// Package handler implements service debug handler embedded in go-micro services
package handler

import (
	"context"
	"runtime"
	"time"

	"github.com/micro/go-micro/debug/log"
	proto "github.com/micro/go-micro/debug/service/proto"
	"github.com/micro/go-micro/server"
)

var (
	// DefaultHandler is default debug handler
	DefaultHandler = newDebug()
)

type Debug struct {
	started int64
	proto.DebugHandler
	log log.Log
}

func newDebug() *Debug {
	return &Debug{
		started: time.Now().Unix(),
		log:     log.DefaultLog,
	}
}

func (d *Debug) Health(ctx context.Context, req *proto.HealthRequest, rsp *proto.HealthResponse) error {
	rsp.Status = "ok"
	return nil
}

func (d *Debug) Stats(ctx context.Context, req *proto.StatsRequest, rsp *proto.StatsResponse) error {
	var mstat runtime.MemStats
	runtime.ReadMemStats(&mstat)

	rsp.Timestamp = uint64(time.Now().Unix())
	rsp.Started = uint64(d.started)
	rsp.Uptime = uint64(time.Now().Unix() - d.started)
	rsp.Memory = mstat.Alloc
	rsp.Gc = mstat.PauseTotalNs
	rsp.Threads = uint64(runtime.NumGoroutine())
	return nil
}

func (d *Debug) Log(ctx context.Context, stream server.Stream) error {
	req := new(proto.LogRequest)
	if err := stream.Recv(req); err != nil {
		return err
	}

	var options []log.ReadOption

	since := time.Unix(req.Since, 0)
	if !since.IsZero() {
		options = append(options, log.Since(since))
	}

	count := int(req.Count)
	if count > 0 {
		options = append(options, log.Count(count))
	}

	if req.Stream {
		// TODO: we need to figure out how to close the log stream
		// It seems like when a client disconnects,
		// the connection stays open until some timeout expires
		// or something like that; that means the map of streams
		// might end up leaking memory if not cleaned up properly
		lgStream, err := d.log.Stream()
		if err != nil {
			return err
		}
		defer lgStream.Stop()

		for record := range lgStream.Chan() {
			if err := d.sendRecord(record, stream); err != nil {
				return err
			}
		}

		// done streaming, return
		return nil
	}

	// get the log records
	records, err := d.log.Read(options...)
	if err != nil {
		return err
	}

	// send all the logs downstream
	for _, record := range records {
		if err := d.sendRecord(record, stream); err != nil {
			return err
		}
	}

	return nil
}

func (d *Debug) sendRecord(record log.Record, stream server.Stream) error {
	metadata := make(map[string]string)
	for k, v := range record.Metadata {
		metadata[k] = v
	}

	return stream.Send(&proto.Record{
		Timestamp: record.Timestamp.Unix(),
		Message:   record.Message.(string),
		Metadata:  metadata,
	})
}