-- LegacyWorlds Beta 6
-- PostgreSQL database scripts
--
-- Technology definitions
--
-- Copyright(C) 2004-2012, DeepClone Development
-- --------------------------------------------------------


/*
 * Technology definitions
 * -----------------------
 * 
 * This table contains all defined technologies. It includes references to
 * the various I18N strings used to describe the technology, as well as its
 * cost in research points.
 * 
 * FIXME: for now it also includes the monetary cost, but that will go away
 *		when the full resource system is completed.
 */
CREATE TABLE defs.technologies(
	/* Name of the technology (I18N string) */
	technology_name_id			INT NOT NULL PRIMARY KEY ,

	/* Category of the technology (I18N string) */
	technology_category_id		INT NOT NULL ,

	/* Text to display when the technology is discovered (I18N string) */
	technology_discovery_id		INT NOT NULL ,
	
	/* A more "factual" description of the technology (I18N string) */
	technology_description_id	INT NOT NULL ,
	
	/* Monetary price of the technology - FIXME: will be removed later */
	technology_price			BIGINT NOT NULL
									CHECK( technology_price > 0 ) ,

	/* Cost of the technology in terms of research points */
	technology_points			BIGINT NOT NULL
									CHECK( technology_points > 0 )
);

CREATE INDEX idx_techs_category
	ON defs.technologies( technology_category_id );
CREATE UNIQUE INDEX idx_techs_discovery
	ON defs.technologies( technology_discovery_id );
CREATE UNIQUE INDEX idx_techs_description
	ON defs.technologies( technology_description_id );

ALTER TABLE defs.technologies
	ADD CONSTRAINT fk_techs_name
		FOREIGN KEY ( technology_name_id ) REFERENCES defs.strings ,
	ADD CONSTRAINT fk_techs_category
		FOREIGN KEY ( technology_category_id ) REFERENCES defs.strings ,
	ADD CONSTRAINT fk_techs_discovery
		FOREIGN KEY ( technology_discovery_id ) REFERENCES defs.strings ,
	ADD CONSTRAINT fk_techs_description
		FOREIGN KEY ( technology_description_id ) REFERENCES defs.strings;



/*
 * Technology dependencies
 * ------------------------
 *
 * This table list dependencies between technologies. It stores pairs of
 * dependent / dependency references.
 */
CREATE TABLE defs.technology_dependencies(
	/* Identifier of the dependency itself. Makes integrity checks easier */
	techdep_id					SERIAL NOT NULL PRIMARY KEY ,
	
	/* Identifier of the dependent technology */
	technology_name_id			INT NOT NULL ,

	/* Identifier of the technology being depended on */
	technology_name_id_depends	INT NOT NULL
);

CREATE UNIQUE INDEX idx_techdeps_techs
	ON defs.technology_dependencies( technology_name_id , technology_name_id_depends );
CREATE INDEX idx_techdeps_dependency
	ON defs.technology_dependencies( technology_name_id_depends );

ALTER TABLE defs.technology_dependencies
	ADD CONSTRAINT fk_techdeps_dependent
		FOREIGN KEY ( technology_name_id ) REFERENCES defs.technologies ,
	ADD CONSTRAINT fk_techdeps_dependency
		FOREIGN KEY ( technology_name_id_depends ) REFERENCES defs.technologies;


/*
 * Technology dependencies graph cache
 * ------------------------------------
 *
 * This table is a cache of all dependency relationships between technologies.
 * It serves two purposes. First, it allows dependencies to be checked to
 * maintain the graph's integrity. Second, it allows all dependencies or
 * reverse dependencies of a technology to be looked up in one single SELECT
 * statement.
 *
 * It works by maintaining, for each node of the graph, a set of trees which
 * correspond to the dependencies or reverse dependencies. Each part of a
 * tree that is not determined solely by the dependency itself is a copy of
 * another tree. Because of that, multiple copies of the same tree may exist
 * in the records for a single technology.
 *
 * Technologies which have no dependencies or reverse dependencies are also
 * present in the table, as it makes things easier when dependencies are added.
 */
CREATE TABLE defs.techdep_cache(
	/* Identifier of the technology represented by this node */
	technology_name_id			INT NOT NULL,

	/* Whether the node is part of a forward or reverse dependencies tree */
	tdcache_reverse				BOOLEAN NOT NULL ,

	/* Identifier of the cache entry itself */
	tdcache_id					SERIAL NOT NULL ,

	/* Identifier of the parent cache entry, if any */
	tdcache_id_parent			INT ,

	/* Depth of the dependency relationship */
	tdcache_depth				INT NOT NULL ,

	/* Identifier of the technology of the entry this entry is a copy of */
	technology_name_id_copyof	INT NOT NULL ,

	/* Identifier of the entry this entry is a copy of */
	tdcache_id_copyof			INT ,

	/* Identifier of the dependency because of which the entry exists, or
	 * NULL if the entry exists because of a technology definition.
	 */
	techdep_id					INT ,

	PRIMARY KEY( technology_name_id , tdcache_reverse , tdcache_id )
);

CREATE INDEX idx_tdcache_reversetechs
	ON defs.techdep_cache ( tdcache_reverse , tdcache_id_parent );
CREATE INDEX idx_tdcache_copyof
	ON defs.techdep_cache ( technology_name_id_copyof );
CREATE INDEX idx_tdcache_techdep
	ON defs.techdep_cache ( techdep_id );

ALTER TABLE defs.techdep_cache
	ADD CONSTRAINT fk_tdcache_technology
		FOREIGN KEY ( technology_name_id ) REFERENCES defs.technologies
			ON DELETE CASCADE ,
	ADD CONSTRAINT fk_tdcache_techdep
		FOREIGN KEY ( techdep_id ) REFERENCES defs.technology_dependencies
			ON DELETE CASCADE ,
	ADD CONSTRAINT fk_tdcache_copyof
		FOREIGN KEY( technology_name_id_copyof , tdcache_reverse , tdcache_id_copyof )
			REFERENCES defs.techdep_cache( technology_name_id , tdcache_reverse , tdcache_id )
				ON DELETE CASCADE ,
	ADD CONSTRAINT fk_tdcache_parent
		FOREIGN KEY( technology_name_id , tdcache_reverse , tdcache_id_parent )
			REFERENCES defs.techdep_cache( technology_name_id , tdcache_reverse , tdcache_id )
				ON DELETE CASCADE;