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())
	}
}