A bunch of sql changes

Creates the users, folders and co_owners tables.  Move user preferences
inside the main database.

Makes use of sqlite triggers and foreign key constraints.  Not a huge
fan of these, but they do fit the use case and this isn't a case where
scaling is a concern.

NOTES.md

@@ -19,6 +19,8 @@ Look up how to run migrations on the db from embedded files.
 Figure out readline completion.  Case sensitive - issue?  Building from
 repl.commands?
 
+sqlite trigger tracing: `.trace stdout --row --profile --stmt --expanded --plain --close`
+
 ## Things to do
 
   * Implement a better dclish parser.

accounts/accounts.go

@@ -2,15 +2,11 @@
 package accounts
 
 import (
-	"database/sql"
 	"errors"
 	"fmt"
-	"os"
-	"path"
 	"strings"
 
 	"git.lyda.ie/kevin/bulletin/folders"
-	"github.com/adrg/xdg"
 	_ "modernc.org/sqlite" // Loads sqlite driver.
 )
 
@@ -19,7 +15,6 @@ import (
 type UserData struct {
 	Account        string
 	FullName       string
-	pref           *sql.DB
 	Folders        *folders.Store
 	CurrentFolder  string
 	CurrentMessage int
@@ -49,18 +44,7 @@ func Open(acc string) error {
 		Account: acc,
 	}
 
-	prefdir := path.Join(xdg.ConfigHome, "BULLETIN")
-	err = os.MkdirAll(prefdir, 0700)
-	if err != nil {
-		return errors.New("account preference directory problem")
-	}
-	User.pref, err = sql.Open("sqlite", path.Join(prefdir, fmt.Sprintf("%s.%s", acc, ".db")))
-	if err != nil {
-		return errors.New("account preference database problem")
-	}
-	// TODO: run prefs migration - move this to a storage module.
-
-	User.Folders, err = folders.Open()
+	User.Folders, err = folders.Open(acc)
 	if err != nil {
 		return err
 	}
@@ -70,7 +54,6 @@ func Open(acc string) error {
 
 // Close closes the resources open for the account.
 func (u *UserData) Close() {
-	u.pref.Close()
 	u.Folders.Close()
 }
 

folders/folders.go

@@ -5,7 +5,6 @@ import (
 	"database/sql"
 	"embed"
 	"errors"
-	"log"
 	"os"
 	"path"
 
@@ -23,11 +22,12 @@ var fs embed.FS
 
 // Store is the store for folders.
 type Store struct {
+	user string
 	db   *sql.DB
 }
 
 // Open opens the folders database.
-func Open() (*Store, error) {
+func Open(user string) (*Store, error) {
 	fdir := path.Join(xdg.DataHome, "BULLETIN")
 	err := os.MkdirAll(fdir, 0700)
 	if err != nil {
@@ -39,18 +39,18 @@ func Open() (*Store, error) {
 	if err != nil {
 		return nil, err
 	}
-	m, err := migrate.NewWithSourceInstance("iofs", sqldir, "sqlite://"+fdb)
+	m, err := migrate.NewWithSourceInstance("iofs", sqldir, "sqlite://"+fdb+"?_pragma=foreign_keys(1)")
 	if err != nil {
-		log.Fatal(err)
+		return nil, err
 	}
 	err = m.Up()
-	if err != nil {
+	if err != nil && err != migrate.ErrNoChange {
 		return nil, err
 	}
 	m.Close()
 
-	store := &Store{}
-	store.db, err = sql.Open("sqlite", fdb)
+	store := &Store{user: user}
+	store.db, err = sql.Open("sqlite", "file://"+fdb+"?_pragma=foreign_keys(1)")
 	if err != nil {
 		return nil, errors.New("bulletin database problem")
 	}

folders/sql/1_create_table.down.sql

+--- Dropped in reverse order to deal with foreign keys.
+DROP TRIGGER co_owners_after_update_update_at;
+DROP TABLE co_owners;
+
+DROP TRIGGER folders_before_delete_protect;
+DROP TRIGGER folders_after_update_update_at;
+DROP TRIGGER folders_before_update_validate;
+DROP TRIGGER folders_before_insert_validate;
 DROP TABLE folders;
+
+DROP TRIGGER users_before_delete_protect;
+DROP TRIGGER users_before_update_protect;
+DROP TRIGGER users_after_update_update_at;
+DROP TABLE users;

folders/sql/1_create_table.up.sql

+CREATE TABLE users (
+  login       VARCHAR(25)  NOT NULL PRIMARY KEY,
+  name        VARCHAR(53)  NOT NULL,
+  admin       INT          DEFAULT 0,
+  create_at   TIMESTAMP    DEFAULT CURRENT_TIMESTAMP NOT NULL,
+  update_at   TIMESTAMP    DEFAULT CURRENT_TIMESTAMP NOT NULL
+) WITHOUT ROWID;
+
+CREATE TRIGGER users_after_update_update_at
+  AFTER UPDATE ON users FOR EACH ROW
+  WHEN NEW.update_at = OLD.update_at    --- avoid infinite loop
+BEGIN
+  UPDATE users SET update_at=CURRENT_TIMESTAMP WHERE login=NEW.login;
+END;
+
+INSERT INTO users (login, name, admin)
+       VALUES ('SYSTEM', 'System User', 1);
+
+CREATE TRIGGER users_before_update_protect
+  AFTER UPDATE ON users FOR EACH ROW
+  WHEN OLD.login = 'SYSTEM' AND (NEW.login != OLD.login OR NEW.admin != 1)
+BEGIN
+  SELECT RAISE (ABORT, 'SYSTEM user is protected');
+END;
+
+CREATE TRIGGER users_before_delete_protect
+  BEFORE DELETE on users FOR EACH ROW
+  WHEN OLD.login = 'SYSTEM'
+BEGIN
+  SELECT RAISE (ABORT, 'SYSTEM user is protected');
+END;
+
 CREATE TABLE folders (
-  name        VARCHAR(25)  NOT NULL UNIQUE,
+  name        VARCHAR(25)  NOT NULL PRIMARY KEY,
   always      INT          DEFAULT 0,
   brief       INT          DEFAULT 0,
-  description VARCHAR(53),
-  co_owners   TEXT,
+  description VARCHAR(53)  NOT NULL,
   notify      INT          DEFAULT 0,
-  owner       TEXT,
+  owner       VARCHAR(25)  REFERENCES users(login) ON UPDATE CASCADE,
   readnew     INT          DEFAULT 0,
   shownew     INT          DEFAULT 0,
   system      INT          DEFAULT 0,
   expire      INT          DEFAULT 14,
-  visibility  TEXT         DEFAULT "public"
-);
+  visibility  TEXT         DEFAULT 'public',
+  create_at   TIMESTAMP    DEFAULT CURRENT_TIMESTAMP NOT NULL,
+  update_at   TIMESTAMP    DEFAULT CURRENT_TIMESTAMP NOT NULL
+) WITHOUT ROWID;
+
+CREATE TRIGGER folders_before_insert_validate
+  BEFORE INSERT on folders
+BEGIN
+  SELECT
+    CASE
+      WHEN NEW.name != UPPER(NEW.name) OR NEW.name GLOB '*[^A-Z0-9_-]*' THEN
+        RAISE (ABORT, 'Invalid folder name')
+    END;
+END;
+
+CREATE TRIGGER folders_before_update_validate
+  BEFORE UPDATE on folders
+BEGIN
+  SELECT
+    CASE
+      WHEN NEW.name != UPPER(NEW.name) OR NEW.name GLOB '*[^A-Z0-9_-]*' THEN
+        RAISE (ABORT, 'Invalid folder name')
+      WHEN OLD.name = 'GENERAL' AND OLD.name != NEW.name THEN
+        RAISE (ABORT, 'GENERAL folder is protected')
+    END;
+END;
+
+CREATE TRIGGER folders_after_update_update_at
+  AFTER UPDATE ON folders FOR EACH ROW
+    WHEN NEW.update_at = OLD.update_at    --- avoid infinite loop
+BEGIN
+  UPDATE folders SET update_at=CURRENT_TIMESTAMP WHERE name=NEW.name;
+END;
+
+CREATE TRIGGER folders_before_delete_protect
+  BEFORE DELETE on folders FOR EACH ROW
+  WHEN OLD.name = 'GENERAL'
+BEGIN
+  SELECT RAISE (ABORT, 'GENERAL folder is protected');
+END;
 
 INSERT INTO folders (name, description, system, shownew, owner)
-       VALUES ("GENERAL", "Default general bulletin folder.", 1, 1, "SYSTEM");
+       VALUES ('GENERAL', 'Default general bulletin folder.', 1, 1, 'SYSTEM');
+
+CREATE TABLE co_owners (
+  folder      VARCHAR(25)  REFERENCES folders(name) ON UPDATE CASCADE,
+  owner       VARCHAR(25)  REFERENCES users(login) ON UPDATE CASCADE,
+  create_at   TIMESTAMP    DEFAULT CURRENT_TIMESTAMP NOT NULL,
+  update_at   TIMESTAMP    DEFAULT CURRENT_TIMESTAMP NOT NULL,
+  PRIMARY KEY (folder, owner)
+) WITHOUT ROWID;
 
+CREATE TRIGGER co_owners_after_update_update_at
+  AFTER UPDATE ON co_owners FOR EACH ROW
+    WHEN NEW.update_at = OLD.update_at    --- avoid infinite loop
+BEGIN
+  UPDATE co_owners SET update_at=CURRENT_TIMESTAMP WHERE folder=NEW.folder AND owner=NEW.owner;
+END;

repl/command.go

@@ -678,7 +678,9 @@ file exists, the file would be appended to that file.`,
 	"HELP": {
 		Description: `To obtain help on any topic, type:
 
-        HELP  topic`,
+        HELP  topic
+
+Type "HELP Topics" to get a list of topics.`,
 		MaxArgs: 1,
 		Action:  ActionHelp,
 	},