#pragma once

#include <set>
#include <string>
#include <vector>
#include <cppmariadb.h>

#include "../fields/field.h"
#include "../fields/fields.h"

namespace cpphibernate {
namespace mariadb {

    struct filter_t;
    struct schema_t;
    struct base_context;
    struct init_context;
    struct read_context;
    struct create_update_context;
    struct destroy_context;

    enum init_stage
    {
        unknown = 0,
        stage1,
        stage2,
    };

    /**
     * @brief Abstract table class.
     */
    struct table_t
    {
    public:
        using size_vector  = std::vector<size_t>;                   //!< vector of size_t
        using table_vector = std::vector<const table_t *>;          //!< vector of constant field pointers
        using field_vector = std::vector<const field_t *>;          //!< vector of constant field pointers
        using table_set    = std::set<const table_t *>;             //!< set of tables

    public:
        size_t              id                      { 0 };          //!< unique id of the table assigned by the user
        size_t              dataset_id              { 0 };          //!< unique id of the dataset type
        size_t              base_dataset_id         { 0 };          //!< unique id of the dataset type
        size_vector         derived_dataset_ids;                    //!< vector of ids of all derived dataset

        bool                is_used_in_container    { false };      //!< indicates if this table is used inside a container

        std::string         name;                                   //!< name of the table
        const schema_t&     schema;                                 //!< schema this table is owned by
        fields_t            fields;                                 //!< vector of fields managed by this table

        const table_t *     base_table              { nullptr };    //!< base table (if has one)
        table_vector        derived_tables;                         //!< vector of pointers of all derived tables

        const field_t *     primary_key_field       { nullptr };    //!< primary key field
        field_vector        foreign_key_fields;                     //!< vector of pointers of all foreign key fields
        field_vector        foreign_table_fields;                   //!< vector of pointers of all foreign table fields
        field_vector        foreign_table_one_fields;               //!< vector of pointers of all foreign table one fields
        field_vector        foreign_table_many_fields;              //!< vector of pointers of all foreign table many fields
        field_vector        data_fields;                            //!< vector of pointers of all normal data fields

    public:
        /**
         * @brief Default constructor.
         */
        inline table_t() = default;

        /**
         * @brief Value constructor. Creates a mariadb table from the cpphibernate table.
         *
         * @param[in] p_owner   Owner of the table.
         * @param[in] p_schema  Cpphibernate schema the table belongs to.
         * @param[in] p_table   Cpphibernate table to create mariadb table for.
         */
        template<
            typename T_schema,
            typename T_table>
        inline table_t(
            const schema_t& p_owner,
            const T_schema& p_schema,
            const T_table&  p_table);

        /**
         * @brief Move constructor.
         */
        inline table_t(table_t&& other) = delete;

        /**
         * @brief Copy constructor.
         */
        inline table_t(const table_t&) = delete;

        /**
         * @brief Destructor.
         */
        virtual ~table_t() = 0;

        /**
         * @brief Print the table to the passed stream.
         */
        std::ostream& print(std::ostream& os) const;

    public:
        /**
         * @brief Initialize the table using the passed context.
         *
         * The initialization is splitted into two stages. In the first stage the
         * table is created. In the second stage the table contraints are added.
         * The first stage must be completed for all tables before stage two of
         * any table is executed.
         *
         * @param[in] context   Context that stores the needed data for the operation.
         * @param[in] stage     Stage to execute.
         */
        void init(const init_context& context, init_stage stage) const;

        /**
         * @brief Execute a read operation on the current table.
         *
         * @param[in] context   Context that stores the needed data for the operation.
         */
        void read(const read_context& context) const;

        /**
         * @brief Execute a create/update operation on the current table.
         *
         * For a polymorphic type this will check the derived tables before executing the actual operation.
         * If the dataset matches one of the dericed tables, the operation is executed on this table.
         * This operation also updates the base table if the dataset has one.
         *
         * @param[in] context   Context that stores the needed data for the operation.
         *
         * @return              Returns the key of the created/updated dataset in it's string representation.
         */
        virtual std::string create_update(const create_update_context& context) const;

        /**
         * @brief Execute a destroy operation on the current table.
         *
         * For a polymorphic type this will check the derived tables before executing the actual operation.
         * If the dataset matches one of the dericed tables, the operation is executed on this table.
         * This operation also updates the base table if the dataset has one.
         *
         * @param[in] context   Context that stores the needed data for the operation.
         */
        virtual void destroy(const destroy_context& context) const;

        /**
         * @brief Cleanup orphaned datasets beginning from this table.
         *
         * This operation will iterate through the different base, derived and foreign tables of this table
         * and delete all datasets that are not referenced at least by one other dataset.
         *
         * @param[in] context       Context that stores the needed data for the operation.
         * @param[in] processed     Contains all tables that are already cleared (to handle ring dependencies).
         * @param[in] check_derived Check the derived tables.
         * @param[in] check_base    Check the base table.
         */
        void cleanup(const base_context& context, table_set& processed, bool check_derived, bool check_base) const;

    public:
        /**
         * @brief Get the value of the primary key of this table.
         *
         * @param[in] context   Data context to get the dataset from.
         *
         * @return              Value of the primary key.
         */
        std::string get_primary_key(const data_context& context) const;

        /**
         * @brief Get the value of the primary key of this table,
         *        by fetching it from the base table.
         *
         * @param[in] context   Data context to get the dataset from.
         *
         * @return              Value of the primary key.
         */
        std::string get_key_from_base(const data_context& context) const;

        /**
         * @brief Execute the actual create/update operation.
         *
         * Other than the normal create_update method  this will not check the derived tables.
         * It will execute the query and forward the operation to the base table if the dataset has one.
         */
        std::string create_update_exec(const create_update_context& context) const;

        /**
         * @brief Execute the actual destroy operation.
         *
         * Other than the normal destroy method this will not check the derived tables.
         * It will execute the query and forward the operation to the base table if the dataset has one.
         */
        void destroy_exec(const destroy_context& context) const;

        /**
         * @brief Delete all datasets from the table that foreign keys are all set to NULL.
         *
         * @param[in] context   Context that stores the needed data for this operation.
         */
        void foreign_many_delete_exec(const base_context& context) const;

        /**
         * @brief Build the delete query for this table.
         *
         * @param[in] where     Where expression to add to the delete query.
         *
         * @return              The requested delete query.
         */
        std::string build_delete_query(const std::string* where) const;

    public:
        /**
         * @brief Emplace new dataset of the type the table represents.
         *
         * @param[in] context   Context to emplace new dataset in.
         */
        virtual void emplace(const read_context& context) const;

        /**
         * @brief Get the derived table by it's dataset id
         *
         * @param[in] p_id  Dataset id to get derived table for.
         *
         * @return          Derived table or nullptr if table was not found.
         */
        inline const table_t* get_derived_by_dataset_id(size_t p_id) const;

        /**
         * @brief Get the derived table by it's table id
         *
         * @param[in] p_id  Table id to get derived table for.
         *
         * @return          Derived table or nullptr if table was not found.
         */
        inline const table_t* get_derived_by_table_id(size_t p_id) const;

    private:
        using statement_ptr_u   = std::unique_ptr<::cppmariadb::statement>;
        using statement_key     = std::tuple<size_t, const field_t*>;
        using statement_map     = std::map<statement_key, ::cppmariadb::statement>;

        mutable statement_ptr_u _statement_key_from_base;       //!< Statement to fetch the key of this table from the base table.
        mutable statement_ptr_u _statement_init_stage1;         //!< Statement for init stage 1 (create table).
        mutable statement_ptr_u _statement_init_stage2;         //!< Statement for init stage 2 (alter table).
        mutable statement_ptr_u _statement_insert_into;         //!< Statement for create operation (inser into)
        mutable statement_map   _statement_select_static;       //!< Statement to select simple datasets from the database
        mutable statement_map   _statement_select_dynamic;      //!< Statement to select dynamic/polymorphic datasets from the database
        mutable statement_map   _statement_update;              //!< Map of all update statements
        mutable statement_ptr_u _statement_foreign_many_delete; //!< Statement to delete all datasets from the table that foreign keys are all set to NULL.
        mutable statement_ptr_u _statement_delete;              //!< Statement to delete datasets from the database

        /**
         * @brief Get the statement to fetch the key of this table from the base table.
         */
        ::cppmariadb::statement& get_statement_key_from_base() const;

        /**
         * @brief Get or create the mariadb statement for init stage 1.
         */
        ::cppmariadb::statement& get_statement_init_stage1() const;

        /**
         * @brief Get or create the mariadb statement for init stage 2.
         */
        ::cppmariadb::statement* get_statement_init_stage2() const;

        /**
         * Get the statement for the create operation. If the statement is empty nullptr is returned.
         */
        ::cppmariadb::statement* get_statement_insert_into() const;

        /**
         * Get the statement for select operations.
         *
         * @param[in] filter    Filter to apply to the statement.
         * @param[in] dynamic   Get select statement for dynamic/polymorphic datasets, for simple datasets otherwise.
         */
        ::cppmariadb::statement& get_statement_select(const filter_t& filter, bool dynamic) const;

        /**
         * Get the statement for the update operation. If the statement is empty nullptr is returned;
         *
         * @param[in] filter    Filter to use for the update statement.
         * @param[in] owner     Field the current dataset is owned by (if this table is used in a foreign field).
         */
        ::cppmariadb::statement* get_statement_update(const filter_t& filter, const field_t * owner) const;

        /**
         * @brief Get the statement to delete all datasets from the table that foreign keys are all set to NULL.
         */
        ::cppmariadb::statement& get_statement_foreign_many_delete() const;

        /**
         * @brief Get statement to delete datasets from the database.
         */
        ::cppmariadb::statement& get_statement_delete() const;
    };

    using table_ptr_u = std::unique_ptr<const table_t>;

    namespace __impl
    {

        /**
         * @brief Helper type to build table.
         */
        template<typename X, typename = void>
        struct table_builder;

    }

    /**
     * @brief Predicate to create mariadb table class.
     */
    constexpr decltype(auto) make_table = mp::generic_predicate<__impl::table_builder> { };

} }