n");
        b.append("<head>\n");
        b.append("<meta http-equiv=\"Content-Type\" content=\"text/html; charset=utf-8\" />\n");
        b.append("<meta http-equiv=\"x-ua-compatible\" content=\"IE=Edge\" />\n");
        /*b.append("<script type=\"text/javascript\"\n");
        b.append("  src=\"https://cdn.mathjax.org/mathjax/latest/MathJax.js?config=TeX-AMS-MML_HTMLorMML\">\n");
        b.append("</script>\n");*/
        b.append("<style type=\"text/css\">\n");
        b.append(STYLESHEET);
        b.append("</style>\n");
        b.append("</head>\n");
        b.append("<body>\n");
    }
    
    private static void addHTMLFooter(StringBuilder b) {
        b.append("</body>\n");
        b.append("</html>\n");
    }
}