package commands

import (
	"bytes"
	"errors"
	"io"
	"strings"
	"text/template"
	"time"

	cmds "github.com/jbenet/go-ipfs/commands"
	diag "github.com/jbenet/go-ipfs/diagnostics"
)

type DiagnosticConnection struct {
	ID string
	// TODO use milliseconds or microseconds for human readability
	NanosecondsLatency uint64
	Count              int
}

var (
	visD3   = "d3"
	visDot  = "dot"
	visFmts = []string{visD3, visDot}
)

type DiagnosticPeer struct {
	ID                string
	UptimeSeconds     uint64
	BandwidthBytesIn  uint64
	BandwidthBytesOut uint64
	Connections       []DiagnosticConnection
}

type DiagnosticOutput struct {
	Peers []DiagnosticPeer
}

var DefaultDiagnosticTimeout = time.Second * 20

var DiagCmd = &cmds.Command{
	Helptext: cmds.HelpText{
		Tagline: "Generates diagnostic reports",
	},

	Subcommands: map[string]*cmds.Command{
		"net": diagNetCmd,
	},
}

var diagNetCmd = &cmds.Command{
	Helptext: cmds.HelpText{
		Tagline: "Generates a network diagnostics report",
		ShortDescription: `
Sends out a message to each node in the network recursively
requesting a listing of data about them including number of
connected peers and latencies between them.
`,
	},

	Options: []cmds.Option{
		cmds.StringOption("timeout", "diagnostic timeout duration"),
		cmds.StringOption("vis", "output vis. one of: "+strings.Join(visFmts, ", ")),
	},

	Run: func(req cmds.Request, res cmds.Response) {
		n, err := req.Context().GetNode()
		if err != nil {
			res.SetError(err, cmds.ErrNormal)
			return
		}

		if !n.OnlineMode() {
			res.SetError(errNotOnline, cmds.ErrClient)
			return
		}

		vis, _, err := req.Option("vis").String()
		if err != nil {
			res.SetError(err, cmds.ErrNormal)
			return
		}

		timeoutS, _, err := req.Option("timeout").String()
		if err != nil {
			res.SetError(err, cmds.ErrNormal)
			return
		}
		timeout := DefaultDiagnosticTimeout
		if timeoutS != "" {
			t, err := time.ParseDuration(timeoutS)
			if err != nil {
				res.SetError(errors.New("error parsing timeout"), cmds.ErrNormal)
				return
			}
			timeout = t
		}

		info, err := n.Diagnostics.GetDiagnostic(timeout)
		if err != nil {
			res.SetError(err, cmds.ErrNormal)
			return
		}

		switch vis {
		case visD3:
			res.SetOutput(bytes.NewReader(diag.GetGraphJson(info)))
		case visDot:
			var buf bytes.Buffer
			w := diag.DotWriter{W: &buf}
			err := w.WriteGraph(info)
			if err != nil {
				res.SetError(err, cmds.ErrNormal)
				return
			}
			res.SetOutput(io.Reader(&buf))
		}

		output, err := stdDiagOutputMarshal(standardDiagOutput(info))
		if err != nil {
			res.SetError(err, cmds.ErrNormal)
			return
		}
		res.SetOutput(output)
	},
}

func stdDiagOutputMarshal(output *DiagnosticOutput) (io.Reader, error) {
	var buf bytes.Buffer
	err := printDiagnostics(&buf, output)
	if err != nil {
		return nil, err
	}
	return &buf, nil
}

func standardDiagOutput(info []*diag.DiagInfo) *DiagnosticOutput {
	output := make([]DiagnosticPeer, len(info))
	for i, peer := range info {
		connections := make([]DiagnosticConnection, len(peer.Connections))
		for j, conn := range peer.Connections {
			connections[j] = DiagnosticConnection{
				ID:                 conn.ID,
				NanosecondsLatency: uint64(conn.Latency.Nanoseconds()),
				Count:              conn.Count,
			}
		}

		output[i] = DiagnosticPeer{
			ID:                peer.ID,
			UptimeSeconds:     uint64(peer.LifeSpan.Seconds()),
			BandwidthBytesIn:  peer.BwIn,
			BandwidthBytesOut: peer.BwOut,
			Connections:       connections,
		}
	}
	return &DiagnosticOutput{output}
}

func printDiagnostics(out io.Writer, info *DiagnosticOutput) error {
	diagTmpl := `
{{ range $peer := .Peers }}
ID {{ $peer.ID }} up {{ $peer.UptimeSeconds }} seconds connected to {{ len .Connections }}:{{ range $connection := .Connections }}
	ID {{ $connection.ID }} connections: {{ $connection.Count }} latency: {{ $connection.NanosecondsLatency }} ns{{ end }}
{{end}}
`

	templ, err := template.New("DiagnosticOutput").Parse(diagTmpl)
	if err != nil {
		return err
	}

	err = templ.Execute(out, info)
	if err != nil {
		return err
	}

	return nil
}