/* ************************************************************************
 * Copyright (c) 2020-2021 Advanced Micro Devices, Inc.
 * ************************************************************************ */
// This emulates the required functionality of boost::program_options

#pragma once

#include <cinttypes>
#include <cstdio>
#include <iomanip>
#include <map>
#include <ostream>
#include <regex>
#include <stdexcept>
#include <string>
#include <utility>
#include <vector>

namespace roc
{
// Regular expression for token delimiters (whitespace and commas)
static const std::regex program_options_regex{"[, \\f\\n\\r\\t\\v]+", std::regex_constants::optimize};

// Polymorphic base class to use with dynamic_cast
class value_base
{
protected:
    bool m_has_actual = false;
    bool m_has_default = false;

public:
    virtual ~value_base() = default;

    bool has_actual() const
    {
        return m_has_actual;
    }

    bool has_default() const
    {
        return m_has_default;
    }
};

// Value parameters
template <typename T>
class value : public value_base
{
    T m_var; // Variable to be modified if no pointer provided
    T* m_var_ptr; // Pointer to variable to be modified

public:
    // Constructor
    explicit value()
        : m_var_ptr(nullptr)
    {
    }

    explicit value(T var, bool defaulted)
        : m_var(var)
        , m_var_ptr(nullptr)
    {
        m_has_actual = !defaulted;
        m_has_default = defaulted;
    }

    explicit value(T* var_ptr)
        : m_var_ptr(var_ptr)
    {
    }

    // Allows actual_value() and default_value()
    value* operator->()
    {
        return this;
    }

    // Get the value
    const T& get_value() const
    {
        if(m_var_ptr)
            return *m_var_ptr;
        else
            return m_var;
    }

    // Set actual value
    value& actual_value(T val)
    {
        if(m_var_ptr)
            *m_var_ptr = std::move(val);
        else
            m_var = std::move(val);
        m_has_actual = true;
        return *this;
    }

    // Set default value
    value& default_value(T val)
    {
        if(!m_has_actual)
        {
            if(m_var_ptr)
                *m_var_ptr = std::move(val);
            else
                m_var = std::move(val);
            m_has_default = true;
        }
        return *this;
    }
};

// bool_switch is a value<bool>, which is handled specially
using bool_switch = value<bool>;

class variable_value
{
    std::shared_ptr<value_base> m_val;

public:
    // Constructor
    explicit variable_value() = default;

    template <typename T>
    explicit variable_value(const T& xv, bool xdefaulted)
        : m_val(std::make_shared<value<T>>(xv, xdefaulted))
    {
    }

    explicit variable_value(std::shared_ptr<value_base> val)
        : m_val(val)
    {
    }

    // Member functions
    bool empty() const
    {
        return !m_val.get() || (!m_val->has_actual() && !m_val->has_default());
    }

    bool defaulted() const
    {
        return m_val.get() && !m_val->has_actual() && m_val->has_default();
    }

    template <typename T>
    const T& as() const
    {
        if(value<T>* val = dynamic_cast<value<T>*>(m_val.get()))
            return val->get_value();
        else
            throw std::logic_error("Internal error: Invalid cast");
    }
};

using variables_map = std::map<std::string, variable_value>;

class options_description
{
    // desc_option describes a particular option
    class desc_option
    {
        std::string m_opts;
        std::shared_ptr<value_base> m_val;
        std::string m_desc;

    public:
        // Constructor with options, value and description
        template <typename T>
        desc_option(std::string opts, value<T> val, std::string desc)
            : m_opts(std::move(opts))
            , m_val(new auto(std::move(val)))
            , m_desc(std::move(desc))
        {
        }

        // Constructor with options and description
        desc_option(std::string opts, std::string desc)
            : m_opts(std::move(opts))
            , m_val(nullptr)
            , m_desc(std::move(desc))
        {
        }

        // Accessors
        const std::string& get_opts() const
        {
            return m_opts;
        }

        const std::shared_ptr<value_base> get_val() const
        {
            return m_val;
        }

        const std::string& get_desc() const
        {
            return m_desc;
        }

        // Set a value
        void set_val(int& argc, char**& argv, std::string inopt) const
        {
            // We test all supported types with dynamic_cast and parse accordingly
            bool match = false;
            if(auto* ptr = dynamic_cast<value<int32_t>*>(m_val.get()))
            {
                int32_t val;
                match = argc && sscanf(*argv, "%" SCNd32, &val) == 1;
                ptr->actual_value(val);
            }
            else if(auto* ptr = dynamic_cast<value<uint32_t>*>(m_val.get()))
            {
                uint32_t val;
                match = argc && sscanf(*argv, "%" SCNu32, &val) == 1;
                ptr->actual_value(val);
            }
            else if(auto* ptr = dynamic_cast<value<int64_t>*>(m_val.get()))
            {
                int64_t val;
                match = argc && sscanf(*argv, "%" SCNd64, &val) == 1;
                ptr->actual_value(val);
            }
            else if(auto* ptr = dynamic_cast<value<uint64_t>*>(m_val.get()))
            {
                uint64_t val;
                match = argc && sscanf(*argv, "%" SCNu64, &val) == 1;
                ptr->actual_value(val);
            }
            else if(auto* ptr = dynamic_cast<value<float>*>(m_val.get()))
            {
                float val;
                match = argc && sscanf(*argv, "%f", &val) == 1;
                ptr->actual_value(val);
            }
            else if(auto* ptr = dynamic_cast<value<double>*>(m_val.get()))
            {
                double val;
                match = argc && sscanf(*argv, "%lf", &val) == 1;
                ptr->actual_value(val);
            }
            else if(auto* ptr = dynamic_cast<value<char>*>(m_val.get()))
            {
                char val;
                match = argc && sscanf(*argv, " %c", &val) == 1;
                ptr->actual_value(val);
            }
            else if(auto* ptr = dynamic_cast<value<bool>*>(m_val.get()))
            {
                // We handle bool specially, setting the value to true without argument
                ptr->actual_value(true);
                return;
            }
            else if(auto* ptr = dynamic_cast<value<std::string>*>(m_val.get()))
            {
                if(argc)
                {
                    ptr->actual_value(*argv);
                    match = true;
                }
            }
            else
            {
                throw std::logic_error("Internal error: Unsupported data type");
            }

            if(!match)
                throw std::invalid_argument(argc ? "Invalid value for " + inopt
                                                 : "Missing required value for " + inopt);

            // Skip past the argument's value
            ++argv;
            --argc;
        }
    };

    // Description and option list
    std::string m_desc;
    std::vector<desc_option> m_optlist;

    // desc_optionlist allows chains of options to be parenthesized
    class desc_optionlist
    {
        std::vector<desc_option>& m_list;

    public:
        explicit desc_optionlist(std::vector<desc_option>& list)
            : m_list(list)
        {
        }

        template <typename... Ts>
        desc_optionlist operator()(Ts&&... arg)
        {
            m_list.push_back(desc_option(std::forward<Ts>(arg)...));
            return *this;
        }
    };

    // Parse an option at the current (argc, argv) position
    void parse_option(int& argc, char**& argv, variables_map& vm, bool ignoreUnknown) const
    {
        // Iterate across all options
        for(const auto& opt : m_optlist)
        {
            // Canonical name used for map
            std::string canonical_name;

            // Iterate across tokens in the opts
            for(std::sregex_token_iterator tok{opt.get_opts().begin(), opt.get_opts().end(),
                                               program_options_regex, -1};
                tok != std::sregex_token_iterator(); ++tok)
            {
                // The first option in a list of options is the canonical name
                if(!canonical_name.length())
                    canonical_name = tok->str();

                // If the length of the option is 1, it is single-dash; otherwise double-dash
                const char* prefix = tok->length() == 1 ? "-" : "--";

                // If option matches
                if(*argv == prefix + tok->str())
                {
                    ++argv;
                    --argc;

                    // If option has a value, set it
                    if(opt.get_val().get())
                        opt.set_val(argc, argv, prefix + tok->str());

                    // Add seen options to map
                    vm[canonical_name] = variable_value(opt.get_val());

                    return; // Return successfully
                }
            }
        }

        // No options were matched
        if(ignoreUnknown)
        {
            ++argv;
            --argc;
        }
        else
            throw std::invalid_argument("Option " + std::string(argv[0]) + " is not defined.");
    }

public:
    // Constructor
    explicit options_description(std::string desc)
        : m_desc(std::move(desc))
    {
    }

    // Start a desc_optionlist chain
    desc_optionlist add_options() &
    {
        return desc_optionlist(m_optlist);
    }

    // Parse all options
    void parse_options(int& argc, char**& argv, variables_map& vm, bool ignoreUnknown = false) const
    {
        // Add options with default values to map
        for(const auto& opt : m_optlist)
        {
            std::sregex_token_iterator tok{opt.get_opts().begin(), opt.get_opts().end(),
                                           program_options_regex, -1};

            // Canonical name used for map
            std::string canonical_name = tok->str();

            if(opt.get_val().get() && opt.get_val()->has_default())
                vm[canonical_name] = variable_value(opt.get_val());
        }

        // Parse options
        while(argc)
            parse_option(argc, argv, vm, ignoreUnknown);
    }

    // Formatted output of command-line arguments description
    friend std::ostream& operator<<(std::ostream& os, const options_description& d)
    {
        // Iterate across all options
        for(const auto& opt : d.m_optlist)
        {
            bool first = true, printvalue = true;
            const char* delim = "";
            std::ostringstream left;

            // Iterate across tokens in the opts
            for(std::sregex_token_iterator tok{opt.get_opts().begin(), opt.get_opts().end(),
                                               program_options_regex, -1};
                tok != std::sregex_token_iterator(); ++tok, first = false, delim = " ")
            {
                // If the length of the option is 1, it is single-dash; otherwise double-dash
                const char* prefix = tok->length() == 1 ? "-" : "--";
                left << delim << (first ? "" : "|") << prefix << tok->str();

                if(tok->str() == "help" || tok->str() == "h")
                    printvalue = false;
            }

            if(printvalue)
                left << " <value>";
            os << std::setw(26) << std::left << left.str() << " " << opt.get_desc() << " ";
            left.str(std::string());

            // Print the default value of the variable type if it exists
            // We do not print the default value for bool
            const value_base* val = opt.get_val().get();
            if(val && !dynamic_cast<const value<bool>*>(val))
            {
                if(val->has_default())
                {
                    // We test all supported types with dynamic_cast and print accordingly
                    left << " (Default value is: ";
                    if(dynamic_cast<const value<int32_t>*>(val))
                        left << dynamic_cast<const value<int32_t>*>(val)->get_value();
                    else if(dynamic_cast<const value<uint32_t>*>(val))
                        left << dynamic_cast<const value<uint32_t>*>(val)->get_value();
                    else if(dynamic_cast<const value<int64_t>*>(val))
                        left << dynamic_cast<const value<int64_t>*>(val)->get_value();
                    else if(dynamic_cast<const value<uint64_t>*>(val))
                        left << dynamic_cast<const value<uint64_t>*>(val)->get_value();
                    else if(dynamic_cast<const value<float>*>(val))
                        left << dynamic_cast<const value<float>*>(val)->get_value();
                    else if(dynamic_cast<const value<double>*>(val))
                        left << dynamic_cast<const value<double>*>(val)->get_value();
                    else if(dynamic_cast<const value<char>*>(val))
                        left << dynamic_cast<const value<char>*>(val)->get_value();
                    else if(dynamic_cast<const value<std::string>*>(val))
                        left << dynamic_cast<const value<std::string>*>(val)->get_value();
                    else
                        throw std::logic_error("Internal error: Unsupported data type");
                    left << ")";
                }
            }
            os << left.str() << "\n\n";
        }
        return os << std::flush;
    }
};

// Class representing command line parser
class parse_command_line
{
    variables_map m_vm;

public:
    parse_command_line(int argc, char** argv, const options_description& desc, bool ignoreUnknown = false)
    {
        ++argv; // Skip argv[0]
        --argc;
        desc.parse_options(argc, argv, m_vm, ignoreUnknown);
    }

    // Copy the variables_map
    friend void store(const parse_command_line& p, variables_map& vm)
    {
        vm = p.m_vm;
    }

    // Move the variables_map
    friend void store(parse_command_line&& p, variables_map& vm)
    {
        vm = std::move(p.m_vm);
    }
};

// We can define the notify() function as a no-op for our purposes
inline void notify(const variables_map&) {}

}