package services

import (
	"context"
	"errors"
	"fmt"
	"math/rand/v2"
	"net/netip"
	"platform/pkg/u"
	"platform/web/core"
	g "platform/web/globals"
	m "platform/web/models"
	q "platform/web/queries"
	"strconv"
	"time"

	"github.com/redis/go-redis/v9"
	"gorm.io/gen/field"
)

// 通道服务
var Channel = &channelServer{
	provider: &channelBaiyinProvider{},
}

type ChannelServiceProvider interface {
	CreateChannels(source netip.Addr, resourceId int32, authWhitelist bool, authPassword bool, count int, edgeFilter *EdgeFilter) ([]*m.Channel, error)
	RemoveChannels(batch string) error
}

type channelServer struct {
	provider ChannelServiceProvider
}

func (s *channelServer) CreateChannels(source netip.Addr, resourceId int32, authWhitelist bool, authPassword bool, count int, edgeFilter *EdgeFilter) ([]*m.Channel, error) {
	return s.provider.CreateChannels(source, resourceId, authWhitelist, authPassword, count, edgeFilter)
}

func (s *channelServer) RemoveChannels(batch string) error {
	return s.provider.RemoveChannels(batch)
}

// 授权方式
type ChannelAuthType int

const (
	ChannelAuthTypeIp ChannelAuthType = iota + 1
	ChannelAuthTypePass
)

// 生成用户名和密码对
func genPassPair() (string, string) {
	var alphabet = []rune("abcdefghjkmnpqrstuvwxyz")
	var numbers = []rune("23456789")

	var username = make([]rune, 6)
	var password = make([]rune, 6)
	for i := range 6 {
		if i < 2 {
			username[i] = alphabet[rand.N(len(alphabet))]
		} else {
			username[i] = numbers[rand.N(len(numbers))]
		}
		password[i] = numbers[rand.N(len(numbers))]
	}

	return string(username), string(password)
}

// 查找资源
func findResource(resourceId int32, now time.Time) (*ResourceView, error) {
	resource, err := q.Resource.
		Preload(field.Associations).
		Where(
			q.Resource.ID.Eq(resourceId),
			q.Resource.Active.Is(true),
		).
		Take()
	if err != nil {
		return nil, ErrResourceNotExist
	}
	if resource.User == nil {
		return nil, ErrResourceNotExist
	}
	var info = &ResourceView{
		Id:     resource.ID,
		User:   *resource.User,
		Active: resource.Active,
		Type:   resource.Type,
	}

	switch resource.Type {
	case m.ResourceTypeShort:
		var sub = resource.Short
		info.ShortId = &sub.ID
		info.ExpireAt = sub.ExpireAt
		info.Live = time.Duration(sub.Live) * time.Minute
		info.Mode = sub.Type
		info.Quota = sub.Quota
		info.Used = sub.Used
		info.Daily = sub.Daily
		info.LastAt = sub.LastAt
		if sub.LastAt != nil && u.IsSameDate(*sub.LastAt, now) {
			info.Today = int(sub.Daily)
		}

	case m.ResourceTypeLong:
		var sub = resource.Long
		info.LongId = &sub.ID
		info.ExpireAt = sub.ExpireAt
		info.Live = time.Duration(sub.Live) * time.Hour
		info.Mode = sub.Type
		info.Quota = sub.Quota
		info.Used = sub.Used
		info.Daily = sub.Daily
		info.LastAt = sub.LastAt
		if sub.LastAt != nil && u.IsSameDate(*sub.LastAt, now) {
			info.Today = int(sub.Daily)
		}
	}

	if info.Mode == m.ResourceModeTime && info.ExpireAt == nil {
		return nil, errors.New("检查套餐获取时间失败")
	}

	return info, nil
}

// ResourceView 套餐数据的简化视图，便于直接获取主要数据
type ResourceView struct {
	Id       int32
	User     m.User
	Active   bool
	Type     m.ResourceType
	ShortId  *int32
	LongId   *int32
	Live     time.Duration
	Mode     m.ResourceMode
	Quota    int32
	ExpireAt *time.Time
	Used     int32
	Daily    int32
	LastAt   *time.Time
	Today    int // 今日用量
}

// 检查用户是否可提取
func ensure(now time.Time, source netip.Addr, resourceId int32, count int) (*ResourceView, []string, error) {
	if count > 400 {
		return nil, nil, core.NewBizErr("单次最多提取 400 个")
	}

	// 获取用户套餐
	resource, err := findResource(resourceId, now)
	if err != nil {
		return nil, nil, err
	}

	// 检查用户
	user := resource.User
	if user.IDToken == nil || *user.IDToken == "" {
		return nil, nil, core.NewBizErr("账号未实名")
	}

	// 获取用户白名单并检查用户 ip 地址
	whitelists, err := q.Whitelist.Where(
		q.Whitelist.UserID.Eq(user.ID),
	).Find()
	if err != nil {
		return nil, nil, err
	}

	ips := make([]string, len(whitelists))
	pass := false
	for i, item := range whitelists {
		ips[i] = item.IP.String()
		if item.IP.Addr == source {
			pass = true
		}
	}
	if !pass {
		return nil, nil, core.NewBizErr(fmt.Sprintf("IP 地址 %s 不在白名单内", source.String()))
	}

	// 检查套餐使用情况
	switch resource.Mode {
	default:
		return nil, nil, core.NewBizErr("不支持的套餐模式")

	// 包时
	case m.ResourceModeTime:
		// 检查过期时间
		if resource.ExpireAt.Before(now) {
			return nil, nil, ErrResourceExpired
		}
		// 检查每日限额
		if count+resource.Today > int(resource.Quota) {
			return nil, nil, ErrResourceDailyLimit
		}

	// 包量
	case m.ResourceModeQuota:
		// 检查可用配额
		if int(resource.Quota)-int(resource.Used) < count {
			return nil, nil, ErrResourceExhausted
		}
	}

	return resource, ips, nil
}

var (
	freeChansKey = "channel:free"
	usedChansKey = "channel:used"
)

// 扩容通道
func regChans(proxy int32, chans []netip.AddrPort) error {
	strs := make([]any, len(chans))
	for i, ch := range chans {
		strs[i] = ch.String()
	}

	key := freeChansKey + ":" + strconv.Itoa(int(proxy))
	err := g.Redis.SAdd(context.Background(), key, strs...).Err()
	if err != nil {
		return fmt.Errorf("扩容通道失败: %w", err)
	}
	return nil
}

// 缩容通道
func remChans(proxy int32) error {
	key := freeChansKey + ":" + strconv.Itoa(int(proxy))
	err := g.Redis.Del(context.Background(), key).Err()
	if err != nil {
		return fmt.Errorf("缩容通道失败: %w", err)
	}
	return nil
}

// 取用通道
func lockChans(proxy int32, batch string, count int) ([]netip.AddrPort, error) {
	pid := strconv.Itoa(int(proxy))
	chans, err := RedisScriptLockChans.Run(
		context.Background(),
		g.Redis,
		[]string{
			freeChansKey + ":" + pid,
			usedChansKey + ":" + pid + ":" + batch,
		},
		count,
	).StringSlice()
	if err != nil {
		return nil, fmt.Errorf("获取通道失败: %w", err)
	}

	addrs := make([]netip.AddrPort, len(chans))
	for i, ch := range chans {
		addr, err := netip.ParseAddrPort(ch)
		if err != nil {
			return nil, fmt.Errorf("解析通道数据失败: %w", err)
		}
		addrs[i] = addr
	}

	return addrs, nil
}

var RedisScriptLockChans = redis.NewScript(`
local free_key  = KEYS[1]
local batch_key = KEYS[2]
local count     = tonumber(ARGV[1])

local free_count = redis.call("SCARD", free_key)
if count <= 0 or free_count < count then
    return nil
end

local ports = redis.call("SPOP", free_key, count)
redis.call("RPUSH", batch_key, unpack(ports))

return ports
`)

// 归还通道
func freeChans(proxy int32, batch string) error {
	pid := strconv.Itoa(int(proxy))
	err := RedisScriptFreeChans.Run(
		context.Background(),
		g.Redis,
		[]string{
			freeChansKey + ":" + pid,
			usedChansKey + ":" + pid + ":" + batch,
		},
	).Err()
	if err != nil {
		return core.NewBizErr("释放通道失败", err)
	}

	return nil
}

var RedisScriptFreeChans = redis.NewScript(`
local free_key  = KEYS[1]
local batch_key = KEYS[2]

local chans = redis.call("LRANGE", batch_key, 0, -1)
if #chans == 0 then
    return 1
end

redis.call("SADD", free_key, unpack(chans))
redis.call("DEL", batch_key)

return 1
`)

// 错误信息
var (
	ErrResourceNotExist   = core.NewBizErr("套餐不存在")
	ErrResourceInvalid    = core.NewBizErr("套餐不可用")
	ErrResourceExhausted  = core.NewBizErr("套餐已用完")
	ErrResourceExpired    = core.NewBizErr("套餐已过期")
	ErrResourceDailyLimit = core.NewBizErr("套餐每日配额已用完")
	ErrEdgesNoAvailable   = core.NewBizErr("没有可用的节点")
)