/* Copyright 2022 Andrew Myers, Burlen Loring, Luca Fedeli
 * Maxence Thevenet, Remi Lehe, Revathi Jambunathan
 *
 * This file is part of WarpX.
 *
 * License: BSD-3-Clause-LBNL
 */

#ifndef WARPX_UTILS_PARSER_PARSERUTILS_H_
#define WARPX_UTILS_PARSER_PARSERUTILS_H_

#include <AMReX_ParmParse.H>
#include <AMReX_Parser.H>
#include <AMReX_REAL.H>
#include <AMReX_Vector.H>

#include <cmath>
#include <string>
#include <type_traits>

namespace utils::parser
{
    /**
    * \brief Do a safe cast of a real to an int
    * This ensures that the float value is within the range of ints and if not,
    * raises an exception.
    *
    * \param x Real value to cast
    * \param real_name String, the name of the variable being casted to use in the error message
    */
    int
    safeCastToInt(amrex::Real x, const std::string& real_name);


    /**
    * \brief Do a safe cast of a real to a long
    * This ensures that the float value is within the range of longs and if not,
    * raises an exception.
    *
    * \param x Real value to cast
    * \param real_name String, the name of the variable being casted to use in the error message
    */
    long
    safeCastToLong(amrex::Real x, const std::string& real_name);


    /**
    * \brief Initialize an amrex::Parser object from a string containing a math expression
    *
    * \param parse_function String to read to initialize the parser.
    * \param varnames A list of predefined independent variables
    */
    amrex::Parser makeParser (
        std::string const& parse_function,
        amrex::Vector<std::string> const& varnames);


    /**
    * \brief Parse a string (typically a mathematical expression) from the
    * input file and store it into a variable.
    *
    * \param pp used to read the query_string `pp.<function>=string`
    * \param query_string ParmParse.query will look for this string
    * \param stored_string variable in which the string to parse is stored
    */
    void Store_parserString(
        const amrex::ParmParse &pp,
        std::string query_string,
        std::string& stored_string);


    /** Parse a string and return as a double precision floating point number
    *
    * In case the string cannot be interpreted as a double,
    * this function ... <throws an exception? aborts with error message?>
    *
    * \param str The string to be parsed
    * \return representation as a double
    */
    double parseStringtoDouble(const std::string& str);


    /** Parse a string and return an int
     *
     * In case the string cannot be interpreted as Real,
     * this function ... <throws an exception? aborts with error message?>
     *
     * \param str The string to be parsed
     * \param name For integers, the name, to be used in error messages
     * \return rounded closest integer
     */
    int parseStringtoInt(const std::string& str, const std::string& name);


    template <int N>
    amrex::ParserExecutor<N> compileParser (amrex::Parser const* parser)
    {
        if (parser) {
            return parser->compile<N>();
        } else {
            return amrex::ParserExecutor<N>{};
        }
    }


    /** Similar to amrex::ParmParse::query, but also supports math expressions for the value.
     *
     * amrex::ParmParse::query reads a name and a value from the input file. This function does the
     * same, and applies the amrex::Parser to the value, so the user has the choice to specify a value or
     * a math expression (including user-defined constants).
     * Works for amrex::Real numbers and integers.
     *
     * \param[in] a_pp amrex::ParmParse object
     * \param[in] str name of the parameter to read
     * \param[out] val where the value queried and parsed is stored, either a scalar or vector
     */
    template <typename T>
    int queryWithParser (const amrex::ParmParse& a_pp, char const * const str, T& val)
    {
        // call amrex::ParmParse::query, check if the user specified str.
        std::string tmp_str;
        const int is_specified = a_pp.query(str, tmp_str);
        if (is_specified)
        {
            // If so, create a parser object and apply it to the value provided by the user.
            std::string str_val;
            Store_parserString(a_pp, str, str_val);

            auto parser = makeParser(str_val, {});

            if (std::is_same<T, int>::value) {

                val = safeCastToInt(std::round(parser.compileHost<0>()()), str);
            }
            else {
                val = static_cast<T>(parser.compileHost<0>()());
            }
        }
        // return the same output as amrex::ParmParse::query
        return is_specified;
    }


    template <typename T>
    int queryArrWithParser (const amrex::ParmParse& a_pp, char const * const str, std::vector<T>& val)
    {
        // call amrex::ParmParse::query, check if the user specified str.
        std::vector<std::string> tmp_str_arr;
        const int is_specified = a_pp.queryarr(str, tmp_str_arr);
        if (is_specified)
        {
            // If so, create parser objects and apply them to the values provided by the user.
            int const n = static_cast<int>(tmp_str_arr.size());
            val.resize(n);
            for (int i=0 ; i < n ; i++) {
                auto parser = makeParser(tmp_str_arr[i], {});
                if (std::is_same<T, int>::value) {
                    val[i] = safeCastToInt(std::round(parser.compileHost<0>()()), str);
                }
                else {
                    val[i] = static_cast<T>(parser.compileHost<0>()());
                }
            }
        }
        // return the same output as amrex::ParmParse::query
        return is_specified;
    }


    /** Similar to amrex::ParmParse::query, but also supports math expressions for the value.
     *
     * amrex::ParmParse::query reads a name and a value from the input file. This function does the
     * same, and applies the amrex::Parser to the value, so the user has the choice to specify a value or
     * a math expression (including user-defined constants).
     * Works for amrex::Real numbers and integers.
     *
     * \param[in] a_pp amrex::ParmParse object
     * \param[in] str name of the parameter to read
     * \param[out] val where the value queried and parsed is stored, either a scalar or vector
     * \param[in] start_ix start index in the list of inputs values (optional with arrays, default is
     * amrex::ParmParse::FIRST for starting with the first input value)
     * \param[in] num_val number of input values to use (optional with arrays, default is
     * amrex::ParmParse::LAST for reading until the last input value)
     */
    template <typename T>
    int queryArrWithParser (const amrex::ParmParse& a_pp, char const * const str, std::vector<T>& val,
                            const int start_ix, const int num_val)
    {
        // call amrex::ParmParse::query, check if the user specified str.
        std::vector<std::string> tmp_str_arr;
        const int is_specified = a_pp.queryarr(str, tmp_str_arr, start_ix, num_val);
        if (is_specified)
        {
            // If so, create parser objects and apply them to the values provided by the user.
            int const n = static_cast<int>(tmp_str_arr.size());
            val.resize(n);
            for (int i=0 ; i < n ; i++) {
                auto parser = makeParser(tmp_str_arr[i], {});
                if (std::is_same<T, int>::value) {
                    val[i] = safeCastToInt(std::round(parser.compileHost<0>()()), str);
                }
                else {
                    val[i] = static_cast<T>(parser.compileHost<0>()());
                }
            }
        }
        // return the same output as amrex::ParmParse::query
        return is_specified;
    }


    /** Similar to amrex::ParmParse::get, but also supports math expressions for the value.
     *
     * amrex::ParmParse::get reads a name and a value from the input file. This function does the
     * same, and applies the Parser to the value, so the user has the choice to specify a value or
     * a math expression (including user-defined constants).
     * Works for amrex::Real numbers and integers.
     *
     * \param[in] a_pp amrex::ParmParse object
     * \param[in] str name of the parameter to read
     * \param[out] val where the value queried and parsed is stored
     */
    template <typename T>
    void getWithParser (const amrex::ParmParse& a_pp, char const * const str, T& val)
    {
        // If so, create a parser object and apply it to the value provided by the user.
        std::string str_val;
        Store_parserString(a_pp, str, str_val);

        auto parser = makeParser(str_val, {});
        if (std::is_same<T, int>::value) {
            val = safeCastToInt(std::round(parser.compileHost<0>()()), str);
        }
        else {
            val = static_cast<T>(parser.compileHost<0>()());
        }
    }

    template <typename T>
    void getArrWithParser (const amrex::ParmParse& a_pp, char const * const str, std::vector<T>& val)
    {
        // Create parser objects and apply them to the values provided by the user.
        std::vector<std::string> tmp_str_arr;
        a_pp.getarr(str, tmp_str_arr);

        int const n = static_cast<int>(tmp_str_arr.size());
        val.resize(n);
        for (int i=0 ; i < n ; i++) {
            auto parser = makeParser(tmp_str_arr[i], {});
            if (std::is_same<T, int>::value) {
                val[i] = safeCastToInt(std::round(parser.compileHost<0>()()), str);
            }
            else {
                val[i] = static_cast<T>(parser.compileHost<0>()());
            }
        }
    }


    /** Similar to amrex::ParmParse::get, but also supports math expressions for the value.
     *
     * amrex::ParmParse::get reads a name and a value from the input file. This function does the
     * same, and applies the Parser to the value, so the user has the choice to specify a value or
     * a math expression (including user-defined constants).
     * Works for amrex::Real numbers and integers.
     *
     * \param[in] a_pp amrex::ParmParse object
     * \param[in] str name of the parameter to read
     * \param[out] val where the value queried and parsed is stored
     * \param[in] start_ix start index in the list of inputs values (optional with arrays, default is
     * amrex::ParmParse::FIRST for starting with the first input value)
     * \param[in] num_val number of input values to use (optional with arrays, default is
     * amrex::ParmParse::LAST for reading until the last input value)
     */
    template <typename T>
    void getArrWithParser (const amrex::ParmParse& a_pp, char const * const str, std::vector<T>& val,
                        const int start_ix, const int num_val)
    {
        // Create parser objects and apply them to the values provided by the user.
        std::vector<std::string> tmp_str_arr;
        a_pp.getarr(str, tmp_str_arr, start_ix, num_val);

        int const n = static_cast<int>(tmp_str_arr.size());
        val.resize(n);
        for (int i=0 ; i < n ; i++) {
            auto parser = makeParser(tmp_str_arr[i], {});
            if (std::is_same<T, int>::value) {
                val[i] = safeCastToInt(std::round(parser.compileHost<0>()()), str);
            }
            else {
                val[i] = static_cast<T>(parser.compileHost<0>()());
            }
        }
    }

}

#endif // WARPX_UTILS_PARSER_PARSERUTILS_H_