add sql patching facilities

This includes the patches to get from the initial version of the
database to its current state - for the purpose of documentation.

Beware, if you already have an existing database, running this code
will likely result in an error and/or lead to some minor data loss.
You need to follow these steps to fix your DB:
1. delete all *.sql files from unwind/sql/
2. remove the .disabled suffix from unwind/sql/00000001-fix-db.sql.disabled
3. start the application once, this will fix up the database
4. revert all changes to unwind/sql/ – or leave it, it doesn't matter.

unwind/sql/00000000-init-0.sql

@@ -0,0 +1,36 @@
+PRAGMA foreign_keys = ON;;
+
+CREATE TABLE IF NOT EXISTS users (
+    id TEXT NOT NULL PRIMARY KEY,
+    imdb_id TEXT NOT NULL UNIQUE,
+    name TEXT NOT NULL
+);;
+
+CREATE TABLE IF NOT EXISTS movies (
+    id TEXT NOT NULL PRIMARY KEY,
+    title TEXT NOT NULL,
+    release_year NUMBER NOT NULL,
+    media_type TEXT NOT NULL,
+    imdb_id TEXT NOT NULL UNIQUE,
+    score NUMBER NOT NULL,
+    runtime NUMBER,
+    genres TEXT NOT NULL,
+    updated TEXT NOT NULL
+);;
+
+CREATE TABLE IF NOT EXISTS ratings (
+    id TEXT NOT NULL PRIMARY KEY,
+    movie_id TEXT NOT NULL,
+    user_id TEXT NOT NULL,
+    score NUMBER NOT NULL,
+    rating_date TEXT NOT NULL,
+    favorite NUMBER,
+    finished NUMBER,
+    FOREIGN KEY(movie_id) REFERENCES movies(id),
+    FOREIGN KEY(user_id) REFERENCES users(id)
+);;
+
+CREATE UNIQUE INDEX IF NOT EXISTS ratings_index ON ratings (
+    movie_id,
+    user_id
+);;

unwind/sql/00000000-init-1.sql

@@ -0,0 +1,40 @@
+-- add original_title to movies table
+
+-- see https://www.sqlite.org/lang_altertable.html#caution
+-- 1. Create new table
+-- 2. Copy data
+-- 3. Drop old table
+-- 4. Rename new into old 
+
+CREATE TABLE _migrate_movies (
+    id TEXT NOT NULL PRIMARY KEY,
+    title TEXT NOT NULL,
+    original_title TEXT,
+    release_year NUMBER NOT NULL,
+    media_type TEXT NOT NULL,
+    imdb_id TEXT NOT NULL UNIQUE,
+    score NUMBER,
+    runtime NUMBER,
+    genres TEXT NOT NULL,
+    updated TEXT NOT NULL
+);;
+
+INSERT INTO _migrate_movies
+SELECT
+    id,
+    title,
+    NULL,
+    release_year,
+    media_type,
+    imdb_id,
+    score,
+    runtime,
+    genres,
+    updated
+FROM movies
+WHERE true;;
+
+DROP TABLE movies;;
+
+ALTER TABLE _migrate_movies
+RENAME TO movies;;

unwind/sql/00000000-init-2.sql

@@ -0,0 +1,46 @@
+-- only set original_title if it differs from title,
+-- and normalize media_type with an extra table.
+
+CREATE TABLE mediatypes (
+    id INTEGER PRIMARY KEY NOT NULL,
+    name TEXT NOT NULL UNIQUE
+);;
+
+INSERT INTO mediatypes (name)
+SELECT DISTINCT media_type
+FROM movies
+WHERE true;;
+
+CREATE TABLE _migrate_movies (
+    id TEXT PRIMARY KEY NOT NULL,
+    title TEXT NOT NULL,
+    original_title TEXT,
+    release_year INTEGER NOT NULL,
+    media_type_id INTEGER NOT NULL,
+    imdb_id TEXT NOT NULL UNIQUE,
+    score INTEGER,
+    runtime INTEGER,
+    genres TEXT NOT NULL,
+    updated TEXT NOT NULL,
+    FOREIGN KEY(media_type_id) REFERENCES mediatypes(id)
+);;
+
+INSERT INTO _migrate_movies
+SELECT
+    id,
+    title,
+    (CASE WHEN original_title=title THEN NULL ELSE original_title END),
+    release_year,
+    (SELECT id FROM mediatypes WHERE name=media_type) AS media_type_id,
+    imdb_id,
+    score,
+    runtime,
+    genres,
+    updated
+FROM movies
+WHERE true;;
+
+DROP TABLE movies;;
+
+ALTER TABLE _migrate_movies
+RENAME TO movies;;

unwind/sql/00000000-init-3.sql

@@ -0,0 +1,62 @@
+-- add convenient view for movies
+
+CREATE VIEW IF NOT EXISTS movies_view
+AS SELECT
+    movies.id,
+    movies.title,
+    movies.original_title,
+    movies.release_year,
+    mediatypes.name AS media_type,
+    movies.imdb_id,
+    movies.score,
+    movies.runtime,
+    movies.genres,
+    movies.updated
+FROM movies
+JOIN mediatypes ON mediatypes.id=movies.media_type_id;;
+
+CREATE TRIGGER IF NOT EXISTS insert_movies_view
+    INSTEAD OF INSERT
+    ON movies_view
+BEGIN
+    INSERT INTO movies (
+        id,
+        title,
+        original_title,
+        release_year,
+        media_type_id,
+        imdb_id,
+        score,
+        runtime,
+        genres,
+        updated
+    ) VALUES (
+        NEW.id,
+        NEW.title,
+        NEW.original_title,
+        NEW.release_year,
+        (SELECT id FROM mediatypes WHERE name=NEW.media_type),
+        NEW.imdb_id,
+        NEW.score,
+        NEW.runtime,
+        NEW.genres,
+        NEW.updated
+    );
+END;;
+
+CREATE TRIGGER IF NOT EXISTS update_movies_view
+    INSTEAD OF UPDATE OF media_type
+    ON movies_view
+BEGIN
+    UPDATE movies
+    SET media_type_id=(SELECT id FROM mediatypes WHERE name=NEW.media_type)
+    WHERE id=OLD.id;
+END;;
+
+CREATE TRIGGER IF NOT EXISTS delete_movies_view
+    INSTEAD OF DELETE
+    ON movies_view
+BEGIN
+    DELETE FROM movies
+    WHERE movies.id=OLD.id;
+END;;

unwind/sql/00000000-init-4.sql

@@ -0,0 +1,37 @@
+-- denormalize movie media_type
+
+CREATE TABLE _migrate_movies (
+    id TEXT PRIMARY KEY NOT NULL,
+    title TEXT NOT NULL,
+    original_title TEXT,
+    release_year INTEGER NOT NULL,
+    media_type TEXT NOT NULL,
+    imdb_id TEXT NOT NULL UNIQUE,
+    score INTEGER,
+    runtime INTEGER,
+    genres TEXT NOT NULL,
+    updated TEXT NOT NULL
+);;
+
+INSERT INTO _migrate_movies
+SELECT
+    id,
+    title,
+    original_title,
+    release_year,
+    (SELECT name FROM mediatypes WHERE id=media_type_id) AS media_type,
+    imdb_id,
+    score,
+    runtime,
+    genres,
+    updated
+FROM movies
+WHERE true;;
+
+DROP TABLE movies;;
+
+ALTER TABLE _migrate_movies
+RENAME TO movies;;
+
+DROP VIEW movies_view;;
+DROP TABLE mediatypes;;

unwind/sql/00000001-fix-db.sql.disabled

@@ -0,0 +1,2 @@
+-- see the commit of this file for details.
+;;