/**
 * DStruct - Object-Relation Mapping for D programming language, with interface similar to Hibernate. 
 * 
 * Hibernate documentation can be found here:
 * $(LINK http://hibernate.org/docs)$(BR)
 * 
 * Source file dstruct/annotations.d.
 *
 * This module contains declarations of DStruct Annotations - User Defined Attribues used to markup D classes and their properties for ORM.
 * 
 * Copyright: Copyright 2013
 * License:   $(LINK www.boost.org/LICENSE_1_0.txt, Boost License 1.0).
 * Author:   Vadim Lopatin
 */
module dstruct.annotations;



/**
 * @Transient - mark class or field as transient, to not generate DStruct persistence metadata for it.
 * Use this annotation in cases when field you won't persist will be considered as persistent otherwise.
 */
struct Transient {
    immutable bool dummy;
}


/** 
 * Class level annotations.
 * 
 * DStruct maps values of some class to DB table. This class is referred as Entity.
 * 
 * Entity contains one or more properties - which are usually mapped to DB table columns.
 */

/**
 * Mark class with this annotation if you want to make it persistable.
 * @Entity or @Entity() - marks class as entity, using class name as entity name.
 */
struct Entity {
	//immutable string name;
    immutable bool dummy;
    //	this(string name) { this.name = name; }
}

/**
 * @Embeddable or @Embeddable() - mark class as entity which can only be embedded into other entities, and doesn't have separate columns.
 * Columns for each of Embeddable entity properties will be placed into parent entity's table, where this embeddable entity is embedded
 */
struct Embeddable {
	immutable bool dummy;
//	this(bool enabled) {}
}

/**
 * Use to specify table name for entity.
 * @Table("table_name") - specifies table name to store entity in, different from default generated.
 * If this annotation not present, table name will be autogenerated as lowercase entity name with conversion of 
 * CamelCaseEntityName to camel_case_entity_name.
 */
struct Table {
	immutable string name;
//	this(string name) { this.name = name; }
}

/** 
 * Property level annotations.
 * 
 * Supported simple types for properties (may be stored in single DB table column):
 *     byte, short, int, long, ubyte, ushort, uint, ulong, float, double, byte[], ubyte[], string, DateTime, Date, TimeOfDay
 * 
 * Other possible types of properties:
 *     Embeddable entity class -- implementation in progress
 *     Entity class Lazy!class -- ManyToOne or OneToOne relation
 *     Entity class array or LazyCollection!class -- collection for OneToMany or ManyToMany
 * 
 * Supported kinds of property holders:
 *     field -- just public field
 *     @property -- D language read/write property
 *     getField()/setField(x) method pair
 * 
 * Each entity property has a name. It's derived from field, @property or getter/setter name.
 * For field and D @property - name of field of property is used as name of entity property, with first letter lowercased.
 * For getters/setters, get/set/is prefix is removed from mothod name, and the rest with lowercased first letter is used as property name.
 */

/**
 * Mark property as simple persistent property (must be of one of simple types).
 * 
 * @Column or @Column() - simple column, with name derived from field/property name.
 * @Column("column_name") - simple column with specified name.
 * @Column("column_name", field_length) - simple column with specified name and length (e.g. for varchar).
 * @Column(field_length) - simple column with specified length; column name will be autogenerated
 * 
 * If column name is not specified, lowercased name of property with _ delimited camelCase words is used as column name.
 * Field name camelCasePropertyName will be converted to camel_case_property_name column name.
 */
struct Column {
	immutable string name;
	immutable int length;
//	this(string name) { this.name = name; }
//	this(string name, int length) { this.name = name; this.length = length; }
//	this(int length) { this.length = length; }
}

/**
 * @Id or @Id() - mark simple property as primary key of entity.
 */
struct Id {
	immutable bool dummy;
}

/**
 * @Generated or @Generated() - mark simple property as column as server generated value (e.g. AUTO INCREMENT field)
 */
struct Generated {
	immutable bool dummy;
}

/**
 * @Generator(code) - specify code to call for generation of simple property key value (will be inserted into definition Variant function(Connection conn, PropertyInfo prop) { return Variant($code); }
 */
struct Generator {
    string code;
}

/// standard generator - generates random UUID - for use as @Generator() annotation parameter. Don't forget to import std.uuid
const string UUID_GENERATOR = "std.uuid.randomUUID().toString()";

/**
 * @NotNull or @NotNull() - mark entity property as not null (NULLs are not allowed in DB)
 * If neither @NotNull nor @Null specified, nullability will be derived from field type (e.g. NotNull for int, long; Null for string, byte[], Nullable!int)
 */
struct NotNull {
	immutable bool dummy;
}

/**
 * @Null or @Null() - mark entity property as nullable (NULLs are allowed in DB)
 * If neither @NotNull nor @Null specified, nullability will be derived from field type (e.g. NotNull for int, long; Null for string, byte[], Nullable!int)
 */
struct Null {
	immutable bool dummy;
}

/**
 * @UniqueKey or @UniqueKey() - mark entity property as unique (UNIQUE INDEX will be created for this column, with autogenerated index name)
 * @UniqueKey(indexName) - mark entity property as unique (UNIQUE INDEX will be created for this column, with specified index name)
 * For multiple column unique constraints, use Entity level annotations (TODO).
 */
struct UniqueKey {
    immutable string name;
}


/**
 * @OneToOne(propertyName) - referenced object uses one-to-one relation, propertyName is referenced entity's property to join with current entity's primary key.
 * @OneToOne or @OneToOne() - referenced object uses one-to-one relation, requires additional @JoinColumn annotation to specify foreign key column in current entity to join with current entity's primary key.
 */
struct OneToOne {
	immutable string name;
//	this(string referencedPropertyName) { this.name = name; }
}

/**
 * @ManyToOne or @ManyToOne() - referenced object uses many-to-one relation, requires additional @JoinColumn annotation to specify foreign key column in current entity to join with current entity's primary key.
 */
struct ManyToOne {
    immutable bool dummy;
}

/**
 * @JoinColumn(columnName) - specify foreign key column name to join other entity's by its primary key - for @OneToOne relation.
 * @JoinColumn or @JoinColumn() - foreign key column name will be autogenerated from referenced entity name, with _fk suffix.
 * This annotation is mandatory if property has @OneToOne annotation w/o parameter or @ManyToOne annotation
 */
struct JoinColumn {
	immutable string name;
//	this(string columnName) { this.name = name; }
}

/**
 * @OneToMany(referencedProperty) - referenced objects use one-to-many relation, requires additional property name in target entity which has specified foreign key column and ManyToOne to join with current entity's primary key.
 */
struct OneToMany {
    immutable string name;
}

/**
 * @ManyToMany(joinTableName, joinColumn1, joinColumn2) - referenced objects use many-to-many relation via additional join table, requires additional parameters to specify join table to implement relation, and fk columns to referene this and related entities.
 * @ManyToMany or @ManyToMany() - referenced objects use many-to-many relation via additional join table, will autogenerate join table name to implement relation, and fk column names to referene this and related entities.
 */
struct ManyToMany {
    immutable string joinTableName;
    immutable string joinColumn1;
    immutable string joinColumn2;
}


unittest {

	@Entity
	@Table("user")
	class User {

		@Id @Generated
		@Column("id")
		int id;

		@Column("name")
		string name;
	}

}