/*
 * RequestParser.java
 *
 * Created on 3.2.2009
 *
 */


package netukar.tinybrowser.request;

import java.net.MalformedURLException;
import netukar.tinybrowser.exceptions.RequestSyntaxException;
import org.apache.commons.httpclient.HttpMethod;
import org.apache.commons.httpclient.URI;
import org.apache.commons.httpclient.URIException;
import org.apache.commons.httpclient.methods.DeleteMethod;
import org.apache.commons.httpclient.methods.EntityEnclosingMethod;
import org.apache.commons.httpclient.methods.GetMethod;
import org.apache.commons.httpclient.methods.HeadMethod;
import org.apache.commons.httpclient.methods.PostMethod;
import org.apache.commons.httpclient.methods.PutMethod;
import org.apache.commons.httpclient.methods.StringRequestEntity;

/**
 *
 * @author Radovan Netuka
 */
public class RequestParser {

    /**
     * Creates a new instance of RequestParser.
     */
    private RequestParser() {
    }


    public static HttpMethod parse(String text) throws RequestSyntaxException, MalformedURLException {
        return parse(null, text);
    }

    public static HttpMethod parse(String url, String text)
            throws RequestSyntaxException, MalformedURLException {

        HttpMethod result;
        String overridenUrl = null;
        String[] lines = text.split("\n");

        // Try both styles here, ie. "GET" or "GET /index.html HTTP/1.1"
        String[] keywords = lines[0].split(" ");
        String method;
        String path = null;
        String httpVersion = null;

        if (keywords.length == 1) {
            // contains only method name
            method = keywords[0];
        }
        else if (keywords.length == 3) {
            // contains all 3 keywords - method, path and http version
            method = keywords[0];
            path = keywords[1];
            httpVersion = keywords[2];
        }
        else {
            throw new RequestSyntaxException("Invalid keywords count for the first line");
        }

        if (method.equals("GET")) {
            result = new GetMethod();
        }
        else if (method.equals("POST")) {
            result = new PostMethod();
        }
        else if (method.equals("PUT")) {
            result = new PutMethod();
        }
        else if (method.equals("DELETE")) {
            result = new DeleteMethod();
        }
        else if (method.equals("HEAD")) {
            result = new HeadMethod();
        }
        else {
            throw new RequestSyntaxException("Invalid method name for request");
        }

        if (path != null) {

        }

        if (httpVersion != null) {
            if (! (httpVersion.equals("HTTP/1.0") || httpVersion.equals("HTTP/1.1"))) {
                throw new RequestSyntaxException("Invalid HTTP version");
            }
        }

        // HTTP header fields
        int i;
        for (i = 1; i < lines.length; i++) {
            if (lines[i].length() == 0) {
                // empty line found - end of headers
                break;
            } else if (lines[i].startsWith("Host: ")) {
                String host = lines[i].substring("Host: ".length());
                if (path != null) {
                    overridenUrl = "http://" + host + path;
                }
            } else {
                try {
                    int colonIndex = lines[i].indexOf(':');
                    String name = lines[i].substring(0, colonIndex);
                    String value = lines[i].substring(colonIndex + 2);
                    result.setRequestHeader(name, value);
                } catch (IndexOutOfBoundsException ex) {
                    throw new RequestSyntaxException("Invalid syntax for request header fields");
                }
            }
        }
        
        // HTTP entity
        StringBuilder b = new StringBuilder();
        for (i = i + 1; i < lines.length; i++) {
            b.append(lines[i]).append('\n');
        }
        String body = b.toString();
        if (! body.isEmpty()) {
            if (result instanceof EntityEnclosingMethod) {
                ((EntityEnclosingMethod) result).setRequestEntity(new StringRequestEntity(body));
            }
        }

        try {
            if (overridenUrl != null) {
                result.setURI(new URI(overridenUrl, false));
            } else {
                result.setURI(new URI(url, false));
            }
        } catch (URIException ex) {
            throw new RequestSyntaxException("Invalid URI");
        }
        return result;
    }

}