dchain/node/feed_e2e_test.go

// End-to-end integration tests for the social feed (v2.0.0).
//
// These tests exercise the full HTTP surface against a real in-process
// setup: a BadgerDB chain, a BadgerDB feed-mailbox, the media scrubber,
// and a net/http ServeMux with all feed routes wired. Requests hit the
// real handlers (including rate-limiters, auth, and scrubber) so we
// catch wire-level regressions that unit tests miss.
//
// Layout of a typical test:
//
//	h := newFeedHarness(t)
//	defer h.Close()
//	author := h.newUser("alice")
//	h.fund(author, 1_000_000)   // give them tokens
//	resp := h.publish(author, "Hello #world", nil)  // POST /feed/publish
//	h.commitCreatePost(author, resp)                // chain tx
//	got := h.getPost(resp.PostID)
//	...
package node

import (
	"bytes"
	"context"
	"crypto/sha256"
	"encoding/base64"
	"encoding/hex"
	"encoding/json"
	"fmt"
	"image"
	"image/color"
	"image/jpeg"
	"io"
	"net/http"
	"net/http/httptest"
	"os"
	"strings"
	"testing"
	"time"

	"go-blockchain/blockchain"
	"go-blockchain/identity"
	"go-blockchain/media"
	"go-blockchain/relay"
)

// ── Harness ──────────────────────────────────────────────────────────────

type feedHarness struct {
	t *testing.T

	chainDir string
	feedDir  string
	chain    *blockchain.Chain
	mailbox  *relay.FeedMailbox
	scrubber *media.Scrubber
	server   *httptest.Server
	validator *identity.Identity
	tip       *blockchain.Block
}

func newFeedHarness(t *testing.T) *feedHarness {
	t.Helper()
	chainDir, err := os.MkdirTemp("", "dchain-e2e-chain-*")
	if err != nil {
		t.Fatalf("MkdirTemp chain: %v", err)
	}
	feedDir, err := os.MkdirTemp("", "dchain-e2e-feed-*")
	if err != nil {
		t.Fatalf("MkdirTemp feed: %v", err)
	}
	c, err := blockchain.NewChain(chainDir)
	if err != nil {
		t.Fatalf("NewChain: %v", err)
	}
	fm, err := relay.OpenFeedMailbox(feedDir, 24*time.Hour, 0)
	if err != nil {
		t.Fatalf("OpenFeedMailbox: %v", err)
	}

	validator, err := identity.Generate()
	if err != nil {
		t.Fatalf("identity.Generate: %v", err)
	}
	// Bootstrap a genesis block so the validator has funds to disburse.
	genesis := blockchain.GenesisBlock(validator.PubKeyHex(), validator.PrivKey)
	if err := c.AddBlock(genesis); err != nil {
		t.Fatalf("AddBlock genesis: %v", err)
	}

	scrubber := media.NewScrubber(media.SidecarConfig{}) // no sidecar — images only
	cfg := FeedConfig{
		Mailbox:              fm,
		HostingRelayPub:      validator.PubKeyHex(),
		Scrubber:             scrubber,
		AllowUnscrubbedVideo: false,
		GetPost:              c.Post,
		LikeCount:            c.LikeCount,
		HasLiked:             c.HasLiked,
		PostsByAuthor:        c.PostsByAuthor,
		Following:            c.Following,
	}
	mux := http.NewServeMux()
	RegisterFeedRoutes(mux, cfg)
	srv := httptest.NewServer(mux)

	h := &feedHarness{
		t: t, chainDir: chainDir, feedDir: feedDir,
		chain: c, mailbox: fm, scrubber: scrubber,
		server: srv, validator: validator, tip: genesis,
	}
	t.Cleanup(h.Close)
	return h
}

// Close releases all handles and removes the temp directories. Safe to
// call multiple times.
func (h *feedHarness) Close() {
	if h.server != nil {
		h.server.Close()
		h.server = nil
	}
	if h.mailbox != nil {
		_ = h.mailbox.Close()
		h.mailbox = nil
	}
	if h.chain != nil {
		_ = h.chain.Close()
		h.chain = nil
	}
	// Retry because Windows holds mmap files briefly after Close.
	for _, dir := range []string{h.chainDir, h.feedDir} {
		for i := 0; i < 20; i++ {
			if err := os.RemoveAll(dir); err == nil {
				break
			}
			time.Sleep(10 * time.Millisecond)
		}
	}
}

// newUser generates a fresh identity. Not funded — call fund() separately.
func (h *feedHarness) newUser(label string) *identity.Identity {
	h.t.Helper()
	id, err := identity.Generate()
	if err != nil {
		h.t.Fatalf("%s identity: %v", label, err)
	}
	return id
}

// fund sends `amount` µT from the genesis validator to `target`, committing
// the transfer in its own block.
func (h *feedHarness) fund(target *identity.Identity, amount uint64) {
	h.t.Helper()
	tx := &blockchain.Transaction{
		ID:        h.nextTxID(h.validator.PubKeyHex(), blockchain.EventTransfer),
		Type:      blockchain.EventTransfer,
		From:      h.validator.PubKeyHex(),
		To:        target.PubKeyHex(),
		Amount:    amount,
		Fee:       blockchain.MinFee,
		Timestamp: time.Now().UTC(),
	}
	h.commit(tx)
}

// commit wraps one or more txs into a block, signs, and appends.
func (h *feedHarness) commit(txs ...*blockchain.Transaction) {
	h.t.Helper()
	// Small sleep to guarantee distinct tx IDs across calls.
	time.Sleep(2 * time.Millisecond)
	var totalFees uint64
	for _, tx := range txs {
		totalFees += tx.Fee
	}
	b := &blockchain.Block{
		Index:        h.tip.Index + 1,
		Timestamp:    time.Now().UTC(),
		Transactions: txs,
		PrevHash:     h.tip.Hash,
		Validator:    h.validator.PubKeyHex(),
		TotalFees:    totalFees,
	}
	b.ComputeHash()
	b.Sign(h.validator.PrivKey)
	if err := h.chain.AddBlock(b); err != nil {
		h.t.Fatalf("AddBlock: %v", err)
	}
	h.tip = b
}

func (h *feedHarness) nextTxID(from string, typ blockchain.EventType) string {
	// Hash (from, type, now_nanos) for uniqueness.
	sum := sha256.Sum256([]byte(fmt.Sprintf("%s:%s:%d", from, typ, time.Now().UnixNano())))
	return hex.EncodeToString(sum[:16])
}

// publish POSTs /feed/publish as `author` with signed request body. On
// success returns the server's response so the caller can commit the
// on-chain CREATE_POST with matching metadata.
func (h *feedHarness) publish(author *identity.Identity, content string, attachment []byte) feedPublishResponse {
	h.t.Helper()
	attachB64 := ""
	attachMIME := ""
	if len(attachment) > 0 {
		attachB64 = base64.StdEncoding.EncodeToString(attachment)
		attachMIME = "image/jpeg"
	}
	// Client-side hash matches the server's canonical bytes rule:
	//   publish:<post_id>:<sha256(content||attachment) hex>:<ts>
	// The client knows its own attachment before any server-side scrub,
	// so this is the hash over the "raw upload". The server recomputes
	// over SCRUBBED bytes and returns that as content_hash — the client
	// then uses server's number for CREATE_POST.
	idHash := sha256.Sum256([]byte(fmt.Sprintf("%s-%d-%s",
		author.PubKeyHex(), time.Now().UnixNano(), content)))
	postID := hex.EncodeToString(idHash[:16])
	// Build signature over CLIENT-side hash.
	h256 := sha256.New()
	h256.Write([]byte(content))
	h256.Write(attachment)
	clientHash := hex.EncodeToString(h256.Sum(nil))
	ts := time.Now().Unix()
	sigBytes := author.Sign([]byte(fmt.Sprintf("publish:%s:%s:%d", postID, clientHash, ts)))

	req := feedPublishRequest{
		PostID:         postID,
		Author:         author.PubKeyHex(),
		Content:        content,
		AttachmentB64:  attachB64,
		AttachmentMIME: attachMIME,
		Sig:            base64.StdEncoding.EncodeToString(sigBytes),
		Ts:             ts,
	}
	var resp feedPublishResponse
	h.postJSON("/feed/publish", req, &resp)
	return resp
}

// commitCreatePost sends the on-chain CREATE_POST tx that pays the
// hosting relay (this node's validator in the harness). Must be called
// after publish() so the two agree on the content hash and size.
func (h *feedHarness) commitCreatePost(author *identity.Identity, pub feedPublishResponse) {
	h.t.Helper()
	contentHash, err := hex.DecodeString(pub.ContentHash)
	if err != nil {
		h.t.Fatalf("decode content hash: %v", err)
	}
	payload := blockchain.CreatePostPayload{
		PostID:       pub.PostID,
		ContentHash:  contentHash,
		Size:         pub.Size,
		HostingRelay: pub.HostingRelay,
	}
	pbytes, _ := json.Marshal(payload)
	tx := &blockchain.Transaction{
		ID:        h.nextTxID(author.PubKeyHex(), blockchain.EventCreatePost),
		Type:      blockchain.EventCreatePost,
		From:      author.PubKeyHex(),
		Amount:    0,
		Fee:       pub.EstimatedFeeUT,
		Payload:   pbytes,
		Timestamp: time.Now().UTC(),
	}
	h.commit(tx)
}

// like / unlike / follow / unfollow helpers — all just small tx builders.

func (h *feedHarness) like(liker *identity.Identity, postID string) {
	payload, _ := json.Marshal(blockchain.LikePostPayload{PostID: postID})
	tx := &blockchain.Transaction{
		ID:        h.nextTxID(liker.PubKeyHex(), blockchain.EventLikePost),
		Type:      blockchain.EventLikePost,
		From:      liker.PubKeyHex(),
		Fee:       blockchain.MinFee,
		Payload:   payload,
		Timestamp: time.Now().UTC(),
	}
	h.commit(tx)
}

func (h *feedHarness) follow(follower *identity.Identity, target string) {
	tx := &blockchain.Transaction{
		ID:        h.nextTxID(follower.PubKeyHex(), blockchain.EventFollow),
		Type:      blockchain.EventFollow,
		From:      follower.PubKeyHex(),
		To:        target,
		Fee:       blockchain.MinFee,
		Payload:   []byte(`{}`),
		Timestamp: time.Now().UTC(),
	}
	h.commit(tx)
}

// deletePost commits an on-chain EventDeletePost for the given post,
// signed by the author.
func (h *feedHarness) deletePost(author *identity.Identity, postID string) {
	payload, _ := json.Marshal(blockchain.DeletePostPayload{PostID: postID})
	tx := &blockchain.Transaction{
		ID:        h.nextTxID(author.PubKeyHex(), blockchain.EventDeletePost),
		Type:      blockchain.EventDeletePost,
		From:      author.PubKeyHex(),
		Fee:       blockchain.MinFee,
		Payload:   payload,
		Timestamp: time.Now().UTC(),
	}
	h.commit(tx)
}

// ── HTTP helpers ──────────────────────────────────────────────────────────

func (h *feedHarness) postJSON(path string, req any, out any) {
	h.t.Helper()
	body, _ := json.Marshal(req)
	resp, err := http.Post(h.server.URL+path, "application/json", bytes.NewReader(body))
	if err != nil {
		h.t.Fatalf("POST %s: %v", path, err)
	}
	defer resp.Body.Close()
	if resp.StatusCode >= 400 {
		raw, _ := io.ReadAll(resp.Body)
		h.t.Fatalf("POST %s → %d: %s", path, resp.StatusCode, string(raw))
	}
	if out != nil {
		if err := json.NewDecoder(resp.Body).Decode(out); err != nil {
			h.t.Fatalf("decode %s response: %v", path, err)
		}
	}
}

func (h *feedHarness) postJSONExpectStatus(path string, req any, want int) string {
	h.t.Helper()
	body, _ := json.Marshal(req)
	resp, err := http.Post(h.server.URL+path, "application/json", bytes.NewReader(body))
	if err != nil {
		h.t.Fatalf("POST %s: %v", path, err)
	}
	defer resp.Body.Close()
	raw, _ := io.ReadAll(resp.Body)
	if resp.StatusCode != want {
		h.t.Fatalf("POST %s → %d, want %d: %s", path, resp.StatusCode, want, string(raw))
	}
	return string(raw)
}

func (h *feedHarness) getJSON(path string, out any) {
	h.t.Helper()
	resp, err := http.Get(h.server.URL + path)
	if err != nil {
		h.t.Fatalf("GET %s: %v", path, err)
	}
	defer resp.Body.Close()
	if resp.StatusCode >= 400 {
		raw, _ := io.ReadAll(resp.Body)
		h.t.Fatalf("GET %s → %d: %s", path, resp.StatusCode, string(raw))
	}
	if out != nil {
		if err := json.NewDecoder(resp.Body).Decode(out); err != nil {
			h.t.Fatalf("decode %s response: %v", path, err)
		}
	}
}

// getStatus fetches path and returns status + body; doesn't fail on non-2xx.
func (h *feedHarness) getStatus(path string) (int, string) {
	resp, err := http.Get(h.server.URL + path)
	if err != nil {
		h.t.Fatalf("GET %s: %v", path, err)
	}
	defer resp.Body.Close()
	raw, _ := io.ReadAll(resp.Body)
	return resp.StatusCode, string(raw)
}

// postRaw is for endpoints like /feed/post/{id}/view that take no body.
func (h *feedHarness) postRaw(path string, out any) {
	h.t.Helper()
	resp, err := http.Post(h.server.URL+path, "application/json", nil)
	if err != nil {
		h.t.Fatalf("POST %s: %v", path, err)
	}
	defer resp.Body.Close()
	if resp.StatusCode >= 400 {
		raw, _ := io.ReadAll(resp.Body)
		h.t.Fatalf("POST %s → %d: %s", path, resp.StatusCode, string(raw))
	}
	if out != nil {
		if err := json.NewDecoder(resp.Body).Decode(out); err != nil {
			h.t.Fatalf("decode %s response: %v", path, err)
		}
	}
}

// ── Tests ─────────────────────────────────────────────────────────────────

// TestE2EFullFlow runs the whole publish → commit → read cycle end-to-end.
//
// Covers: /feed/publish signature, /feed/post/{id} body fetch, /feed/post/{id}/stats,
// /feed/post/{id}/view counter, CREATE_POST fee debit to author + credit to
// hosting relay, PostsByAuthor enrichment, DELETE soft-delete → 410.
func TestE2EFullFlow(t *testing.T) {
	h := newFeedHarness(t)

	alice := h.newUser("alice")
	h.fund(alice, 10*blockchain.Token)

	hostBalBefore, _ := h.chain.Balance(h.validator.PubKeyHex())

	// 1. PUBLISH → body lands in feed mailbox.
	pub := h.publish(alice, "Hello from the feed #dchain #intro", nil)
	if pub.PostID == "" || pub.ContentHash == "" {
		t.Fatalf("publish response missing required fields: %+v", pub)
	}
	if pub.HostingRelay != h.validator.PubKeyHex() {
		t.Errorf("hosting_relay: got %s, want %s", pub.HostingRelay, h.validator.PubKeyHex())
	}
	wantTags := []string{"dchain", "intro"}
	if len(pub.Hashtags) != len(wantTags) {
		t.Errorf("hashtags: got %v, want %v", pub.Hashtags, wantTags)
	}

	// Before the CREATE_POST tx lands the body is available but /stats
	// says 0 likes. That's the expected "just published, not committed" state.

	// 2. COMMIT on-chain CREATE_POST tx.
	h.commitCreatePost(alice, pub)

	// Hosting relay should have been credited tx.Fee.
	hostBalAfter, _ := h.chain.Balance(h.validator.PubKeyHex())
	if hostBalAfter <= hostBalBefore {
		t.Errorf("hosting relay balance did not increase after CREATE_POST: %d → %d",
			hostBalBefore, hostBalAfter)
	}

	// 3. READ via HTTP — body comes back.
	var got struct {
		PostID  string `json:"post_id"`
		Author  string `json:"author"`
		Content string `json:"content"`
	}
	h.getJSON("/feed/post/"+pub.PostID, &got)
	if got.Content != "Hello from the feed #dchain #intro" {
		t.Errorf("content: got %q, want original", got.Content)
	}
	if got.Author != alice.PubKeyHex() {
		t.Errorf("author: got %s, want %s", got.Author, alice.PubKeyHex())
	}

	// 4. VIEW COUNTER increments.
	var viewResp struct {
		Views uint64 `json:"views"`
	}
	for i := 1; i <= 3; i++ {
		h.postRaw("/feed/post/"+pub.PostID+"/view", &viewResp)
		if viewResp.Views != uint64(i) {
			t.Errorf("views #%d: got %d, want %d", i, viewResp.Views, i)
		}
	}

	// 5. STATS aggregate is correct.
	var stats postStatsResponse
	h.getJSON("/feed/post/"+pub.PostID+"/stats", &stats)
	if stats.Views != 3 {
		t.Errorf("stats.views: got %d, want 3", stats.Views)
	}
	if stats.Likes != 0 {
		t.Errorf("stats.likes: got %d, want 0", stats.Likes)
	}

	// 6. AUTHOR listing merges chain record + body + stats.
	var authorResp struct {
		Count int              `json:"count"`
		Posts []feedAuthorItem `json:"posts"`
	}
	h.getJSON("/feed/author/"+alice.PubKeyHex(), &authorResp)
	if authorResp.Count != 1 {
		t.Fatalf("author count: got %d, want 1", authorResp.Count)
	}
	if authorResp.Posts[0].Views != 3 {
		t.Errorf("author post views: got %d, want 3", authorResp.Posts[0].Views)
	}
	if len(authorResp.Posts[0].Hashtags) != 2 {
		t.Errorf("author post hashtags: got %v, want 2", authorResp.Posts[0].Hashtags)
	}

	// 7. DELETE → body stays in mailbox but chain marks deleted → 410 on fetch.
	h.deletePost(alice, pub.PostID)
	status, body := h.getStatus("/feed/post/" + pub.PostID)
	if status != http.StatusGone {
		t.Errorf("GET deleted post: got status %d, want 410; body: %s", status, body)
	}
}

// TestE2ELikeUnlikeAffectsStats: on-chain LIKE_POST updates /stats.
func TestE2ELikeUnlikeAffectsStats(t *testing.T) {
	h := newFeedHarness(t)
	alice := h.newUser("alice")
	bob := h.newUser("bob")
	h.fund(alice, 10*blockchain.Token)
	h.fund(bob, 10*blockchain.Token)

	pub := h.publish(alice, "likeable", nil)
	h.commitCreatePost(alice, pub)

	// Bob likes alice's post.
	h.like(bob, pub.PostID)

	var stats postStatsResponse
	h.getJSON("/feed/post/"+pub.PostID+"/stats?me="+bob.PubKeyHex(), &stats)
	if stats.Likes != 1 {
		t.Errorf("likes after like: got %d, want 1", stats.Likes)
	}
	if stats.LikedByMe == nil || !*stats.LikedByMe {
		t.Errorf("liked_by_me: got %v, want true", stats.LikedByMe)
	}

	// And a non-liker sees liked_by_me=false.
	carol := h.newUser("carol")
	h.getJSON("/feed/post/"+pub.PostID+"/stats?me="+carol.PubKeyHex(), &stats)
	if stats.LikedByMe == nil || *stats.LikedByMe {
		t.Errorf("liked_by_me for carol: got %v, want false", stats.LikedByMe)
	}
}

// TestE2ETimeline: follow graph merges posts newest-first.
func TestE2ETimeline(t *testing.T) {
	h := newFeedHarness(t)
	alice := h.newUser("alice")
	bob := h.newUser("bob")
	carol := h.newUser("carol")
	// Fund everyone.
	for _, u := range []*identity.Identity{alice, bob, carol} {
		h.fund(u, 10*blockchain.Token)
	}

	// Alice follows bob + carol.
	h.follow(alice, bob.PubKeyHex())
	h.follow(alice, carol.PubKeyHex())

	// Bob + carol each publish a post. Sleep 1.1s between so the tx
	// timestamps land in distinct unix seconds — the chain chrono index
	// is second-resolution, not millisecond.
	pubBob := h.publish(bob, "post from bob", nil)
	h.commitCreatePost(bob, pubBob)
	time.Sleep(1100 * time.Millisecond)
	pubCarol := h.publish(carol, "post from carol", nil)
	h.commitCreatePost(carol, pubCarol)

	var tl struct {
		Count int              `json:"count"`
		Posts []feedAuthorItem `json:"posts"`
	}
	h.getJSON("/feed/timeline?follower="+alice.PubKeyHex(), &tl)
	if tl.Count != 2 {
		t.Fatalf("timeline count: got %d, want 2", tl.Count)
	}
	// Newest first — carol was published last, so her post should be [0].
	if tl.Posts[0].PostID != pubCarol.PostID {
		t.Errorf("timeline[0]: got %s, want carol's post %s", tl.Posts[0].PostID, pubCarol.PostID)
	}
	if tl.Posts[1].PostID != pubBob.PostID {
		t.Errorf("timeline[1]: got %s, want bob's post %s", tl.Posts[1].PostID, pubBob.PostID)
	}
}

// TestE2ETrendingRanking: post with more engagement floats to the top.
func TestE2ETrendingRanking(t *testing.T) {
	h := newFeedHarness(t)
	alice := h.newUser("alice")
	bob := h.newUser("bob")
	carol := h.newUser("carol")
	for _, u := range []*identity.Identity{alice, bob, carol} {
		h.fund(u, 10*blockchain.Token)
	}

	lowPost := h.publish(alice, "low-engagement post", nil)
	h.commitCreatePost(alice, lowPost)
	hotPost := h.publish(alice, "hot post", nil)
	h.commitCreatePost(alice, hotPost)

	// Hot post gets 2 likes + 5 views; low post stays at 0.
	h.like(bob, hotPost.PostID)
	h.like(carol, hotPost.PostID)
	var viewResp struct{ Views uint64 }
	for i := 0; i < 5; i++ {
		h.postRaw("/feed/post/"+hotPost.PostID+"/view", &viewResp)
	}

	var tr struct {
		Count int              `json:"count"`
		Posts []feedAuthorItem `json:"posts"`
	}
	h.getJSON("/feed/trending?limit=10", &tr)
	if tr.Count < 2 {
		t.Fatalf("trending: got %d posts, want ≥2", tr.Count)
	}
	// Hot post MUST be first (likes × 3 + views = 11 vs 0).
	if tr.Posts[0].PostID != hotPost.PostID {
		t.Errorf("trending[0]: got %s, want hot post %s", tr.Posts[0].PostID, hotPost.PostID)
	}
}

// TestE2EForYouFilters: recommendations exclude followed authors,
// already-liked posts, and the user's own posts.
func TestE2EForYouFilters(t *testing.T) {
	h := newFeedHarness(t)
	alice := h.newUser("alice")   // asking for recs
	bob := h.newUser("bob")       // alice follows bob → bob's posts excluded
	carol := h.newUser("carol")   // stranger → should surface
	dave := h.newUser("dave")     // post liked by alice → excluded

	for _, u := range []*identity.Identity{alice, bob, carol, dave} {
		h.fund(u, 10*blockchain.Token)
	}

	// Alice follows bob.
	h.follow(alice, bob.PubKeyHex())

	// Each non-alice user publishes a post, plus alice herself.
	postOwn := h.publish(alice, "my own post", nil)
	h.commitCreatePost(alice, postOwn)
	postBob := h.publish(bob, "from bob (followed)", nil)
	h.commitCreatePost(bob, postBob)
	postCarol := h.publish(carol, "from carol (stranger)", nil)
	h.commitCreatePost(carol, postCarol)
	postDave := h.publish(dave, "from dave", nil)
	h.commitCreatePost(dave, postDave)

	// Alice likes dave's post — so it should NOT appear in her ForYou.
	h.like(alice, postDave.PostID)

	var fy struct {
		Count int              `json:"count"`
		Posts []feedAuthorItem `json:"posts"`
	}
	h.getJSON("/feed/foryou?pub="+alice.PubKeyHex()+"&limit=20", &fy)

	// Expected: only carol's post. The others are excluded.
	seen := map[string]bool{}
	for _, p := range fy.Posts {
		seen[p.PostID] = true
	}
	if seen[postOwn.PostID] {
		t.Errorf("ForYou included alice's own post %s", postOwn.PostID)
	}
	if seen[postBob.PostID] {
		t.Errorf("ForYou included followed author bob's post %s", postBob.PostID)
	}
	if seen[postDave.PostID] {
		t.Errorf("ForYou included already-liked post from dave %s", postDave.PostID)
	}
	if !seen[postCarol.PostID] {
		t.Errorf("ForYou missing carol's post %s (should surface)", postCarol.PostID)
	}
}

// TestE2EHashtagSearch: a tag returns only posts that used it.
func TestE2EHashtagSearch(t *testing.T) {
	h := newFeedHarness(t)
	alice := h.newUser("alice")
	h.fund(alice, 10*blockchain.Token)

	goPost := h.publish(alice, "learning #golang today", nil)
	h.commitCreatePost(alice, goPost)
	rustPost := h.publish(alice, "later — #rust", nil)
	h.commitCreatePost(alice, rustPost)
	untagged := h.publish(alice, "no tags", nil)
	h.commitCreatePost(alice, untagged)

	var tag struct {
		Tag   string           `json:"tag"`
		Count int              `json:"count"`
		Posts []feedAuthorItem `json:"posts"`
	}
	h.getJSON("/feed/hashtag/golang", &tag)
	if tag.Count != 1 || tag.Posts[0].PostID != goPost.PostID {
		t.Errorf("hashtag(golang): got %+v, want [%s]", tag, goPost.PostID)
	}
	h.getJSON("/feed/hashtag/rust", &tag)
	if tag.Count != 1 || tag.Posts[0].PostID != rustPost.PostID {
		t.Errorf("hashtag(rust): got %+v, want [%s]", tag, rustPost.PostID)
	}
}

// TestE2EScrubberStripsEXIF: uploaded image with EXIF canary comes back
// without the canary in the stored body. Proves server-side scrub is
// mandatory and working at the HTTP boundary.
func TestE2EScrubberStripsEXIF(t *testing.T) {
	h := newFeedHarness(t)
	alice := h.newUser("alice")
	h.fund(alice, 1*blockchain.Token)

	// Build a JPEG with an injected EXIF segment containing a canary.
	var jpegBuf bytes.Buffer
	img := image.NewRGBA(image.Rect(0, 0, 16, 16))
	for y := 0; y < 16; y++ {
		for x := 0; x < 16; x++ {
			img.Set(x, y, color.RGBA{uint8(x * 16), uint8(y * 16), 100, 255})
		}
	}
	if err := jpeg.Encode(&jpegBuf, img, &jpeg.Options{Quality: 80}); err != nil {
		t.Fatalf("jpeg encode: %v", err)
	}
	withEXIF := injectEXIFSegment(t, jpegBuf.Bytes(),
		"SUPERSECRETGPS-51.5N-0.1W-iPhone-Serial-A1B2C3")

	// Pre-flight: the upload bytes DO contain the canary.
	if !bytes.Contains(withEXIF, []byte("SUPERSECRETGPS")) {
		t.Fatalf("test setup: canary not injected")
	}

	pub := h.publish(alice, "look at this photo", withEXIF)
	if pub.PostID == "" {
		t.Fatalf("publish failed")
	}
	h.commitCreatePost(alice, pub)

	// Fetch the stored body back. The attachment field is the cleaned bytes.
	var fetched struct {
		Attachment string `json:"attachment"` // base64
	}
	h.getJSON("/feed/post/"+pub.PostID, &fetched)
	if fetched.Attachment == "" {
		t.Fatalf("attachment not returned")
	}
	decoded, err := base64.StdEncoding.DecodeString(fetched.Attachment)
	if err != nil {
		t.Fatalf("decode attachment: %v", err)
	}
	if bytes.Contains(decoded, []byte("SUPERSECRETGPS")) {
		t.Errorf("CRITICAL: EXIF canary survived server-side scrub — metadata leaked")
	}
	// Sanity: still a valid JPEG after scrub.
	if _, err := jpeg.Decode(bytes.NewReader(decoded)); err != nil {
		t.Errorf("scrubbed attachment is not a valid JPEG: %v", err)
	}
}

// TestE2ERejectsMIMEMismatch: claimed MIME vs magic bytes.
func TestE2ERejectsMIMEMismatch(t *testing.T) {
	h := newFeedHarness(t)
	alice := h.newUser("alice")
	h.fund(alice, 1*blockchain.Token)

	// Build a PNG but claim it's a JPEG.
	fake := []byte{0x89, 'P', 'N', 'G', '\r', '\n', 0x1a, '\n',
		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}
	ts := time.Now().Unix()
	postID := "mimecheck"
	hash := sha256.Sum256(append([]byte("mislabel"), fake...))
	sig := alice.Sign([]byte(fmt.Sprintf("publish:%s:%s:%d",
		postID, hex.EncodeToString(hash[:]), ts)))
	req := feedPublishRequest{
		PostID:         postID,
		Author:         alice.PubKeyHex(),
		Content:        "mislabel",
		AttachmentB64:  base64.StdEncoding.EncodeToString(fake),
		AttachmentMIME: "image/jpeg", // LIE — it's PNG magic
		Sig:            base64.StdEncoding.EncodeToString(sig),
		Ts:             ts,
	}
	h.postJSONExpectStatus("/feed/publish", req, http.StatusBadRequest)
}

// TestE2ERejectsBadSignature: wrong signer cannot publish.
func TestE2ERejectsBadSignature(t *testing.T) {
	h := newFeedHarness(t)
	alice := h.newUser("alice")
	eve := h.newUser("eve")
	h.fund(alice, 1*blockchain.Token)
	h.fund(eve, 1*blockchain.Token)

	ts := time.Now().Unix()
	postID := "forgery"
	hash := sha256.Sum256([]byte("evil"))
	// Eve signs over data but claims to be alice.
	sig := eve.Sign([]byte(fmt.Sprintf("publish:%s:%s:%d",
		postID, hex.EncodeToString(hash[:]), ts)))
	req := feedPublishRequest{
		PostID:  postID,
		Author:  alice.PubKeyHex(), // claim alice
		Content: "evil",
		Sig:     base64.StdEncoding.EncodeToString(sig),
		Ts:      ts,
	}
	h.postJSONExpectStatus("/feed/publish", req, http.StatusForbidden)
}

// TestE2ERejectsStaleTimestamp: publish with ts way in the past must be rejected.
func TestE2ERejectsStaleTimestamp(t *testing.T) {
	h := newFeedHarness(t)
	alice := h.newUser("alice")
	h.fund(alice, 1*blockchain.Token)

	ts := time.Now().Add(-1 * time.Hour).Unix() // 1 hour stale
	postID := "stale"
	hash := sha256.Sum256([]byte("old"))
	sig := alice.Sign([]byte(fmt.Sprintf("publish:%s:%s:%d",
		postID, hex.EncodeToString(hash[:]), ts)))
	req := feedPublishRequest{
		PostID:  postID,
		Author:  alice.PubKeyHex(),
		Content: "old",
		Sig:     base64.StdEncoding.EncodeToString(sig),
		Ts:      ts,
	}
	h.postJSONExpectStatus("/feed/publish", req, http.StatusBadRequest)
}

// injectEXIFSegment splices an APP1 EXIF segment with the given canary
// string into a JPEG. Mirrors media/scrub_test.go but local to keep the
// integration test self-contained.
func injectEXIFSegment(t *testing.T, src []byte, canary string) []byte {
	t.Helper()
	if len(src) < 2 || src[0] != 0xFF || src[1] != 0xD8 {
		t.Fatalf("not a JPEG")
	}
	payload := []byte("Exif\x00\x00" + canary)
	segLen := len(payload) + 2
	out := make([]byte, 0, len(src)+segLen+4)
	out = append(out, src[0], src[1]) // SOI
	out = append(out, 0xFF, 0xE1, byte(segLen>>8), byte(segLen&0xff))
	out = append(out, payload...)
	out = append(out, src[2:]...)
	return out
}

// Silence unused-import lint if strings gets trimmed by refactor.
var _ = strings.TrimSpace
var _ = context.TODO