package main

import (
	"crypto/sha256"
	"fmt"
	"net/http"
	"net/http/httptest"
	"net/url"
	"os"
	"os/exec"
	"path/filepath"
	"regexp"
	"strings"
	"testing"
	"time"
)

func logLines(lines ...string) string { return strings.Join(lines, "\n") + "\n" }

const (
	noteA = `{"time":"2026-07-20T10:00:00Z","op":"note","session":"s1","agent":"codex","model":"gpt-5.6-sol","reasoning":"max","dir":"/repo","change":"aaa","file":"src/lib.rs","start":10,"end":20,"note_id":1,"type":"struct","text":"Cache is a two-level map"}`
	noteB = `{"time":"2026-07-25T10:00:00Z","op":"note","session":"s2","agent":"claude","model":"claude-fable-5","reasoning":"xhigh","dir":"/repo","change":"aaa","file":"src/main.rs","note_id":1,"text":"entry point does too much"}`
	readA = `{"time":"2026-07-20T09:59:00Z","op":"read","session":"s1","agent":"codex","model":"gpt-5.6-sol","dir":"/repo","change":"aaa","file":"src/lib.rs","start":1,"end":30}`
	grepA = `{"time":"2026-07-20T09:58:00Z","op":"grep","session":"s1","agent":"codex","dir":"/repo","change":"aaa","file":"src/lib.rs","pattern":"Cache","matches":3}`
)

func testSite(t *testing.T) *Site {
	t.Helper()
	s := buildModel("test", parseLog([]byte(logLines(grepA, readA, noteA, noteB))), "")
	s.Theme, s.Light = loadTheme("", "", "dark"), loadTheme("", "", "light")
	return s
}

func TestBuildModel(t *testing.T) {
	s := testSite(t)
	if s.Change != "aaa" {
		t.Errorf("site change = %q, want aaa", s.Change)
	}
	if len(s.Agents) != 2 || s.Agents[0].Bit != 1 || s.Agents[1].Bit != 2 {
		t.Errorf("agents = %+v", s.Agents)
	}
	f := s.Files["src/lib.rs"]
	if f == nil || f.Reads != 1 || f.Greps != 1 || len(f.Notes) != 1 {
		t.Fatalf("src/lib.rs = %+v", f)
	}
	if f.Cov[15] != 1 || f.Mask != 1 {
		t.Errorf("coverage = %v mask %d", f.Cov, f.Mask)
	}
	if got := s.Notes[0].When; got == "" {
		t.Error("note has no rendered timestamp")
	}
}

// A ninth agent gets no color instead of overflowing the uint8 mask (and the
// per-mask CSS it would generate).
func TestAgentColorsAreBounded(t *testing.T) {
	var lines []string
	for i := 0; i < maxAgents+3; i++ {
		lines = append(lines, `{"time":"2026-07-20T10:00:00Z","op":"note","agent":"a`+string(rune('a'+i))+`","change":"aaa","note_id":1,"text":"x"}`)
	}
	s := buildModel("t", parseLog([]byte(logLines(lines...))), "")
	if len(s.Agents) != maxAgents+3 {
		t.Fatalf("agents = %d", len(s.Agents))
	}
	for i, a := range s.Agents {
		if i < maxAgents && a.Bit == 0 {
			t.Errorf("agent %d has no bit", i)
		}
		if i >= maxAgents && a.Bit != 0 {
			t.Errorf("agent %d got bit %d, want none", i, a.Bit)
		}
	}
	if n := len(s.masks()); n != 1<<maxAgents-1 {
		t.Errorf("masks = %d, want %d", n, 1<<maxAgents-1)
	}
}

// A view of one change holds only what was recorded there — but note ids stay
// positional over the whole log, so links survive the scope changing.
func TestModelScopedToAChange(t *testing.T) {
	otherChange := `{"time":"2026-07-26T10:00:00Z","op":"note","session":"s3","agent":"codex","dir":"/repo","change":"bbb","file":"src/lib.rs","start":5,"end":6,"note_id":1,"text":"at another change"}`
	otherRead := `{"time":"2026-07-26T09:00:00Z","op":"read","session":"s3","agent":"codex","dir":"/repo","change":"bbb","file":"src/other.rs","start":1,"end":9}`
	entries := parseLog([]byte(logLines(grepA, readA, noteA, noteB, otherRead, otherChange)))

	all := buildModel("t", entries, "")
	if len(all.Notes) != 3 || all.NotesTotal != 3 {
		t.Fatalf("unscoped notes = %d of %d", len(all.Notes), all.NotesTotal)
	}
	if all.Change != "aaa" || all.Votes["aaa"] != 4 || all.Votes["bbb"] != 2 {
		t.Errorf("change %q votes %v", all.Change, all.Votes)
	}
	if strings.Join(all.Ranked, ",") != "aaa,bbb" {
		t.Errorf("ranked = %v, want the most-logged change first", all.Ranked)
	}

	one := buildModel("t", entries, "aaa")
	if len(one.Notes) != 2 {
		t.Fatalf("scoped notes = %d, want the two at aaa", len(one.Notes))
	}
	if one.NotesTotal != 3 || one.NotesAt["aaa"] != 2 || one.NotesAt["bbb"] != 1 {
		t.Errorf("a scoped view must still know the whole log: %d %v", one.NotesTotal, one.NotesAt)
	}
	if _, ok := one.Files["src/other.rs"]; ok {
		t.Error("a file only read at another change leaked into the view")
	}
	// the read at bbb covered lines 1-9 of another file; lib.rs keeps only aaa's
	if f := one.Files["src/lib.rs"]; f == nil || f.Reads != 1 || len(f.Notes) != 1 {
		t.Errorf("src/lib.rs at aaa = %+v", f)
	}
	// ids are the note's position in the log, the same in both views
	ids := map[string]int{}
	for _, n := range all.Notes {
		ids[n.Text] = n.ID
	}
	for _, n := range one.Notes {
		if ids[n.Text] != n.ID {
			t.Errorf("note %q is id %d scoped, %d unscoped", n.Text, n.ID, ids[n.Text])
		}
	}
	// agent colors come from the whole log, so they do not shuffle when the
	// scope narrows
	if len(one.Agents) != len(all.Agents) {
		t.Errorf("agents = %d scoped, %d unscoped", len(one.Agents), len(all.Agents))
	}
	for i := range all.Agents {
		if one.Agents[i].Name != all.Agents[i].Name || one.Agents[i].Bit != all.Agents[i].Bit {
			t.Errorf("agent %d differs: %+v vs %+v", i, one.Agents[i], all.Agents[i])
		}
	}
}

func TestFilterNotes(t *testing.T) {
	s := testSite(t)
	for _, tc := range []struct {
		name string
		f    NoteFilter
		want []string
	}{
		{"all", NoteFilter{}, []string{"src/main.rs", "src/lib.rs"}}, // newest first
		{"text", NoteFilter{Text: "two-level"}, []string{"src/lib.rs"}},
		{"text is case-insensitive", NoteFilter{Text: "CACHE"}, []string{"src/lib.rs"}},
		{"file substring", NoteFilter{File: "main"}, []string{"src/main.rs"}},
		{"agent", NoteFilter{Agent: "claude"}, []string{"src/main.rs"}},
		{"model", NoteFilter{Model: "gpt-5.6-sol"}, []string{"src/lib.rs"}},
		{"session", NoteFilter{Session: "s2"}, []string{"src/main.rs"}},
		{"kind", NoteFilter{Kind: "struct"}, []string{"src/lib.rs"}},
		{"from", NoteFilter{From: "2026-07-21"}, []string{"src/main.rs"}},
		{"to", NoteFilter{To: "2026-07-21"}, []string{"src/lib.rs"}},
		{"range", NoteFilter{From: "2026-07-19", To: "2026-07-26"}, []string{"src/main.rs", "src/lib.rs"}},
		{"combined", NoteFilter{Agent: "codex", Text: "map"}, []string{"src/lib.rs"}},
		{"no match", NoteFilter{Agent: "codex", Text: "nothing"}, nil},
	} {
		t.Run(tc.name, func(t *testing.T) {
			var got []string
			for _, n := range s.FilterNotes(tc.f) {
				got = append(got, n.File)
			}
			if strings.Join(got, ",") != strings.Join(tc.want, ",") {
				t.Errorf("got %v, want %v", got, tc.want)
			}
		})
	}
}

func TestFacetsAreDistinctAndSorted(t *testing.T) {
	fa := testSite(t).Facets()
	if strings.Join(fa.Agents, ",") != "claude,codex" {
		t.Errorf("agents = %v", fa.Agents)
	}
	if strings.Join(fa.Kinds, ",") != "struct" {
		t.Errorf("kinds = %v", fa.Kinds)
	}
	if strings.Join(fa.Sessions, ",") != "s1,s2" {
		t.Errorf("sessions = %v", fa.Sessions)
	}
}

func TestSessionsReportWhatIsRunning(t *testing.T) {
	now := time.Date(2026, 7, 25, 10, 1, 0, 0, time.UTC)
	ss := testSite(t).Sessions(now, liveWindow, 10)
	if len(ss) != 2 {
		t.Fatalf("sessions = %d", len(ss))
	}
	if ss[0].ID != "s2" || !ss[0].Live {
		t.Errorf("newest session = %+v, want s2 live", ss[0])
	}
	if ss[1].ID != "s1" || ss[1].Live {
		t.Errorf("older session = %+v, want s1 not live", ss[1])
	}
	if ss[1].LastOp != "note on src/lib.rs" || ss[1].Reads != 1 || ss[1].Greps != 1 {
		t.Errorf("s1 activity = %q %d/%d", ss[1].LastOp, ss[1].Reads, ss[1].Greps)
	}
}

func TestNextNoteIDCountsPerSession(t *testing.T) {
	entries := parseLog([]byte(logLines(noteA, noteB)))
	if got := nextNoteID(entries, "s1"); got != 2 {
		t.Errorf("s1 next = %d, want 2", got)
	}
	if got := nextNoteID(entries, "web:me"); got != 1 {
		t.Errorf("fresh session next = %d, want 1", got)
	}
}

// The graph art in front of a templated row must not end up inside a field.
func TestParseRows(t *testing.T) {
	out := "@  \x1eabc123\x1fabc1\x1fdef456\x1fdef4\x1fme@x\x1f2026-07-20 10:00\x1fmain\x1fworking copy\x1ffix the thing\n" +
		"│\n" +
		"~\n"
	rows := parseRows([]byte(out), false)
	if len(rows) != 3 {
		t.Fatalf("rows = %d", len(rows))
	}
	r := rows[0]
	if r.Graph != "@  " || r.ID != "abc123" || r.Short != "abc1" || r.CommitShort != "def4" ||
		r.Author != "me@x" || r.Refs != "main" || r.Flags != "working copy" || r.Desc != "fix the thing" {
		t.Errorf("row = %+v", r)
	}
	if !rows[1].Blank() || rows[1].Graph != "│" {
		t.Errorf("graph-only row = %+v", rows[1])
	}
	op := parseRows([]byte("@  \x1eopid\x1fopid1\x1f\x1f\x1fme@host\x1f2026-07-20 10:00:00\x1f\x1f10:00:05\x1fsnapshot\n"), true)
	if len(op) != 1 || op[0].End != "10:00:05" || op[0].Flags != "" || op[0].Desc != "snapshot" {
		t.Errorf("op row = %+v", op)
	}
}

func TestCheckRevsetRejectsFlags(t *testing.T) {
	if err := checkRevset("--config=x"); err == nil {
		t.Error("a leading dash must be refused, jj would read it as a flag")
	}
	if err := checkRevset("all() & file(x)"); err != nil {
		t.Errorf("plain revset refused: %v", err)
	}
}

func TestHrefModes(t *testing.T) {
	live := &page{Live: true, Root: "/"}
	if got := live.Href("code", "src/a b.rs"); got != "/code/src/a%20b.rs" {
		t.Errorf("live code href = %q", got)
	}
	live.Rev = "xyz"
	if got := live.Href("code", "src/a.rs"); got != "/code/src/a.rs?rev=xyz" {
		t.Errorf("live code href with rev = %q", got)
	}
	// notes are read against a change too, so the link keeps it
	if got := live.Href("notes"); got != "/notes?rev=xyz" {
		t.Errorf("live notes href = %q", got)
	}
	// "@" is a revset like any other; dropping it would slide the reader back
	// to the change the log points at
	if got := (&page{Live: true, Root: "/", Rev: "@"}).Href("files"); got != "/files?rev=%40" {
		t.Errorf("href browsing @ = %q", got)
	}
	wide := &page{Live: true, Root: "/", Kind: "file", Rev: "xyz", Scope: "all", Path: "/code/a.rs"}
	if got := wide.Href("files"); got != "/files?rev=xyz&scope=all" {
		t.Errorf("wide files href = %q", got)
	}
	if got := wide.ScopeHref("change"); got != "/code/a.rs?rev=xyz" {
		t.Errorf("narrowing href = %q", got)
	}
	if got := wide.BackHref(); got != "/code/a.rs?scope=all" {
		t.Errorf("back href = %q", got)
	}
	if got := (&page{Live: true, Kind: "change", Path: "/change/abc"}).JumpPath(); got != "/files" {
		t.Errorf("jump path from a change page = %q", got)
	}
	static := &page{Root: "../"}
	if got := static.Href("code", "src/a.rs"); got != "../code/src/a.rs.html" {
		t.Errorf("static code href = %q", got)
	}
	// a note link carries the note itself, so the page can open focused on it
	n := &Note{ID: 7, File: "src/a.rs", Start: 12, End: 20}
	if got := (&page{Live: true, Root: "/"}).NoteHref(n); got != "/code/src/a.rs?note=7#L12" {
		t.Errorf("live note href = %q", got)
	}
	if got := (&page{Live: true, Root: "/", Rev: "xyz"}).NoteHref(n); got != "/code/src/a.rs?rev=xyz&note=7#L12" {
		t.Errorf("note href at a revision = %q", got)
	}
	if got := static.NoteHref(n); got != "../code/src/a.rs.html?note=7#L12" {
		t.Errorf("static note href = %q", got)
	}
	if got := static.Href("change", "abc"); got != "" {
		t.Errorf("static change href = %q, want none", got)
	}
}

// ── the web app, end to end ───────────────────────────────────────────────

// testRepo makes a one-commit jj repo and returns its path plus the change id.
func testRepo(t *testing.T) (string, string) {
	t.Helper()
	if _, err := exec.LookPath("jj"); err != nil {
		t.Skip("jj not installed")
	}
	dir := t.TempDir()
	env := append(os.Environ(), "JJ_USER=test", "JJ_EMAIL=test@example.com", "HOME="+dir)
	runJJ := func(args ...string) {
		t.Helper()
		cmd := exec.Command("jj", args...)
		cmd.Dir, cmd.Env = dir, env
		if out, err := cmd.CombinedOutput(); err != nil {
			t.Fatalf("jj %s: %v\n%s", strings.Join(args, " "), err, out)
		}
	}
	runJJ("git", "init")
	if err := os.WriteFile(filepath.Join(dir, "hello.txt"), []byte("one\ntwo\nthree\n"), 0o644); err != nil {
		t.Fatal(err)
	}
	runJJ("describe", "-m", "first change")
	change, err := resolveChange(dir, "@")
	if err != nil {
		t.Fatal(err)
	}
	return dir, change
}

func testServer(t *testing.T) (*server, string, string) {
	t.Helper()
	repo, change := testRepo(t)
	logPath := filepath.Join(t.TempDir(), "trace.jsonl")
	entry := `{"time":"2026-07-20T10:00:00Z","op":"read","session":"s1","agent":"codex","model":"gpt-5.6-sol","dir":"` +
		repo + `","change":"` + change + `","file":"hello.txt","start":1,"end":2}`
	note := `{"time":"2026-07-20T10:01:00Z","op":"note","session":"s1","agent":"codex","model":"gpt-5.6-sol","dir":"` +
		repo + `","change":"` + change + `","file":"hello.txt","start":2,"end":2,"note_id":1,"text":"second line matters"}`
	if err := os.WriteFile(logPath, []byte(logLines(entry, note)), 0o644); err != nil {
		t.Fatal(err)
	}
	sv := newServer(logPath, repo, "test", "tester", loadTheme("", "", "dark"), loadTheme("", "", "light"))
	return sv, logPath, change
}

func get(t *testing.T, h http.Handler, path string, hx bool) *httptest.ResponseRecorder {
	t.Helper()
	r := httptest.NewRequest("GET", path, nil)
	if hx {
		r.Header.Set("HX-Request", "true")
	}
	w := httptest.NewRecorder()
	h.ServeHTTP(w, r)
	return w
}

func TestServerPages(t *testing.T) {
	sv, _, change := testServer(t)
	h := sv.handler()
	for _, tc := range []struct{ path, want string }{
		{"/", "second line matters"},
		{"/files", "hello.txt"},
		{"/tree", `class="file`},
		{"/notes", "second line matters"},
		{"/code/hello.txt", "three"},
		{"/jj", "revset"},
		{"/change/" + change, "first change"},
		{"/style.css", "--am1"},
		{"/app.js", "vrsite-mode"},
		{"/htmx.min.js", "htmx"},
	} {
		w := get(t, h, tc.path, false)
		if w.Code != 200 {
			t.Errorf("GET %s = %d", tc.path, w.Code)
			continue
		}
		if !strings.Contains(w.Body.String(), tc.want) {
			t.Errorf("GET %s does not mention %q", tc.path, tc.want)
		}
	}
}

// The current change is on every page, and the view follows it.
func TestCurrentChangeRunsTheView(t *testing.T) {
	sv, logPath, change := testServer(t)

	// a second change with nothing recorded at it
	empty := filepath.Join(sv.repo, "later.txt")
	if err := os.WriteFile(empty, []byte("later\n"), 0o644); err != nil {
		t.Fatal(err)
	}
	cmd := exec.Command("jj", "new", "-m", "a later change")
	cmd.Dir, cmd.Env = sv.repo, append(os.Environ(), "JJ_USER=test", "JJ_EMAIL=test@example.com", "HOME="+sv.repo)
	if out, err := cmd.CombinedOutput(); err != nil {
		t.Fatalf("jj new: %v\n%s", err, out)
	}
	later, err := resolveChange(sv.repo, "@")
	if err != nil {
		t.Fatal(err)
	}
	h := sv.handler()

	// the default page is the change the log points at, scoped to it
	body := get(t, h, "/", false).Body.String()
	for _, want := range []string{short(change), "notes here", `class="changebar`} {
		if !strings.Contains(body, want) {
			t.Errorf("the index does not show the current change (%q missing)", want)
		}
	}
	if !strings.Contains(body, "second line matters") {
		t.Error("the note recorded at this change is missing")
	}

	// browsing a change nothing was recorded at must not look empty: it says so
	// and falls back to the whole log
	body = get(t, h, "/?rev="+later, false).Body.String()
	if !strings.Contains(body, "nothing recorded at this change") {
		t.Errorf("no explanation for an empty change:\n%s", body[:min(len(body), 900)])
	}
	if !strings.Contains(body, "second line matters") {
		t.Error("the fallback should show the whole log, not nothing")
	}

	// a note written from a page at that change is recorded there
	form := url.Values{"text": {"written at the later change"}, "rev": {later}}
	r := httptest.NewRequest("POST", "/notes", strings.NewReader(form.Encode()))
	r.Header.Set("Content-Type", "application/x-www-form-urlencoded")
	w := httptest.NewRecorder()
	h.ServeHTTP(w, r)
	if w.Code != http.StatusSeeOther {
		t.Fatalf("POST /notes = %d", w.Code)
	}
	entries := parseLog(mustRead(t, logPath))
	if last := entries[len(entries)-1]; last.Change != later {
		t.Errorf("note recorded at %q, want the change being browsed %q", last.Change, later)
	}

	// a note written with no change named lands on the one the log points at,
	// not on the working copy, which has moved on
	form = url.Values{"text": {"written with nothing named"}}
	r = httptest.NewRequest("POST", "/notes", strings.NewReader(form.Encode()))
	r.Header.Set("Content-Type", "application/x-www-form-urlencoded")
	w = httptest.NewRecorder()
	h.ServeHTTP(w, r)
	entries = parseLog(mustRead(t, logPath))
	if last := entries[len(entries)-1]; last.Change != change {
		t.Errorf("unaimed note recorded at %q, want the log's change %q", last.Change, change)
	}

	// now that change has a note, scoping to it shows that one alone
	body = get(t, h, "/notes?rev="+later, false).Body.String()
	if strings.Contains(body, "second line matters") {
		t.Error("a note from another change leaked into the scoped view")
	}
	if !strings.Contains(body, "written at the later change") {
		t.Error("the note recorded here is missing")
	}
	// and the wide view has both, with the other change's note marked
	body = get(t, h, "/notes?rev="+later+"&scope=all", false).Body.String()
	if !strings.Contains(body, "second line matters") || !strings.Contains(body, "written at the later change") {
		t.Error("scope=all must show every change's notes")
	}
	if !strings.Contains(body, "note am1 away") && !strings.Contains(body, "away") {
		t.Error("a note from another change is not marked as such")
	}
	// links keep both the change and the scope
	if !strings.Contains(body, "rev="+later+"&amp;scope=all") {
		t.Error("links drop the change or the scope")
	}
}

func mustRead(t *testing.T, path string) []byte {
	t.Helper()
	b, err := os.ReadFile(path)
	if err != nil {
		t.Fatal(err)
	}
	return b
}

// ── the server keeps nothing of its own ───────────────────────────────────
//
// Every byte it writes goes to the log; everything it holds in memory is a
// cache of the log and the repo, so a restart changes nothing and a repo that
// moves underneath it is followed, not remembered.

func repoState(t *testing.T, repo string) string {
	t.Helper()
	sum := sha256.New()
	err := filepath.WalkDir(repo, func(path string, d os.DirEntry, err error) error {
		if err != nil {
			return err
		}
		name := d.Name()
		if d.IsDir() {
			if name == ".jj" || name == ".git" {
				return filepath.SkipDir // caches and mtimes of their own
			}
			return nil
		}
		b, err := os.ReadFile(path)
		if err != nil {
			return err
		}
		fmt.Fprintf(sum, "%s %x\n", path, sha256.Sum256(b))
		return nil
	})
	if err != nil {
		t.Fatal(err)
	}
	// the operation log head: proof we never asked jj to do anything
	op, err := jjRun(repo, "op", "log", "-n", "1", "--no-graph", "-T", "id")
	if err != nil {
		t.Fatal(err)
	}
	return fmt.Sprintf("%x %s", sum.Sum(nil), op)
}

func TestServerWritesOnlyTheLog(t *testing.T) {
	sv, logPath, change := testServer(t)
	h := sv.handler()
	before := repoState(t, sv.repo)
	logBefore := len(mustRead(t, logPath))

	for _, path := range []string{"/", "/files", "/notes", "/code/hello.txt", "/tree",
		"/jj?revset=all()", "/jj?kind=op", "/change/" + change, "/activity", "/style.css"} {
		if w := get(t, h, path, false); w.Code != 200 {
			t.Errorf("GET %s = %d", path, w.Code)
		}
	}
	form := url.Values{"text": {"a note from the browser"}, "file": {"hello.txt"}, "change": {change}}
	r := httptest.NewRequest("POST", "/notes", strings.NewReader(form.Encode()))
	r.Header.Set("Content-Type", "application/x-www-form-urlencoded")
	h.ServeHTTP(httptest.NewRecorder(), r)

	if after := repoState(t, sv.repo); after != before {
		t.Errorf("the repository changed:\n%s\n%s", before, after)
	}
	if len(mustRead(t, logPath)) <= logBefore {
		t.Error("the note did not reach the log")
	}
	// nothing else appeared next to the log either
	dir := filepath.Dir(logPath)
	names, err := os.ReadDir(dir)
	if err != nil {
		t.Fatal(err)
	}
	if len(names) != 1 || filepath.Join(dir, names[0].Name()) != logPath {
		var got []string
		for _, n := range names {
			got = append(got, n.Name())
		}
		t.Errorf("the server left files of its own: %v", got)
	}
}

var agoRe = regexp.MustCompile(`\d+[smhd] ago|just now`)

func TestServerHoldsNoStateOfItsOwn(t *testing.T) {
	sv, logPath, change := testServer(t)
	h := sv.handler()
	form := url.Values{"text": {"written before the restart"}, "file": {"hello.txt"},
		"start": {"2"}, "change": {change}}
	r := httptest.NewRequest("POST", "/notes", strings.NewReader(form.Encode()))
	r.Header.Set("Content-Type", "application/x-www-form-urlencoded")
	h.ServeHTTP(httptest.NewRecorder(), r)

	// a second server that has only ever seen the log file
	fresh := newServer(logPath, sv.repo, "test", "tester", sv.theme, sv.light).handler()
	for _, path := range []string{"/", "/notes", "/notes?scope=all", "/code/hello.txt",
		"/files", "/tree", "/change/" + change} {
		was := agoRe.ReplaceAllString(get(t, h, path, false).Body.String(), "AGO")
		is := agoRe.ReplaceAllString(get(t, fresh, path, false).Body.String(), "AGO")
		if was != is {
			t.Errorf("GET %s differs after a restart — the server is holding state the log does not", path)
		}
	}
}

// A change id is a pointer: editing files rewrites the commit under it. Pages
// must follow the content, not a cached snapshot of it.
func TestPagesFollowTheRepo(t *testing.T) {
	sv, _, _ := testServer(t)
	h := sv.handler()
	if body := get(t, h, "/code/hello.txt", false).Body.String(); !strings.Contains(body, "three") {
		t.Fatalf("the file did not render:\n%s", body[:min(len(body), 400)])
	}
	if err := os.WriteFile(filepath.Join(sv.repo, "hello.txt"), []byte("one\ntwo\nrewritten\n"), 0o644); err != nil {
		t.Fatal(err)
	}
	// someone else's jj command snapshots it: same change, new commit
	cmd := exec.Command("jj", "status")
	cmd.Dir, cmd.Env = sv.repo, append(os.Environ(), "JJ_USER=test", "JJ_EMAIL=test@example.com", "HOME="+sv.repo)
	if out, err := cmd.CombinedOutput(); err != nil {
		t.Fatalf("jj status: %v\n%s", err, out)
	}
	body := get(t, h, "/code/hello.txt", false).Body.String()
	if !strings.Contains(body, "rewritten") {
		t.Error("the page still shows the content the change had when it was first read")
	}
	if strings.Contains(body, "three") {
		t.Error("the old content is still on the page")
	}
}

func TestNotesFilterOverHTTP(t *testing.T) {
	sv, _, _ := testServer(t)
	h := sv.handler()
	if b := get(t, h, "/notes/list?text=second", true).Body.String(); !strings.Contains(b, "second line matters") {
		t.Error("matching filter dropped the note")
	}
	b := get(t, h, "/notes/list?text=absent", true).Body.String()
	if strings.Contains(b, "second line matters") || !strings.Contains(b, "no notes match") {
		t.Errorf("non-matching filter kept the note: %s", b)
	}
	if !strings.Contains(b, `id="notecount" hx-swap-oob`) {
		t.Error("list fragment does not carry the out-of-band count")
	}
}

// A comment posted from the browser lands in the log, shows up in the model,
// and leaves the repository alone.
func TestAddNoteAppendsToLog(t *testing.T) {
	sv, logPath, change := testServer(t)
	h := sv.handler()
	before, err := jjRun(sv.repo, "status")
	if err != nil {
		t.Fatal(err)
	}

	form := url.Values{"file": {"hello.txt"}, "start": {"3"}, "end": {"3"},
		"kind": {"line"}, "text": {"written from the browser"}, "rev": {"@"}}
	r := httptest.NewRequest("POST", "/notes", strings.NewReader(form.Encode()))
	r.Header.Set("Content-Type", "application/x-www-form-urlencoded")
	r.Header.Set("HX-Request", "true")
	w := httptest.NewRecorder()
	h.ServeHTTP(w, r)
	if w.Code != 200 {
		t.Fatalf("POST /notes = %d: %s", w.Code, w.Body)
	}
	if !strings.Contains(w.Body.String(), "written from the browser") {
		t.Errorf("response does not contain the new note: %s", w.Body)
	}

	b, err := os.ReadFile(logPath)
	if err != nil {
		t.Fatal(err)
	}
	entries := parseLog(b)
	last := entries[len(entries)-1]
	if last.Op != "note" || last.Agent != "tester" || last.Session != "web:tester" ||
		last.File != "hello.txt" || last.Start != 3 || last.Text != "written from the browser" {
		t.Errorf("appended entry = %+v", last)
	}
	if last.Change != change {
		t.Errorf("note change = %q, want %q", last.Change, change)
	}
	if last.NoteID != 1 {
		t.Errorf("note id = %d, want 1 (first of this session)", last.NoteID)
	}
	if last.Time == "" {
		t.Error("appended entry has no timestamp")
	}

	// visible without a restart, and the line is now marked as noted
	if body := get(t, h, "/code/hello.txt", false).Body.String(); !strings.Contains(body, "written from the browser") {
		t.Error("the new note is not on the file page")
	}
	after, err := jjRun(sv.repo, "status")
	if err != nil {
		t.Fatal(err)
	}
	if string(before) != string(after) {
		t.Errorf("the repository changed:\nbefore %s\nafter %s", before, after)
	}
}

func TestAddNoteRejectsCrossOriginAndEmptyText(t *testing.T) {
	sv, _, _ := testServer(t)
	h := sv.handler()

	form := url.Values{"text": {"hi"}, "rev": {"@"}}
	r := httptest.NewRequest("POST", "/notes", strings.NewReader(form.Encode()))
	r.Header.Set("Content-Type", "application/x-www-form-urlencoded")
	r.Header.Set("Origin", "http://evil.example")
	w := httptest.NewRecorder()
	h.ServeHTTP(w, r)
	if w.Code != http.StatusForbidden {
		t.Errorf("cross-origin POST = %d, want 403", w.Code)
	}

	r = httptest.NewRequest("POST", "/notes", strings.NewReader(url.Values{"text": {"  "}}.Encode()))
	r.Header.Set("Content-Type", "application/x-www-form-urlencoded")
	w = httptest.NewRecorder()
	h.ServeHTTP(w, r)
	if w.Code != http.StatusBadRequest {
		t.Errorf("empty note = %d, want 400", w.Code)
	}
}

func TestJJQueries(t *testing.T) {
	sv, _, change := testServer(t)
	h := sv.handler()

	b := get(t, h, "/jj/log?revset="+url.QueryEscape("all()"), true).Body.String()
	if !strings.Contains(b, `href="/change/`+change) {
		t.Errorf("jj log has no link to the change: %s", b)
	}
	if !strings.Contains(b, "first change") {
		t.Error("jj log does not show the description")
	}
	b = get(t, h, "/jj/op?limit=5", true).Body.String()
	if !strings.Contains(b, "at_op=") {
		t.Errorf("op log has no --at-operation links: %s", b)
	}
	b = get(t, h, "/jj/log?revset="+url.QueryEscape("bogusfn(")+"", true).Body.String()
	if !strings.Contains(b, `class="err"`) {
		t.Errorf("a bad revset should report jj's error: %s", b)
	}
	b = get(t, h, "/jj/log?revset="+url.QueryEscape("--config=ui.paginate=never"), true).Body.String()
	if !strings.Contains(b, "must not start with") {
		t.Errorf("flag-like revset was not refused: %s", b)
	}
}

// Model files are shared across requests and cloned per render; run the
// handlers hard in parallel so -race can complain about it.
func TestConcurrentRequests(t *testing.T) {
	sv, _, change := testServer(t)
	h := sv.handler()
	paths := []string{"/", "/code/hello.txt", "/notes", "/notes/list?text=second",
		"/tree", "/files", "/activity?compact=1", "/change/" + change,
		"/code/hello.txt?rev=" + change}
	done := make(chan struct{})
	for i := 0; i < len(paths)*3; i++ {
		go func(p string) {
			defer func() { done <- struct{}{} }()
			if w := get(t, h, p, false); w.Code != 200 {
				t.Errorf("GET %s = %d", p, w.Code)
			}
		}(paths[i%len(paths)])
	}
	for i := 0; i < len(paths)*3; i++ {
		<-done
	}
}

func TestCodePageAtMissingRevision(t *testing.T) {
	sv, _, _ := testServer(t)
	w := get(t, sv.handler(), "/code/nope.txt", false)
	if w.Code != 200 || !strings.Contains(w.Body.String(), "not present at this change") {
		t.Errorf("missing file = %d: %s", w.Code, w.Body)
	}
}

func TestServerPicksUpLogAppendsFromOtherProcesses(t *testing.T) {
	sv, logPath, change := testServer(t)
	h := sv.handler()
	if strings.Contains(get(t, h, "/notes", false).Body.String(), "from another process") {
		t.Fatal("note exists before it was written")
	}
	f, err := os.OpenFile(logPath, os.O_APPEND|os.O_WRONLY, 0o644)
	if err != nil {
		t.Fatal(err)
	}
	line := `{"time":"2026-07-26T10:00:00Z","op":"note","session":"s9","agent":"vr","change":"` +
		change + `","file":"hello.txt","note_id":1,"text":"from another process"}`
	if _, err := f.WriteString(line + "\n"); err != nil {
		t.Fatal(err)
	}
	f.Close()
	// the poll is stat-based; make sure the mtime moved
	future := time.Now().Add(time.Second)
	os.Chtimes(logPath, future, future)

	if !strings.Contains(get(t, h, "/notes", false).Body.String(), "from another process") {
		t.Error("an append by vr was not picked up")
	}
}