//go:generate ../../../tools/readme_config_includer/generator
package influxdb_v2

import (
	"context"
	"crypto/tls"
	_ "embed"
	"errors"
	"fmt"
	"math/rand"
	"net"
	"net/url"
	"strconv"
	"strings"
	"time"

	"github.com/influxdata/telegraf"
	"github.com/influxdata/telegraf/config"
	"github.com/influxdata/telegraf/internal"
	"github.com/influxdata/telegraf/plugins/common/ratelimiter"
	commontls "github.com/influxdata/telegraf/plugins/common/tls"
	"github.com/influxdata/telegraf/plugins/outputs"
	"github.com/influxdata/telegraf/plugins/serializers/influx"
)

//go:embed sample.conf
var sampleConfig string

type InfluxDB struct {
	URLs             []string                  `toml:"urls"`
	LocalAddr        string                    `toml:"local_address"`
	Token            config.Secret             `toml:"token"`
	Organization     string                    `toml:"organization"`
	Bucket           string                    `toml:"bucket"`
	BucketTag        string                    `toml:"bucket_tag"`
	ExcludeBucketTag bool                      `toml:"exclude_bucket_tag"`
	Timeout          config.Duration           `toml:"timeout"`
	HTTPHeaders      map[string]*config.Secret `toml:"http_headers"`
	HTTPProxy        string                    `toml:"http_proxy"`
	UserAgent        string                    `toml:"user_agent"`
	ContentEncoding  string                    `toml:"content_encoding"`
	UintSupport      bool                      `toml:"influx_uint_support"`
	OmitTimestamp    bool                      `toml:"influx_omit_timestamp"`
	PingTimeout      config.Duration           `toml:"ping_timeout"`
	ReadIdleTimeout  config.Duration           `toml:"read_idle_timeout"`
	Log              telegraf.Logger           `toml:"-"`
	commontls.ClientConfig
	ratelimiter.RateLimitConfig

	clients    []*httpClient
	encoder    internal.ContentEncoder
	serializer ratelimiter.Serializer
	tlsCfg     *tls.Config
}

func (*InfluxDB) SampleConfig() string {
	return sampleConfig
}

func (i *InfluxDB) Init() error {
	// Set defaults
	if i.UserAgent == "" {
		i.UserAgent = internal.ProductToken()
	}

	if len(i.URLs) == 0 {
		i.URLs = append(i.URLs, "http://localhost:8086")
	}

	// Init encoding if configured
	switch i.ContentEncoding {
	case "", "gzip":
		i.ContentEncoding = "gzip"
		enc, err := internal.NewGzipEncoder()
		if err != nil {
			return fmt.Errorf("setting up gzip encoder failed: %w", err)
		}
		i.encoder = enc
	case "identity":
	default:
		return fmt.Errorf("invalid content encoding %q", i.ContentEncoding)
	}

	// Setup the limited serializer
	serializer := &influx.Serializer{
		UintSupport:   i.UintSupport,
		OmitTimestamp: i.OmitTimestamp,
	}
	if err := serializer.Init(); err != nil {
		return fmt.Errorf("setting up serializer failed: %w", err)
	}
	i.serializer = ratelimiter.NewIndividualSerializer(serializer)

	// Setup the client config
	tlsCfg, err := i.ClientConfig.TLSConfig()
	if err != nil {
		return fmt.Errorf("setting up TLS failed: %w", err)
	}
	i.tlsCfg = tlsCfg

	return nil
}

func (i *InfluxDB) Connect() error {
	for _, u := range i.URLs {
		parts, err := url.Parse(u)
		if err != nil {
			return fmt.Errorf("error parsing url [%q]: %w", u, err)
		}

		var proxy *url.URL
		if len(i.HTTPProxy) > 0 {
			proxy, err = url.Parse(i.HTTPProxy)
			if err != nil {
				return fmt.Errorf("error parsing proxy_url [%s]: %w", i.HTTPProxy, err)
			}
		}

		var localAddr *net.TCPAddr
		if i.LocalAddr != "" {
			// Resolve the local address into IP address and the given port if any
			addr, sPort, err := net.SplitHostPort(i.LocalAddr)
			if err != nil {
				if !strings.Contains(err.Error(), "missing port") {
					return fmt.Errorf("invalid local address: %w", err)
				}
				addr = i.LocalAddr
			}
			local, err := net.ResolveIPAddr("ip", addr)
			if err != nil {
				return fmt.Errorf("cannot resolve local address: %w", err)
			}

			var port int
			if sPort != "" {
				p, err := strconv.ParseUint(sPort, 10, 16)
				if err != nil {
					return fmt.Errorf("invalid port: %w", err)
				}
				port = int(p)
			}

			localAddr = &net.TCPAddr{IP: local.IP, Port: port, Zone: local.Zone}
		}

		switch parts.Scheme {
		case "http", "https", "unix":
			limiter, err := i.RateLimitConfig.CreateRateLimiter()
			if err != nil {
				return err
			}
			c := &httpClient{
				url:              parts,
				localAddr:        localAddr,
				token:            i.Token,
				organization:     i.Organization,
				bucket:           i.Bucket,
				bucketTag:        i.BucketTag,
				excludeBucketTag: i.ExcludeBucketTag,
				timeout:          time.Duration(i.Timeout),
				headers:          i.HTTPHeaders,
				proxy:            proxy,
				userAgent:        i.UserAgent,
				contentEncoding:  i.ContentEncoding,
				tlsConfig:        i.tlsCfg,
				pingTimeout:      i.PingTimeout,
				readIdleTimeout:  i.ReadIdleTimeout,
				encoder:          i.encoder,
				rateLimiter:      limiter,
				serializer:       i.serializer,
				log:              i.Log,
			}

			if err := c.Init(); err != nil {
				return fmt.Errorf("error creating HTTP client [%s]: %w", parts, err)
			}

			i.clients = append(i.clients, c)
		default:
			return fmt.Errorf("unsupported scheme [%q]: %q", u, parts.Scheme)
		}
	}

	return nil
}

func (i *InfluxDB) Close() error {
	for _, client := range i.clients {
		client.Close()
	}
	return nil
}

// Write sends metrics to one of the configured servers, logging each
// unsuccessful. If all servers fail, return an error.
func (i *InfluxDB) Write(metrics []telegraf.Metric) error {
	ctx := context.Background()

	for _, n := range rand.Perm(len(i.clients)) {
		client := i.clients[n]
		if err := client.Write(ctx, metrics); err != nil {
			i.Log.Errorf("When writing to [%s]: %v", client.url, err)
			var werr *internal.PartialWriteError
			if errors.As(err, &werr) || errors.Is(err, internal.ErrSizeLimitReached) {
				return err
			}
			continue
		}
		return nil
	}

	return errors.New("failed to send metrics to any configured server(s)")
}

func init() {
	outputs.Add("influxdb_v2", func() telegraf.Output {
		return &InfluxDB{
			Timeout: config.Duration(time.Second * 5),
		}
	})
}
