package main

import (
	"database/sql"
	_ "embed"
	"errors"
	_ "github.com/glebarez/go-sqlite"
	"log"
	"os"
)

const dbFileName = "healthr.db"
const driverName = "sqlite"

type Database interface {
	Initialize() error
	GetAllStatus() ([]Service, error)
	Get(serviceName string) *Service
	Update(service Service) error
}

type SqliteDatabase struct {
}

//go:embed sql_queries/init-db.sql
var initDbQuery string

func (sqldb *SqliteDatabase) Initialize() error {
	fileInfo, err := os.Stat(dbFileName)
	if fileInfo != nil && fileInfo.IsDir() {
		return errors.New(dbFileName + " is exists, but is a directory instead of a file")
	}

	if err == nil {
		return nil
	}

	db, err := sql.Open(driverName, dbFileName)
	if err != nil {
		log.Fatal(err.Error())
	}
	defer db.Close()

	db.Exec(initDbQuery)
	log.Default().Println("Database initialized!")

	return nil
}

//go:embed sql_queries/get-service.sql
var getServiceQuery string

func (sqldb *SqliteDatabase) Get(serviceName string) *Service {
	db, err := sql.Open(driverName, dbFileName)
	if err != nil {
		log.Fatal(err.Error())
	}
	defer db.Close()

	rows, err := db.Query(getServiceQuery, serviceName)
	if err != nil {
		log.Fatal(err.Error())
	}
	defer rows.Close()

	hasItem := rows.Next()
	if !hasItem {
		return nil
	}

	var service Service
	err = rows.Scan(&service.Name, &service.Healthy)
	if err != nil {
		log.Fatal(err.Error())
		return nil
	}

	return &service
}

//go:embed sql_queries/get-all.sql
var getAllQuery string

func (sqldb *SqliteDatabase) GetAllStatus() ([]Service, error) {
	db, err := sql.Open(driverName, dbFileName)
	if err != nil {
		log.Fatal(err)
	}
	defer db.Close()

	rows, err := db.Query(getAllQuery)
	if err != nil {
		log.Fatal(err)
	}
	defer rows.Close()

	services := make([]Service, 0)

	for rows.Next() {
		var service Service
		if err := rows.Scan(&service.Name, &service.Healthy); err != nil {
			log.Default().Print("Error while parsing row", err)
		}

		services = append(services, service)
	}

	return services, nil
}

func (sqldb *SqliteDatabase) Update(service Service) error {
	sqldb.Get(service.Name)
	existingService := sqldb.Get(service.Name)

	if existingService == nil {
		return sqldb.insert(service)
	} else {
		return sqldb.update(service)
	}
}

//go:embed sql_queries/insert-service.sql
var insertQuery string

func (sqldb *SqliteDatabase) insert(service Service) error {
	db, err := sql.Open(driverName, dbFileName)
	if err != nil {
		log.Fatal(err.Error())
	}
	defer db.Close()

	_, err = db.Exec(insertQuery, service.Name, service.Healthy)

	if err != nil {
		println("ERROR", err.Error())
		return err
	}

	return nil
}

//go:embed sql_queries/update-service.sql
var updateQuery string

func (sqldb *SqliteDatabase) update(service Service) error {
	db, err := sql.Open(driverName, dbFileName)
	if err != nil {
		log.Fatal(err.Error())
	}
	defer db.Close()

	_, err = db.Exec(updateQuery, service.Name, service.Healthy, service.Name)

	if err != nil {
		println("ERROR", err.Error())
		return err
	}

	return nil
}