#pragma once

namespace sql {

    template <typename T>
    struct Column {
        constexpr explicit Column(const std::string_view& name) : name{name} { }

        const std::string name;
    };

    struct BindingNameGenerator {
        public:
            [[nodiscard]] static std::string generate(size_t index) {
                assert(index > 0);
                std::string result{};
                result.resize(std::max(index >> 4U, 1UL));
                for(auto it = result.begin(); index > 0; index >>= 4U)
                    *(it++) = number_map[index & 0xFU];
                return result;
            }

        private:
            constexpr static std::array<char, 16> number_map{
                    'a', 'b', 'c', 'd', 'e', 'f',
                    'g', 'h', 'i', 'j', 'k', 'l',
                    'm', 'n', 'o', 'p'
            };
    };

    template <typename... ColTypes>
    struct InsertQueryGenerator {
        struct GenerateOptions {
            bool enable_ignore{false};
            sql::SqlType target{sql::SqlType::TYPE_SQLITE};
        };

        explicit InsertQueryGenerator(std::string target_table, Column<ColTypes>... columns) : table_name{std::move(target_table)}, columns{std::move(columns.name)...} { }

        [[nodiscard]] constexpr inline auto column_count() const { return sizeof...(ColTypes); };

        [[nodiscard]] inline std::string generate_query(size_t entry_count, sql::SqlType target = sql::SqlType::TYPE_SQLITE, bool enable_ignore = false) const {
            if(entry_count == 0) return "-- No entries given";

            std::string result{"INSERT "};
            if(enable_ignore) {
                if(target == sql::TYPE_MYSQL)
                    result += "IGNORE ";
                else
                    result += "OR IGNORE ";
            }

            result += this->table_name + " (";
            //"INSERT INTO " + this->table_name + " ("
            for(auto it = this->columns.begin();;) {
                result += "`" + *it + "`";
                if(++it != this->columns.end()) {
                    result += ", ";
                } else {
                    break;
                }
            }
            result += ") VALUES (";
            for(size_t index{1}; index <= this->column_count() * entry_count; index++)
                result += ":" + BindingNameGenerator::generate(index) + ", ";
            result = result.substr(0, result.length() - 2) + ");";
            return result;
        }

        const std::string table_name{};
        const std::array<std::string, sizeof...(ColTypes)> columns{};
    };

    template <typename... ColTypes>
    struct InsertQuery : public InsertQueryGenerator<ColTypes...> {
        struct ExecuteResult {
            std::vector<std::tuple<size_t, sql::result>> failed_entries{};

            [[nodiscard]] inline auto has_succeeded() const { return this->failed_entries.empty(); }
        };

        explicit InsertQuery(const std::string& target_table, Column<ColTypes>... columns) : InsertQueryGenerator<ColTypes...>{target_table, std::move(columns)...} { }

        inline void reserve_entries(size_t amount) {
            this->entries.reserve(amount);
        }

        inline void add_entry(const ColTypes&... values) {
            this->entries.push_back(std::array<variable, sizeof...(ColTypes)>{variable{"", values}...});
        }

        inline ExecuteResult execute(sql::SqlManager* sql, bool ignore_fails = false) {
            if(this->entries.empty()) return ExecuteResult{};

            ExecuteResult result{};

            const auto chunk_size = std::min(2UL, this->entries.size());
            sql::model chunk_base{sql, this->generate_query(chunk_size, sql->getType(), ignore_fails)};
            sql::model entry_model{sql, this->generate_query(1, sql->getType(), ignore_fails)};

            for(size_t chunk{0}; chunk < this->entries.size() / chunk_size; chunk++) {
                auto command = chunk_base.command();
                size_t parameter_index{1};
                for(size_t index{chunk * chunk_size}; index < (chunk + 1) * chunk_size; index++) {
                    for(auto& var : this->entries[index]) {
                        var.set_key(":" + BindingNameGenerator::generate(parameter_index++));
                        command.value(var);
                    }
                }

                auto exec_result = command.execute();
                if(!exec_result) {
                    /* try every entry 'till we've found the error one */
                    for(size_t index{chunk * chunk_size}; index < (chunk + 1) * chunk_size; index++) {
                        parameter_index = 1;

                        auto entry_command = entry_model.command();
                        for(auto& var : this->entries[index]) {
                            var.set_key(":" + BindingNameGenerator::generate(parameter_index++));
                            entry_command.value(var);
                        }
                        exec_result = entry_command.execute();
                        if(!exec_result) {
                            result.failed_entries.emplace_back(index, std::move(exec_result));
                            if(!ignore_fails)
                                return result;
                        }
                    }
                }
            }

            for(size_t index{(this->entries.size() / chunk_size) * chunk_size}; index < this->entries.size(); index++) {
                size_t parameter_index{1};
                auto entry_command = entry_model.command();
                for(auto& var : this->entries[index]) {
                    var.set_key(":" + BindingNameGenerator::generate(parameter_index++));
                    entry_command.value(var);
                }
                auto exec_result = entry_command.execute();
                if(!exec_result) {
                    result.failed_entries.emplace_back(index, std::move(exec_result));
                    if(!ignore_fails)
                        return result;
                }
            }

            return result;
        }

        std::vector<std::array<variable, sizeof...(ColTypes)>> entries{};
    };

}