initial commit

set up the database with full text search and a simple prompt template
engine

database/db.go

@@ -0,0 +1,143 @@
+package database
+
+import (
+	"context"
+	"fmt"
+	"log"
+	"zombiezen.com/go/sqlite"
+	"zombiezen.com/go/sqlite/sqlitemigration"
+	"zombiezen.com/go/sqlite/sqlitex"
+)
+
+const dbLocation = "./context.db"
+
+var schema = sqlitemigration.Schema{
+	// Each element of the Migrations slice is applied in sequence. When you
+	// want to change the schema, add a new SQL script to this list.
+	//
+	// Existing databases will pick up at the same position in the Migrations
+	// slice as they last left off.
+	Migrations: []string{
+
+		// sqlite create a table called context_store with an id, key, and content column
+		"CREATE TABLE IF NOT EXISTS context_store ( id INTEGER PRIMARY KEY, key_name TEXT NOT NULL, value TEXT );",
+
+		// sqlite create a virtual table called context using fts5 with a key and value column
+		"CREATE VIRTUAL TABLE context_search USING fts5 ( key_name, value );",
+
+		`CREATE TRIGGER context_ai AFTER INSERT ON context_store BEGIN
+			INSERT INTO context_search(rowid, key_name, value) VALUES (new.id, new.key_name, new.value);
+		END;`,
+		`CREATE TRIGGER context_ad AFTER DELETE ON context_store BEGIN
+			DELETE FROM context_search WHERE key_name = old.key_name AND value = old.value;
+		END;`,
+		`CREATE TRIGGER context_au AFTER UPDATE ON context_store BEGIN
+			UPDATE context_search SET key_name = new.key_name, value = new.value WHERE id = old.id;
+		END;`,
+	},
+}
+
+type DB struct {
+	db *sqlitex.Pool
+}
+
+func NewDB() (*DB, error) {
+
+	err := runMigrations()
+	if err != nil {
+		return nil, fmt.Errorf("error running migrations | %w", err)
+	}
+
+	dbpool, err := sqlitex.Open(dbLocation, 0, 10)
+	if err != nil {
+		return nil, fmt.Errorf("error opening db | %w", err)
+	}
+	return &DB{
+		db: dbpool,
+	}, nil
+}
+
+func (d *DB) Close() error {
+	return d.db.Close()
+}
+
+func runMigrations() error {
+	// Open a pool. This does not block, and will start running any migrations
+	// asynchronously.
+	pool := sqlitemigration.NewPool(dbLocation, schema, sqlitemigration.Options{
+		Flags: sqlite.OpenReadWrite | sqlite.OpenCreate,
+		PrepareConn: func(conn *sqlite.Conn) error {
+			// Enable foreign keys. See https://sqlite.org/foreignkeys.html
+			return sqlitex.ExecuteTransient(conn, "PRAGMA foreign_keys = ON;", nil)
+		},
+		OnError: func(e error) {
+			log.Println(e)
+		},
+	})
+	defer pool.Close()
+
+	// Get a connection. This blocks until the migration completes.
+	conn, err := pool.Get(context.Background())
+	if err != nil {
+		return fmt.Errorf("error getting db connection | %w", err)
+	}
+	defer pool.Put(conn)
+
+	// Print the list of schema objects created.
+	const listSchemaQuery = `SELECT "type", "name" FROM sqlite_master ORDER BY 1, 2;`
+	err = sqlitex.ExecuteTransient(conn, listSchemaQuery, &sqlitex.ExecOptions{
+		ResultFunc: func(stmt *sqlite.Stmt) error {
+			//fmt.Printf("%-5s %s\n", stmt.ColumnText(0), stmt.ColumnText(1))
+			return nil
+		},
+	})
+	if err != nil {
+		return fmt.Errorf("error executing query | %w", err)
+	}
+	return nil
+}
+
+func (d *DB) Get(ctx context.Context, search string) ([]string, error) {
+	conn := d.db.Get(ctx)
+	if conn == nil {
+		return []string{}, fmt.Errorf("error getting db connection")
+	}
+	defer d.db.Put(conn)
+
+	query := "SELECT * FROM context_search WHERE context_search MATCH $search;"
+
+	stmt := conn.Prep(query)
+	defer stmt.Finalize()
+	stmt.SetText("$search", search)
+	for {
+		if hasRow, err := stmt.Step(); err != nil {
+			return []string{}, fmt.Errorf("error getting value from db | %w", err)
+		} else if !hasRow {
+			break
+		}
+		keyName := stmt.GetText("key_name")
+		value := stmt.GetText("value")
+		return []string{keyName, value}, nil
+	}
+	return []string{}, nil
+}
+
+func (d *DB) Save(ctx context.Context, key, value string) error {
+	conn := d.db.Get(ctx)
+	if conn == nil {
+		return fmt.Errorf("error getting db connection to save info")
+	}
+	defer d.db.Put(conn)
+
+	query := "INSERT INTO context_store (key_name, value) VALUES ($key, $value);"
+	stmt := conn.Prep(query)
+	defer stmt.Finalize()
+	stmt.SetText("$key", key)
+	stmt.SetText("$value", value)
+
+	_, err := stmt.Step()
+	if err != nil {
+		return fmt.Errorf("error inserting new context | %w", err)
+	}
+	return nil
+}