/**
 * Java Web Archive Toolkit - Software to read and validate ARC, WARC
 * and GZip files. (http://jwat.org/)
 * Copyright 2011-2012 Netarkivet.dk (http://netarkivet.dk/)
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.jwat.common;

import java.io.IOException;
import java.io.PushbackInputStream;
import java.util.Collections;
import java.util.HashMap;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;

/**
 * This class represents a recognized HTTP response or request header with optional payload.
 *
 * @author lbihanic, selghissassi, nicl
 */
public class HttpHeader extends PayloadWithHeaderAbstract {

    /** Response header type. */
    public static final int HT_RESPONSE = 1;

    /** Request header type. */
    public static final int HT_REQUEST = 2;

    /** HTTP scheme. */
    public static final String PROTOCOL_HTTP = "http";

    /** HTTPS scheme. */
    public static final String PROTOCOL_HTTPS = "https";

    /** HTTP Version suffix. */
    protected static final String HTTP_VERSION_SUFFIX = "HTTP/";

    /** Content-type header name. */
    protected static final String CONTENT_TYPE = "Content-Type".toUpperCase();

    /** Header type of this object. */
    public int headerType;

    /*
     * Request-Line.
     */

    /** HTTP Method. */
    public String method;

    /** HTTP Request-URI. */
    public String requestUri;

    /*
     * Http-Version.
     */

    /** HTTP-Version. */
    public String httpVersion;

    /** HTTP-Version major. */
    public Integer httpVersionMajor;

    /** HTTP-Version minor. */
    public Integer httpVersionMinor;

    /*
     * Status-Line.
     */

    /** HTTP Status-Code. */
    public String statusCodeStr;

    /** HTTP Status-Code. */
    public Integer statusCode;

    /** HTTP Reason-Phrase. */
    public String reasonPhrase;

    /*
     * Header-Fields.
     */

    /** List of parsed header fields. */
    protected List<HeaderLine> headerList = new LinkedList<HeaderLine>();

    /** Map of parsed header fields. */
    protected Map<String, HeaderLine> headerMap = new HashMap<String, HeaderLine>();

    /** HTTP content Content-type. */
    public String contentType;

    /**
     * Non public constructor.
     */
    protected HttpHeader() {
    }

    /**
     * Boolean indicating whether a protocol is supported by this
     * payload inspector.
     * @param protocol protocol name
     * @return true/false if the protocol is supported or not.
     */
    public static boolean isSupported(String protocol) {
        return ((PROTOCOL_HTTP.equalsIgnoreCase(protocol)
                || PROTOCOL_HTTPS.equalsIgnoreCase(protocol)));
    }

    /**
     * Reads the HTTP protocol response or request and returns it as an object.
     * It is important to understand that the maximum size of a parsed header
     * is equal to the size of the PushbackInputStream's buffer!
     * @param headerType HTTP header type to parse, request or response
     * @param pbin payload input stream
     * @param length payload length
     * @param digestAlgorithm digest algorithm to use on payload or null if we
     * don't want a digest of the payload
     * @return <code>HttpResponse</code> based on the http headers
     * @throws IOException if an error occur while processing http header.
     */
    public static HttpHeader processPayload(int headerType, ByteCountingPushBackInputStream pbin,
                    long length, String digestAlgorithm) throws IOException {
        if (headerType != HT_RESPONSE && headerType != HT_REQUEST) {
            throw new IllegalArgumentException(
                    "Invalid 'headerType' argument: " + headerType);
        }
        if (pbin == null) {
            throw new IllegalArgumentException(
                    "The inputstream 'pbin' is null");
        }
        if (length < 0) {
            throw new IllegalArgumentException(
                    "The 'length' is less than zero: " + length);
        }
        HttpHeader hh = new HttpHeader();
        hh.headerType = headerType;
        hh.in_pb = pbin;
        hh.totalLength = length;
        hh.digestAlgorithm = digestAlgorithm;
        hh.diagnostics = new Diagnostics();
        hh.initProcess();
        return hh;
    }

    @Override
    protected boolean readHeader(MaxLengthRecordingInputStream in, long payloadLength)
                            throws IOException {
        // TODO too low!
        PushbackInputStream pbin = new PushbackInputStream(in, in_pb.getPushbackSize());
        HeaderLineReader hlr = HeaderLineReader.getHeaderLineReader();
        hlr.bNameValue = false;
        hlr.encoding = HeaderLineReader.ENC_ISO8859_1;
        hlr.bLWS = false;
        hlr.bQuotedText = false;
        hlr.bEncodedWords = false;
        boolean bValidHttpHeader = false;
        HeaderLine line = hlr.readLine(pbin);
        int bfErrors = 0;
        if (!hlr.bEof && line.type == HeaderLine.HLT_LINE && line.line != null && line.line.length() > 0) {
            bfErrors = (line.bfErrors & ~HeaderLineReader.E_BIT_INVALID_SEPARATOR_CHAR);
            if (headerType == HT_RESPONSE) {
                bValidHttpHeader = isHttpStatusLineValid(line.line);
            } else if (headerType == HT_REQUEST) {
                bValidHttpHeader = isHttpRequestLineValid(line.line);
            } else {
                throw new IllegalStateException("Invalid headerType!");
            }
        }
        hlr.bNameValue = true;
        hlr.bLWS = true;
        hlr.bQuotedText = true;
        hlr.bEncodedWords = true;
        HeaderLine tmpLine;
        boolean bLoop = bValidHttpHeader;
        while (bLoop) {
            line = hlr.readLine(pbin);
            bfErrors |= line.bfErrors;
            if (!hlr.bEof) {
                switch (line.type) {
                case HeaderLine.HLT_HEADERLINE:
                    //System.out.println(line.name);
                    //System.out.println(line.value);
                    if (CONTENT_TYPE.equals(line.name.toUpperCase())) {
                        contentType = line.value;
                    }
                    // A HeaderLine object contains a list of additional lines.
                    tmpLine = headerMap.get(line.name.toLowerCase());
                    if (tmpLine == null) {
                        headerMap.put(line.name.toLowerCase(), line);
                    } else {
                        tmpLine.lines.add(line);
                    }
                    headerList.add(line);
                    break;
                case HeaderLine.HLT_LINE:
                    if (line.line.length() == 0) {
                        bLoop = false;
                    } else {
                        // Errors reported by bfErrors.
                    }
                    break;
                }
            } else {
                // Accept truncated http header if it is the length of the payload.
                if ((bfErrors & HeaderLineReader.E_BIT_EOF) == 0 || in.record.size() != payloadLength) {
                    /*
                    System.out.println("Epic fail!");
                    System.out.println(Integer.toBinaryString(hlr.bfErrors));
                    System.out.println(new String(in.getRecording()));
                    */
                    bValidHttpHeader = false;
                }
                bLoop = false;
            }
        }
        HeaderLineReader.report_error(bfErrors, diagnostics);
        if (bValidHttpHeader) {
            this.payloadLength = payloadLength - in.record.size();
        }
        return bValidHttpHeader;
    }

    /**
     * Checks a HTTP Response Status-Line for validity.
     * @param statusLine the Status-Line of the HTTP Response
     * @return true/false based on whether the Status-Line is valid or not.
     */
    protected boolean isHttpStatusLineValid(String statusLine) {
        int idx;
        int prevIdx;
        boolean bIsHttpStatusLineValid = (statusLine != null) && (statusLine.length() > 0);
        if (bIsHttpStatusLineValid) {
            idx = statusLine.indexOf(' ');
            if (idx > 0) {
                bIsHttpStatusLineValid = isHttpVersionValid(statusLine.substring(0, idx));
            } else {
                if (idx == -1) {
                    httpVersion = statusLine;
                }
                bIsHttpStatusLineValid = false;
            }
            if (bIsHttpStatusLineValid) {
                prevIdx = ++idx;
                idx = statusLine.indexOf(' ', idx);
                if (idx == -1) {
                    idx = statusLine.length();
                }
                if (idx > prevIdx) {
                    statusCodeStr = statusLine.substring(prevIdx, idx);
                    try {
                        statusCode = Integer.parseInt(statusCodeStr);
                        if (statusCode < 100 || statusCode > 999) {
                            bIsHttpStatusLineValid = false;
                        }
                    } catch(NumberFormatException e) {
                        bIsHttpStatusLineValid = false;
                    }
                } else {
                    bIsHttpStatusLineValid = false;
                }
                if (bIsHttpStatusLineValid) {
                    if (idx < statusLine.length()) {
                        ++idx;
                        reasonPhrase = statusLine.substring(idx);
                    }
                }
            }
        }
        return bIsHttpStatusLineValid;
    }

    /**
     * Checks a HTTP-Version string for validity.
     * @param versionString the HTTP-Version of the HTTP header
     * @return true/false based on whether the HTTP-Version is valid or not.
     */
    protected boolean isHttpVersionValid(String versionString) {
        int idx;
        httpVersion = versionString;
        boolean bIsHttpVersionValid = versionString.startsWith(HTTP_VERSION_SUFFIX);
        if (bIsHttpVersionValid) {
            idx = versionString.indexOf('.', HTTP_VERSION_SUFFIX.length());
            if (idx > 0) {
                try {
                    httpVersionMajor = Integer.parseInt(versionString.substring(HTTP_VERSION_SUFFIX.length(), idx));
                    if (httpVersionMajor < 0) {
                        bIsHttpVersionValid = false;
                    }
                } catch (NumberFormatException e) {
                    bIsHttpVersionValid = false;
                }
                try {
                    httpVersionMinor = Integer.parseInt(versionString.substring(idx + 1));
                    if (httpVersionMinor < 0) {
                        bIsHttpVersionValid = false;
                    }
                } catch (NumberFormatException e) {
                    bIsHttpVersionValid = false;
                }
            } else {
                bIsHttpVersionValid = false;
            }
        } else if (versionString.equals("HTTP")) {
            // IA-local change: be lenient with broken version field.
            // See https://webarchive.jira.com/browse/WWM-160
            httpVersionMajor = 1;
            httpVersionMinor = 0;
            bIsHttpVersionValid = true;
        }
        return bIsHttpVersionValid;
    }

    /**
     * Checks a HTTP Request Request-Line for validity.
     * @param requestLine the Request-Line of the HTTP Request
     * @return true/false based on whether the Request-Line is valid or not.
     */
    protected boolean isHttpRequestLineValid(String requestLine) {
        int idx;
        int prevIdx;
        boolean bIsHttpRequestLineValid = (requestLine != null) && (requestLine.length() > 0);
        if (bIsHttpRequestLineValid) {
            idx = requestLine.indexOf(' ');
            if (idx > 0) {
                method = requestLine.substring(0, idx);
            } else {
                if (idx == -1) {
                    method = requestLine;
                }
                bIsHttpRequestLineValid = false;
            }
            if (bIsHttpRequestLineValid) {
                prevIdx = ++idx;
                idx = requestLine.indexOf(' ', idx);
                if (idx > prevIdx) {
                    requestUri = requestLine.substring(prevIdx, idx);
                } else {
                    if (idx == -1) {
                        requestUri = requestLine.substring(prevIdx);
                    }
                    bIsHttpRequestLineValid = false;
                }
                if (bIsHttpRequestLineValid) {
                    ++idx;
                    bIsHttpRequestLineValid = isHttpVersionValid(requestLine.substring(idx));
                }
            }
        }
        return bIsHttpRequestLineValid;
    }

    @Override
    public List<HeaderLine> getHeaderList() {
        return Collections.unmodifiableList(headerList);
    }

    @Override
    public HeaderLine getHeader(String field) {
        if (field != null && field.length() > 0) {
            return headerMap.get(field.toLowerCase());
        } else {
            return null;
        }
    }

    /**
     * Result-Code string getter
     * @return the ResultCode
     */
    public String getProtocolStatusCodeStr() {
        return statusCodeStr;
    }

    /**
     * Result-Code integer getter
     * @return the ResultCode
     */
    public Integer getProtocolStatusCode() {
        return statusCode;
    }

    /**
     * protocolVersion getter
     * @return the protocolVersion
     */
    public String getProtocolVersion() {
        return httpVersion;
    }

    /**
     * Content-Type getter
     * @return the Content-Type
     */
    public String getProtocolContentType() {
        return contentType;
    }

    @Override
    public String toString() {
        StringBuilder builder = new StringBuilder(256);
        builder.append("\nHttpHeader : [\n");
        if (statusCode != null) {
            builder.append(", HttpResultCode: ")
                .append(statusCode);
        }
        if (httpVersion != null) {
            builder.append(", HttpProtocolVersion: ")
                .append(httpVersion);
        }
        if (contentType != null) {
            builder.append(", HttpContentType: ")
                .append(contentType);
        }
        builder.append("]\n");
        return builder.toString();
    }

}