/*****************************************************************************
 *
 * This file is part of Mapnik (c++ mapping toolkit)
 *
 * Copyright (C) 2021 Artem Pavlenko
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 *
 *****************************************************************************/

#include "sqlite.hpp"

// mapnik
#include <mapnik/datasource.hpp>
#include <mapnik/wkb.hpp>
#include <mapnik/feature.hpp>
#include <mapnik/global.hpp>
#include <mapnik/sql_utils.hpp>
#include <mapnik/util/conversions.hpp>
#include <mapnik/geometry/is_empty.hpp>
#include <mapnik/geometry/envelope.hpp>

#include "connection_manager.hpp"
#include "cursorresultset.hpp"

#include <mapnik/warning.hpp>
MAPNIK_DISABLE_WARNING_PUSH
#include <mapnik/warning_ignore.hpp>
#include <boost/algorithm/string.hpp>
MAPNIK_DISABLE_WARNING_POP

// st
#include <cstdint>
#include <iostream>
#include <fstream>
#include <memory>

static std::string numeric2string(const char* buf)
{
    std::int16_t ndigits = int2net(buf);
    std::int16_t weight = int2net(buf + 2);
    std::int16_t sign = int2net(buf + 4);
    std::int16_t dscale = int2net(buf + 6);

    const std::unique_ptr<std::int16_t[]> digits(new std::int16_t[ndigits]);
    for (int n = 0; n < ndigits; ++n)
    {
        digits[n] = int2net(buf + 8 + n * 2);
    }

    std::ostringstream ss;

    if (sign == 0x4000)
        ss << "-";

    int i = std::max(weight, std::int16_t(0));
    int d = 0;

    // Each numeric "digit" is actually a value between 0000 and 9999 stored in a 16 bit field.
    // For example, the number 1234567809990001 is stored as four digits: [1234] [5678] [999] [1].
    // Note that the last two digits show that the leading 0's are lost when the number is split.
    // We must be careful to re-insert these 0's when building the string.

    while (i >= 0)
    {
        if (i <= weight && d < ndigits)
        {
            // All digits after the first must be padded to make the field 4 characters long
            if (d != 0)
            {
#ifdef _WIN32
                int dig = digits[d];
                if (dig < 10)
                {
                    ss << "000"; // 0000 - 0009
                }
                else if (dig < 100)
                {
                    ss << "00"; // 0010 - 0099
                }
                else
                {
                    ss << "0"; // 0100 - 0999;
                }
#else
                switch (digits[d])
                {
                    case 0 ... 9:
                        ss << "000"; // 0000 - 0009
                        break;
                    case 10 ... 99:
                        ss << "00"; // 0010 - 0099
                        break;
                    case 100 ... 999:
                        ss << "0"; // 0100 - 0999
                        break;
                }
#endif
            }
            ss << digits[d++];
        }
        else
        {
            if (d == 0)
                ss << "0";
            else
                ss << "0000";
        }

        i--;
    }
    if (dscale > 0)
    {
        ss << '.';
        // dscale counts the number of decimal digits following the point, not the numeric digits
        while (dscale > 0)
        {
            int value;
            if (i <= weight && d < ndigits)
                value = digits[d++];
            else
                value = 0;

            // Output up to 4 decimal digits for this value
            if (dscale > 0)
            {
                ss << (value / 1000);
                value %= 1000;
                dscale--;
            }
            if (dscale > 0)
            {
                ss << (value / 100);
                value %= 100;
                dscale--;
            }
            if (dscale > 0)
            {
                ss << (value / 10);
                value %= 10;
                dscale--;
            }
            if (dscale > 0)
            {
                ss << value;
                dscale--;
            }

            i--;
        }
    }
    return ss.str();
}

namespace mapnik {

template<typename Connection>
void pgsql2sqlite(Connection conn,
                  std::string const& query,
                  std::string const& output_table_name,
                  std::string const& output_filename)
{
    namespace sqlite = mapnik::sqlite;
    sqlite::database db(output_filename);

    std::shared_ptr<ResultSet> rs = conn->executeQuery("select * from (" + query + ") as query limit 0;");
    int count = rs->getNumFields();

    std::ostringstream select_sql;

    select_sql << "select ";

    for (int i = 0; i < count; ++i)
    {
        if (i != 0)
            select_sql << ",";
        select_sql << "\"" << rs->getFieldName(i) << "\"";
    }

    select_sql << " from (" << query << ") as query";

    std::string table_name = mapnik::sql_utils::table_from_sql(query);

    std::string schema_name = "";
    std::string::size_type idx = table_name.find_last_of('.');
    if (idx != std::string::npos)
    {
        schema_name = table_name.substr(0, idx);
        table_name = table_name.substr(idx + 1);
    }
    else
    {
        table_name = table_name.substr(0);
    }

    std::ostringstream geom_col_sql;
    geom_col_sql << "select f_geometry_column,srid,type from geometry_columns ";
    geom_col_sql << "where f_table_name='" << table_name << "'";
    if (schema_name.length() > 0)
    {
        geom_col_sql << " and f_table_schema='" << schema_name << "'";
    }

    rs = conn->executeQuery(geom_col_sql.str());

    int srid = -1;
    std::string geom_col = "UNKNOWN";
    std::string geom_type = "UNKNOWN";

    if (rs->next())
    {
        if (!mapnik::util::string2int(rs->getValue("srid"), srid))
        {
            std::clog << "could not convert srid to integer\n";
        }
        geom_col = rs->getValue("f_geometry_column");
        geom_type = rs->getValue("type");
    }

    // add AsBinary(<geometry_column>) modifier
    std::string select_sql_str = select_sql.str();
    boost::algorithm::replace_all(select_sql_str,
                                  "\"" + geom_col + "\"",
                                  "ST_AsBinary(" + geom_col + ") as " + geom_col);

#ifdef MAPNIK_DEBUG
    std::cout << select_sql_str << "\n";
#endif

    std::ostringstream cursor_sql;
    std::string cursor_name("my_cursor");

    cursor_sql << "DECLARE " << cursor_name << " BINARY INSENSITIVE NO SCROLL CURSOR WITH HOLD FOR " << select_sql_str
               << " FOR READ ONLY";
    conn->execute(cursor_sql.str());

    std::shared_ptr<CursorResultSet> cursor(new CursorResultSet(conn, cursor_name, 10000));

    unsigned num_fields = cursor->getNumFields();

    if (num_fields == 0)
        return;

    std::string feature_id = "fid";

    std::ostringstream create_sql;
    create_sql << "create table if not exists " << output_table_name << " (" << feature_id
               << " INTEGER PRIMARY KEY AUTOINCREMENT,";

    int geometry_oid = -1;

    std::string output_table_insert_sql = "insert into " + output_table_name + " values (?";

    context_ptr ctx = std::make_shared<context_type>();

    for (unsigned pos = 0; pos < num_fields; ++pos)
    {
        const char* field_name = cursor->getFieldName(pos);
        ctx->push(field_name);

        if (pos > 0)
        {
            create_sql << ",";
        }
        output_table_insert_sql += ",?";
        int oid = cursor->getTypeOID(pos);
        if (geom_col == cursor->getFieldName(pos))
        {
            geometry_oid = oid;
            create_sql << "'" << cursor->getFieldName(pos) << "' BLOB";
        }
        else
        {
            create_sql << "'" << cursor->getFieldName(pos);
            switch (oid)
            {
                case 20:
                case 21:
                case 23:
                    create_sql << "' INTEGER";
                    break;
                case 700:
                case 701:
                    create_sql << "' REAL";
                    break;
                default:
                    create_sql << "' TEXT";
                    break;
            }
        }
    }

    create_sql << ");";
    output_table_insert_sql += ")";

    std::cout << "client_encoding=" << conn->client_encoding() << "\n";
    std::cout << "geometry_column=" << geom_col << "(" << geom_type << ") srid=" << srid << " oid=" << geometry_oid
              << "\n";

    db.execute("begin;");
    // output table sql
    db.execute(create_sql.str());

    // spatial index sql
    std::string spatial_index_sql =
      "create virtual table idx_" + output_table_name + "_" + geom_col + " using rtree(pkid, xmin, xmax, ymin, ymax)";

    db.execute(spatial_index_sql);

    // blob_to_hex hex;
    int pkid = 0;

    std::string spatial_index_insert_sql =
      "insert into idx_" + output_table_name + "_" + geom_col + " values (?,?,?,?,?)";

    sqlite::prepared_statement spatial_index(db, spatial_index_insert_sql);

#ifdef MAPNIK_DEBUG
    std::cout << output_table_insert_sql << "\n";
#endif

    sqlite::prepared_statement output_table(db, output_table_insert_sql);

    while (cursor->next())
    {
        ++pkid;

        sqlite::record_type output_rec;
        output_rec.push_back(sqlite::value_type(pkid));
        bool empty_geom = true;
        const char* buf = 0;
        for (unsigned pos = 0; pos < num_fields; ++pos)
        {
            if (!cursor->isNull(pos))
            {
                int size = cursor->getFieldLength(pos);
                int oid = cursor->getTypeOID(pos);
                buf = cursor->getValue(pos);

                switch (oid)
                {
                    case 25:
                    case 1042:
                    case 1043: {
                        std::string text(buf);
                        boost::algorithm::replace_all(text, "'", "''");
                        output_rec.push_back(sqlite::value_type(text));
                        break;
                    }
                    case 23:
                        output_rec.emplace_back(int4net(buf));
                        break;
                    case 21:
                        output_rec.emplace_back(int(int2net(buf)));
                        break;
                    case 700: {
                        float val;
                        float4net(val, buf);
                        output_rec.emplace_back(double(val));
                        break;
                    }
                    case 701: {
                        double val;
                        float8net(val, buf);
                        output_rec.emplace_back(val);
                        break;
                    }
                    case 1700: {
                        std::string str = numeric2string(buf);
                        double val;
                        if (mapnik::util::string2double(str, val))
                        {
                            output_rec.emplace_back(val);
                        }
                        break;
                    }

                    default: {
                        if (oid == geometry_oid)
                        {
                            mapnik::feature_impl feat(ctx, pkid);
                            mapnik::geometry::geometry<double> geom = geometry_utils::from_wkb(buf, size, wkbGeneric);
                            if (!mapnik::geometry::is_empty(geom))
                            {
                                box2d<double> bbox = mapnik::geometry::envelope(geom);
                                if (bbox.valid())
                                {
                                    sqlite::record_type rec;
                                    rec.push_back(sqlite::value_type(pkid));
                                    rec.push_back(sqlite::value_type(bbox.minx()));
                                    rec.push_back(sqlite::value_type(bbox.maxx()));
                                    rec.push_back(sqlite::value_type(bbox.miny()));
                                    rec.push_back(sqlite::value_type(bbox.maxy()));
                                    spatial_index.insert_record(rec);
                                    empty_geom = false;
                                }
                            }
                            output_rec.push_back(sqlite::blob(buf, size));
                        }
                        else
                        {
                            output_rec.push_back(sqlite::null_type());
                        }
                        break;
                    }
                }
            }
            else
            {
                output_rec.push_back(sqlite::null_type());
            }
        }

        if (!empty_geom)
            output_table.insert_record(output_rec);

        if (pkid % 1000 == 0)
        {
            std::cout << "\r processing " << pkid << " features";
            std::cout.flush();
        }

        if (pkid % 100000 == 0)
        {
            db.execute("commit;begin;");
        }
    }
    // commit
    db.execute("commit;");
    std::cout << "\r processed " << pkid << " features";
    db.execute("VACUUM;");
    std::cout << "\r vacumming";
    std::cout << "\n Done!" << std::endl;
}
} // namespace mapnik
