package migration

import (
	"flag"
	"fmt"
	"log"
	"os"
	"reflect"

	"gopkg.in/yaml.v3"
	"gorm.io/driver/postgres"
	"gorm.io/gorm"
	"gorm.io/gorm/schema"
)

type DbConf struct {
	Dsn     string
	Dialect string
}

// Migrate all tables at once, one time only for exam purpose
func Migrate() {
	// use default config file location or use flat
	cfgFile := "./config.yml"
	flag.StringVar(&cfgFile, "config-file", "./config.yml", "Configuration path (default=./config.yaml)")
	flag.Parse()

	// read the config file
	yamlFile, err := os.ReadFile(cfgFile)
	if err != nil {
		log.Fatalf("%v", err)
	}

	// parse into config struct
	var dbConf DbConf
	err = yaml.Unmarshal(yamlFile, &dbConf)
	if err != nil {
		log.Fatal(err)
	}
	log.Print("config is loaded successfully")

	// create database connection
	db, err := gorm.Open(postgres.Open(dbConf.Dsn), &gorm.Config{
		NamingStrategy: schema.NamingStrategy{
			SingularTable: true,
			NoLowerCase:   true,
		},
	})
	if err != nil {
		log.Fatal(err)
	}
	log.Print("database-connection is established successfully")

	// migrate all the tables
	modelList := []any{
		// &single.Single{}}, // example

	}

	argsWithProg := os.Args
	if len(argsWithProg) > 1 {
		if argsWithProg[1] == "gradually" {
			for _, v := range modelList {
				name := ""
				if t := reflect.TypeOf(v); t.Kind() == reflect.Ptr {
					name = "*" + t.Elem().Name()
				} else {
					name = t.Name()
				}
				fmt.Println("Migrating ", name)
				db.AutoMigrate(v)
			}
		} else {
			for _, v := range modelList {
				name := ""
				if t := reflect.TypeOf(v); t.Kind() == reflect.Ptr {
					name = "*" + t.Elem().Name()
				} else {
					name = t.Name()
				}
				if name == argsWithProg[1] {
					fmt.Println("Migrating ", name)
					db.AutoMigrate(v)
				}
			}
		}
	} else {
		fmt.Println("Migrating all tables")
		db.AutoMigrate(modelList...)
	}

	log.Printf("migration is complete")
}