/*==LICENSE==*

CyanWorlds.com Engine - MMOG client, server and tools
Copyright (C) 2011  Cyan Worlds, Inc.

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.

Additional permissions under GNU GPL version 3 section 7

If you modify this Program, or any covered work, by linking or
combining it with any of RAD Game Tools Bink SDK, Autodesk 3ds Max SDK,
NVIDIA PhysX SDK, Microsoft DirectX SDK, OpenSSL library, Independent
JPEG Group JPEG library, Microsoft Windows Media SDK, or Apple QuickTime SDK
(or a modified version of those libraries),
containing parts covered by the terms of the Bink SDK EULA, 3ds Max EULA,
PhysX SDK EULA, DirectX SDK EULA, OpenSSL and SSLeay licenses, IJG
JPEG Library README, Windows Media SDK EULA, or QuickTime SDK EULA, the
licensors of this Program grant you additional
permission to convey the resulting work. Corresponding Source for a
non-source form of such a combination shall include the source code for
the parts of OpenSSL and IJG JPEG Library used as well as that of the covered
work.

You can contact Cyan Worlds, Inc. by email legal@cyan.com
 or by snail mail at:
      Cyan Worlds, Inc.
      14617 N Newport Hwy
      Mead, WA   99021

*==LICENSE==*/
/*****************************************************************************
*
*   $/Plasma20/Sources/Plasma/NucleusLib/pnMail/pnMail.cpp
*   
***/

#include "Pch.h"
#pragma hdrstop


/*****************************************************************************
*
*   Private
*
***/

enum EMailStep {
    kMailStepConnect,       // wait for 220, then send "helo" command
    kMailStepAuth,          // wait for 250, then send "AUTH PLAIN <base64data>"
    kMailStepSender,        // wait for 235/250, then send "mail from:" command
    kMailStepRecipient,     // wait for 250, then send "rcpt to:" command
    kMailStepStartLetter,   // wait for 250, then send "data" command
    kMailStepLetter,        // wait for 354, then send letter
    kMailStepQuit,          // wait for 250, then send "quit" command
    kMailStepDisconnect,    // wait for 221, then disconnect
};


struct MailTransaction {
    LINK(MailTransaction)       link;
    AsyncSocket                 sock;
    const char **               stepTable;
    EMailStep                   step;
    unsigned                    subStep;
    EMailError                  error;
    FMailResult                 callback;
    void *                      param;

    char *                      smtp;
    char *                      sender;
    char *                      recipient;
    char *                      replyTo;
    char *                      subject;
    char *                      bodyEncoding;
    char *                      body;
    char *                      auth;
    char                        buffer[1];
};

static bool MailNotifyProc (
    AsyncSocket         sock,
    EAsyncNotifySocket  code,
    AsyncNotifySocket * notify,
    void **             userState
);

static void __cdecl Send (
    AsyncSocket sock,
    const char  str[],
    ...
);


/*****************************************************************************
*
*   Private data
*
***/

static bool                             s_shutdown;
static CCritSect                        s_critsect;
static LISTDECL(MailTransaction, link)  s_mail;


//===========================================================================
// Authenticated email sequence
//      -> "220 catherine.cyan.com ESMTP\r\n"
//      <- "HELO cyan.com\r\n"
//      -> "250 catherine.cyan.com\r\n"
//      <- "AUTH PLAIN XXXXXXXXX\r\n"
//      -> "235 go ahead\r\n"
//      <- "MAIL FROM:<UruClient@cyanworlds.com>\r\n"
//      -> "250 ok mail from accepted\r\n"
//      <- "RCPT TO:<UruCrashReport@cyanworlds.com>\r\n"
//      -> "250 ok recipient accepted\r\n"
//      <- "DATA\r\n"
//      -> "354 ok, go ahead:\r\n"
//      ->  <message> + "\r\n.\r\n"
//      -> "250 message accepted for delivery\r\n"
//      <- "QUIT\r\n"
//      -> "221 catherine.cyan.com\r\n"
//===========================================================================
static const char * s_waitStrAuth[] = {
    "220 ", // kMailStepConnect
    "250 ", // kMailStepAuth
    "235 ", // kMailStepSender
    "250 ", // kMailStepRecipient
    "250 ", // kMailStepStartLetter
    "354 ", // kMailStepLetter
    "250 ", // kMailStepQuit
    "221 ", // kMailStepDisconnect
};

//===========================================================================
// Unauthenticated email seqeunce
//      -> "220 catherine.cyan.com ESMTP\r\n"
//      <- "HELO cyan.com\r\n"
//      -> "250 catherine.cyan.com\r\n"
//      <- "MAIL FROM:<UruClient@cyanworlds.com>\r\n"
//      -> "250 ok mail from accepted\r\n"
//      <- "RCPT TO:<UruCrashReport@cyanworlds.com>\r\n"
//      -> "250 ok recipient accepted\r\n"
//      <- "DATA\r\n"
//      -> "354 ok, go ahead:\r\n"
//      ->  <message> + "\r\n.\r\n"
//      -> "250 message accepted for delivery\r\n"
//      <- "QUIT\r\n"
//      -> "221 catherine.cyan.com\r\n"
//===========================================================================
static const char * s_waitStrNoAuth[] = {
    "220 ", // kMailStepConnect
    nil,    // kMailStepAuth
    "250 ", // kMailStepSender
    "250 ", // kMailStepRecipient
    "250 ", // kMailStepStartLetter
    "354 ", // kMailStepLetter
    "250 ", // kMailStepQuit
    "221 ", // kMailStepDisconnect
};



/*****************************************************************************
*
*   Internal functions
*
***/

//===========================================================================
static bool AdvanceStep (
    MailTransaction *   transaction,
    AsyncSocket         sock
) {
    switch (transaction->step) {
        case kMailStepConnect: {
            const char * host      = transaction->sender;
            const char * separator = StrChr(host, '@');
            if (separator)
                host = separator + 1;
            Send(sock, "helo ", host, "\r\n", nil);
            transaction->step = kMailStepSender;

            if (transaction->auth[0])
                transaction->step = kMailStepAuth;
        }
        break;

        case kMailStepAuth:
            Send(sock, "AUTH PLAIN ", transaction->auth, "\r\n", nil);
            transaction->step = kMailStepSender;
        break;

        case kMailStepSender:
            Send(sock, "mail from:<", transaction->sender, ">\r\n", nil);
            transaction->step    = kMailStepRecipient;
        break;

        case kMailStepRecipient: {
            const char * start = transaction->recipient + transaction->subStep;
            while (*start == ' ')
                ++start;
            const char * term = StrChr(start, ';');
            if (term) {
                char * buffer = ALLOCA(char, term + 1 - start);
                StrCopy(buffer, start, term + 1 - start);
                Send(sock, "rcpt to:<", buffer, ">\r\n", nil);
                transaction->subStep = term + 1 - transaction->recipient;
            }
            else {
                Send(sock, "rcpt to:<", start, ">\r\n", nil);
                transaction->step       = kMailStepStartLetter;
                transaction->subStep    = 0;
            }
        }
        break;

        case kMailStepStartLetter:
            Send(sock, "data\r\n", nil);
            transaction->step = kMailStepLetter;
        break;

        case kMailStepLetter:
            if (transaction->replyTo[0]) {
                Send(
                    sock,
                    "Reply-to: ",
                    transaction->replyTo,
                    "\r\n",
                    nil
                );
            }
            if (transaction->bodyEncoding) {
                Send(
                    sock, 
                    "From: ",
                    transaction->sender,
                    "\r\nTo: ",
                    transaction->recipient,
                    "\r\nSubject: ",
                    transaction->subject,
                    "\r\nContent-Type: text/plain; charset=",
                    transaction->bodyEncoding,
                    "\r\n\r\n",
                    transaction->body,
                    "\r\n.\r\n",
                    nil
                );
            }
            else {
                Send(
                    sock, 
                    "From: ",
                    transaction->sender,
                    "\r\nTo: ",
                    transaction->recipient,
                    "\r\nSubject: ",
                    transaction->subject,
                    "\r\n\r\n",
                    transaction->body,
                    "\r\n.\r\n",
                    nil
                );
            }
            transaction->step = kMailStepQuit;
        break;

        case kMailStepQuit:
            Send(sock, "quit\r\n", nil);
            transaction->step = kMailStepDisconnect;
        break;

        case kMailStepDisconnect:
        return false;

        DEFAULT_FATAL(transaction->step);
    }

    return true;
}

//===========================================================================
static bool NotifyRead (
    AsyncSocket             sock,
    AsyncNotifySocketRead * read,
    MailTransaction *       transaction
) {

    // Parse available lines looking for an acknowledgement of last command
    const char * compareStr = transaction->stepTable[transaction->step];
    unsigned     compareLen = StrLen(compareStr);
    unsigned     offset     = 0;
    for (;;) {
        const char * source = (const char *)&read->buffer[offset];

        // Search for an end-of-line marker
        const char * eol = StrChr(source, '\n', read->bytes - offset);
        if (!eol)
            break;
        offset += (eol + 1 - source);

        // Search for an acknowledgement
        if (!StrCmp(source, compareStr, compareLen)) {
            read->bytesProcessed = offset;
            return AdvanceStep(transaction, sock);
        }

        // An error was received; log it and bail
        LogMsg(
            kLogError,
            "Mail: step %u error '%.*s'",
            transaction->step,
            eol - source - 1,
            source
        );
        transaction->error = kMailErrServerError;
        return false;
    }

    // We did not find an acknowledgement, so skip past fully-received lines
    // and wait for more data to arrive
    read->bytesProcessed = offset;
    return true;

}

//===========================================================================
static void DestroyTransaction (MailTransaction * transaction) {
   
    // Remove transaction from list so that it can
    // be safely deleted outside the critical section
    s_critsect.Enter();
    {
        s_mail.Unlink(transaction);
    }
    s_critsect.Leave();

    // Perform callback if requested
    if (transaction->callback) {
        transaction->callback(
            transaction->param,
            transaction->error
        );
    }

    DEL(transaction);
}

//===========================================================================
static void MailLookupProc (
    void *              param,
    const wchar_t *       ,
    unsigned            addrCount,
    const NetAddress    addrs[]
) {

    // If no address was found, cancel the transaction
    MailTransaction * transaction = (MailTransaction *) param;
    if (!addrCount) {
        LogMsg(kLogError,"Mail: failed to resolve %s", transaction->smtp);
        transaction->error = kMailErrDnsFailed;
        DestroyTransaction(transaction);
        return;
    }

    // Initiate a connection
    AsyncCancelId cancelId;
    AsyncSocketConnect(
        &cancelId,
        addrs[0],
        MailNotifyProc,
        transaction
    );

}

//===========================================================================
static bool MailNotifyProc (
    AsyncSocket         sock,
    EAsyncNotifySocket  code,
    AsyncNotifySocket * notify,
    void **             userState
) {
    switch (code) {
        case kNotifySocketConnectFailed: {
            MailTransaction * transaction = (MailTransaction *)notify->param;
            LogMsg(kLogError, "Mail: unable to connect to %s", transaction->smtp);
            transaction->error = kMailErrConnectFailed;
            DestroyTransaction(transaction);
        }
        break;

        case kNotifySocketConnectSuccess: {
            MailTransaction * transaction   = (MailTransaction *) notify->param;
            *userState                      = notify->param;
            transaction->sock               = sock;
        }
        break;

        case kNotifySocketRead: {
            MailTransaction * transaction = (MailTransaction *) *userState;
            return NotifyRead(sock, (AsyncNotifySocketRead *) notify, transaction);
        }
        break;

        case kNotifySocketDisconnect: {
            MailTransaction * transaction = (MailTransaction *) *userState;
            if ((transaction->step != kMailStepDisconnect) && !transaction->error) {
                transaction->error = kMailErrDisconnected;
                LogMsg(kLogError, "Mail: unexpected disconnection from %s", transaction->smtp);
            }
            DestroyTransaction(transaction);
            AsyncSocketDelete(sock);
        }
        break;
    }

    return !s_shutdown;
}

//===========================================================================
static void __cdecl Send (
    AsyncSocket sock,
    const char  str[],
    ...
) {
    // Count bytes
    unsigned bytes = 1;
    {
        va_list argList;
        va_start(argList, str);
        for (const char * source = str; source; source = va_arg(argList, const char *))
            bytes += StrLen(source);
        va_end(argList);
    }

    // Allocate string buffer
    char * packed;
    const unsigned kStackBufSize = 8 * 1024;
    if (bytes > kStackBufSize)
        packed = (char *) ALLOC(bytes);
    else
        packed = (char *) _alloca(bytes);

    // Pack the string
    {
        va_list argList;
        va_start(argList, str);
        char * dest = packed;
        for (const char * source = str; source; source = va_arg(argList, const char *))
            dest += StrCopyLen(dest, source, packed + bytes - dest);
        va_end(argList);
    }

    // Send the string
    AsyncSocketSend(sock, packed, bytes - 1);

    // Free the string
    if (bytes > kStackBufSize)
        FREE(packed);
}

//===========================================================================
static void IMail (
    const char *    stepTable[],
    const char      smtp[],
    const char      sender[],
    const char      recipient[],
    const char      replyTo[],
    const char      subject[],
    const char      body[],
    const char      auth[],
    EMailEncoding   bodyEncoding,
    FMailResult     callback,
    void *          param
) {
    static const char * utf8  = "\"utf-8\"";
    const char * encodingStr;

    if (bodyEncoding == kMailEncodeUtf8)
        encodingStr = utf8;
    else
        encodingStr = "";
    
    // Calculate string lengths
    unsigned lenSmtp         = StrLen(smtp);
    unsigned lenSender       = StrLen(sender);
    unsigned lenRecipient    = StrLen(recipient);
    unsigned lenReplyTo      = StrLen(replyTo);
    unsigned lenSubject      = StrLen(subject);
    unsigned lenBodyEncoding = StrLen(encodingStr);
    unsigned lenBody         = StrLen(body);
    unsigned lenAuth         = StrLen(auth);

    // Calculate the required buffer size for all strings
    unsigned bytes = (
        lenSmtp         + 1 +
        lenSender       + 1 +
        lenRecipient    + 1 +
        lenReplyTo      + 1 +
        lenSubject      + 1 +
        lenBody         + 1 +
        lenAuth         + 1
    ) * sizeof(char);

    if (lenBodyEncoding)
        bytes += (lenBodyEncoding + 1) * sizeof(char);

    // Create a transaction record
    MailTransaction * transaction = new(
        ALLOC(offsetof(MailTransaction, buffer) + bytes)
    ) MailTransaction;
    transaction->stepTable  = stepTable;
    transaction->sock       = nil;
    transaction->step       = kMailStepConnect;
    transaction->subStep    = 0;
    transaction->error      = kMailSuccess;
    transaction->callback   = callback;
    transaction->param      = param;

    unsigned offset = 0;
    transaction->smtp     = transaction->buffer + offset;
    offset += StrCopyLen(transaction->smtp,      smtp,       lenSmtp       + 1) + 1;
    transaction->sender    = transaction->buffer + offset;
    offset += StrCopyLen(transaction->sender,    sender,     lenSender     + 1) + 1;
    transaction->recipient = transaction->buffer + offset;
    offset += StrCopyLen(transaction->recipient, recipient,  lenRecipient  + 1) + 1;
    transaction->replyTo   = transaction->buffer + offset;
    offset += StrCopyLen(transaction->replyTo,   replyTo,    lenReplyTo    + 1) + 1;
    transaction->subject   = transaction->buffer + offset;
    offset += StrCopyLen(transaction->subject,   subject,    lenSubject    + 1) + 1;
    if (lenBodyEncoding) {
        transaction->bodyEncoding = transaction->buffer + offset;
        offset += StrCopyLen(transaction->bodyEncoding, encodingStr, lenBodyEncoding + 1) + 1;
    }
    else {
        transaction->bodyEncoding = nil;
    }
    transaction->body      = transaction->buffer + offset;
    offset += StrCopyLen(transaction->body,      body,       lenBody       + 1) + 1;
    transaction->auth      = transaction->buffer + offset;
    offset += StrCopyLen(transaction->auth,      auth,       lenAuth       + 1) + 1;
    ASSERT(offset == bytes);

    // Start the transaction with a dns lookup
    const unsigned kSmtpPort = 25;
    wchar_t smtpName[256];
    StrToUnicode(smtpName, smtp, arrsize(smtpName));

    // Add transaction to global list
    bool shutdown;
    s_critsect.Enter();
    {
        shutdown = s_shutdown;
        s_mail.Link(transaction);
    }
    s_critsect.Leave();

    if (shutdown) {
        DestroyTransaction(transaction);
    }
    else {
        NetAddress addr;
        if (NetAddressFromString(&addr, smtpName, kSmtpPort)) {
            AsyncCancelId cancelId;
            AsyncSocketConnect(
                &cancelId,
                addr,
                MailNotifyProc,
                transaction
            );
        }
        else {
            AsyncCancelId cancelId;
            AsyncAddressLookupName(
                &cancelId,
                MailLookupProc,
                smtpName,
                kSmtpPort,
                transaction
            );
        }
    }
}

/****************************************************************************
*
*   Exported functions
*
***/

//===========================================================================
void MailEncodePassword (
    const char      username[],
    const char      password[],
    ARRAY(char) *   emailAuth
) {
    // base64_encode("\0#{user}\0#{secret}")
    emailAuth->Reserve(512);
    emailAuth->Push(0);
    emailAuth->Add(username, StrBytes(username));
    emailAuth->Add(password, StrBytes(password));
    unsigned srcChars = emailAuth->Bytes();

    // Allocate space for encoded data
    unsigned dstChars   = Base64EncodeSize(srcChars);
    char * dstData      = emailAuth->New(dstChars);

    // Encode data and move it back to the front of the array
    dstChars = Base64Encode(
        srcChars,
        (const uint8_t *) emailAuth->Ptr(),
        dstChars,
        dstData
    );
    emailAuth->Move(
        0,
        srcChars,
        dstChars
    );
    emailAuth->SetCountFewer(dstChars);
}

//===========================================================================
void Mail (
    const char      smtp[],
    const char      sender[],
    const char      recipient[], // multiple recipients separated by semicolons
    const char      subject[],
    const char      body[],
    const char      username[],
    const char      password[],
    const char      replyTo[],
    EMailEncoding   bodyEncoding,
    FMailResult     callback,
    void *          param
) {
    s_shutdown = false;

    // Get email authorization
    const char * auth;
    const char ** stepTable;
    ARRAY(char) authBuffer;
    if (!password || !*password) {
        // No password is specified, use non-authenticated email
        auth        = "";
        stepTable   = s_waitStrNoAuth;
    }
    else if (!username || !*username) {
        // No username specified, user is providing the base64 encoded secret
        auth        = password;
        stepTable   = s_waitStrAuth;
    }
    else {
        MailEncodePassword(username, password, &authBuffer);
        auth        = authBuffer.Ptr();
        stepTable   = s_waitStrAuth;
    }

    IMail(
        stepTable,
        smtp,
        sender,
        recipient,
        replyTo ? replyTo : "",
        subject,
        body,
        auth,
        bodyEncoding,
        callback,
        param
    );
}

//===========================================================================
void MailStop () {
    s_critsect.Enter();
    {
        s_shutdown = true;
        MailTransaction * transaction = s_mail.Head();
        for (; transaction; transaction = s_mail.Next(transaction)) {
            if (transaction->sock)
                AsyncSocketDisconnect(transaction->sock, true);
            transaction->error = kMailErrClientCanceled;
        }
    }
    s_critsect.Leave();

    AsyncAddressLookupCancel(
        MailLookupProc,
        0   // cancel all
    );
    AsyncSocketConnectCancel(
        MailNotifyProc,
        0   // cancel all
    );
}

//===========================================================================
bool MailQueued () {
    bool queued;
    s_critsect.Enter();
    queued = s_mail.Head() != nil;
    s_critsect.Leave();
    return queued;
}

//============================================================================
const wchar_t * MailErrorToString (EMailError error) {

    switch (error) {
        case kMailSuccess:              return L"kMailSuccess";
        case kMailErrDnsFailed:         return L"kMailErrDnsFailed";
        case kMailErrConnectFailed:     return L"kMailErrConnectFailed";
        case kMailErrDisconnected:      return L"kMailErrDisconnected";
        case kMailErrClientCanceled:    return L"kMailErrClientCanceled";
        case kMailErrServerError:       return L"kMailErrServerError";
        DEFAULT_FATAL(error);
    }
}