/* =============================================================================
 * PostgreSQL Schema V2 - designs for a new HPR database
 *
 * File:        hpr_schema_2.pgsql
 * Created:     2017-10-22
 * Updated:     2019-04-15
 * =============================================================================
 */

/* ------------------------------------------------------------------------------
 * Design decisions made:
 *
 * - Plural names for tables ('episodes' not 'episode')
 * - Table names all lower case with underscores
 * - Field names all lower case with underscores
 * - Primary keys named "[singularOfTableName]ID", so 'episodeID' in the
 *   'episodes' table TODO: make it 'episode_ID'??
 * - Foreign keys named consistently in all tables
 * - Explicit sequences called "[singularOfTableName]_seq"
 * - Cross reference tables shouldn't call their fields
 *   "[pluralTableName]_id" but "[singularOfTableName]_id" because
 *   'episodes_id' seems stupid.
 *
 * ------------------------------------------------------------------------------
 */

/* ------------------------------------------------------------------------------
 * Drop everything to start with. The order is important because of the
 * relations between tables. Also, some items are dependent and go with the
 * tables.
 * ------------------------------------------------------------------------------
 */

-- {{{

DROP TABLE IF EXISTS comments CASCADE;
DROP TABLE IF EXISTS episodes CASCADE;
DROP TABLE IF EXISTS episodes_hosts_xref CASCADE;
DROP TABLE IF EXISTS episodes_series_xref CASCADE;
DROP TABLE IF EXISTS episodes_tags_xref CASCADE;
DROP TABLE IF EXISTS hosts CASCADE;
DROP TABLE IF EXISTS licenses CASCADE;
DROP TABLE IF EXISTS series CASCADE;
DROP TABLE IF EXISTS tags CASCADE;
DROP TABLE IF EXISTS assets CASCADE;

--  DROP INDEX IF EXISTS episode_release_date_key;

DROP SEQUENCE IF EXISTS comment_seq;
DROP SEQUENCE IF EXISTS episode_seq;
DROP SEQUENCE IF EXISTS host_seq;
DROP SEQUENCE IF EXISTS license_seq;
DROP SEQUENCE IF EXISTS series_seq;
DROP SEQUENCE IF EXISTS tag_seq;
DROP SEQUENCE IF EXISTS assets_seq;

-- DROP VIEW IF EXISTS eht_view;

DROP FUNCTION IF EXISTS id_in_licenses(sname varchar);
DROP FUNCTION IF EXISTS id_in_episodes(ekey varchar);
DROP TRIGGER IF EXISTS comment_changed ON comments CASCADE;
DROP FUNCTION IF EXISTS comment_changed();

-- }}}

--  \/\/ licenses \/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/

-- {{{

/* ------------------------------------------------------------------------------
 * Table 'licenses' - licenses relating to episodes (needed because 'episodes'
 * and hosts' reference it)
 *
 * license_id   primary key, the licence number
 * short_name   brief name of CC licence
 * long_name    longer name of CC licence
 * url          link to details of licence at creativecommons.org
 *
 * ------------------------------------------------------------------------------
 */
CREATE SEQUENCE license_seq;

ALTER TABLE license_seq
  OWNER TO hpradmin;

CREATE TABLE licenses (
    license_id          integer default nextval('license_seq') PRIMARY KEY,
    short_name          varchar(11) NOT NULL UNIQUE,
    long_name           varchar(40) NOT NULL,
    url                 varchar(80) NOT NULL
);

ALTER TABLE licenses
  OWNER TO hpradmin;

/*
 * Load the table since it's quite short. Don't set the license_id to ensure
 * the sequence is updated properly.
 */
INSERT INTO licenses (short_name, long_name, url) VALUES
('CC-0', 'Public Domain Dedication', 'http://creativecommons.org/publicdomain/zero/1.0/'),
('CC-BY', 'Attribution', 'http://creativecommons.org/licenses/by/4.0'),
('CC-BY-SA', 'Attribution-ShareAlike', 'http://creativecommons.org/licenses/by-sa/3.0'),
('CC-BY-ND', 'Attribution-NoDerivs', 'http://creativecommons.org/licenses/by-nd/4.0'),
('CC-BY-NC', 'Attribution-NonCommercial', 'http://creativecommons.org/licenses/by-nc/4.0'),
('CC-BY-NC-SA', 'Attribution-NonCommercial-ShareAlike', 'http://creativecommons.org/licenses/by-nc-sa/4.0'),
('CC-BY-NC-ND', 'Attribution-NonCommercial-NoDerivs', 'http://creativecommons.org/licenses/by-nc-nd/4.0');

/*
 * Define a simple function to return the license_id number corresponding to
 * a short name in the licenses table. This simplifies setting a default value
 * in a foreign key definition in other tables. It's not resilient to errors
 * as it stands.
 */
CREATE OR REPLACE FUNCTION id_in_licenses(sname varchar) RETURNS integer AS
$$
    SELECT license_id FROM licenses WHERE short_name = sname;
$$
LANGUAGE SQL STABLE;

ALTER FUNCTION id_in_licenses(sname varchar)
  OWNER TO hpradmin;

-- }}}

--  \/\/ episodes \/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/

-- {{{

/* ------------------------------------------------------------------------------
 * Table 'episodes' - TWAT and HPR shows
 *
 * episode_id   primary key (NOT the episode number)
 * episode_key  episode designator
 * release_date date the episode was released
 * title        title of the episode
 * summary      summary of the episode content
 * notes        the show notes (as an HTML fragment)
 * explicit     a Boolean; true for explicit, false for otherwise
 * license      the licence which the show is under (US spelling)
 * duration     the duration (time) of the audio
 * downloads    number of downloads
 * archived     a Boolean; true if the episode has been uploaded to the IA
 * archive_date date the episode was archived
 * IA_URL       URL to the episode on archive.org
 * journal      a journal of actions performed on this episode
 *
 * TODO: Do we need a function to determine the next 'episode_key'?
 * NOTE: The 'valid' column has been removed.
 *
 * ------------------------------------------------------------------------------ */
CREATE SEQUENCE episode_seq;

ALTER TABLE episode_seq
  OWNER TO hpradmin;

CREATE TYPE episode_status AS ENUM ('reserved', 'processing', 'posted');

CREATE TABLE episodes (
    episode_id          integer default nextval('episode_seq') PRIMARY KEY,
    episode_key         varchar(40) NOT NULL,
    release_date        date NOT NULL,
    title               varchar(128) NOT NULL,
    summary             varchar(128),
    notes               text NOT NULL,
    explicit            boolean NOT NULL DEFAULT TRUE,
    license             integer NOT NULL DEFAULT id_in_licenses('CC-BY-SA')
                            REFERENCES licenses (license_id),
    duration            interval NOT NULL DEFAULT '00:00:00',
    downloads           integer NOT NULL DEFAULT 0,
    archived            boolean NOT NULL DEFAULT FALSE,
    archive_date        date,
    IA_URL              text,
    status              episode_status,
    journal             text
);

ALTER TABLE episodes
  OWNER TO hpradmin;

CREATE INDEX episode_key_idx
  ON episodes
  USING btree
  (episode_key);

CREATE INDEX episode_release_date_idx
  ON episodes
  USING btree
  (release_date);

/*
 * Define a simple function to return the episode_id number corresponding to
 * an episode key in the 'episodes' table.
 */
CREATE OR REPLACE FUNCTION id_in_episodes(ekey varchar) RETURNS integer AS
$$
    SELECT episode_id FROM episodes WHERE episode_key = ekey;
$$
LANGUAGE SQL STABLE;

ALTER FUNCTION id_in_episodes(ekey varchar)
  OWNER TO hpradmin;

-- }}}

--  \/\/ hosts /\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/

-- {{{

/* ------------------------------------------------------------------------------
 * Table 'hosts' - hosts contributing shows
 *
 * host_id      primary key, host number
 * host         host name or handle
 * email        host email address (cannot be unique because some hosts need
 *              to have their mail directed to admin@hpr)
 * profile      text describing the host, HTML preferred
 * license      the default licence chosen by the host (US spelling)
 * local_image  true if there's a host-supplied image for the host
 * gpg          the host's GPG key
 * espeak_name  the host name written so that 'espeak' speaks it properly
 * when_added   the date the host was added to the database
 *
 * TODO: Do we need the 'valid' field? Removed for the moment.
 * NOTE: Is there any point in the added date? Most will start as the date the
 * table was created in this database, and effort will be needed to set
 * approximate dates in the past (from the date of their first shows).
 *
 * ------------------------------------------------------------------------------ */
CREATE SEQUENCE host_seq;

ALTER TABLE host_seq
  OWNER TO hpradmin;

CREATE TABLE hosts (
    host_id             integer default nextval('host_seq') PRIMARY KEY,
    host                varchar(1024) UNIQUE NOT NULL,
    email               varchar(1024) UNIQUE NOT NULL,
    profile             text,
    license             integer NOT NULL DEFAULT id_in_licenses('CC-BY-SA')
                            REFERENCES licenses (license_id),
    local_image         boolean NOT NULL DEFAULT FALSE,
    gpg                 text,
--  valid               boolean NOT NULL DEFAULT TRUE,
    espeak_name         text,
    when_added          date NOT NULL DEFAULT now()
);

ALTER TABLE hosts
  OWNER TO hpradmin;

/* ------------------------------------------------------------------------------
 * Table 'episodes_hosts_xref' - joining table between 'episodes' and 'hosts'
 *
 * episode_id   primary key of the episodes table
 * host_id      primary key of the hosts table
 *
 * The two fields jointly make the primary key of this table
 *
 * TODO: Check the deletion actions
 *
 * ------------------------------------------------------------------------------ */
CREATE TABLE episodes_hosts_xref (
    episode_id          integer REFERENCES episodes(episode_id)
                                ON DELETE RESTRICT,
    host_id             integer REFERENCES hosts(host_id)
                                ON DELETE CASCADE,
                        PRIMARY KEY (episode_id, host_id)
);

ALTER TABLE episodes_hosts_xref
  OWNER TO hpradmin;

-- }}}

--  \/\/ tags \/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/

-- {{{

/* ------------------------------------------------------------------------------
 * Table 'tags' - tags relating to episodes
 *
 * tag_id       primary key, tag number
 * tag          a tag
 *
 * TODO: Tags are case-sensitive. Should they be?
 * TODO: Should tags have a unique key on them?
 *
 * ------------------------------------------------------------------------------ */
CREATE SEQUENCE tag_seq;

ALTER TABLE tag_seq
  OWNER TO hpradmin;

CREATE TABLE tags (
    tag_id              integer default nextval('tag_seq') PRIMARY KEY,
    tag                 varchar(1024) NOT NULL
);

ALTER TABLE tags
  OWNER TO hpradmin;

/* ------------------------------------------------------------------------------
 * Table 'episodes_tags_xref' - joining table between 'episodes' and 'tags'
 *
 * episode_id   primary key of the episodes table
 * tag_id       primary key of the tags table
 *
 * The two fields jointly make the primary key of this table
 *
 * TODO: Check the deletion actions
 *
 * ------------------------------------------------------------------------------ */
CREATE TABLE episodes_tags_xref (
    episode_id          integer REFERENCES episodes(episode_id)
                            ON DELETE RESTRICT,
    tag_id              integer REFERENCES tags(tag_id)
                            ON DELETE CASCADE,
                        PRIMARY KEY (episode_id, tag_id)
);

ALTER TABLE episodes_tags_xref
  OWNER TO hpradmin;

-- }}}

--  \/\/ series \/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/

-- {{{

/* ------------------------------------------------------------------------------
 * Table 'series' - series grouping for episodes
 *
 * series_id    primary key, series number
 * name         name of series
 * description  description of series (HTML preferred)
 * private      whether others may contribute to the series
 * image        ??
 *
 * NOTE: Removed 'valid'
 *
 * ------------------------------------------------------------------------------ */
CREATE SEQUENCE series_seq;

ALTER TABLE series_seq
  OWNER TO hpradmin;

CREATE TABLE series (
    series_id           integer default nextval('series_seq') PRIMARY KEY,
    name                varchar(100) NOT NULL,
    description         text NOT NULL,
    private             boolean NOT NULL DEFAULT FALSE,
    image               text
--  valid               boolean NOT NULL DEFAULT TRUE
);

ALTER TABLE series
  OWNER TO hpradmin;

/* ------------------------------------------------------------------------------
 * Table 'episodes_series_xref' - joining table between 'episodes' and 'series'
 *
 * episodes_id  primary key of the episodes table
 * series_id    primary key of the series table
 *
 * The two fields jointly make the primary key of this table
 *
 * TODO: Check the deletion actions
 *
 * ------------------------------------------------------------------------------ */
CREATE TABLE episodes_series_xref (
    episode_id          integer REFERENCES episodes(episode_id)
                            ON DELETE RESTRICT,
    series_id           integer REFERENCES series(series_id)
                            ON DELETE CASCADE,
                        PRIMARY KEY (episode_id, series_id)
);

ALTER TABLE episodes_series_xref
  OWNER TO hpradmin;

-- }}}

--  \/\/ comments \/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/

-- {{{

/* ------------------------------------------------------------------------------
 * Table 'comments' - comments relating to episodes
 *
 * comment_id           primary key, comment number
 * episode_id           primary key of the episodes table
 * comment_timestamp    UTC timestamp when comment was submitted
 * comment_author_name  name given by the comment author
 * comment_title        title given by the comment author
 * comment_text         text of the comment (NO HTML)
 * last_changed         UTC timestamp of the last change to the row
 *
 * TODO: Check the deletion FK actions
 *
 * ------------------------------------------------------------------------------ */
CREATE SEQUENCE comment_seq;

ALTER TABLE comment_seq
  OWNER TO hpradmin;

CREATE TABLE comments (
    comment_id          integer default nextval('comment_seq') PRIMARY KEY,
    episode_id          integer REFERENCES episodes(episode_id)
                            ON DELETE RESTRICT,
    comment_timestamp   timestamp without time zone NOT NULL,
    comment_author_name varchar(1024),
    comment_title       varchar(1024),
    comment_text        text,
    last_changed        timestamp without time zone NOT NULL
                            DEFAULT timezone('UTC'::text, now())
);

ALTER TABLE comments
  OWNER TO hpradmin;

/* ------------------------------------------------------------------------------
 * Trigger function 'comment_changed' and trigger on the 'comments' table
 *
 * ------------------------------------------------------------------------------ */
CREATE FUNCTION comment_changed() RETURNS trigger AS $comment_changed$
    BEGIN
        -- Remember when the comment row was changed
        NEW.last_changed := current_timestamp;
        RETURN NEW;
    END;
$comment_changed$ LANGUAGE plpgsql;

ALTER FUNCTION comment_changed()
  OWNER TO hpradmin;

CREATE TRIGGER comment_changed BEFORE UPDATE ON comments
    FOR EACH ROW EXECUTE PROCEDURE comment_changed();


-- }}}

--  \/\/ assets \/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/

-- {{{

/* ------------------------------------------------------------------------------
 * Table 'assets' - assets relating to episodes
 *
 * asset_id             primary key
 * episode_id           link to episodes.episode_id (show the link was found in)
 * URL                  URL of the asset (on the HPR site)
 * filename             filename (or path) component (after percent decoding)
 * uploaded             Boolean showing if an asset has been uploaded to the IA
 *
 * TODO: should we consider recording the IA URL of an asset?
 *
 * ------------------------------------------------------------------------------ */
CREATE SEQUENCE asset_seq;

ALTER TABLE asset_seq
  OWNER TO hpradmin;

CREATE TABLE assets (
    asset_id            integer default nextval('asset_seq') PRIMARY KEY,
    episode_id          integer REFERENCES episodes(episode_id)
                            ON DELETE RESTRICT,
    URL                 text NOT NULL,
    filename            text NOT NULL,
    uploaded            boolean NOT NULL DEFAULT FALSE
);

ALTER TABLE assets
  OWNER TO hpradmin;

-- }}}

-- Footer ---------------------------------------------------------------------

-- vim: syntax=pgsql:ts=8:sw=4:ai:tw=78:et:fo=tcrqn21:fdm=marker:nu:rnu