package pilgrim_conf

import (
	"fmt"
	"log"
	"regexp"
	"slices"
	"strings"
)

const EmptyString = ""

type DbDriver string

const (
	DbDriver_MySQL    DbDriver = "mysql"
	DbDriver_MSSQL    DbDriver = "mssql"
	DbDriver_Postgres DbDriver = "postgres"
	DbDriver_Oracle   DbDriver = "oracle"
	DbDriver_SQLite   DbDriver = "sqlite"
	DbDriver_MariaDB  DbDriver = "mariadb"
)

var AvailableDbDrivers []DbDriver = []DbDriver{
	DbDriver_MySQL,
	DbDriver_MSSQL,
	DbDriver_Postgres,
	DbDriver_Oracle,
	DbDriver_SQLite,
	DbDriver_MariaDB,
}

type UrlParts struct {
	Host,
	Port,
	Username,
	Password string

	Driver DbDriver

	Segments  []string
	Arguments map[string]string
}

const DbUrlRegex = `^(?:([^:\/?#\s]+):\/{2})?(?:([^@\/?#\s]+)@)?([^\/?#\s]+)?(?:\/([^?#\s]*))?(?:[?]([^#\s]+))?\S*$`

func ParseDatabaseUrl(url string) UrlParts {
	urlRegex, err := regexp.Compile(DbUrlRegex)

	if err != nil {
		log.Fatalf("Regex %s could not be compiled", DbUrlRegex) // The developer wrote the regex wrong.
	}

	parsed := urlRegex.FindAllStringSubmatch(url, -1)

	if parsed == nil || parsed[0] == nil {
		return UrlParts{}
	}

	parsedUrl := parsed[0]

	driver := DbDriver(parsedUrl[1])
	username := ""
	password := ""
	host := ""
	port := ""
	var segments []string
	var arguments map[string]string = make(map[string]string)

	// Parse username and password ( username:password )
	if parsedUrl[2] != EmptyString && strings.Contains(parsedUrl[2], ":") {
		splitUserAndPass := strings.Split(parsedUrl[2], ":")
		username = splitUserAndPass[0]
		password = splitUserAndPass[1]
	}

	// Parse host and port ( host:port )
	if parsedUrl[3] != EmptyString && strings.Contains(parsedUrl[3], ":") {
		splitHostAndPort := strings.Split(parsedUrl[3], ":")
		host = splitHostAndPort[0]
		port = splitHostAndPort[1]
	}

	// Parse segments ( segment1/segment2 )
	if parsedUrl[4] != EmptyString {
		segments = ParseSegments(parsedUrl[4])
	}

	// Parse arguments ( arg1=value1&arg2=value2 )
	if parsedUrl[5] != EmptyString {
		arguments = ParseArguments(parsedUrl[5])
	}

	return UrlParts{
		Driver:    driver,
		Username:  username,
		Password:  password,
		Host:      host,
		Port:      port,
		Segments:  segments,
		Arguments: arguments,
	}
}

func ParseSegments(segments string) []string {
	if segments == EmptyString {
		return []string{}
	}

	return strings.Split(segments, "/")
}

func ParseArguments(arguments string) map[string]string {
	if arguments == EmptyString {
		return make(map[string]string)
	}

	var argsMap map[string]string = make(map[string]string)

	splitArguments := strings.Split(arguments, "&")

	for _, arg := range splitArguments {
		if !strings.Contains(arg, "=") {
			continue
		}

		splitArgAndValue := strings.Split(arg, "=")

		argsMap[splitArgAndValue[0]] = splitArgAndValue[1]
	}

	return argsMap
}

// Returns true if valid, with nil error, or false if invalid, with the validation error
func (urlParts *UrlParts) Validate() (bool, error) {
	if !slices.Contains(AvailableDbDrivers, DbDriver(urlParts.Driver)) {
		return false, PilgrimInvalidError(fmt.Sprintf("URLParts invalid: Provided driver %v is not currently supported ( must be one of %v )", urlParts.Driver, AvailableDbDrivers))
	}

	return true, nil
}