-- Process with:

-- sqlite lsr < create-db-subtag.sql  

DROP TABLE Descriptions_languages;
DROP TABLE Descriptions_scripts;
DROP TABLE Descriptions_regions;
DROP TABLE Descriptions_variants;
DROP TABLE Descriptions;
DROP TABLE Prefixes;
DROP TABLE Languages;
DROP TABLE Extlangs;
DROP TABLE Scripts;
DROP TABLE Regions;
DROP TABLE Variants;

-- A few things to remember about SQLite:
--
-- 1) If you declare a column as "INTEGER PRIMARY KEY", it will
--      autoincrement (http://www.sqlite.org/faq.html#q1)
--
-- 2) Types and constraints are almost always ignored
--    (http://www.sqlite.org/datatype3.html or
--    http://www.sqlite.org/faq.html#q2)

CREATE TABLE Scripts (
    id INTEGER PRIMARY KEY NOT NULL,
    code TEXT UNIQUE NOT NULL, 
    added DATE,
    comments TEXT);

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

CREATE TABLE Variants (
    id INTEGER PRIMARY KEY NOT NULL,
    code TEXT UNIQUE NOT NULL, 
    added DATE,
    comments TEXT);

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

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

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

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