HttpHeaders.h

/****
 * Sming Framework Project - Open Source framework for high efficiency native ESP8266 development.
 * Created 2015 by Skurydin Alexey
 * http://github.com/SmingHub/Sming
 * All files of the Sming Core are provided under the LGPL v3 license.
 *
 * HttpHeaders.h
 *
 * @author: 2018 - Mikee47 <mike@sillyhouse.net>
 *
 *  Encapsulate encoding and decoding of HTTP header fields
 *  Used for HTTP connections and SMTP mail
 *
 *  The HttpHeaders class was an empty HashMap class living in 'Structures.h'.
 *  It has been expanded here to simplify code, and to provide enumerated keys
 *  for common field names.
 *
 ****/

#ifndef _SMING_CORE_NETWORK_HTTP_HTTP_HEADERS_H_
#define _SMING_CORE_NETWORK_HTTP_HTTP_HEADERS_H_

#include "Data/CStringArray.h"
#include "WString.h"
#include "WHashMap.h"
#include "DateTime.h"

/*
 * Common HTTP header field names. Enumerating these simplifies matching
 * and generating headers. The strings themselves are stored in flash to
 * save RAM.
 *
 * According to RFC 2616: 4.2, field names are case-insensitive.
 *
 * A brief description of each header field is given for information purposes.
 * For details see https://www.iana.org/assignments/message-headers/message-headers.xhtml
 *
 */
#define HTTP_HEADER_FIELDNAME_MAP(XX)                                                                                  \
    XX(ACCESS_CONTROL_ALLOW_ORIGIN, "Access-Control-Allow-Origin", "")                                                 \
    XX(AUTHORIZATION, "Authorization", "Basic user agent authentication")                                              \
    XX(CC, "Cc", "email field")                                                                                        \
    XX(CONNECTION, "Connection", "Indicates sender's desired control options")                                         \
    XX(CONTENT_DISPOSITION, "Content-Disposition", "Additional information about how to process response payload")     \
    XX(CONTENT_ENCODING, "Content-Encoding", "Applied encodings in addition to content type")                          \
    XX(CONTENT_LENGTH, "Content-Length", "Anticipated size for payload when not using transfer encoding")              \
    XX(CONTENT_TYPE, "Content-Type",                                                                                   \
       "Payload media type indicating both data format and intended manner of processing by recipient")                \
    XX(CONTENT_TRANSFER_ENCODING, "Content-Transfer-Encoding", "Coding method used in a MIME message body part")       \
    XX(CACHE_CONTROL, "Cache-Control", "Directives for caches along the request/response chain")                       \
    XX(DATE, "Date", "Message originating date/time")                                                                  \
    XX(ETAG, "ETag",                                                                                                   \
       "Validates resource, such as a file, so recipient can confirm whether it has changed - generally more "         \
       "reliable than Date")                                                                                           \
    XX(FROM, "From", "email address of human user who controls the requesting user agent")                             \
    XX(HOST, "Host",                                                                                                   \
       "Request host and port information for target URI; allows server to service requests for multiple hosts on a "  \
       "single IP address")                                                                                            \
    XX(IF_MATCH, "If-Match",                                                                                           \
       "Precondition check using ETag to avoid accidental overwrites when servicing multiple user requests. Ensures "  \
       "resource entity tag matches before proceeding.")                                                               \
    XX(IF_MODIFIED_SINCE, "If-Modified-Since", "Precondition check using Date")                                        \
    XX(LAST_MODIFIED, "Last-Modified", "Server timestamp indicating date and time resource was last modified")         \
    XX(LOCATION, "Location", "Used in redirect responses, amongst other places")                                       \
    XX(SEC_WEBSOCKET_ACCEPT, "Sec-WebSocket-Accept", "Server response to opening Websocket handshake")                 \
    XX(SEC_WEBSOCKET_VERSION, "Sec-WebSocket-Version",                                                                 \
       "Websocket opening request indicates acceptable protocol version. Can appear more than once.")                  \
    XX(SEC_WEBSOCKET_KEY, "Sec-WebSocket-Key", "Websocket opening request validation key")                             \
    XX(SEC_WEBSOCKET_PROTOCOL, "Sec-WebSocket-Protocol",                                                               \
       "Websocket opening request indicates supported protocol(s), response contains negotiated protocol(s)")          \
    XX(SERVER, "Server", "Identifies software handling requests")                                                      \
    XX(SET_COOKIE, "Set-Cookie", "Server may pass name/value pairs and associated metadata to user agent (client)")    \
    XX(SUBJECT, "Subject", "email subject line")                                                                       \
    XX(TO, "To", "email intended recipient address")                                                                   \
    XX(TRANSFER_ENCODING, "Transfer-Encoding", "e.g. Chunked, compress, deflate, gzip")                                \
    XX(UPGRADE, "Upgrade",                                                                                             \
       "Used to transition from HTTP to some other protocol on the same connection. e.g. Websocket")                   \
    XX(USER_AGENT, "User-Agent", "Information about the user agent originating the request")                           \
    XX(WWW_AUTHENTICATE, "WWW-Authenticate", "Indicates HTTP authentication scheme(s) and applicable parameters")

enum HttpHeaderFieldName {
    HTTP_HEADER_UNKNOWN = 0,
#define XX(_tag, _str, _comment) HTTP_HEADER_##_tag,
    HTTP_HEADER_FIELDNAME_MAP(XX)
#undef XX
        HTTP_HEADER_CUSTOM // First custom header tag value
};

class HttpHeaders : private HashMap<HttpHeaderFieldName, String>
{
public:
    HttpHeaders() = default;

    HttpHeaders(const HttpHeaders& headers)
    {
        *this = headers;
    }

    String toString(HttpHeaderFieldName name) const;

    static String toString(const String& name, const String& value);

    String toString(HttpHeaderFieldName name, const String& value) const
    {
        return toString(toString(name), value);
    }

    HttpHeaderFieldName fromString(const String& name) const;

    using HashMap::operator[];

    const String& operator[](const String& name) const
    {
        auto field = fromString(name);
        if(field == HTTP_HEADER_UNKNOWN) {
            return nil;
        }
        return operator[](field);
    }

    String& operator[](const String& name)
    {
        auto field = fromString(name);
        if(field == HTTP_HEADER_UNKNOWN) {
            field = static_cast<HttpHeaderFieldName>(HTTP_HEADER_CUSTOM + customFieldNames.count());
            customFieldNames.add(name);
        }
        return operator[](field);
    }

    String operator[](unsigned index) const
    {
        return toString(keyAt(index), valueAt(index));
    }

    using HashMap::contains;

    bool contains(const String& name) const
    {
        return contains(fromString(name));
    }

    using HashMap::remove;

    void remove(const String& name)
    {
        remove(fromString(name));
    }

    void setMultiple(const HttpHeaders& headers)
    {
        for(unsigned i = 0; i < headers.count(); i++) {
            HttpHeaderFieldName fieldName = headers.keyAt(i);
            auto fieldNameString = headers.toString(fieldName);
            operator[](fieldNameString) = headers.valueAt(i);
        }
    }

    HttpHeaders& operator=(const HttpHeaders& headers)
    {
        clear();
        setMultiple(headers);
        return *this;
    }

    void clear()
    {
        customFieldNames.clear();
        HashMap::clear();
    }

    using HashMap::count;

    DateTime getLastModifiedDate() const
    {
        DateTime dt;
        String strLM = operator[](HTTP_HEADER_LAST_MODIFIED);
        return dt.fromHttpDate(strLM) ? dt : DateTime();
    }

    DateTime getServerDate() const
    {
        DateTime dt;
        String strSD = operator[](HTTP_HEADER_DATE);
        return dt.fromHttpDate(strSD) ? dt : DateTime();
    }

private:
    HttpHeaderFieldName findCustomFieldName(const String& name) const;

    CStringArray customFieldNames;
};

#endif /* _SMING_CORE_NETWORK_HTTP_HTTP_HEADERS_H_ */