/* Copyright (C) 2005 J.F.Dockes
 *   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 2 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, write to the
 *   Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */
#ifndef TEST_MH_MBOX
#include "autoconfig.h"

#include <stdio.h>
#include <errno.h>
#include <sys/types.h>
#include "safesysstat.h"
#include <time.h>

#include <cstring>
#include <map>
#include <mutex>

#include "cstr.h"
#include "mimehandler.h"
#include "log.h"
#include "readfile.h"
#include "mh_mbox.h"
#include "smallut.h"
#include "rclconfig.h"
#include "md5ut.h"
#include "conftree.h"

using namespace std;

// Define maximum message size for safety. 100MB would seem reasonable
static const unsigned int max_mbox_member_size = 100 * 1024 * 1024;

class FpKeeper { 
public:
    FpKeeper(FILE **fpp) : m_fpp(fpp) {}
    ~FpKeeper() 
    {
        if (m_fpp && *m_fpp) {
            fclose(*m_fpp);
            *m_fpp = 0;
        }
    }
private: FILE **m_fpp;
};

static std::mutex o_mcache_mutex;

/**
 * Handles a cache for message numbers to offset translations. Permits direct
 * accesses inside big folders instead of having to scan up to the right place
 *
 * Message offsets are saved to files stored under cfg(mboxcachedir), default
 * confdir/mboxcache. Mbox files smaller than cfg(mboxcacheminmbs) are not
 * cached.
 * Cache files are named as the md5 of the file UDI, which is kept in
 * the first block for possible collision detection. The 64 bits
 * offsets for all message "From_" lines follow. The format is purely
 * binary, values are not even byte-swapped to be proc-idependant.
 */

#ifdef _WIN32
// vc++ does not let define an array of size o_b1size because non-const??
#define M_o_b1size 1024
#else
#define M_o_b1size o_b1size
#endif

class MboxCache {
public:
    typedef MimeHandlerMbox::mbhoff_type mbhoff_type;
    MboxCache()
        : m_ok(false), m_minfsize(0)
    { 
        // Can't access rclconfig here, we're a static object, would
        // have to make sure it's initialized.
    }

    ~MboxCache() {}
    mbhoff_type get_offset(RclConfig *config, const string& udi, int msgnum)
    {
        LOGDEB0("MboxCache::get_offsets: udi [" << (udi) << "] msgnum " << (msgnum) << "\n");
        if (!ok(config)) {
            LOGDEB0("MboxCache::get_offsets: init failed\n");
            return -1;
        }
        std::unique_lock<std::mutex> locker(o_mcache_mutex);
        string fn = makefilename(udi);
        FILE *fp = 0;
        if ((fp = fopen(fn.c_str(), "r")) == 0) {
            LOGDEB("MboxCache::get_offsets: open failed, errno " << (errno) << "\n");
            return -1;
        }
        FpKeeper keeper(&fp);

        char blk1[M_o_b1size];
        if (fread(blk1, 1, o_b1size, fp) != o_b1size) {
            LOGDEB0("MboxCache::get_offsets: read blk1 errno " << (errno) << "\n");
            return -1;
        }
        ConfSimple cf(string(blk1, o_b1size));
        string fudi;
        if (!cf.get("udi", fudi) || fudi.compare(udi)) {
            LOGINFO("MboxCache::get_offset:badudi fn " << (fn) << " udi [" << (udi) << "], fudi [" << (fudi) << "]\n");
            return -1;
        }
        if (fseeko(fp, cacheoffset(msgnum), SEEK_SET) != 0) {
            LOGDEB0("MboxCache::get_offsets: seek " << (lltodecstr(cacheoffset(msgnum))) << " errno " << (errno) << "\n");
            return -1;
        }
        mbhoff_type offset = -1;
        size_t ret;
        if ((ret = fread(&offset, 1, sizeof(mbhoff_type), fp))
            != sizeof(mbhoff_type)) {
            LOGDEB0("MboxCache::get_offsets: read ret " << (ret) << " errno " << (errno) << "\n");
            return -1;
        }
        LOGDEB0("MboxCache::get_offsets: ret " << (lltodecstr(offset)) << "\n");
        return offset;
    }

    // Save array of offsets for a given file, designated by Udi
    void put_offsets(RclConfig *config, const string& udi, mbhoff_type fsize,
                     vector<mbhoff_type>& offs)
    {
        LOGDEB0("MboxCache::put_offsets: " << (offs.size()) << " offsets\n");
        if (!ok(config) || !maybemakedir())
            return;
        if (fsize < m_minfsize)
            return;
        std::unique_lock<std::mutex> locker(o_mcache_mutex);
        string fn = makefilename(udi);
        FILE *fp;
        if ((fp = fopen(fn.c_str(), "w")) == 0) {
            LOGDEB("MboxCache::put_offsets: fopen errno " << (errno) << "\n");
            return;
        }
        FpKeeper keeper(&fp);
        string blk1;
        blk1.append("udi=");
        blk1.append(udi);
        blk1.append(cstr_newline);
        blk1.resize(o_b1size, 0);
        if (fwrite(blk1.c_str(), 1, o_b1size, fp) != o_b1size) {
            LOGDEB("MboxCache::put_offsets: fwrite errno " << (errno) << "\n");
            return;
        }

        for (vector<mbhoff_type>::const_iterator it = offs.begin();
             it != offs.end(); it++) {
            mbhoff_type off = *it;
            if (fwrite((char*)&off, 1, sizeof(mbhoff_type), fp) != 
                sizeof(mbhoff_type)) {
                return;
            }
        }
    }

    // Check state, possibly initialize
    bool ok(RclConfig *config) {
        std::unique_lock<std::mutex> locker(o_mcache_mutex);
        if (m_minfsize == -1)
            return false;
        if (!m_ok) {
            int minmbs = 5;
            config->getConfParam("mboxcacheminmbs", &minmbs);
            if (minmbs < 0) {
                // minmbs set to negative to disable cache
                m_minfsize = -1;
                return false;
            }
            m_minfsize = minmbs * 1000 * 1000;

            m_dir = config->getMboxcacheDir();
            m_ok = true;
        }
        return m_ok;
    }

private:
    bool m_ok;

    // Place where we store things
    string m_dir;
    // Don't cache smaller files. If -1, don't do anything.
    mbhoff_type m_minfsize;
    static const size_t o_b1size;

    // Create the cache directory if it does not exist
    bool maybemakedir()
    {
        struct stat st;
        if (stat(m_dir.c_str(), &st) != 0 && mkdir(m_dir.c_str(), 0700) != 0) {
            return false;
        }
        return true;
    }
    // Compute file name from udi
    string makefilename(const string& udi)
    {
        string digest, xdigest;
        MD5String(udi, digest);
        MD5HexPrint(digest, xdigest);
        return path_cat(m_dir, xdigest);
    }

    // Compute offset in cache file for the mbox offset of msgnum
    mbhoff_type cacheoffset(int msgnum)
    {// Msgnums are from 1
        return o_b1size + (msgnum-1) * sizeof(mbhoff_type);
    }
};

const size_t MboxCache::o_b1size = 1024;
static class MboxCache o_mcache;

static const string cstr_keyquirks("mhmboxquirks");

MimeHandlerMbox::~MimeHandlerMbox()
{
    clear();
}

void MimeHandlerMbox::clear_impl()
{
    m_fn.erase();
    if (m_vfp) {
	fclose((FILE *)m_vfp);
	m_vfp = 0;
    }
    m_msgnum =  m_lineno = 0;
    m_ipath.erase();
    m_offsets.clear();
}

bool MimeHandlerMbox::set_document_file_impl(const string& mt, const string &fn)
{
    LOGDEB("MimeHandlerMbox::set_document_file(" << fn << ")\n");
    m_fn = fn;
    if (m_vfp) {
	fclose((FILE *)m_vfp);
	m_vfp = 0;
    }

    m_vfp = fopen(fn.c_str(), "r");
    if (m_vfp == 0) {
	LOGERR("MimeHandlerMail::set_document_file: error opening " << fn <<
               "\n");
	return false;
    }
#if defined O_NOATIME && O_NOATIME != 0
    if (fcntl(fileno((FILE *)m_vfp), F_SETFL, O_NOATIME) < 0) {
        // perror("fcntl");
    }
#endif
    // Used to use ftell() here: no good beyond 2GB
    {struct stat st;
	if (fstat(fileno((FILE*)m_vfp), &st) < 0) {
	    LOGERR("MimeHandlerMbox:setdocfile: fstat(" << fn <<
                   ") failed errno " << errno << "\n");
	    return false;
	}
	m_fsize = st.st_size;
    }
    m_havedoc = true;
    m_offsets.clear();
    m_quirks = 0;

    // Check for location-based quirks:
    string quirks;
    if (m_config && m_config->getConfParam(cstr_keyquirks, quirks)) {
	if (quirks == "tbird") {
	    LOGDEB("MimeHandlerMbox: setting quirks TBIRD\n");
	    m_quirks |= MBOXQUIRK_TBIRD;
	}
    }

    // And double check for thunderbird 
    string tbirdmsf = fn + ".msf";
    if ((m_quirks&MBOXQUIRK_TBIRD) == 0 && path_exists(tbirdmsf)) {
	LOGDEB("MimeHandlerMbox: detected unconfigured tbird mbox in " << (fn) << "\n");
	m_quirks |= MBOXQUIRK_TBIRD;
    }

    return true;
}

#define LL 1024
typedef char line_type[LL+10];
static inline void stripendnl(line_type& line, int& ll)
{
    ll = int(strlen(line));
    while (ll > 0) {
	if (line[ll-1] == '\n' || line[ll-1] == '\r') {
	    line[ll-1] = 0;
	    ll--;
	} else 
	    break;
    }
}

// The mbox format uses lines beginning with 'From ' as separator.
// Mailers are supposed to quote any other lines beginning with 
// 'From ', turning it into '>From '. This should make it easy to detect
// message boundaries by matching a '^From ' regular expression
// Unfortunately this quoting is quite often incorrect in the real world.
//
// The rest of the format for the line is somewhat variable, but there will 
// be a 4 digit year somewhere... 
// The canonic format is the following, with a 24 characters date: 
//         From toto@tutu.com Sat Sep 30 16:44:06 2000
// This resulted into the pattern for versions up to 1.9.0: 
//         "^From .* [1-2][0-9][0-9][0-9]$"
//
// Some mailers add a time zone to the date, this is non-"standard", 
// but happens, like in: 
//    From toto@truc.com Sat Sep 30 16:44:06 2000 -0400 
//
// This is taken into account in the new regexp, which also matches more
// of the date format, to catch a few actual issues like
//     From http://www.itu.int/newsroom/press/releases/1998/NP-2.html:
// Note that this *should* have been quoted.
//
// http://www.qmail.org/man/man5/mbox.html seems to indicate that the
// fact that From_ is normally preceded by a blank line should not be
// used, but we do it anyway (for now).
// The same source indicates that arbitrary data can follow the date field
//
// A variety of pathologic From_ lines:
//   Bad date format:
//      From uucp Wed May 22 11:28 GMT 1996
//   Added timezone at the end (ok, part of the "any data" after the date)
//      From qian2@fas.harvard.edu Sat Sep 30 16:44:06 2000 -0400
//  Emacs VM botch ? Adds tz between hour and year
//      From dockes Wed Feb 23 10:31:20 +0100 2005
//      From dockes Fri Dec  1 20:36:39 +0100 2006
// The modified regexp gives the exact same results on the ietf mail archive
// and my own's.
// Update, 2008-08-29: some old? Thunderbird versions apparently use a date
// in "Date: " header format, like:   From - Mon, 8 May 2006 10:57:32
// This was added as an alternative format. By the way it also fools "mail" and
// emacs-vm, Recoll is not alone
// Update: 2009-11-27: word after From may be quoted string: From "john bull"
static const string frompat{
"^From[ ]+([^ ]+|\"[^\"]+\")[ ]+"    // 'From (toto@tutu|"john bull") '
"[[:alpha:]]{3}[ ]+[[:alpha:]]{3}[ ]+[0-3 ][0-9][ ]+" // Fri Oct 26
"[0-2][0-9]:[0-5][0-9](:[0-5][0-9])?[ ]+"             // Time, seconds optional
"([^ ]+[ ]+)?"                                        // Optional tz
"[12][0-9][0-9][0-9]"            // Year, unanchored, more data may follow
"|"      // Or standard mail Date: header format
"^From[ ]+[^ ]+[ ]+"                                   // From toto@tutu
"[[:alpha:]]{3},[ ]+[0-3]?[0-9][ ]+[[:alpha:]]{3}[ ]+" // Mon, 8 May
"[12][0-9][0-9][0-9][ ]+"                              // Year
"[0-2][0-9]:[0-5][0-9](:[0-5][0-9])?"                  // Time, secs optional
    };

// Extreme thunderbird brokiness. Will sometimes use From lines
// exactly like: From ^M (From followed by space and eol). We only
// test for this if QUIRKS_TBIRD is set
static const string miniTbirdFrom{"^From $"};

static SimpleRegexp fromregex(frompat, SimpleRegexp::SRE_NOSUB);
static SimpleRegexp minifromregex(miniTbirdFrom, SimpleRegexp::SRE_NOSUB);

bool MimeHandlerMbox::next_document()
{
    if (m_vfp == 0) {
	LOGERR("MimeHandlerMbox::next_document: not open\n");
	return false;
    }
    if (!m_havedoc) {
	return false;
    }
    FILE *fp = (FILE *)m_vfp;
    int mtarg = 0;
    if (!m_ipath.empty()) {
	sscanf(m_ipath.c_str(), "%d", &mtarg);
    } else if (m_forPreview) {
	// Can't preview an mbox. 
	LOGDEB("MimeHandlerMbox::next_document: can't preview folders!\n");
	return false;
    }
    LOGDEB0("MimeHandlerMbox::next_document: fn " << m_fn << ", msgnum " <<
            m_msgnum << " mtarg " << mtarg << " \n");
    if (mtarg == 0)
	mtarg = -1;


    // If we are called to retrieve a specific message, seek to bof
    // (then scan up to the message). This is for the case where the
    // same object is reused to fetch several messages (else the fp is
    // just opened no need for a seek).  We could also check if the
    // current message number is lower than the requested one and
    // avoid rereading the whole thing in this case. But I'm not sure
    // we're ever used in this way (multiple retrieves on same
    // object).  So:
    bool storeoffsets = true;
    if (mtarg > 0) {
        mbhoff_type off;
        line_type line;
        LOGDEB0("MimeHandlerMbox::next_doc: mtarg " << mtarg << " m_udi[" <<
                m_udi << "]\n");
        if (!m_udi.empty() && 
            (off = o_mcache.get_offset(m_config, m_udi, mtarg)) >= 0 && 
            fseeko(fp, (off_t)off, SEEK_SET) >= 0 && 
            fgets(line, LL, fp) &&
            (fromregex(line) || ((m_quirks & MBOXQUIRK_TBIRD) && 
                                 minifromregex(line)))	) {
                LOGDEB0("MimeHandlerMbox: Cache: From_ Ok\n");
                fseeko(fp, (off_t)off, SEEK_SET);
                m_msgnum = mtarg -1;
		storeoffsets = false;
        } else {
            fseek(fp, 0, SEEK_SET);
            m_msgnum = 0;
        }
    }

    off_t message_end = 0;
    bool iseof = false;
    bool hademptyline = true;
    string& msgtxt = m_metaData[cstr_dj_keycontent];
    msgtxt.erase();
    line_type line;
    for (;;) {
	message_end = ftello(fp);
	if (!fgets(line, LL, fp)) {
	    LOGDEB2("MimeHandlerMbox:next: eof\n");
	    iseof = true;
	    m_msgnum++;
	    break;
	}
	m_lineno++;
	int ll;
	stripendnl(line, ll);
	LOGDEB2("mhmbox:next: hadempty " << hademptyline << " lineno " <<
                m_lineno << " ll " << ll << " Line: [" << line << "]\n");
	if (hademptyline) {
	    if (ll > 0) {
		// Non-empty line with empty line flag set, reset flag
		// and check regex.
		if (!(m_quirks & MBOXQUIRK_TBIRD)) {
		    // Tbird sometimes ommits the empty line, so avoid
		    // resetting state (initially true) and hope for
		    // the best
		    hademptyline = false;
		}
		/* The 'F' compare is redundant but it improves performance
		   A LOT */
		if (line[0] == 'F' && (
                        fromregex(line) || 
                        ((m_quirks & MBOXQUIRK_TBIRD) && minifromregex(line)))
		    ) {
		    LOGDEB0("MimeHandlerMbox: msgnum " << m_msgnum <<
                            ", From_ at line " << m_lineno << ": [" << line
                            << "]\n");
		    if (storeoffsets)
			m_offsets.push_back(message_end);
		    m_msgnum++;
		    if ((mtarg <= 0 && m_msgnum > 1) || 
			(mtarg > 0 && m_msgnum > mtarg)) {
			// Got message, go do something with it
			break;
		    }
		    // From_ lines are not part of messages
		    continue;
		} 
	    }
	} else if (ll <= 0) {
	    hademptyline = true;
	}

	if (mtarg <= 0 || m_msgnum == mtarg) {
	    // Accumulate message lines
	    line[ll] = '\n';
	    line[ll+1] = 0;
	    msgtxt += line;
	    if (msgtxt.size() > max_mbox_member_size) {
		LOGERR("mh_mbox: huge message (more than " <<
                       max_mbox_member_size/(1024*1024) << " MB) inside " <<
                       m_fn << ", giving up\n");
		return false;
	    }
	}
    }
    LOGDEB2("Message text length " << msgtxt.size() << "\n");
    LOGDEB2("Message text: [" << msgtxt << "]\n");
    char buf[20];
    // m_msgnum was incremented when hitting the next From_ or eof, so the data
    // is for m_msgnum - 1
    sprintf(buf, "%d", m_msgnum - 1); 
    m_metaData[cstr_dj_keyipath] = buf;
    m_metaData[cstr_dj_keymt] = "message/rfc822";
    if (iseof) {
	LOGDEB2("MimeHandlerMbox::next: eof hit\n");
	m_havedoc = false;
	if (!m_udi.empty() && storeoffsets) {
	    o_mcache.put_offsets(m_config, m_udi, m_fsize, m_offsets);
	}
    }
    return msgtxt.empty() ? false : true;
}

#else // Test driver ->

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>

#include <iostream>
#include <string>
using namespace std;

#include "rclconfig.h"
#include "rclinit.h"
#include "cstr.h"
#include "mh_mbox.h"

static char *thisprog;

static char usage [] = 
"Test driver for mbox walking function\n"
"mh_mbox [-m num] mboxfile\n"
"  \n\n"
;
static void
Usage(void)
{
    fprintf(stderr, "%s: usage:\n%s", thisprog, usage);
    exit(1);
}
static RclConfig *config;
static int     op_flags;
#define OPT_MOINS 0x1
#define OPT_m	  0x2
//#define OPT_t     0x4

int main(int argc, char **argv)
{
    string msgnum;
    thisprog = argv[0];
    argc--; argv++;

    while (argc > 0 && **argv == '-') {
	(*argv)++;
	if (!(**argv))
	    /* Cas du "adb - core" */
	    Usage();
	while (**argv)
	    switch (*(*argv)++) {
	    case 'm':	op_flags |= OPT_m; if (argc < 2)  Usage();
		msgnum = *(++argv);
		argc--; 
		goto b1;
//	    case 't':	op_flags |= OPT_t;break;
	    default: Usage();	break;
	    }
    b1: argc--; argv++;
    }

    if (argc != 1)
	Usage();
    string filename = *argv++;argc--;
    string reason;
    config = recollinit(RclInitFlags(0), 0, 0, reason, 0);
    if (config == 0) {
	cerr << "init failed " << reason << endl;
	exit(1);
    }
    config->setKeyDir(path_getfather(filename));
    MimeHandlerMbox mh(config, "some_id");
    if (!mh.set_document_file("text/x-mail", filename)) {
	cerr << "set_document_file failed" << endl;
	exit(1);
    }
    if (!msgnum.empty()) {
	mh.skip_to_document(msgnum);
	if (!mh.next_document()) {
	    cerr << "next_document failed after skipping to " << msgnum << endl;
	    exit(1);
	}
	map<string, string>::const_iterator it = 
	    mh.get_meta_data().find(cstr_dj_keycontent);
	int size;
	if (it == mh.get_meta_data().end()) {
	    size = -1;
	    cerr << "No content!!" << endl;
	    exit(1);
	}
	cout << "Doc " << msgnum << ":" << endl;
	cout << it->second << endl;
	exit(0);
    }

    int docnt = 0;
    while (mh.has_documents()) {
	if (!mh.next_document()) {
	    cerr << "next_document failed" << endl;
	    exit(1);
	}
	docnt++;
	map<string, string>::const_iterator it = 
	    mh.get_meta_data().find(cstr_dj_keycontent);
	int size;
	if (it == mh.get_meta_data().end()) {
	    size = -1;
	} else {
	    size = it->second.length();
	}
	cout << "Doc " << docnt << " size " << size << endl;
    }
    cout << docnt << " documents found in " << filename << endl;
    exit(0);
}


#endif // TEST_MH_MBOX