#pragma once

#include <stdio.h>

#include <string.h>

#include <string>

#include <vector>

#include <unordered_map>

#include <iostream>

#include <memory>

namespace crow

{

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

// qs_parse (modified)

// https://github.com/bartgrantham/qs_parse

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

/*  Similar to strncmp, but handles URL-encoding for either string  */

int qs_strncmp(const char* s, const char* qs, size_t n);

/*  Finds the beginning of each key/value pair and stores a pointer in qs_kv.

 *  Also decodes the value portion of the k/v pair *in-place*.  In a future

 *  enhancement it will also have a compile-time option of sorting qs_kv

 *  alphabetically by key.  */

size_t qs_parse(char* qs, char* qs_kv[], size_t qs_kv_size, bool parse_url);

/*  Used by qs_parse to decode the value portion of a k/v pair  */

int qs_decode(char * qs);

/*  Looks up the value according to the key on a pre-processed query string

 *  A future enhancement will be a compile-time option to look up the key

 *  in a pre-sorted qs_kv array via a binary search.  */

//char * qs_k2v(const char * key, char * qs_kv[], int qs_kv_size);

 char * qs_k2v(const char * key, char * const * qs_kv, size_t qs_kv_size, int nth);

/*  Non-destructive lookup of value, based on key.  User provides the

 *  destinaton string and length.  */

char * qs_scanvalue(const char * key, const char * qs, char * val, size_t val_len);

// TODO: implement sorting of the qs_kv array; for now ensure it's not compiled

#undef _qsSORTING

// isxdigit _is_ available in <ctype.h>, but let's avoid another header instead

#define CROW_QS_ISHEX(x)    ((((x)>='0'&&(x)<='9') || ((x)>='A'&&(x)<='F') || ((x)>='a'&&(x)<='f')) ? 1 : 0)

#define CROW_QS_HEX2DEC(x)  (((x)>='0'&&(x)<='9') ? (x)-48 : ((x)>='A'&&(x)<='F') ? (x)-55 : ((x)>='a'&&(x)<='f') ? (x)-87 : 0)

#define CROW_QS_ISQSCHR(x) ((((x)=='=')||((x)=='#')||((x)=='&')||((x)=='\0')) ? 0 : 1)

inline int qs_strncmp(const char * s, const char * qs, size_t n)

{

    unsigned char u1, u2, unyb, lnyb;

    while(n-- > 0)

    {

        u1 = static_cast<unsigned char>(*s++);

        u2 = static_cast<unsigned char>(*qs++);

        if ( ! CROW_QS_ISQSCHR(u1) ) {  u1 = '\0';  }

        if ( ! CROW_QS_ISQSCHR(u2) ) {  u2 = '\0';  }

        if ( u1 == '+' ) {  u1 = ' ';  }

        if ( u1 == '%' ) // easier/safer than scanf

        {

            unyb = static_cast<unsigned char>(*s++);

            lnyb = static_cast<unsigned char>(*s++);

            if ( CROW_QS_ISHEX(unyb) && CROW_QS_ISHEX(lnyb) )

                u1 = (CROW_QS_HEX2DEC(unyb) * 16) + CROW_QS_HEX2DEC(lnyb);

            else

                u1 = '\0';

        }

        if ( u2 == '+' ) {  u2 = ' ';  }

        if ( u2 == '%' ) // easier/safer than scanf

        {

            unyb = static_cast<unsigned char>(*qs++);

            lnyb = static_cast<unsigned char>(*qs++);

            if ( CROW_QS_ISHEX(unyb) && CROW_QS_ISHEX(lnyb) )

                u2 = (CROW_QS_HEX2DEC(unyb) * 16) + CROW_QS_HEX2DEC(lnyb);

            else

                u2 = '\0';

        }

        if ( u1 != u2 )

            return u1 - u2;

        if ( u1 == '\0' )

            return 0;

    }

    if ( CROW_QS_ISQSCHR(*qs) )

        return -1;

    else

        return 0;

}

inline size_t qs_parse(char* qs, char* qs_kv[], size_t qs_kv_size, bool parse_url = true)

{

    size_t i, j;

    char * substr_ptr;

    for(i=0; i<qs_kv_size; i++)  qs_kv[i] = NULL;

    // find the beginning of the k/v substrings or the fragment

    substr_ptr = parse_url ? qs + strcspn(qs, "?#") : qs;

    if (parse_url)

    {

        if (substr_ptr[0] != '\0')

            substr_ptr++;

        else

            return 0; // no query or fragment

    }

    i=0;

    while(i<qs_kv_size)

    {

        qs_kv[i] = substr_ptr;

        j = strcspn(substr_ptr, "&");

        if ( substr_ptr[j] == '\0' ) { i++; break;  } // x &'s -> means x iterations of this loop -> means *x+1* k/v pairs

        substr_ptr += j + 1;

        i++;

    }

    // we only decode the values in place, the keys could have '='s in them

    // which will hose our ability to distinguish keys from values later

    for(j=0; j<i; j++)

    {

        substr_ptr = qs_kv[j] + strcspn(qs_kv[j], "=&#");

        if ( substr_ptr[0] == '&' || substr_ptr[0] == '\0')  // blank value: skip decoding

            substr_ptr[0] = '\0';

        else

            qs_decode(++substr_ptr);

    }

#ifdef _qsSORTING

// TODO: qsort qs_kv, using qs_strncmp() for the comparison

#endif

    return i;

}

inline int qs_decode(char * qs)

{

    int i=0, j=0;

    while( CROW_QS_ISQSCHR(qs[j]) )

    {

        if ( qs[j] == '+' ) {  qs[i] = ' ';  }

        else if ( qs[j] == '%' ) // easier/safer than scanf

        {

            if ( ! CROW_QS_ISHEX(qs[j+1]) || ! CROW_QS_ISHEX(qs[j+2]) )

            {

                qs[i] = '\0';

                return i;

            }

            qs[i] = (CROW_QS_HEX2DEC(qs[j+1]) * 16) + CROW_QS_HEX2DEC(qs[j+2]);

            j+=2;

        }

        else

        {

            qs[i] = qs[j];

        }

        i++;  j++;

    }

    qs[i] = '\0';

    return i;

}

inline char * qs_k2v(const char * key, char * const * qs_kv, size_t qs_kv_size, int nth = 0)

{

    size_t i;

    size_t key_len, skip;

    key_len = strlen(key);

#ifdef _qsSORTING

// TODO: binary search for key in the sorted qs_kv

#else  // _qsSORTING

    for(i=0; i<qs_kv_size; i++)

    {

        // we rely on the unambiguous '=' to find the value in our k/v pair

        if ( qs_strncmp(key, qs_kv[i], key_len) == 0 )

        {

            skip = strcspn(qs_kv[i], "=");

            if ( qs_kv[i][skip] == '=' )

                skip++;

            // return (zero-char value) ? ptr to trailing '\0' : ptr to value

            if(nth == 0)

                return qs_kv[i] + skip;

            else

                --nth;

        }

    }

#endif  // _qsSORTING

    return nullptr;

}

inline std::unique_ptr<std::pair<std::string, std::string>> qs_dict_name2kv(const char * dict_name, char * const * qs_kv, size_t qs_kv_size, int nth = 0)

{

    size_t i;

    size_t name_len, skip_to_eq, skip_to_brace_open, skip_to_brace_close;

    name_len = strlen(dict_name);

#ifdef _qsSORTING

// TODO: binary search for key in the sorted qs_kv

#else  // _qsSORTING

    for(i=0; i<qs_kv_size; i++)

    {

        if ( strncmp(dict_name, qs_kv[i], name_len) == 0 )

        {

            skip_to_eq = strcspn(qs_kv[i], "=");

            if ( qs_kv[i][skip_to_eq] == '=' )

                skip_to_eq++;

            skip_to_brace_open = strcspn(qs_kv[i], "[");

            if ( qs_kv[i][skip_to_brace_open] == '[' )

                skip_to_brace_open++;

            skip_to_brace_close = strcspn(qs_kv[i], "]");

            if ( skip_to_brace_open <= skip_to_brace_close &&

                 skip_to_brace_open > 0 &&

                 skip_to_brace_close > 0 &&

                 nth == 0 )

            {

                auto key = std::string(qs_kv[i] + skip_to_brace_open, skip_to_brace_close - skip_to_brace_open);

                auto value = std::string(qs_kv[i] + skip_to_eq);

                return std::unique_ptr<std::pair<std::string, std::string>>(new std::pair<std::string, std::string>(key, value));

            }

            else

            {

                --nth;

            }

        }

    }

#endif  // _qsSORTING

    return nullptr;

}

inline char * qs_scanvalue(const char * key, const char * qs, char * val, size_t val_len)

{

    size_t i, key_len;

    const char * tmp;

    // find the beginning of the k/v substrings

    if ( (tmp = strchr(qs, '?')) != NULL )

        qs = tmp + 1;

    key_len = strlen(key);

    while(qs[0] != '#' && qs[0] != '\0')

    {

        if ( qs_strncmp(key, qs, key_len) == 0 )

            break;

        qs += strcspn(qs, "&") + 1;

    }

    if ( qs[0] == '\0' ) return NULL;

    qs += strcspn(qs, "=&#");

    if ( qs[0] == '=' )

    {

        qs++;

        i = strcspn(qs, "&=#");

#ifdef _MSC_VER

        strncpy_s(val, val_len, qs, (val_len - 1)<(i + 1) ? (val_len - 1) : (i + 1));

#else

        strncpy(val, qs, (val_len - 1)<(i + 1) ? (val_len - 1) : (i + 1));

#endif

    qs_decode(val);

    }

    else

    {

        if ( val_len > 0 )

            val[0] = '\0';

    }

    return val;

}

}

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

namespace crow

{

    struct request;

    /// A class to represent any data coming after the `?` in the request URL into key-value pairs.

    class query_string

    {

    public:

        static const int MAX_KEY_VALUE_PAIRS_COUNT = 256;

        query_string() = default;

        query_string(const query_string& qs):

          url_(qs.url_)

        {

            for (auto p : qs.key_value_pairs_)

            {

                key_value_pairs_.push_back((char*)(p - qs.url_.c_str() + url_.c_str()));

            }

        }

        query_string& operator=(const query_string& qs)

        {

            url_ = qs.url_;

            key_value_pairs_.clear();

            for (auto p : qs.key_value_pairs_)

            {

                key_value_pairs_.push_back((char*)(p - qs.url_.c_str() + url_.c_str()));

            }

            return *this;

        }

        query_string& operator=(query_string&& qs) noexcept

        {

            key_value_pairs_ = std::move(qs.key_value_pairs_);

            char* old_data = (char*)qs.url_.c_str();

            url_ = std::move(qs.url_);

            for (auto& p : key_value_pairs_)

            {

                p += (char*)url_.c_str() - old_data;

            }

            return *this;

        }

        query_string(std::string params, bool url = true):

          url_(std::move(params))

        {

            if (url_.empty())

                return;

            key_value_pairs_.resize(MAX_KEY_VALUE_PAIRS_COUNT);

            size_t count = qs_parse(&url_[0], &key_value_pairs_[0], MAX_KEY_VALUE_PAIRS_COUNT, url);

            key_value_pairs_.resize(count);

            key_value_pairs_.shrink_to_fit();

        }

        void clear()

        {

            key_value_pairs_.clear();

            url_.clear();

        }

        friend std::ostream& operator<<(std::ostream& os, const query_string& qs)

        {

            os << "[ ";

            for (size_t i = 0; i < qs.key_value_pairs_.size(); ++i)

            {

                if (i)

                    os << ", ";

                os << qs.key_value_pairs_[i];

            }

            os << " ]";

            return os;

        }

        /// Get a value from a name, used for `?name=value`.

        ///

        /// Note: this method returns the value of the first occurrence of the key only, to return all occurrences, see \ref get_list().

        char* get(const std::string& name) const

        {

            char* ret = qs_k2v(name.c_str(), key_value_pairs_.data(), key_value_pairs_.size());

            return ret;

        }

        /// Works similar to \ref get() except it removes the item from the query string.

        char* pop(const std::string& name)

        {

            char* ret = get(name);

            if (ret != nullptr)

            {

                const std::string key_name = name + '=';

                for (unsigned int i = 0; i < key_value_pairs_.size(); i++)

                {

                    std::string str_item(key_value_pairs_[i]);

                    if (str_item.find(key_name)==0)

                    {

                        key_value_pairs_.erase(key_value_pairs_.begin() + i);

                        break;

                    }

                }

            }

            return ret;

        }

        /// Returns a list of values, passed as `?name[]=value1&name[]=value2&...name[]=valuen` with n being the size of the list.

        ///

        /// Note: Square brackets in the above example are controlled by `use_brackets` boolean (true by default). If set to false, the example becomes `?name=value1,name=value2...name=valuen`

        std::vector<char*> get_list(const std::string& name, bool use_brackets = true) const

        {

            std::vector<char*> ret;

            std::string plus = name + (use_brackets ? "[]" : "");

            char* element = nullptr;

            int count = 0;

            while (1)

            {

                element = qs_k2v(plus.c_str(), key_value_pairs_.data(), key_value_pairs_.size(), count++);

                if (!element)

                    break;

                ret.push_back(element);

            }

            return ret;

        }

        /// Similar to \ref get_list() but it removes the

        std::vector<char*> pop_list(const std::string& name, bool use_brackets = true)

        {

            std::vector<char*> ret = get_list(name, use_brackets);

            const size_t name_len = name.length();

            if (!ret.empty())

            {

                for (unsigned int i = 0; i < key_value_pairs_.size(); i++)

                {

                    std::string str_item(key_value_pairs_[i]);

                    if (str_item.find(name)==0) {

                      if (use_brackets && str_item.find("[]=",name_len)==name_len) {

                        key_value_pairs_.erase(key_value_pairs_.begin() + i--);

                      } else if (!use_brackets && str_item.find('=',name_len)==name_len ) {

                           key_value_pairs_.erase(key_value_pairs_.begin() + i--);

                       }

                    }

                }

            }

            return ret;

        }

        /// Works similar to \ref get_list() except the brackets are mandatory must not be empty.

        ///

        /// For example calling `get_dict(yourname)` on `?yourname[sub1]=42&yourname[sub2]=84` would give a map containing `{sub1 : 42, sub2 : 84}`.

        ///

        /// if your query string has both empty brackets and ones with a key inside, use pop_list() to get all the values without a key before running this method.

        std::unordered_map<std::string, std::string> get_dict(const std::string& name) const

        {

            std::unordered_map<std::string, std::string> ret;

            int count = 0;

            while (1)

            {

                if (auto element = qs_dict_name2kv(name.c_str(), key_value_pairs_.data(), key_value_pairs_.size(), count++))

                    ret.insert(*element);

                else

                    break;

            }

            return ret;

        }

        /// Works the same as \ref get_dict() but removes the values from the query string.

        std::unordered_map<std::string, std::string> pop_dict(const std::string& name)

        {

            const std::string name_value = name +'[';

            std::unordered_map<std::string, std::string> ret = get_dict(name);

            if (!ret.empty())

            {

                for (unsigned int i = 0; i < key_value_pairs_.size(); i++)

                {

                    std::string str_item(key_value_pairs_[i]);

                    if (str_item.find(name_value)==0)

                    {

                        key_value_pairs_.erase(key_value_pairs_.begin() + i--);

                    }

                }

            }

            return ret;

        }

        std::vector<std::string> keys() const

        {

            std::vector<std::string> keys;

            keys.reserve(key_value_pairs_.size());

            for (const char* const element : key_value_pairs_)

            {

                const char* delimiter = strchr(element, '=');

                if (delimiter)

                    keys.emplace_back(element, delimiter);

                else

                    keys.emplace_back(element);

            }

            return keys;

        }

    private:

        std::string url_;

        std::vector<char*> key_value_pairs_;

    };

} // namespace crow