package web

import (
	"strconv"

	"bugabinga.net/luci/internal/history"
	"bugabinga.net/luci/internal/inbox"
	"bugabinga.net/luci/internal/proquint"
	"bugabinga.net/luci/internal/runstate"
)

// shortener computes jj-style shortest unique prefixes: run ids to proquint
// blocks, revisions to leading hex characters.
type shortener struct {
	runShort map[string]string
	revShort map[string]string
}

func buildShortener(events []history.Event, pending []inbox.Pending, active []runstate.Active) shortener {
	ids := map[string]bool{}
	for _, event := range events {
		ids[event.RunID] = true
	}
	for _, current := range pending {
		ids[current.ID] = true
	}
	for _, current := range active {
		ids[current.RunID] = true
	}
	revs := map[string]bool{}
	for _, event := range events {
		if event.Rev != "" {
			revs[event.Rev] = true
		}
	}
	for _, current := range active {
		if current.Rev != "" {
			revs[current.Rev] = true
		}
	}
	runPrefixCounts := map[string]int{}
	encodedIDs := make(map[string]string, len(ids))
	for id := range ids {
		encoded := proquint.Encode(parseID(id))
		encodedIDs[id] = encoded
		for keep := 1; keep <= 4; keep++ {
			runPrefixCounts[encoded[:keep*6-1]]++
		}
	}
	runShort := map[string]string{}
	for id, encoded := range encodedIDs {
		for keep := 1; keep <= 4; keep++ {
			prefix := encoded[:keep*6-1]
			if runPrefixCounts[prefix] == 1 {
				runShort[id] = prefix
				break
			}
		}
	}
	revPrefixCounts := map[string]int{}
	for rev := range revs {
		for length := 4; length <= len(rev); length++ {
			revPrefixCounts[rev[:length]]++
		}
	}
	revShort := map[string]string{}
	for rev := range revs {
		for length := 4; length <= len(rev); length++ {
			prefix := rev[:length]
			if revPrefixCounts[prefix] == 1 {
				revShort[rev] = prefix
				break
			}
		}
	}
	return shortener{runShort: runShort, revShort: revShort}
}

func parseID(id string) int64 {
	value, err := strconv.ParseInt(id, 10, 64)
	if err != nil {
		return 0
	}
	return value
}

// apply shortens one view in place, splitting full forms for emphasis.
func (s shortener) apply(view *runView) {
	if short, ok := s.runShort[view.RunID]; ok && view.Pronounce != "" {
		view.PronounceShort = short
		if len(short) < len(view.Pronounce) {
			view.PronounceHead, view.PronounceTail = view.Pronounce[:len(short)], view.Pronounce[len(short):]
		} else {
			view.PronounceHead = view.Pronounce
		}
	} else if view.Pronounce != "" {
		view.PronounceShort, view.PronounceHead = view.Pronounce, view.Pronounce
	}
	rev := view.FullRev
	if rev != "" && rev != "\u2014" {
		if short, ok := s.revShort[rev]; ok {
			view.Rev = short
			if len(short) < len(rev) {
				view.FullHead, view.FullTail = rev[:len(short)], rev[len(short):]
			} else {
				view.FullHead = rev
			}
		}
	}
}