package watch

import (
	"bytes"
	"encoding/json"
	"net/http"
	"net/http/httptest"
	"path/filepath"
	"strings"
	"testing"

	"github.com/david/knox/internal/db"
)

func tmpKnoxDB(t *testing.T) *db.KnoxDB {
	t.Helper()
	kdb, err := db.Open(filepath.Join(t.TempDir(), "index.db"))
	if err != nil {
		t.Fatalf("open db: %v", err)
	}
	t.Cleanup(func() { kdb.Close() })
	return kdb
}

func seedObs(k *db.KnoxDB, prefix string) {
	// Insert distinct observations only via RecordObservation so they get this
	// node's node_id and HCL.
	for i := 0; i < 3; i++ {
		_, _, err := k.RecordObservation(db.ObservationRecord{
			Fingerprint:     prefix + ":" + string(rune('a'+i)),
			SourceID:        "test",
			SourcePath:      prefix,
			Project:         "itest",
			ContentType:     "test",
			Title:           prefix + string(rune('a'+i)),
			Summary:         "summary " + prefix + string(rune('a'+i)),
			CreatedAt:       "2026-08-29T00:00:00Z",
			LineEnd:         0,
			Confidence:      0.9,
			IngesterVersion: "itest/v1",
		})
		if err != nil {
			panic(err)
		}
	}
}

// TestGossipConvergence starts two nodes, seeds disjoint observations, and runs
// a bidirectional handshake. Both must end with the concatenation of both logs.
func TestGossipConvergence(t *testing.T) {
	a := tmpKnoxDB(t)
	b := tmpKnoxDB(t)

	seedObs(a, "AAA")
	seedObs(b, "BBB")

	// Wire a and b as peer HTTP servers.
	nodeA := &Node{Kdb: a, Name: "A"}
	sa := httptest.NewServer(nodeA.Handler())
	defer sa.Close()

	nodeB := &Node{Kdb: b, Name: "B"}
	sb := httptest.NewServer(nodeB.Handler())
	defer sb.Close()

	// A pulls from B, then B pulls from A (bidirectional sweep).
	Run(a, nil, []string{sb.URL})
	Run(b, nil, []string{sa.URL})

	av, err := a.KnowledgeVector()
	if err != nil {
		t.Fatalf("a vector: %v", err)
	}
	bv, err := b.KnowledgeVector()
	if err != nil {
		t.Fatalf("b vector: %v", err)
	}

	if len(av) != 2 || len(bv) != 2 {
		t.Fatalf("expected both nodes to hold 2 source logs, got a=%v b=%v", av, bv)
	}

	// Same maximum HCL per origin node on both sides.
	for nid, hcl := range av {
		if bv[nid] != hcl {
			t.Errorf("node %s max hcl mismatch: a=%d b=%d", nid, hcl, bv[nid])
		}
	}
}

// TestGossipSwarmDiscovery: C only knows A. A knows B. When C sweeps A, it must
// learn about B through A's ping, enqueue B, and pull B's observations — with no
// direct configuration of B (no relay of data, only membership).
func TestGossipSwarmDiscovery(t *testing.T) {
	a := tmpKnoxDB(t)
	b := tmpKnoxDB(t)
	c := tmpKnoxDB(t)

	seedObs(a, "AAA")
	seedObs(b, "BBB")
	seedObs(c, "CCC")

	nodeA := &Node{Kdb: a, Name: "A"}
	sa := httptest.NewServer(nodeA.Handler())
	defer sa.Close()
	nodeB := &Node{Kdb: b, Name: "B"}
	sb := httptest.NewServer(nodeB.Handler())
	defer sb.Close()
	nodeC := &Node{Kdb: c, Name: "C"}
	sc := httptest.NewServer(nodeC.Handler())
	defer sc.Close()

	// A discovers B (A pings B) so A can advertise B to the swarm.
	Run(a, nil, []string{sb.URL})

	// C only knows A. A single sweep should surface B (membership in ping)
	// and pull B's observations directly.
	Run(c, nil, []string{sa.URL})

	// C must know B and hold all three origin logs.
	peers, err := c.ListPeers()
	if err != nil {
		t.Fatalf("list peers: %v", err)
	}
	foundB := false
	for _, p := range peers {
		if p.PeerID == b.NodeID() {
			foundB = true
		}
	}
	if !foundB {
		t.Fatalf("C did not discover B via A's membership list; peers=%v", peers)
	}

	vec, err := c.KnowledgeVector()
	if err != nil {
		t.Fatalf("c vector: %v", err)
	}
	if len(vec) != 3 {
		t.Errorf("C should hold 3 origin logs (A, B, C), got %v", vec)
	}

	// C's copy of B's log must match B's own max hcl.
	bmax := c.MaxHCLForNode(b.NodeID())
	bm, err := bNodeMax(b)
	if err != nil {
		t.Fatal(err)
	}
	if bmax != bm {
		t.Errorf("C max hcl for B=%d, B reports %d", bmax, bm)
	}
}

// bNodeMax is a helper reading the max hcl B holds for its own node.
func bNodeMax(b *db.KnoxDB) (int64, error) {
	rows, err := b.KnowledgeVector()
	if err != nil {
		return 0, err
	}
	return rows[b.NodeID()], nil
}
func TestGossipDiff(t *testing.T) {
	a := tmpKnoxDB(t)
	b := tmpKnoxDB(t)

	seedObs(a, "AAA")
	seedObs(b, "BBB")

	nodeA := &Node{Kdb: a, Name: "A"}
	sa := httptest.NewServer(nodeA.Handler())
	defer sa.Close()

	c := &Client{Addr: sa.URL}
	d, err := c.Diff()
	if err != nil {
		t.Fatalf("diff: %v", err)
	}
	if d.NodeID != a.NodeID() {
		t.Errorf("diff node mismatch: %s != %s", d.NodeID, a.NodeID())
	}
	if len(d.Fingerprints) != 3 {
		t.Errorf("expected 3 fingerprints in diff, got %d", len(d.Fingerprints))
	}
}

// TestGossipDiffTombstones confirms resolved auto-threads surface in diff.
func TestGossipDiffTombstones(t *testing.T) {
	a := tmpKnoxDB(t)

	id, _, err := a.CreateThreadCluster("Test thread", "motivation", "medium", "[]", `{"trigger":"auto_thread"}`, "cluster:testkey")
	if err != nil {
		t.Fatalf("create thread: %v", err)
	}
	if err := a.CloseThread(id); err != nil {
		t.Fatalf("close thread: %v", err)
	}

	nodeA := &Node{Kdb: a, Name: "A"}
	sa := httptest.NewServer(nodeA.Handler())
	defer sa.Close()

	c := &Client{Addr: sa.URL}
	d, err := c.Diff()
	if err != nil {
		t.Fatalf("diff: %v", err)
	}
	if len(d.ThreadStatus) != 1 {
		t.Errorf("expected 1 thread in diff, got %d", len(d.ThreadStatus))
	}
	for k, st := range d.ThreadStatus {
		if k != "cluster:testkey" {
			t.Errorf("unexpected thread key %s", k)
		}
		if st != "resolved" {
			t.Errorf("thread %s should be resolved, got %q", k, st)
		}
	}
}

// TestGossipIdempotent ensures a repeated sweep does not duplicate observations.
func TestGossipIdempotent(t *testing.T) {
	a := tmpKnoxDB(t)
	b := tmpKnoxDB(t)

	seedObs(a, "AAA")

	nodeA := &Node{Kdb: a, Name: "A"}
	sa := httptest.NewServer(nodeA.Handler())
	defer sa.Close()
	nodeB := &Node{Kdb: b, Name: "B"}
	sb := httptest.NewServer(nodeB.Handler())
	defer sb.Close()

	Run(b, nil, []string{sa.URL})
	entryBefore, err := b.EntryCount()
	if err != nil {
		t.Fatal(err)
	}
	stats, err := b.Stats()
	if err != nil {
		t.Fatal(err)
	}
	obsBefore, _ := stats["total_observations"].(int)

	Run(b, nil, []string{sa.URL})

	entryAfter, err := b.EntryCount()
	if err != nil {
		t.Fatal(err)
	}
	if entryBefore != entryAfter {
		t.Errorf("second sweep changed entry count: %d -> %d", entryBefore, entryAfter)
	}
	stats, err = b.Stats()
	if err != nil {
		t.Fatal(err)
	}
	obsAfter, _ := stats["total_observations"].(int)
	if obsBefore != obsAfter {
		t.Errorf("second sweep duplicated observations: %d -> %d", obsBefore, obsAfter)
	}
}

// TestHandleBatchRejectsOversizedBatch: more than maxBatchRows in one POST
// must be refused up front, before any insert work.
func TestHandleBatchRejectsOversizedBatch(t *testing.T) {
	b := tmpKnoxDB(t)
	node := &Node{Kdb: b, Name: "B"}
	sv := httptest.NewServer(node.Handler())
	defer sv.Close()

	rows := make([]db.GossipObservation, maxBatchRows+1)
	for i := range rows {
		rows[i] = db.GossipObservation{
			NodeID: "0123456789abcdef0123456789abcdef", HCL: int64(i + 1),
			Fingerprint: "fp:oversized", SourceID: "test", Title: "t", Summary: "s",
			CollectedAt: "2026-08-29T00:00:00Z",
		}
	}
	body, _ := json.Marshal(rows)
	resp, err := http.Post(sv.URL+"/v1/obs/batch", "application/json", bytes.NewReader(body))
	if err != nil {
		t.Fatalf("post: %v", err)
	}
	defer resp.Body.Close()
	if resp.StatusCode != http.StatusBadRequest {
		t.Errorf("oversized batch: want 400, got %d", resp.StatusCode)
	}
}

// TestHandleBatchRejectsHugeBody: an oversized body (beyond the 4 MiB cap)
// must be refused even when the row count is small.
func TestHandleBatchRejectsHugeBody(t *testing.T) {
	b := tmpKnoxDB(t)
	node := &Node{Kdb: b, Name: "B"}
	sv := httptest.NewServer(node.Handler())
	defer sv.Close()

	rows := []db.GossipObservation{{
		NodeID: "0123456789abcdef0123456789abcdef", HCL: 1,
		Fingerprint: "fp:huge", SourceID: "test", Title: "t",
		Summary: strings.Repeat("x", 5<<20), // 5 MiB summary
		CollectedAt: "2026-08-29T00:00:00Z",
	}}
	body, _ := json.Marshal(rows)
	resp, err := http.Post(sv.URL+"/v1/obs/batch", "application/json", bytes.NewReader(body))
	if err != nil {
		t.Fatalf("post: %v", err)
	}
	defer resp.Body.Close()
	if resp.StatusCode != http.StatusBadRequest {
		t.Errorf("huge body: want 400, got %d", resp.StatusCode)
	}
}

// TestHandleBatchSkipsSelfRows: rows claiming the receiver's own node_id are
// dropped at the HTTP layer too (the poisoning vector), reported as conflicts.
func TestHandleBatchSkipsSelfRows(t *testing.T) {
	b := tmpKnoxDB(t)
	node := &Node{Kdb: b, Name: "B"}
	sv := httptest.NewServer(node.Handler())
	defer sv.Close()

	rows := []db.GossipObservation{
		{NodeID: b.NodeID(), HCL: 1, Fingerprint: "fp:self1", SourceID: "test", Title: "t", Summary: "s", CollectedAt: "2026-08-29T00:00:00Z"},
		{NodeID: b.NodeID(), HCL: 2, Fingerprint: "fp:self2", SourceID: "test", Title: "t", Summary: "s", CollectedAt: "2026-08-29T00:00:00Z"},
	}
	body, _ := json.Marshal(rows)
	resp, err := http.Post(sv.URL+"/v1/obs/batch", "application/json", bytes.NewReader(body))
	if err != nil {
		t.Fatalf("post: %v", err)
	}
	defer resp.Body.Close()
	if resp.StatusCode != http.StatusOK {
		t.Fatalf("want 200, got %d", resp.StatusCode)
	}
	var out struct {
		Accepted int `json:"accepted"`
		Conflict int `json:"conflict"`
	}
	if err := json.NewDecoder(resp.Body).Decode(&out); err != nil {
		t.Fatalf("decode: %v", err)
	}
	if out.Accepted != 0 || out.Conflict != 2 {
		t.Errorf("self rows: want accepted=0 conflict=2, got accepted=%d conflict=%d", out.Accepted, out.Conflict)
	}
}