package resolver

import (
	"strings"

	"github.com/zzet/gortex/internal/graph"
)

// myBatisStubPrefix is the placeholder namespace the MyBatis mapper-XML
// extractor emits for the call edge that runs from a SQL statement node
// back to the Java DAO method that executes it
// (`unresolved::mybatis::<namespace>::<id>`).
const myBatisStubPrefix = unresolvedPrefix + "mybatis::"

// ResolveMyBatisCalls is the graph-wide materialisation pass for the
// MyBatis mapper layer. The mapper-XML extractor emits one node per
// `<select>/<insert>/<update>/<delete>` statement (ID `<namespace>::<id>`)
// plus an EdgeCalls edge from that statement node to a
// `unresolved::mybatis::<namespace>::<id>` placeholder, carrying
// `Meta["via"]="mybatis.mapper"` plus `mybatis_namespace` /
// `mybatis_statement`. This pass joins each such edge onto the Java DAO /
// Mapper interface method the statement implements.
//
// The `<mapper namespace>` is the Java interface FQCN
// (`com.app.UserMapper`); the statement `id` is the method name
// (`findUser`). The Java extractor emits interface methods as
// `<filePath>::<SimpleClassName>.<method>`-shaped nodes carrying
// `Meta["receiver"]=<SimpleClassName>`. The join therefore suffix-matches
// `<SimpleClassName>.<id>` (the trailing `::Class.method` component of the
// Java node ID) against every Java method node, preferring a same-repo
// candidate and falling back to a unique workspace-wide match.
//
// The pass is a full recompute and idempotent: every mybatis.mapper
// edge's target is recomputed from its own `mybatis_namespace` /
// `mybatis_statement` meta on each call, so a reindex of either the mapper
// XML or the Java interface leaves the meta intact and the next pass
// re-lands (or un-lands) the edge. graph.ReindexEdges keeps the out/in
// buckets consistent. An edge whose method is no longer in the graph is
// reset back to the placeholder and loses its resolution-tier metadata.
//
// Resolved edges are stamped with provenance Meta
// (`synthesized_by="mybatis"`, `provenance="heuristic"`) so downstream
// consumers can tell a framework-synthesized binding from a directly
// extracted call.
//
// Returns the number of mybatis.mapper edges pointing at a resolved Java
// method after the pass.
func ResolveMyBatisCalls(g graph.Store) int {
	if g == nil {
		return 0
	}

	idx := buildMyBatisMethodIndex(g)
	resolved := 0
	var reindexBatch []graph.EdgeReindex

	// First sweep: collect every mybatis.mapper edge plus the From IDs we
	// need to read RepoPrefix off, so the per-edge GetNode below collapses
	// to a single GetNodesByIDs batch on disk backends.
	type stubEdge struct {
		edge                 *graph.Edge
		namespace, statement string
	}
	var stubs []stubEdge
	fromIDs := map[string]struct{}{}
	for e := range g.EdgesByKind(graph.EdgeCalls) {
		if e == nil || e.Meta == nil {
			continue
		}
		if v, _ := e.Meta["via"].(string); v != "mybatis.mapper" {
			continue
		}
		ns, _ := e.Meta["mybatis_namespace"].(string)
		stmt, _ := e.Meta["mybatis_statement"].(string)
		if ns == "" || stmt == "" {
			continue
		}
		stubs = append(stubs, stubEdge{edge: e, namespace: ns, statement: stmt})
		if e.From != "" {
			fromIDs[e.From] = struct{}{}
		}
	}
	fromList := make([]string, 0, len(fromIDs))
	for id := range fromIDs {
		fromList = append(fromList, id)
	}
	fromNodes := g.GetNodesByIDs(fromList)

	for _, s := range stubs {
		e := s.edge
		callerRepo := ""
		if from := fromNodes[e.From]; from != nil {
			callerRepo = from.RepoPrefix
		}
		methodID, origin, conf := idx.lookup(s.namespace, s.statement, callerRepo)

		want := methodID
		if want == "" {
			want = myBatisStubPlaceholder(s.namespace, s.statement)
		}
		if e.To == want {
			if methodID != "" {
				resolved++
			}
			continue
		}

		oldTo := e.To
		e.To = want
		if e.Meta == nil {
			e.Meta = map[string]any{}
		}
		if methodID != "" {
			e.Origin = origin
			e.Confidence = conf
			e.ConfidenceLabel = graph.ConfidenceLabelFor(graph.EdgeCalls, conf)
			e.Meta["synthesized_by"] = "mybatis"
			e.Meta["provenance"] = "heuristic"
			e.Meta["mybatis_resolution"] = origin
			resolved++
		} else {
			// Re-orphaned (method removed since the last pass): drop the
			// resolution-tier metadata so the edge reads as a plain
			// unresolved placeholder again.
			e.Origin = ""
			e.Confidence = 0
			e.ConfidenceLabel = ""
			delete(e.Meta, "synthesized_by")
			delete(e.Meta, "provenance")
			delete(e.Meta, "mybatis_resolution")
		}
		reindexBatch = append(reindexBatch, graph.EdgeReindex{Edge: e, OldTo: oldTo})
	}
	if len(reindexBatch) > 0 {
		g.ReindexEdges(reindexBatch)
	}
	return resolved
}

// myBatisStubPlaceholder is the canonical placeholder target for an
// unresolved MyBatis mapper-statement call.
func myBatisStubPlaceholder(namespace, statement string) string {
	return myBatisStubPrefix + namespace + "::" + statement
}

// myBatisMethodIndex maps a "<SimpleClassName>.<method>" key to the Java
// method nodes that match it.
type myBatisMethodIndex struct {
	byKey map[string][]*graph.Node
}

// lookup returns the Java DAO method node for (namespace, statement),
// preferring a same-repo candidate over a cross-repo one. namespace is
// the interface FQCN (`com.app.UserMapper`); its simple class name plus
// the statement id form the join key. Returns ("", "", 0) when no unique
// method is found.
func (idx *myBatisMethodIndex) lookup(namespace, statement, callerRepo string) (id, origin string, confidence float64) {
	key := myBatisJoinKey(namespace, statement)
	if key == "" {
		return "", "", 0
	}
	cands := idx.byKey[key]
	if len(cands) == 0 {
		return "", "", 0
	}
	var sameRepo []*graph.Node
	for _, n := range cands {
		if callerRepo != "" && n.RepoPrefix == callerRepo {
			sameRepo = append(sameRepo, n)
		}
	}
	if len(sameRepo) == 1 {
		return sameRepo[0].ID, graph.OriginASTInferred, 0.7
	}
	if len(sameRepo) == 0 && len(cands) == 1 {
		return cands[0].ID, graph.OriginASTInferred, 0.7
	}
	return "", "", 0
}

// buildMyBatisMethodIndex walks every Java method node once and indexes
// it by its "<SimpleClassName>.<method>" key, derived from the trailing
// `::Class.method` component of the node ID (with the node's `receiver`
// Meta as a cross-check). One pass replaces an AllNodes scan per edge.
func buildMyBatisMethodIndex(g graph.Store) *myBatisMethodIndex {
	idx := &myBatisMethodIndex{byKey: map[string][]*graph.Node{}}
	for n := range g.NodesByKind(graph.KindMethod) {
		if n == nil || n.Language != "java" {
			continue
		}
		key := javaMethodJoinKey(n)
		if key == "" {
			continue
		}
		idx.byKey[key] = append(idx.byKey[key], n)
	}
	return idx
}

// myBatisJoinKey builds the "<SimpleClassName>.<statement>" join key from
// a mapper namespace (interface FQCN) and a statement id. The simple
// class name is the last dotted component of the FQCN
// (`com.app.UserMapper` → `UserMapper`).
func myBatisJoinKey(namespace, statement string) string {
	if namespace == "" || statement == "" {
		return ""
	}
	simple := namespace
	if i := strings.LastIndex(simple, "."); i >= 0 {
		simple = simple[i+1:]
	}
	if simple == "" {
		return ""
	}
	return simple + "." + statement
}

// javaMethodJoinKey returns the "<SimpleClassName>.<method>" key for a
// Java method node. The Java extractor emits method node IDs shaped
// `<filePath>::<ClassName>.<method>` and stamps `Meta["receiver"]` with
// the class name; the trailing `::`-delimited component of the ID is the
// canonical source, with the receiver Meta as a fallback when the ID
// carries a disambiguating suffix (e.g. `_L42`).
func javaMethodJoinKey(n *graph.Node) string {
	if n == nil {
		return ""
	}
	tail := n.ID
	if i := strings.LastIndex(tail, "::"); i >= 0 {
		tail = tail[i+2:]
	}
	// The tail is normally "Class.method"; honour a one-off
	// line-disambiguated suffix the extractor appends on collisions
	// ("Class.method_L42") by reconstructing from receiver + Name.
	if recv, _ := n.Meta["receiver"].(string); recv != "" && n.Name != "" {
		simple := recv
		if i := strings.LastIndex(simple, "."); i >= 0 {
			simple = simple[i+1:]
		}
		return simple + "." + n.Name
	}
	if tail == "" || !strings.Contains(tail, ".") {
		return ""
	}
	return tail
}