package npcinteractions

import (
	"sort"

	"gitea.maximumdirect.net/eric/notarius/internal/core/source"
	"gitea.maximumdirect.net/eric/notarius/internal/modules/dnd"
)

func canonicalizeResponse(response *extractionResponse, doc *source.SourceDocument) {
	if response == nil {
		return
	}
	for index := range response.Interactions {
		canonicalizeInteraction(&response.Interactions[index])
	}
	sort.SliceStable(response.Interactions, func(i, j int) bool {
		left, leftOK := earliestSourcePosition(doc, response.Interactions[i])
		right, rightOK := earliestSourcePosition(doc, response.Interactions[j])
		if leftOK != rightOK {
			return leftOK
		}
		if !leftOK {
			return false
		}
		return left < right
	})
}

func canonicalizeInteraction(interaction *interactionResponse) {
	if interaction == nil {
		return
	}
	sort.SliceStable(interaction.SourceRefs, func(i, j int) bool {
		left := interaction.SourceRefs[i]
		right := interaction.SourceRefs[j]
		if unitSortValue(left.StartUnitID) != unitSortValue(right.StartUnitID) {
			return unitSortValue(left.StartUnitID) < unitSortValue(right.StartUnitID)
		}
		return unitSortValue(left.EndUnitID) < unitSortValue(right.EndUnitID)
	})
	interaction.SourceRefs = dedupeSourceRefs(interaction.SourceRefs)
}

func dedupeSourceRefs(refs []interactionSourceRefResponse) []interactionSourceRefResponse {
	if len(refs) < 2 {
		return refs
	}
	out := refs[:0]
	var previous interactionSourceRefResponse
	for index, ref := range refs {
		if index > 0 && previous == ref {
			continue
		}
		out = append(out, ref)
		previous = ref
	}
	return out
}

func earliestSourcePosition(doc *source.SourceDocument, interaction interactionResponse) (int, bool) {
	if doc == nil {
		return 0, false
	}
	found := false
	earliest := 0
	for _, ref := range interaction.SourceRefs {
		candidate := source.SourceRef{SourceID: doc.ID, StartUnitID: ref.StartUnitID, EndUnitID: ref.EndUnitID}
		if err := source.ValidateRef(doc, candidate); err != nil {
			continue
		}
		index, ok := source.UnitIndex(doc, candidate.StartUnitID)
		if !ok || (found && index >= earliest) {
			continue
		}
		earliest = index
		found = true
	}
	return earliest, found
}

func unitSortValue(value int) int {
	if value <= 0 {
		return int(^uint(0) >> 1)
	}
	return value
}

func canonicalInteractionList(response extractionResponse, sourceID string) dnd.NPCInteractionList {
	interactions := make([]dnd.NPCInteraction, len(response.Interactions))
	for index, interaction := range response.Interactions {
		interactions[index] = dnd.NPCInteraction{
			Name:       interaction.Name,
			Kind:       dnd.NPCInteractionKind(interaction.Kind),
			SourceRefs: canonicalSourceRefs(interaction.SourceRefs, sourceID),
		}
	}
	if response.Interactions == nil {
		interactions = nil
	}
	return dnd.NPCInteractionList{Interactions: interactions}
}

func canonicalSourceRefs(refs []interactionSourceRefResponse, sourceID string) []source.SourceRef {
	if refs == nil {
		return nil
	}
	out := make([]source.SourceRef, len(refs))
	for index, ref := range refs {
		out[index] = source.SourceRef{SourceID: sourceID, StartUnitID: ref.StartUnitID, EndUnitID: ref.EndUnitID}
	}
	return out
}