package proxy

import (
	"fmt"
	"net"
	"strconv"
	"strings"
	"time"
)

type Scheme string

const (
	SchemeHTTP   Scheme = "http"
	SchemeHTTPS  Scheme = "https"
	SchemeSOCKS5 Scheme = "socks5"
)

type Proxy struct {
	ID                string
	Scheme            Scheme
	Host              string
	Port              uint16
	Username          string
	CredentialVersion string
	SecretRef         string
	SourceUpstream    string
	CreatedAt         time.Time
	ExpiresAt         *time.Time
	UsableUntil       *time.Time
	LastCheckedAt     *time.Time
	LastSuccessAt     *time.Time
	Latency           time.Duration
	MaxConcurrency    int64
	State             State
	Tags              map[string]string
}

func (p Proxy) UniqueKey() string {
	host := strings.TrimSuffix(strings.ToLower(strings.TrimSpace(p.Host)), ".")
	return strings.Join([]string{
		string(p.Scheme),
		host,
		strconv.FormatUint(uint64(p.Port), 10),
		p.Username,
		p.CredentialVersion,
	}, "|")
}

func (p Proxy) Address() string {
	return net.JoinHostPort(p.Host, strconv.FormatUint(uint64(p.Port), 10))
}

func (p *Proxy) Transition(next State) error {
	if p == nil {
		return fmt.Errorf("transition proxy: nil proxy")
	}
	if !CanTransition(p.State, next) {
		return fmt.Errorf("transition proxy: %s -> %s is not allowed", p.State, next)
	}
	p.State = next
	return nil
}

func EffectiveExpiry(now time.Time, expiresAt *time.Time, responseTTL, configuredTTL time.Duration) *time.Time {
	if expiresAt != nil {
		value := expiresAt.UTC()
		return &value
	}
	if responseTTL > 0 {
		value := now.UTC().Add(responseTTL)
		return &value
	}
	if configuredTTL > 0 {
		value := now.UTC().Add(configuredTTL)
		return &value
	}
	return nil
}