package redis

import (
	"context"
	"crypto/tls"
	"errors"
	"fmt"
	"net"
	"net/url"
	"runtime"
	"strconv"
	"strings"
	"time"

	"github.com/go-redis/redis/v8/internal"
	"github.com/go-redis/redis/v8/internal/pool"
	"go.opentelemetry.io/otel/api/trace"
	"go.opentelemetry.io/otel/label"
)

	ReportResult(result error)
}

	Addr string

	Dialer func(ctx context.Context, network, addr string) (net.Conn, error)

	OnConnect func(ctx context.Context, cn *Conn) error

	Password string

	DB int

	MaxRetryBackoff time.Duration

	WriteTimeout time.Duration

	IdleCheckFrequency time.Duration

	readOnly bool

	TLSConfig *tls.Config

	Limiter Limiter
}

func (opt *Options) init() {
	if opt.Addr == "" {
		opt.Addr = "localhost:6379"
	}
	if opt.Network == "" {
		if strings.HasPrefix(opt.Addr, "/") {
			opt.Network = "unix"
		} else {
			opt.Network = "tcp"
		}
	}
	if opt.DialTimeout == 0 {
		opt.DialTimeout = 5 * time.Second
	}
	if opt.Dialer == nil {
		opt.Dialer = func(ctx context.Context, network, addr string) (net.Conn, error) {
			netDialer := &net.Dialer{
				Timeout:   opt.DialTimeout,
				KeepAlive: 5 * time.Minute,
			}
			if opt.TLSConfig == nil {
				return netDialer.DialContext(ctx, network, addr)
			}
			return tls.DialWithDialer(netDialer, network, addr, opt.TLSConfig)
		}
	}
	if opt.PoolSize == 0 {
		opt.PoolSize = 10 * runtime.NumCPU()
	}
	switch opt.ReadTimeout {
	case -1:
		opt.ReadTimeout = 0
	case 0:
		opt.ReadTimeout = 3 * time.Second
	}
	switch opt.WriteTimeout {
	case -1:
		opt.WriteTimeout = 0
	case 0:
		opt.WriteTimeout = opt.ReadTimeout
	}
	if opt.PoolTimeout == 0 {
		opt.PoolTimeout = opt.ReadTimeout + time.Second
	}
	if opt.IdleTimeout == 0 {
		opt.IdleTimeout = 5 * time.Minute
	}
	if opt.IdleCheckFrequency == 0 {
		opt.IdleCheckFrequency = time.Minute
	}

	if opt.MaxRetries == -1 {
		opt.MaxRetries = 0
	} else if opt.MaxRetries == 0 {
		opt.MaxRetries = 3
	}
	switch opt.MinRetryBackoff {
	case -1:
		opt.MinRetryBackoff = 0
	case 0:
		opt.MinRetryBackoff = 8 * time.Millisecond
	}
	switch opt.MaxRetryBackoff {
	case -1:
		opt.MaxRetryBackoff = 0
	case 0:
		opt.MaxRetryBackoff = 512 * time.Millisecond
	}
}

func (opt *Options) clone() *Options {
	clone := *opt
	return &clone
}

func ParseURL(redisURL string) (*Options, error) {
	o := &Options{Network: "tcp"}
	u, err := url.Parse(redisURL)
	if err != nil {
		return nil, err
	}

	if u.Scheme != "redis" && u.Scheme != "rediss" {
		return nil, errors.New("invalid redis URL scheme: " + u.Scheme)
	}

	if u.User != nil {
		o.Username = u.User.Username()
		if p, ok := u.User.Password(); ok {
			o.Password = p
		}
	}

	if len(u.Query()) > 0 {
		return nil, errors.New("no options supported")
	}

	h, p, err := net.SplitHostPort(u.Host)
	if err != nil {
		h = u.Host
	}
	if h == "" {
		h = "localhost"
	}
	if p == "" {
		p = "6379"
	}
	o.Addr = net.JoinHostPort(h, p)

	f := strings.FieldsFunc(u.Path, func(r rune) bool {
		return r == '/'
	})
	switch len(f) {
	case 0:
		o.DB = 0
	case 1:
		if o.DB, err = strconv.Atoi(f[0]); err != nil {
			return nil, fmt.Errorf("invalid redis database number: %q", f[0])
		}
	default:
		return nil, errors.New("invalid redis URL path: " + u.Path)
	}

	if u.Scheme == "rediss" {
		o.TLSConfig = &tls.Config{ServerName: h}
	}
	return o, nil
}

func newConnPool(opt *Options) *pool.ConnPool {
	return pool.NewConnPool(&pool.Options{
		Dialer: func(ctx context.Context) (net.Conn, error) {
			var conn net.Conn
			err := internal.WithSpan(ctx, "dialer", func(ctx context.Context) error {
				var err error
				trace.SpanFromContext(ctx).SetAttributes(
					label.String("redis.network", opt.Network),
					label.String("redis.addr", opt.Addr),
				)
				conn, err = opt.Dialer(ctx, opt.Network, opt.Addr)
				if err != nil {
					_ = internal.RecordError(ctx, err)
				}
				return err
			})
			return conn, err
		},
		PoolSize:           opt.PoolSize,
		MinIdleConns:       opt.MinIdleConns,
		MaxConnAge:         opt.MaxConnAge,
		PoolTimeout:        opt.PoolTimeout,
		IdleTimeout:        opt.IdleTimeout,
		IdleCheckFrequency: opt.IdleCheckFrequency,
	})