package apperr

import (
	"sort"
	"time"
)

// Group is one row of the Errors tab: every record sharing a fingerprint
// in the window, summed (spec §3.6).
type Group struct {
	FP       string    `json:"fp"`
	Source   string    `json:"source"`
	Kind     string    `json:"kind,omitempty"`
	Name     string    `json:"name"`
	Level    string    `json:"level,omitempty"`
	Count    int       `json:"count"`
	First    time.Time `json:"first"`
	Last     time.Time `json:"last"`
	Hosts    []string  `json:"hosts"`
	Releases []string  `json:"releases,omitempty"`
	Sample   Record    `json:"sample"`
}

// GroupRecords folds records into groups by FP, newest Last first. The
// sample is the earliest record of the group (its stack and fields are
// the first occurrence's).
func GroupRecords(recs []Record) []Group {
	byFP := make(map[string]*Group)
	var order []string
	for _, r := range recs {
		first, last := r.First, r.Last
		if first.IsZero() {
			first = r.TS
		}
		if last.IsZero() {
			last = r.TS
		}
		count := r.Count
		if count == 0 {
			count = 1
		}
		g := byFP[r.FP]
		if g == nil {
			g = &Group{FP: r.FP, Source: r.Source, Kind: r.Kind, Name: r.Name, Level: r.Level, First: first, Last: last, Sample: r}
			byFP[r.FP] = g
			order = append(order, r.FP)
		}
		g.Count += count
		if first.Before(g.First) {
			g.First = first
			g.Sample = r
		}
		if last.After(g.Last) {
			g.Last = last
		}
		g.Hosts = addUnique(g.Hosts, r.Host)
		g.Releases = addUnique(g.Releases, r.Release)
	}
	out := make([]Group, 0, len(order))
	for _, fp := range order {
		g := byFP[fp]
		sort.Strings(g.Hosts)
		sort.Strings(g.Releases)
		out = append(out, *g)
	}
	sort.SliceStable(out, func(i, j int) bool { return out[i].Last.After(out[j].Last) })
	return out
}

func addUnique(list []string, v string) []string {
	if v == "" {
		return list
	}
	for _, x := range list {
		if x == v {
			return list
		}
	}
	return append(list, v)
}