package main

import (
	"context"
	"encoding/json"
	"flag"
	"fmt"
	"os"
	"sync"
	"time"

	pb "git.ipng.ch/ipng/nginx-logtail/proto/logtailpb"
)

type topNResult struct {
	target string
	resp   *pb.TopNResponse
	err    error
}

func runTopN(args []string) {
	fs := flag.NewFlagSet("topn", flag.ExitOnError)
	sf, targetFlag := bindShared(fs)
	n := fs.Int("n", 10, "number of entries")
	window := fs.String("window", "5m", "time window: 1m 5m 15m 60m 6h 24h")
	groupBy := fs.String("group-by", "website", "group by: website prefix uri status")
	fs.Parse(args)
	sf.resolve(*targetFlag)

	win := parseWindow(*window)
	grp := parseGroupBy(*groupBy)
	filter := buildFilter(sf)

	results := fanOutTopN(sf.targets, filter, grp, *n, win)

	for _, r := range results {
		if hdr := targetHeader(r.target, r.resp.GetSource(), len(sf.targets)); hdr != "" {
			fmt.Println(hdr)
		}
		if r.err != nil {
			fmt.Fprintf(os.Stderr, "error from %s: %v\n", r.target, r.err)
			continue
		}
		if sf.jsonOut {
			printTopNJSON(r)
		} else {
			printTopNTable(r)
		}
		if len(sf.targets) > 1 {
			fmt.Println()
		}
	}
}

func fanOutTopN(targets []string, filter *pb.Filter, groupBy pb.GroupBy, n int, window pb.Window) []topNResult {
	results := make([]topNResult, len(targets))
	var wg sync.WaitGroup
	for i, t := range targets {
		wg.Add(1)
		go func(i int, addr string) {
			defer wg.Done()
			results[i].target = addr
			conn, client, err := dial(addr)
			if err != nil {
				results[i].err = err
				results[i].resp = &pb.TopNResponse{}
				return
			}
			defer conn.Close()
			ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
			defer cancel()
			resp, err := client.TopN(ctx, &pb.TopNRequest{
				Filter:  filter,
				GroupBy: groupBy,
				N:       int32(n),
				Window:  window,
			})
			results[i].resp = resp
			results[i].err = err
		}(i, t)
	}
	wg.Wait()
	return results
}

func printTopNTable(r topNResult) {
	if len(r.resp.Entries) == 0 {
		fmt.Println("(no data)")
		return
	}
	rows := [][]string{{"RANK", "COUNT", "LABEL"}}
	for i, e := range r.resp.Entries {
		rows = append(rows, []string{
			fmt.Sprintf("%4d", i+1),
			fmtCount(e.Count),
			e.Label,
		})
	}
	printTable(os.Stdout, rows)
}

func printTopNJSON(r topNResult) {
	type entry struct {
		Label string `json:"label"`
		Count int64  `json:"count"`
	}
	type out struct {
		Source  string  `json:"source"`
		Target  string  `json:"target"`
		Entries []entry `json:"entries"`
	}
	o := out{
		Source:  r.resp.Source,
		Target:  r.target,
		Entries: make([]entry, len(r.resp.Entries)),
	}
	for i, e := range r.resp.Entries {
		o.Entries[i] = entry{Label: e.Label, Count: e.Count}
	}
	b, _ := json.Marshal(o)
	fmt.Println(string(b))
}