// -*- mode: c++; c-basic-offset:4 -*-

// This file is part of libdap, A C++ implementation of the OPeNDAP Data

// Access Protocol.

// Copyright (c) 2014 OPeNDAP, Inc.

// Author: James Gallagher <jgallagher@opendap.org>

//

// 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 Street, Fifth Floor, Boston, MA  02110-1301  USA

//

// You can contact OPeNDAP, Inc. at PO Box 112, Saunderstown, RI. 02874-0112.

#include <cstdlib>

#include <cerrno>

#include <string>

#include <sstream>

#include <iterator>

//#define DODS_DEBUG

#include "D4FunctionScanner.h"

#include "D4FunctionEvaluator.h"

#include "d4_function_parser.tab.hh"

#include "DMR.h"

#include "D4Group.h"

#include "D4RValue.h"

#include "BaseType.h"

#include "Array.h"

#include "D4Enum.h"

#include "escaping.h"

#include "util.h"

#include "debug.h"

namespace libdap {

/**

 * Parse the DAP4 function expression.

 *

 * Calling this method with a DAP4 function expression builds a

 * D4RvalueList that can then be evaluated. The list of rvalues

 * can be accessed or evaluated (using the result() or eval()

 * methods). Note that the result is a list of rvalues because the

 * input can be zero or more function expressions.

 *

 * @param expr The function expression.

 * @return True if the parse succeeded, false otherwise.

 */

bool D4FunctionEvaluator::parse(const std::string &expr)

{

    d_expr = expr;	// set for error messages. See the %initial-action section of .yy

    std::istringstream iss(expr);

    D4FunctionScanner scanner(iss);

    D4FunctionParser parser(scanner, *this /* driver */);

    if (trace_parsing()) {

        parser.set_debug_level(1);

        parser.set_debug_stream(std::cerr);

    }

    return parser.parse() == 0;

}

/**

 * Evaluate the recently parsed function expression and put the resulting

 * rvalues (which return values packaged in libdap BaseType objects) into

 * the top-level Group of the DMR passed as a param here.

 *

 * @note The DMR passed to this method can (and usually will) be different

 * from the DMR passed to the D4FunctionEvaluator constructor. That DMR is

 * the 'source dataset' for values of variables used by the functions. It

 * is not generally where the results of evaluating the functions wind up.

 * Usually, you'll want those results in their own DMR; the functions

 * effectively make a new dataset. However, you _can_ pass the source dataset

 * DMR into this method and in that case the new variables will be appended

 * to its root Group.

 *

 * @note This code is really just a place to package results. The actual

 * evaluation happens in the D4RValue object when values are accessed.

 * The parse() method here builds the list of D4RValue objects and this

 * code accesses the values which triggers the function evaluation. Thus,

 * if you'd like to build a system that performs lazy evaluation, you can

 * work with the result() method from this class instead of this one.

 *

 * @note Calling this method will delete the D4RValueList object built

 * by the parse() method.

 *

 * @param dmr Store the results here

 * @exception Throws Error if the evaluation fails.

 */

void D4FunctionEvaluator::eval(DMR *function_result)

{

#if 0

    ServerFunctionsList *sf_list = ServerFunctionsList::TheList();

    ServerFunction *scale = new D4TestFunction;

    sf_list->add_function(scale);

    D4FunctionEvaluator parser(dataset, sf_list);

    if (ce_parser_debug) parser.set_trace_parsing(true);

    bool parse_ok = parser.parse(function);

    if (!parse_ok)

    Error(malformed_expr, "Function Expression failed to parse.");

    else {

        if (ce_parser_debug) cerr << "Function Parse OK" << endl;

        D4RValueList *result = parser.result();

        function_result = new DMR(&d4_factory, "function_results");

#endif

    if (!d_result) throw InternalErr(__FILE__, __LINE__, "Must parse() the function expression before calling eval()");

    D4Group *root = function_result->root();	// Load everything in the root group

    for (D4RValueList::iter i = d_result->begin(), e = d_result->end(); i != e; ++i) {

        // Copy the BaseTypes; this means all of the function results can

        // be deleted, which addresses the memory leak issue with function

        // results. This should also copy the D4Dimensions. jhrg 3/17/14

        root->add_var((*i)->value(*d_dmr));

    }

    delete d_result;	// The parser/function allocates the BaseType*s that hold the results.

    d_result = 0;

    // Variables can use Dimensions and Enumerations, so those need to be copied

    // from the source dataset to the result. NB: The variables that refer to these

    // use weak pointers.

    // Make a set of D4Dimensions. For each variable in 'function_result', look

    // for its dimensions in 'dataset' (by name) and add a pointer to those to the

    // set. Then copy all the stuff in the set into the root group of 'function_

    // result.'

    set<D4Dimension*> dim_set;

    for (Constructor::Vars_iter i = root->var_begin(), ie = root->var_end(); i != ie; ++i) {

        if ((*i)->is_vector_type()) {

            Array *a = static_cast<Array*>(*i);

            for (Array::Dim_iter d = a->dim_begin(), de = a->dim_end(); d != de; ++d) {

                if (a->dimension_D4dim(d)) {

                    dim_set.insert(a->dimension_D4dim(d));

                }

            }

        }

    }

    // Copy the D4Dimensions and EnumDefs because this all goes in a new DMR - we don't

    // want to share those across DMRs because the DMRs delete those (so sharing htem

    // across DMRs would lead to dangling pointers.

    for (set<D4Dimension*>::iterator i = dim_set.begin(), e = dim_set.end(); i != e; ++i) {

        root->dims()->add_dim(*i);

    }

    // Now lets do the enumerations....

    set<D4EnumDef*> enum_def_set;

    for (Constructor::Vars_iter i = root->var_begin(), ie = root->var_end(); i != ie; ++i) {

        if ((*i)->type() == dods_enum_c) {

            enum_def_set.insert(static_cast<D4Enum*>(*i)->enumeration());

        }

    }

    for (set<D4EnumDef*>::iterator i = enum_def_set.begin(), e = enum_def_set.end(); i != e; ++i) {

        root->enum_defs()->add_enum(*i);

    }

}

// libdap contains functions (in parser-util.cc) that test if a string

// can be converted to an int32, e.g., but I used a more streamlined

// approach here. 3/13/14 jhrg

/**

 * Build and return a new RValue. Allocates the new D4RValue object.

 * The code tries first to find the id in the DMR - that is, it checks

 * first to see if it is a variable in the current dataset. If that

 * fails it will try to build an unsigned long long, a long long or

 * a double from the string (in that order). If that fails the code

 * converts the id into a string.

 *

 * @param id An identifier (really a string) parsed from the function

 * expression. May contain quotes.

 * @return Return a pointer to the new allocated D4RValue object.

 */

D4RValue *

D4FunctionEvaluator::build_rvalue(const std::string &id)

{

    BaseType *btp = 0;

    // Look for the id in the dataset first

    if (top_basetype()) {

        btp = top_basetype()->var(id);

    }

    else {

        btp = dmr()->root()->find_var(id);

    }

    if (btp) return new D4RValue(btp);

    // If the id is not a variable, try to turn it into a constant,

    // otherwise, its an error.

    char *end_ptr = 0;

    errno = 0;

    long long ll_val = strtoll(id.c_str(), &end_ptr, 0);

    if (*end_ptr == '\0' && errno == 0) return new D4RValue(ll_val);

    // Test for unsigned after signed since strtoull() accepts a minus sign

    // (and will return a huge number if that's the case). jhrg 3/13/14

    errno = 0;

    unsigned long long ull_val = strtoull(id.c_str(), &end_ptr, 0);

    if (*end_ptr == '\0' && errno == 0) return new D4RValue(ull_val);

    errno = 0;

    double d_val = strtod(id.c_str(), &end_ptr);

    if (*end_ptr == '\0' && errno == 0) return new D4RValue(d_val);

    // To be a valid string, the id must be quoted (using double quotes)

    if (is_quoted(id)) return new D4RValue(www2id(id));

    // if it's none of these, return null

    return 0;

}

template<typename T>

std::vector<T> *

D4FunctionEvaluator::init_arg_list(T val)

{

    std::vector<T> *arg_list = new std::vector<T>();

    if (get_arg_length_hint() > 0) arg_list->reserve(get_arg_length_hint());

    arg_list->push_back(val);

    return arg_list;

}

// Force an instantiation so this can be called from within the d4_function.yy

// parser.

template std::vector<dods_byte> *D4FunctionEvaluator::init_arg_list(dods_byte val);

template std::vector<dods_int8> *D4FunctionEvaluator::init_arg_list(dods_int8 val);

template std::vector<dods_uint16> *D4FunctionEvaluator::init_arg_list(dods_uint16 val);

template std::vector<dods_int16> *D4FunctionEvaluator::init_arg_list(dods_int16 val);

template std::vector<dods_uint32> *D4FunctionEvaluator::init_arg_list(dods_uint32 val);

template std::vector<dods_int32> *D4FunctionEvaluator::init_arg_list(dods_int32 val);

template std::vector<dods_uint64> *D4FunctionEvaluator::init_arg_list(dods_uint64 val);

template std::vector<dods_int64> *D4FunctionEvaluator::init_arg_list(dods_int64 val);

template std::vector<dods_float32> *D4FunctionEvaluator::init_arg_list(dods_float32 val);

template std::vector<dods_float64> *D4FunctionEvaluator::init_arg_list(dods_float64 val);

// This method is called from the parser (see d4_function_parser.yy, down in the code

// section). This will be called during the call to D4FunctionParser::parse(), that

// is inside D4FunctionEvaluator::parse(...)

void D4FunctionEvaluator::error(const libdap::location &l, const std::string &m)

{

    ostringstream oss;

    oss << l << ": " << m << ends;

    throw Error(malformed_expr, oss.str());

}

} /* namespace libdap */