package collectors

import (
	"fmt"
	"os"

	cclog "github.com/ClusterCockpit/cc-metric-collector/pkg/ccLogger"
	lp "github.com/ClusterCockpit/cc-metric-collector/pkg/ccMetric"
	"golang.org/x/sys/unix"

	"encoding/json"
	"path/filepath"
	"strconv"
	"strings"
	"time"
)

const IB_BASEPATH = "/sys/class/infiniband/"

type InfinibandCollectorMetric struct {
	name             string
	path             string
	unit             string
	scale            int64
	addToIBTotal     bool
	addToIBTotalPkgs bool
	currentState     int64
	lastState        int64
}

type InfinibandCollectorInfo struct {
	LID              string                      // IB local Identifier (LID)
	device           string                      // IB device
	port             string                      // IB device port
	portCounterFiles []InfinibandCollectorMetric // mapping counter name -> InfinibandCollectorMetric
	tagSet           map[string]string           // corresponding tag list
}

type InfinibandCollector struct {
	metricCollector
	config struct {
		ExcludeDevices     []string `json:"exclude_devices,omitempty"` // IB device to exclude e.g. mlx5_0
		SendAbsoluteValues bool     `json:"send_abs_values"`           // Send absolut values as read from sys filesystem
		SendTotalValues    bool     `json:"send_total_values"`         // Send computed total values
		SendDerivedValues  bool     `json:"send_derived_values"`       // Send derived values e.g. rates
	}
	info          []InfinibandCollectorInfo
	lastTimestamp time.Time // Store time stamp of last tick to derive bandwidths
}

// Init initializes the Infiniband collector by walking through files below IB_BASEPATH
func (m *InfinibandCollector) Init(config json.RawMessage) error {

	// Check if already initialized
	if m.init {
		return nil
	}

	var err error
	m.name = "InfinibandCollector"
	m.setup()
	m.parallel = true
	m.meta = map[string]string{
		"source": m.name,
		"group":  "Network",
	}

	// Set default configuration,
	m.config.SendAbsoluteValues = true
	m.config.SendDerivedValues = false
	// Read configuration file, allow overwriting default config
	if len(config) > 0 {
		err = json.Unmarshal(config, &m.config)
		if err != nil {
			return err
		}
	}

	// Loop for all InfiniBand directories
	globPattern := filepath.Join(IB_BASEPATH, "*", "ports", "*")
	ibDirs, err := filepath.Glob(globPattern)
	if err != nil {
		return fmt.Errorf("unable to glob files with pattern %s: %v", globPattern, err)
	}
	if ibDirs == nil {
		return fmt.Errorf("unable to find any directories with pattern %s", globPattern)
	}

	for _, path := range ibDirs {

		// Skip, when no LID is assigned
		line, err := os.ReadFile(filepath.Join(path, "lid"))
		if err != nil {
			continue
		}
		LID := strings.TrimSpace(string(line))
		if LID == "0x0" {
			continue
		}

		// Get device and port component
		pathSplit := strings.Split(path, string(os.PathSeparator))
		device := pathSplit[4]
		port := pathSplit[6]

		// Skip excluded devices
		skip := false
		for _, excludedDevice := range m.config.ExcludeDevices {
			if excludedDevice == device {
				skip = true
				break
			}
		}
		if skip {
			continue
		}

		// Check access to counter files
		countersDir := filepath.Join(path, "counters")
		portCounterFiles := []InfinibandCollectorMetric{
			{
				name:         "ib_recv",
				path:         filepath.Join(countersDir, "port_rcv_data"),
				unit:         "bytes",
				scale:        4,
				addToIBTotal: true,
				lastState:    -1,
			},
			{
				name:         "ib_xmit",
				path:         filepath.Join(countersDir, "port_xmit_data"),
				unit:         "bytes",
				scale:        4,
				addToIBTotal: true,
				lastState:    -1,
			},
			{
				name:             "ib_recv_pkts",
				path:             filepath.Join(countersDir, "port_rcv_packets"),
				unit:             "packets",
				scale:            1,
				addToIBTotalPkgs: true,
				lastState:        -1,
			},
			{
				name:             "ib_xmit_pkts",
				path:             filepath.Join(countersDir, "port_xmit_packets"),
				unit:             "packets",
				scale:            1,
				addToIBTotalPkgs: true,
				lastState:        -1,
			},
		}
		for _, counter := range portCounterFiles {
			err := unix.Access(counter.path, unix.R_OK)
			if err != nil {
				return fmt.Errorf("unable to access %s: %v", counter.path, err)
			}
		}

		m.info = append(m.info,
			InfinibandCollectorInfo{
				LID:              LID,
				device:           device,
				port:             port,
				portCounterFiles: portCounterFiles,
				tagSet: map[string]string{
					"type":   "node",
					"device": device,
					"port":   port,
					"lid":    LID,
				},
			})
	}

	if len(m.info) == 0 {
		return fmt.Errorf("found no IB devices")
	}

	m.init = true
	return nil
}

// Read reads Infiniband counter files below IB_BASEPATH
func (m *InfinibandCollector) Read(interval time.Duration, output chan lp.CCMetric) {

	// Check if already initialized
	if !m.init {
		return
	}

	// Current time stamp
	now := time.Now()
	// time difference to last time stamp
	timeDiff := now.Sub(m.lastTimestamp).Seconds()
	// Save current timestamp
	m.lastTimestamp = now

	for i := range m.info {
		info := &m.info[i]

		var ib_total, ib_total_pkts int64
		for i := range info.portCounterFiles {
			counterDef := &info.portCounterFiles[i]

			// Read counter file
			line, err := os.ReadFile(counterDef.path)
			if err != nil {
				cclog.ComponentError(
					m.name,
					fmt.Sprintf("Read(): Failed to read from file '%s': %v", counterDef.path, err))
				continue
			}
			data := strings.TrimSpace(string(line))

			// convert counter to int64
			v, err := strconv.ParseInt(data, 10, 64)
			if err != nil {
				cclog.ComponentError(
					m.name,
					fmt.Sprintf("Read(): Failed to convert Infininiband metrice %s='%s' to int64: %v", counterDef.name, data, err))
				continue
			}
			// Scale raw value
			v *= counterDef.scale

			// Save current state
			counterDef.currentState = v

			// Send absolut values
			if m.config.SendAbsoluteValues {
				if y, err :=
					lp.New(
						counterDef.name,
						info.tagSet,
						m.meta,
						map[string]interface{}{
							"value": counterDef.currentState,
						},
						now); err == nil {
					y.AddMeta("unit", counterDef.unit)
					output <- y
				}
			}

			// Send derived values
			if m.config.SendDerivedValues {
				if counterDef.lastState >= 0 {
					rate := float64((counterDef.currentState - counterDef.lastState)) / timeDiff
					if y, err :=
						lp.New(
							counterDef.name+"_bw",
							info.tagSet,
							m.meta,
							map[string]interface{}{
								"value": rate,
							},
							now); err == nil {
						y.AddMeta("unit", counterDef.unit+"/sec")
						output <- y

					}
				}
				counterDef.lastState = counterDef.currentState
			}

			// Sum up total values
			if m.config.SendTotalValues {
				switch {
				case counterDef.addToIBTotal:
					ib_total += counterDef.currentState
				case counterDef.addToIBTotalPkgs:
					ib_total_pkts += counterDef.currentState
				}
			}
		}

		// Send total values
		if m.config.SendTotalValues {
			if y, err :=
				lp.New(
					"ib_total",
					info.tagSet,
					m.meta,
					map[string]interface{}{
						"value": ib_total,
					},
					now); err == nil {
				y.AddMeta("unit", "bytes")
				output <- y
			}

			if y, err :=
				lp.New(
					"ib_total_pkts",
					info.tagSet,
					m.meta,
					map[string]interface{}{
						"value": ib_total_pkts,
					},
					now); err == nil {
				y.AddMeta("unit", "packets")
				output <- y
			}
		}
	}
}

func (m *InfinibandCollector) Close() {
	m.init = false
}