Create DB file

The eng_log_version table will be used to figure out which migrations to
run.

log.go

@@ -0,0 +1,99 @@
+package main
+
+import (
+	"context"
+	"database/sql"
+	"errors"
+	"fmt"
+	_ "github.com/mattn/go-sqlite3"
+	"log"
+	"os"
+	"path"
+)
+
+var __version = 1
+
+type LogCtx struct {
+	db      *sql.DB
+	version int
+}
+
+func Init(db_location string) (*LogCtx, error) {
+	db, err := sql.Open("sqlite3", db_location)
+	if err != nil {
+		return nil, fmt.Errorf("Could not connect to DB. %w", err)
+	}
+	if err := db.Ping(); err != nil {
+		return nil, fmt.Errorf("Could not ping DB. %w", err)
+	}
+
+	ctx := context.Background()
+	tx, err := db.BeginTx(ctx, nil)
+	if err != nil {
+		return nil, err
+	}
+
+	// Optionally add the version table
+	if _, err := tx.Exec(`
+		create table if not exists eng_log_version (id integer not null);
+	`); err != nil {
+		tx.Rollback()
+		return nil, fmt.Errorf("Could not create eng_log_version. %w", err)
+	}
+	// Optionally add the log table
+	if _, err := tx.Exec(`
+		create table if not exists log (id integer not null primary key, title string)
+	`); err != nil {
+		tx.Rollback()
+		return nil, fmt.Errorf("Could not create log. %w", err)
+	}
+
+	var version int
+	// Check the version
+	if err := tx.QueryRow("SELECT IFNULL((SELECT id FROM eng_log_version LIMIT 1), 0)").Scan(&version); err != nil {
+		tx.Rollback()
+		return nil, fmt.Errorf("Could not query for eng_log_version id. %w", err)
+	}
+
+	if version == 0 {
+		_, err := tx.Exec("INSERT INTO eng_log_version (id) VALUES (?)", __version)
+		if err != nil {
+			tx.Rollback()
+			return nil, fmt.Errorf("Could not insert log-version. %w", err)
+		}
+		version = __version
+	} else if version != __version {
+		tx.Rollback()
+		return nil, errors.New(fmt.Sprintf("Wrong version. Expected %d got %d", __version, version))
+	}
+
+	tx.Commit()
+
+	return &LogCtx{db, version}, nil
+}
+
+func (db *LogCtx) AddEntry(title string) int {
+	return 1
+}
+
+func main() {
+
+	home_dir, err := os.UserHomeDir()
+	if err != nil {
+		log.Fatal(err.Error())
+	}
+
+	var db_path = path.Join(home_dir, ".dev-log.sql")
+
+	if _, err := os.Stat(db_path); errors.Is(err, os.ErrNotExist) {
+		_, err := os.Create(db_path)
+		if err != nil {
+			log.Fatal(err.Error())
+		}
+	}
+
+	_, err = Init(db_path)
+	if err != nil {
+		log.Fatal(err.Error())
+	}
+}

log_test.go

@@ -0,0 +1,91 @@
+package main
+
+import (
+	"database/sql"
+	"fmt"
+	"io/ioutil"
+	"log"
+	"os"
+	"testing"
+)
+
+func assert_string(t *testing.T, expected string, actual string) {
+	if actual != expected {
+		t.Fatalf("(%s, %s)", expected, actual)
+	}
+}
+func assert_int(t *testing.T, expected int, actual int) {
+	if actual != expected {
+		t.Fatalf("(%d, %d)", expected, actual)
+	}
+}
+
+func TestInitBasic(t *testing.T) {
+	var db_location = ":memory:"
+	ctx, err := Init(db_location)
+	if err != nil {
+		t.Fatalf(err.Error())
+	}
+	// check that the tables exist
+	var table_name string
+
+	ctx.db.QueryRow(
+		"SELECT name FROM sqlite_master WHERE type='table' AND name='eng_log_version';",
+	).Scan(&table_name)
+	assert_string(t, "eng_log_version", table_name)
+
+	ctx.db.QueryRow(
+		"SELECT name FROM sqlite_master WHERE type='table' AND name='log';",
+	).Scan(&table_name)
+	assert_string(t, "log", table_name)
+
+	// Check that the version stored is correct
+	var version int
+	ctx.db.QueryRow("SELECT id FROM eng_log_version").Scan(&version)
+	assert_int(t, __version, ctx.version)
+	assert_int(t, __version, version)
+}
+
+func TestInitLogVersionTableExists(t *testing.T) {
+	var db_location = ":memory:"
+	db, err := sql.Open("sqlite3", db_location)
+
+	db.Exec(`
+		CREATE TABLE eng_log_version (id INTEGER NOT NULL);
+		INSERT INTO eng_log_version (id) VALUES (1);
+	`)
+	_, err = Init(db_location)
+	if err != nil {
+		t.Fatalf(err.Error())
+	}
+}
+
+func TestInitWrongLogVersionExists(t *testing.T) {
+	file, err := ioutil.TempFile("", "log_test_init_wrong.*.db")
+	defer os.Remove(file.Name()) // clean up
+
+	db, err := sql.Open("sqlite3", file.Name())
+	if err != nil {
+		log.Fatal(err.Error())
+	}
+
+	db.Exec(`
+		CREATE TABLE eng_log_version (id INTEGER NOT NULL);
+	`)
+	db.Exec(`
+		INSERT INTO eng_log_version (id) VALUES (?);
+	`, __version+1)
+
+	var version int
+	db.QueryRow("SELECT id FROM eng_log_version LIMIT 1").Scan(&version)
+
+	_, err = Init(file.Name())
+	if err == nil {
+		t.Fatal("No error when error expected")
+	}
+	assert_string(
+		t,
+		fmt.Sprintf("Wrong version. Expected %d got %d", __version, __version+1),
+		err.Error(),
+	)
+}