package postgres

import (
	"fmt"
	"strings"
)

const (
	defaultUser     string = "postgres"
	defaultDatabase string = "postgres"
)

type SSLMode string

const (
	Prefer     SSLMode = "prefer"
	Disable    SSLMode = "disable"
	Require    SSLMode = "require"
	VerifyCA   SSLMode = "verify-ca"
	VerifyFull SSLMode = "verify-full"
)

func (m SSLMode) String() string {
	switch m {
	case Prefer:
		return "prefer"
	case Disable:
		return "disable"
	case Require:
		return "require"
	case VerifyCA:
		return "verify-ca"
	case VerifyFull:
		return "verify-full"
	}
	return ""
}

// TODO(help_wanted) - should probably expose max conns at least

// DSNOptions ...
// list of all connection string parameters https://pkg.go.dev/github.com/lib/pq#hdr-Connection_String_Parameters
type DSNOptions struct {
	Host     string
	Port     int
	DBName   string
	User     string
	Password string
	SSLMode  SSLMode // underlying pgx lib defaults to "prefer"
}

func (dsn *DSNOptions) ToString() string {
	var parts []string

	if dsn.Host != "" {
		parts = append(parts, fmt.Sprintf("host=%s", dsn.Host))
	}
	if dsn.Port != 0 {
		parts = append(parts, fmt.Sprintf("port=%d", dsn.Port))
	}
	if dsn.DBName != "" {
		// dbname && database both work - https://github.com/jackc/pgconn/blob/15f8e6323e113feb44678e5cb16cfbeba4630bf6/config.go#L495-L497
		parts = append(parts, fmt.Sprintf("database=%s", dsn.DBName))
	} else {
		// default to postgres default value
		parts = append(parts, fmt.Sprintf("database=%s", defaultDatabase))
	}
	if dsn.User != "" {
		parts = append(parts, fmt.Sprintf("user=%s", dsn.User))
	} else {
		// default to postgres default and not pgx value of user.Current(), "os/user" pgconn/defaults.go
		parts = append(parts, fmt.Sprintf("user=%s", defaultUser))
	}
	if dsn.Password != "" {
		parts = append(parts, fmt.Sprintf("password=%s", dsn.Password))
	}
	if dsn.SSLMode != "" {
		parts = append(parts, fmt.Sprintf("sslmode=%s", dsn.SSLMode.String()))
	}

	return strings.Join(parts[:], " ")
}