/*
 * (C) Copyright 1996-2012 ECMWF.
 *
 * This software is licensed under the terms of the Apache Licence Version 2.0
 * which can be obtained at http://www.apache.org/licenses/LICENSE-2.0.
 * In applying this licence, ECMWF does not waive the privileges and immunities
 * granted to it by virtue of its status as an intergovernmental organisation nor
 * does it submit to any jurisdiction.
 */

#include "eckit/sql/expression/StringExpression.h"

#include <cstring>

#include "eckit/exception/Exceptions.h"
#include "eckit/sql/SQLTable.h"
#include "eckit/sql/expression/ColumnExpression.h"
#include "eckit/sql/expression/SQLExpressions.h"
#include "eckit/utils/Regex.h"


//----------------------------------------------------------------------------------------------------------------------

namespace {

bool isColumnRegex(const std::string& s) {
    return (s[0] == '/' && s[s.size() - 1] == '/') || (s[0] == '~' && s[1] == '/' && s[s.size() - 1] == '/');
}

bool matchEx(const std::string& regex, const std::string& s) {
    bool negated   = false;
    std::string rx = regex;
    if (rx[0] == '~') {
        rx.erase(0, 0);
        negated = true;
    }

    // TODO: remove '/'

    bool matches = eckit::Regex(rx).match(s);
    return (negated && !matches) || (!negated && matches);
}

}  // namespace

namespace eckit::sql::expression {

//----------------------------------------------------------------------------------------------------------------------

const eckit::sql::type::SQLType* StringExpression::type() const {
    return type_;
}

StringExpression::StringExpression(const std::string& name) :
    name_(name) {
    size_t len        = name.length();
    size_t lenDoubles = (len == 0) ? 1 : ((len - 1) / sizeof(double)) + 1;
    size_t lenChars   = lenDoubles * sizeof(double);

    value_.resize(lenDoubles);

    char* val = reinterpret_cast<char*>(&value_[0]);

    ::memcpy(val, name.c_str(), len);
    if (len != lenChars) {
        ::memset(val + len, 0, lenChars - len);
    }

    type_ = &type::SQLType::lookup("string", lenDoubles);
}

StringExpression::StringExpression(const StringExpression& o) :
    name_(o.name_), value_(o.value_) {}

void StringExpression::expandStars(const std::vector<std::reference_wrapper<const SQLTable>>& tables,
                                   expression::Expressions& e) {
    std::ostream& L(Log::info());

    // TODO: if(verbose_) {...}
    // Log::info() << "StringExpression::expandStars: name_: '"  << name_ << "', value_: '" << value_ << "'" <<
    // std::endl;

    if (!isColumnRegex(name_)) {
        e.push_back(shared_from_this());
        return;
    }

    unsigned int matched = 0;
    for (const auto& table : tables) {
        std::vector<std::string> names = table.get().columnNames();

        for (size_t i = 0; i < names.size(); i++) {
            const std::string& name = names[i];
            if (!matchEx(name_, name)) {
                L << "StringExpression::expandStars: skip '" << name << "'" << std::endl;
                continue;
            }

            L << "StringExpression::expandStars: adding '" << name << "'" << std::endl;
            ++matched;
            e.push_back(std::make_shared<ColumnExpression>(name, &table.get()));
        }
    }
    if (!matched) {
        throw eckit::UserError(std::string("No columns matching regex '") + name_ + "' found.");
    }
}

std::shared_ptr<SQLExpression> StringExpression::clone() const {
    return std::make_shared<StringExpression>(name_);
}

std::shared_ptr<SQLExpression> StringExpression::reshift(int minColumnShift) const {
    return clone();
}

StringExpression::~StringExpression() {}

double StringExpression::eval(bool& missing) const {
    return value_[0];
}

void StringExpression::eval(double* out, bool& missing) const {
    ::memcpy(out, &value_[0], value_.size() * sizeof(value_[0]));
}

std::string StringExpression::evalAsString(bool& missing) const {
    return name_;
}

void StringExpression::prepare(SQLSelect& sql) {}

void StringExpression::cleanup(SQLSelect& sql) {}

void StringExpression::output(SQLOutput& o) const {
    type_->output(o, &value_[0], false);
}

void StringExpression::print(std::ostream& s) const {
    s << "'" << name_ << "'";
}

//----------------------------------------------------------------------------------------------------------------------

}  // namespace eckit::sql::expression
