package main

type termKey struct {
	termType string
	key      string
}

type termMeta struct {
	termType string
	iri      string
}

func graphFromSparqlBindings(
	bindings []map[string]sparqlTerm,
	nodeLimit int,
	includeBNodes bool,
) (nodes []Node, edges []Edge) {
	nodeIDByKey := map[termKey]int{}
	nodeMeta := make([]termMeta, 0, min(nodeLimit, 4096))

	getOrAdd := func(term sparqlTerm) (int, bool) {
		if term.Type == "" || term.Value == "" {
			return 0, false
		}
		if term.Type == "literal" {
			return 0, false
		}

		var key termKey
		var meta termMeta

		if term.Type == "bnode" {
			if !includeBNodes {
				return 0, false
			}
			key = termKey{termType: "bnode", key: term.Value}
			meta = termMeta{termType: "bnode", iri: "_:" + term.Value}
		} else {
			key = termKey{termType: "uri", key: term.Value}
			meta = termMeta{termType: "uri", iri: term.Value}
		}

		if existing, ok := nodeIDByKey[key]; ok {
			return existing, true
		}
		if len(nodeMeta) >= nodeLimit {
			return 0, false
		}
		nid := len(nodeMeta)
		nodeIDByKey[key] = nid
		nodeMeta = append(nodeMeta, meta)
		return nid, true
	}

	for _, b := range bindings {
		sTerm := b["s"]
		oTerm := b["o"]
		pTerm := b["p"]

		sid, okS := getOrAdd(sTerm)
		oid, okO := getOrAdd(oTerm)
		if !okS || !okO {
			continue
		}

		pred := pTerm.Value
		if pred == "" {
			continue
		}

		edges = append(edges, Edge{
			Source:    sid,
			Target:    oid,
			Predicate: pred,
		})
	}

	nodes = make([]Node, len(nodeMeta))
	for i, m := range nodeMeta {
		nodes[i] = Node{
			ID:       i,
			TermType: m.termType,
			IRI:      m.iri,
			Label:    nil,
			X:        0,
			Y:        0,
		}
	}

	return nodes, edges
}

func min(a, b int) int {
	if a < b {
		return a
	}
	return b
}