// file      : odb/relational/oracle/schema.cxx
// author    : Constantin Michael <constantin@codesynthesis.com>
// copyright : Copyright (c) 2009-2011 Code Synthesis Tools CC
// license   : GNU GPL v3; see accompanying LICENSE file

#include <string>

#include <odb/relational/schema.hxx>

#include <odb/relational/oracle/common.hxx>
#include <odb/relational/oracle/context.hxx>

using namespace std;

namespace relational
{
  namespace oracle
  {
    namespace schema
    {
      namespace relational = relational::schema;

      struct schema_emitter: relational::schema_emitter
      {
        schema_emitter (const base& x): base (x) {}

        virtual void
        line (const std::string& l)
        {
          base::line (l);
          last_ = l;
        }

        virtual void
        post ()
        {
          if (!first_) // Ignore empty statements.
          {
            if (last_ == "END;")
              os << endl
                 << '/' << endl
                 << endl;

            else
              os << ';' << endl
                 << endl;
          }
        }

      private:
        string last_;
      };
      entry<schema_emitter> schema_emitter_;

      //
      // File.
      //

      struct schema_file: relational::schema_file, context
      {
        schema_file (const base& x): base (x) {}

        virtual void
        pre ()
        {
          os << "SET FEEDBACK OFF;" << endl
             << "WHENEVER SQLERROR EXIT FAILURE;" << endl
             << "WHENEVER OSERROR EXIT FAILURE;" << endl
             << endl;
        }

        virtual void
        post ()
        {
          os << "EXIT;" << endl;
        }
      };
      entry<schema_file> schema_file_;

      //
      // Drop.
      //

      struct drop_common: virtual relational::drop_common
      {
        virtual void
        drop_table (string const& table)
        {
          // Oracle has no IF EXISTS conditional for dropping objects. The
          // PL/SQL approach below seems to be the least error-prone and the
          // most widely used of the alternatives.
          //
          os << "BEGIN" << endl
             << "  BEGIN" << endl
             << "    EXECUTE IMMEDIATE 'DROP TABLE " << quote_id (table) <<
            " CASCADE CONSTRAINTS';" << endl
             << "  EXCEPTION" << endl
             << "    WHEN OTHERS THEN" << endl
             << "      IF SQLCODE != -942 THEN RAISE; END IF;" << endl
             << "  END;"
             << "  BEGIN" << endl
             << "    EXECUTE IMMEDIATE 'DROP SEQUENCE " <<
            quote_id (table + "_seq") << "';" << endl
             << "  EXCEPTION" << endl
             << "    WHEN OTHERS THEN" << endl
             << "      IF SQLCODE != -2289 THEN RAISE; END IF;" << endl
             << "  END;" << endl
             << "  BEGIN" << endl
             << "    EXECUTE IMMEDIATE 'DROP TRIGGER " <<
            quote_id (table + "_trig") << "';" << endl
             << "  EXCEPTION" << endl
             << "    WHEN OTHERS THEN" << endl
             << "      IF SQLCODE != -4080 THEN RAISE; END IF;" << endl
             << "  END;" << endl
             << "END;" << endl;
        }
      };

      struct member_drop: relational::member_drop, drop_common
      {
        member_drop (base const& x): base (x) {}
      };
      entry<member_drop> member_drop_;

      struct class_drop: relational::class_drop, drop_common
      {
        class_drop (base const& x): base (x) {}
      };
      entry<class_drop> class_drop_;

      //
      // Create.
      //

      struct object_columns: relational::object_columns, context
      {
        object_columns (base const& x): base (x) {}

        virtual void
        null (semantics::data_member& m)
        {
          sql_type::core_type t (column_sql_type (m, prefix_).type);

          // Oracle interprets empty VARCHAR2 and NVARCHAR2 strings as NULL. As
          // an empty string is always valid within the C++ context, VARCHAR2
          // and NVARCHAR2 columns are always specified as nullable.
          //
          if (t != sql_type::VARCHAR2 && t != sql_type::NVARCHAR2)
            base::null (m);
        }

        virtual void
        default_enum (semantics::data_member& m, tree en, string const&)
        {
          // Make sure the column is mapped to Oracle NUMBER.
          //
          sql_type t (column_sql_type (m));

          if (t.type != sql_type::NUMBER)
          {
            cerr << m.file () << ":" << m.line () << ":" << m.column ()
                 << ": error: column with default value specified as C++ "
                 << "enumerator must map to Oracle NUMBER" << endl;

            throw operation_failed ();
          }

          using semantics::enumerator;

          enumerator& e (dynamic_cast<enumerator&> (*unit.find (en)));

          if (e.enum_ ().unsigned_ ())
            os << " DEFAULT " << e.value ();
          else
            os << " DEFAULT " << static_cast<long long> (e.value ());
        }

        virtual void
        reference (semantics::data_member&)
        {
        }
      };
      entry<object_columns> object_columns_;

      struct object_columns_references:
        object_columns_base, relational::common, context
      {
        object_columns_references (emitter& e,
                                   ostream& os,
                                   string const& table,
                                   string const& prefix = string ())
            : relational::common (e, os),
              table_ (table),
              prefix_ (prefix)
        {
        }

        virtual bool
        traverse_column (semantics::data_member& m, string const& name, bool)
        {
          if (inverse (m))
            return false;

          if (semantics::class_* c = object_pointer (member_type (m, prefix_)))
          {
            pre_statement ();

            os << "ALTER TABLE " << quote_id (table_) << endl
               << "  ADD FOREIGN KEY (" << quote_id (name) << ")" << endl
               << "  REFERENCES " << table_qname (*c) << endl
               << "  DEFERRABLE INITIALLY DEFERRED" << endl;

            post_statement ();
          }
          else if (prefix_ == "id")
          {
            semantics::class_& c (*context::top_object);

            pre_statement ();

            // We don't need INITIALLY DEFERRED here since the object row
            // must exist before any container row.
            //
            os << "ALTER TABLE " << quote_id (table_) << endl
               << "  ADD FOREIGN KEY (" << quote_id (name) << ")" << endl
               << "  REFERENCES " << table_qname (c) << endl
               << "  ON DELETE CASCADE" << endl;

            post_statement ();
          }

          return true;
        }

      private:
        string table_;
        string prefix_;
      };

      struct member_create: object_members_base, context
      {
        member_create (emitter& e, ostream& os, relational::tables& tables)
            : object_members_base (false, true, false),
              e_ (e),
              os_ (os),
              tables_ (tables)
        {
        }

        virtual void
        traverse_container (semantics::data_member& m, semantics::type& t)
        {
          using semantics::type;
          using semantics::data_member;

          // Ignore inverse containers of object pointers.
          //
          if (inverse (m, "value"))
            return;

          string const& name (table_name (m, table_prefix_));

          if (tables_.count (name))
            return;

          type& vt (container_vt (t));

          // object_id
          //
          {
            object_columns_references ocr (e_, os_, name, "id");
            string id_name (column_name (m, "id", "object_id"));
            ocr.traverse_column (m, id_name, true);
          }

          // value
          //
          if (semantics::class_* cvt = composite_wrapper (vt))
          {
            object_columns_references ocr (e_, os_, name);
            ocr.traverse (m, *cvt, "value", "value");
          }
          else
          {
            object_columns_references ocr (e_, os_, name, "value");
            string const& value_name (column_name (m, "value", "value"));
            ocr.traverse_column (m, value_name, true);
          }

          tables_.insert (name);
        }

      private:
        emitter& e_;
        ostream& os_;
        relational::tables& tables_;
      };

      struct class_create: relational::class_create, context
      {
        class_create (base const& x): base (x) {}

        virtual void
        traverse (type& c)
        {
          if (pass_ != 2)
          {
            base::traverse (c);
            return;
          }

          if (c.file () != unit.file ())
            return;

          if (!object (c) || abstract (c))
            return;

          string const& name (table_name (c));

          if (tables_[pass_].count (name))
            return;

          semantics::data_member* id (id_member (c));

          if (id->count ("auto"))
          {
            string seq_name (quote_id (name + "_seq"));

            pre_statement ();

            os_ << "CREATE SEQUENCE " << seq_name << endl
                << "  START WITH 1 INCREMENT BY 1" << endl
                << endl;

            post_statement ();

            pre_statement ();

            os_ << "CREATE TRIGGER " <<
              quote_id (name + "_trig") << endl
                << "  BEFORE INSERT ON " << quote_id (name) << endl
                << "  FOR EACH ROW" << endl
                << "BEGIN" << endl
                << "  SELECT " << seq_name << ".nextval INTO :new." <<
              column_qname (*id) << " FROM DUAL;" << endl
                << "END;" << endl;

            post_statement ();
          }

          object_columns_references ocr (e_, os_, name);
          ocr.traverse (c);

          tables_[pass_].insert (name);

          member_create mc (e_, os_, tables_[pass_]);
          mc.traverse (c);
        }
      };
      entry<class_create> class_create_;
    }
  }
}