DROP VIEW Languages_with_descr;
DROP VIEW Languages_with_all_descr;
DROP VIEW Extlangs_with_descr;
DROP VIEW Extlangs_with_all_descr;
DROP VIEW Scripts_with_descr;
DROP VIEW Scripts_with_all_descr;
DROP VIEW Variants_with_descr;
DROP VIEW Variants_with_all_descr;
DROP VIEW Regions_with_descr;
DROP VIEW Regions_with_all_descr;
DROP TABLE Descriptions_languages;
DROP TABLE Descriptions_extlangs;
DROP TABLE Descriptions_scripts;
DROP TABLE Descriptions_regions;
DROP TABLE Descriptions_variants;
--DROP TABLE Descriptions_extensions;
DROP TABLE Descriptions;
DROP TABLE Prefixes;
DROP TABLE Languages;
DROP TABLE Extlangs;
DROP TABLE Scripts;
DROP TABLE Regions;
DROP TABLE Variants;
DROP TABLE Extensions;

DROP AGGREGATE concatenate(text);

CREATE TABLE Scripts (
    id SERIAL PRIMARY KEY NOT NULL,
    code TEXT UNIQUE NOT NULL, -- TODO: a length and content constraint?
    added DATE,
    deprecated DATE,	
    comments TEXT);

CREATE TABLE Languages (
    id SERIAL PRIMARY KEY NOT NULL,
    code TEXT UNIQUE NOT NULL, -- TODO: a length and content constraint?
    suppressscript TEXT REFERENCES Scripts(code),
    preferredvalue TEXT, -- Yes, it should REFERENCES Languages(code), but
    -- there is a chicken-and-egg problem.
    added DATE,
    deprecated DATE,
    comments TEXT);

CREATE TABLE Extlangs (
    id SERIAL PRIMARY KEY NOT NULL,
    code TEXT UNIQUE NOT NULL, -- TODO: a length and content constraint?
    added DATE,
    prefix TEXT, -- references Languages(code)? Can a prefix be longer (a language and a script, for instance)?
    comments TEXT);

CREATE TABLE Regions (
    id SERIAL PRIMARY KEY NOT NULL,
    code TEXT UNIQUE NOT NULL, -- TODO: a length and content constraint?
    added DATE,
    deprecated DATE,
    comments TEXT);

CREATE TABLE Variants (
    id SERIAL PRIMARY KEY NOT NULL,
    code TEXT UNIQUE NOT NULL, -- TODO: a length and content constraint?
    -- TODO: prefixes
    added DATE,
    deprecated DATE,
    comments TEXT);

CREATE TABLE Extensions (
    id SERIAL PRIMARY KEY NOT NULL,
    code TEXT UNIQUE NOT NULL, -- TODO: a length and content constraint?
    added DATE,
    comments TEXT);

CREATE TABLE Descriptions (
     id SERIAL PRIMARY KEY NOT NULL,
     description TEXT NOT NULL);

CREATE TABLE Descriptions_Languages (
    description INTEGER NOT NULL REFERENCES Descriptions(id),
    lang TEXT NOT NULL REFERENCES Languages(code));

CREATE TABLE Descriptions_Extlangs (
    description INTEGER NOT NULL REFERENCES Descriptions(id),
    extlang TEXT NOT NULL REFERENCES Extlangs(code));

CREATE TABLE Descriptions_Scripts (
    description INTEGER NOT NULL REFERENCES Descriptions(id),
    script TEXT NOT NULL REFERENCES Scripts(code));

CREATE TABLE Descriptions_Regions (
    description INTEGER NOT NULL REFERENCES Descriptions(id),
    region TEXT NOT NULL REFERENCES Regions(code));

CREATE TABLE Descriptions_Variants (
    description INTEGER NOT NULL REFERENCES Descriptions(id),
    variant TEXT NOT NULL REFERENCES Variants(code));

CREATE TABLE Prefixes (
    variant TEXT NOT NULL REFERENCES Variants(code),
    prefix TEXT NOT NULL REFERENCES Languages(code)
);

CREATE OR REPLACE FUNCTION concat2(text, text) RETURNS text AS '
    SELECT CASE WHEN $1 IS NULL OR $1 = '''' THEN $2
	        WHEN $2 IS NULL OR $2 = '''' THEN $1
	        ELSE $1 || '' / '' || $2
	        END; 
 '
 LANGUAGE SQL;

CREATE AGGREGATE concatenate (
    sfunc = concat2,
    basetype = text,
    stype = text,
    initcond = ''
);

CREATE VIEW Languages_with_all_descr AS 
         SELECT l.code, l.added, l.suppressscript, d.description 
     FROM languages l,descriptions d,descriptions_languages WHERE
        descriptions_languages.lang = l.code AND 
        descriptions_languages.description = d.id;

CREATE VIEW Languages_with_descr AS 
         SELECT l.code, l.added, l.suppressscript, 
                concatenate(d.description) as description FROM languages l, descriptions d,
                                                descriptions_languages WHERE
     descriptions_languages.lang = l.code AND 
     descriptions_languages.description = d.id 
          GROUP BY l.code, l.added, l.suppressscript;

CREATE VIEW Variants_with_all_descr AS 
         SELECT v.code, v.added, d.description 
     FROM variants v,descriptions d,descriptions_variants WHERE
        descriptions_variants.variant = v.code AND 
        descriptions_variants.description = d.id;

CREATE VIEW Variants_with_descr AS 
         SELECT v.code, v.added,
                concatenate(d.description) as description FROM 
              variants v, descriptions d,
                                                descriptions_variants WHERE
     descriptions_variants.variant = v.code AND 
     descriptions_variants.description = d.id 
          GROUP BY v.code, v.added;

CREATE VIEW Scripts_with_all_descr AS 
         SELECT s.code, s.added, d.description 
     FROM scripts s,descriptions d,descriptions_scripts WHERE
        descriptions_scripts.script = s.code AND 
        descriptions_scripts.description = d.id;

CREATE VIEW Scripts_with_descr AS 
         SELECT s.code, s.added,
                concatenate(d.description) as description FROM scripts s, descriptions d,
                                                descriptions_scripts WHERE
     descriptions_scripts.script = s.code AND 
     descriptions_scripts.description = d.id 
          GROUP BY s.code, s.added;

CREATE VIEW Regions_with_all_descr AS 
         SELECT r.code, r.added, d.description 
     FROM regions r,descriptions d,descriptions_regions WHERE
        descriptions_regions.region = r.code AND 
        descriptions_regions.description = d.id;

CREATE VIEW Regions_with_descr AS 
         SELECT r.code, r.added,
                concatenate(d.description) as description FROM regions r, descriptions d,
                                                descriptions_regions WHERE
     descriptions_regions.region = r.code AND 
     descriptions_regions.description = d.id 
          GROUP BY r.code, r.added;

CREATE VIEW Extlangs_with_all_descr AS 
         SELECT l.code, l.added, d.description 
     FROM extlangs l,descriptions d,descriptions_extlangs WHERE
        descriptions_extlangs.extlang = l.code AND 
        descriptions_extlangs.description = d.id;

CREATE VIEW Extlangs_with_descr AS 
         SELECT l.code, l.added, 
                concatenate(d.description) as description FROM extlangs l, descriptions d,
                                                descriptions_extlangs WHERE
     descriptions_extlangs.extlang = l.code AND 
     descriptions_extlangs.description = d.id 
          GROUP BY l.code, l.added;

-- You can get all the records with stuff like:
-- select 'language', code, added from languages where added > '2005-10-16' union select 'script', code, added from scripts where added > '2005-10-16';