// Tests for `fluxrec serve`: the poll loop against an httptest fake
// Miniflux (multi-page, mid-run crash), batch assembly split/kinds, and
// the refresh-time computation including the midnight wrap. Helpers
// (testEntry, makeEntries, entriesJSON) come from export_test.go.
package cmds

import (
	"encoding/json"
	"fmt"
	"math/rand"
	"net/http"
	"net/http/httptest"
	"os"
	"path/filepath"
	"strconv"
	"strings"
	"testing"
	"time"

	"fluxrec/core"
	"fluxrec/miniflux"
)

// testModel is a minimal hand-built model: one unigram ("title"), so every
// makeEntries title scores identically and batch ties break by entry ID.
func testModel() *core.ModelEnvelope {
	return &core.ModelEnvelope{
		CreatedAt:    time.Date(2024, 1, 1, 0, 0, 0, 0, time.UTC),
		Meta:         map[string]any{},
		Vectorizer:   map[string]float64{"title": 1.0},
		OrderedVocab: []string{"title"},
		Weights:      []float64{2.0, 0.1},
	}
}

// idServer pages its entry pool by after_entry_id ascending, like the
// serve poll expects, and can be told to die on the Nth request.
type idServer struct {
	entries []testEntry // ascending IDs
	queries []string
	calls   int
	failOn  int // 1-based request number to 500 on; 0 = never
}

func (s *idServer) handler() http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		s.calls++
		s.queries = append(s.queries, r.URL.RawQuery)
		if s.failOn == s.calls {
			http.Error(w, "boom", http.StatusInternalServerError)
			return
		}
		q := r.URL.Query()
		after, _ := strconv.ParseInt(q.Get("after_entry_id"), 10, 64)
		limit, _ := strconv.Atoi(q.Get("limit"))
		if limit <= 0 {
			limit = len(s.entries)
		}
		var page []testEntry
		for _, e := range s.entries {
			if e.ID > after {
				page = append(page, e)
			}
		}
		if len(page) > limit {
			page = page[:limit]
		}
		w.Header().Set("Content-Type", "application/json")
		fmt.Fprint(w, entriesJSON(len(page), page))
	}
}

func serveTestClient(t *testing.T, s http.Handler) *miniflux.Client {
	t.Helper()
	srv := httptest.NewServer(s)
	t.Cleanup(srv.Close)
	return miniflux.NewClientWithHTTP(miniflux.Config{BaseURL: srv.URL, Token: "t"}, srv.Client())
}

func TestPollMultiPage(t *testing.T) {
	// 450 entries => three 200/200/50 pages off one ascending cursor.
	fake := &idServer{entries: makeEntries(450, 1, false, 1)}
	client := serveTestClient(t, fake.handler())

	dir := t.TempDir()
	model := testModel()
	cmd := &ServeCommand{
		Cursor: filepath.Join(dir, "cursor.json"), Runs: filepath.Join(dir, "runs.jsonl"),
		TopN: 15, ExploreFrac: 0.2,
	}
	var out strings.Builder
	rng := rand.New(rand.NewSource(1))
	if err := cmd.pollOnce(client, core.CreateVectorizerFromModel(model), model, rng, &out); err != nil {
		t.Fatalf("pollOnce: %v", err)
	}

	if fake.calls != 3 {
		t.Fatalf("expected 3 paged requests, got %d", fake.calls)
	}
	if !strings.Contains(fake.queries[0], "direction=asc") || !strings.Contains(fake.queries[0], "limit=200") {
		t.Errorf("first query missing direction/limit: %s", fake.queries[0])
	}
	if strings.Contains(fake.queries[0], "after_entry_id") {
		t.Errorf("first query should have no cursor: %s", fake.queries[0])
	}
	if !strings.Contains(fake.queries[1], "after_entry_id=200") ||
		!strings.Contains(fake.queries[2], "after_entry_id=400") {
		t.Errorf("cursor paging wrong: %q", fake.queries)
	}

	cursor, err := loadCursor(cmd.Cursor)
	if err != nil {
		t.Fatalf("loadCursor: %v", err)
	}
	if cursor != 450 {
		t.Errorf("cursor = %d, want 450", cursor)
	}

	rows, err := core.ReadRuns(cmd.Runs)
	if err != nil {
		t.Fatalf("ReadRuns: %v", err)
	}
	if len(rows) != 1 {
		t.Fatalf("expected 1 run row, got %d", len(rows))
	}
	row := rows[0]
	if row.EntriesSeen != 450 {
		t.Errorf("entries_seen = %d, want 450", row.EntriesSeen)
	}
	if len(row.Kept) != 15 {
		t.Errorf("kept = %d, want 15", len(row.Kept))
	}
	if !row.ModelCreatedAt.Equal(model.CreatedAt) {
		t.Errorf("model_created_at = %v, want %v", row.ModelCreatedAt, model.CreatedAt)
	}
}

func TestPollCrashLeavesNoState(t *testing.T) {
	fake := &idServer{entries: makeEntries(450, 1, false, 1), failOn: 2}
	client := serveTestClient(t, fake.handler())

	dir := t.TempDir()
	model := testModel()
	cmd := &ServeCommand{
		Cursor: filepath.Join(dir, "cursor.json"), Runs: filepath.Join(dir, "runs.jsonl"),
		TopN: 15, ExploreFrac: 0.2,
	}
	err := cmd.pollOnce(client, core.CreateVectorizerFromModel(model), model,
		rand.New(rand.NewSource(1)), &strings.Builder{})
	if err == nil {
		t.Fatal("expected pollOnce to fail on the second page")
	}
	// Crash-safe ordering: the page-1 work must not be half-persisted.
	if _, statErr := os.Stat(cmd.Cursor); !os.IsNotExist(statErr) {
		t.Error("cursor file exists despite the failed poll")
	}
	if _, statErr := os.Stat(cmd.Runs); !os.IsNotExist(statErr) {
		t.Error("runs file exists despite the failed poll")
	}
}

func TestPollEmptyWritesNothing(t *testing.T) {
	fake := &idServer{}
	client := serveTestClient(t, fake.handler())

	dir := t.TempDir()
	model := testModel()
	cmd := &ServeCommand{
		Cursor: filepath.Join(dir, "cursor.json"), Runs: filepath.Join(dir, "runs.jsonl"),
		TopN: 15, ExploreFrac: 0.2,
	}
	if err := cmd.pollOnce(client, core.CreateVectorizerFromModel(model), model,
		rand.New(rand.NewSource(1)), &strings.Builder{}); err != nil {
		t.Fatalf("pollOnce: %v", err)
	}
	if rows, _ := core.ReadRuns(cmd.Runs); len(rows) != 0 {
		t.Errorf("empty poll wrote %d rows, want 0 (RSS tail starvation)", len(rows))
	}
}

func TestPollSkipsRecFeed(t *testing.T) {
	fake := &idServer{
		entries: append(makeEntries(10, 1, false, 1), makeEntries(5, 100, false, 99)...),
	}
	client := serveTestClient(t, fake.handler())

	dir := t.TempDir()
	model := testModel()
	cmd := &ServeCommand{
		Cursor: filepath.Join(dir, "cursor.json"), Runs: filepath.Join(dir, "runs.jsonl"),
		TopN: 30, ExploreFrac: 0, RecFeedID: 99,
	}
	if err := cmd.pollOnce(client, core.CreateVectorizerFromModel(model), model,
		rand.New(rand.NewSource(1)), &strings.Builder{}); err != nil {
		t.Fatalf("pollOnce: %v", err)
	}
	rows, _ := core.ReadRuns(cmd.Runs)
	if rows[0].EntriesSeen != 15 || rows[0].RecFeedSkipped != 5 {
		t.Errorf("seen=%d skipped=%d, want 15 / 5", rows[0].EntriesSeen, rows[0].RecFeedSkipped)
	}
	for _, k := range rows[0].Kept {
		if k.EntryID >= 100 {
			t.Errorf("rec-feed entry %d was kept; serve must not re-recommend its own output", k.EntryID)
		}
	}
}

func TestAssembleBatchSplitAndKinds(t *testing.T) {
	// 30 candidates, scores increasing with ID => deterministic ranks.
	entries := make([]scoredEntry, 30)
	for i := range entries {
		entries[i] = scoredEntry{
			entry: miniflux.Entry{ID: int64(i + 1), Title: fmt.Sprintf("T%d", i+1)},
			score: float64(i + 1),
		}
	}
	kept := assembleBatch(entries, 15, 0.2, rand.New(rand.NewSource(7)))
	if len(kept) != 15 {
		t.Fatalf("kept = %d, want 15", len(kept))
	}
	counts := map[string]int{}
	var rankedIDs, runnerUpIDs []int64
	random := map[int64]bool{}
	for _, k := range kept {
		counts[k.Kind]++
		switch k.Kind {
		case core.KindRanked:
			rankedIDs = append(rankedIDs, k.EntryID)
		case core.KindRunnerUp:
			runnerUpIDs = append(runnerUpIDs, k.EntryID)
		case core.KindRandom:
			random[k.EntryID] = true
		}
	}
	if counts[core.KindRanked] != 12 || counts[core.KindRunnerUp] != 1 || counts[core.KindRandom] != 2 {
		t.Errorf("split = %v, want ranked=12 runnerup=1 random=2", counts)
	}
	// Ranked are the top 12 by score, in score order.
	for i, id := range rankedIDs {
		want := int64(30 - i)
		if id != want {
			t.Fatalf("ranked[%d] = %d, want %d", i, id, want)
		}
	}
	// The runner-up is the highest-scored entry below the cut.
	if len(runnerUpIDs) != 1 || runnerUpIDs[0] != 18 {
		t.Errorf("runner-up = %v, want [18]", runnerUpIDs)
	}
	// Random picks come from the tail below the runner-up, no duplicates.
	for id := range random {
		if id > 17 {
			t.Errorf("random pick %d not below the runner-up cut", id)
		}
	}
}

func TestAssembleBatchFewCandidates(t *testing.T) {
	entries := []scoredEntry{
		{entry: miniflux.Entry{ID: 1}, score: 0.1},
		{entry: miniflux.Entry{ID: 2}, score: 0.9},
		{entry: miniflux.Entry{ID: 3}, score: 0.5},
	}
	kept := assembleBatch(entries, 15, 0.2, rand.New(rand.NewSource(1)))
	if len(kept) != 3 {
		t.Fatalf("kept = %d, want all 3 as ranked", len(kept))
	}
	for _, k := range kept {
		if k.Kind != core.KindRanked {
			t.Errorf("kind = %s, want ranked when candidates < cut", k.Kind)
		}
	}
	if kept[0].EntryID != 2 { // highest score first
		t.Errorf("first kept ID = %d, want 2 (highest score)", kept[0].EntryID)
	}
}

func TestParseRefreshAt(t *testing.T) {
	mins, err := parseRefreshAt("18:00,06:00, 12:30")
	if err != nil {
		t.Fatalf("parseRefreshAt: %v", err)
	}
	want := []int{360, 750, 1080}
	if fmt.Sprint(mins) != fmt.Sprint(want) {
		t.Errorf("mins = %v, want %v (sorted)", mins, want)
	}
	for _, bad := range []string{"24:00", "abc", "12", "12:60", ""} {
		if _, err := parseRefreshAt(bad); err == nil {
			t.Errorf("parseRefreshAt(%q) unexpectedly succeeded", bad)
		}
	}
}

func TestNextRefresh(t *testing.T) {
	mins := []int{360, 720, 1080} // 06:00, 12:00, 18:00
	at := func(day, h, m int) time.Time {
		return time.Date(2024, 3, day, h, m, 0, 0, time.UTC)
	}
	cases := []struct {
		now  time.Time
		want time.Time
	}{
		{at(1, 13, 0), at(1, 18, 0)}, // same-day next slot
		{at(1, 6, 0), at(1, 12, 0)},  // exactly on a slot: strictly after
		{at(1, 23, 30), at(2, 6, 0)}, // past last slot: midnight wrap
		{at(1, 0, 0), at(1, 6, 0)},   // before all slots
	}
	for _, tc := range cases {
		if got := nextRefresh(tc.now, mins); !got.Equal(tc.want) {
			t.Errorf("nextRefresh(%v) = %v, want %v", tc.now, got, tc.want)
		}
	}
}

func TestMinGapMinutes(t *testing.T) {
	if got := minGapMinutes([]int{360, 720, 1080}); got != 360 {
		t.Errorf("minGap = %d, want 360", got)
	}
	if got := minGapMinutes([]int{1380, 60}); got != 120 {
		t.Errorf("minGap across midnight = %d, want 120", got)
	}
	if got := minGapMinutes([]int{360}); got != 1440 {
		t.Errorf("single slot minGap = %d, want 1440", got)
	}
}

func TestCatchUpDue(t *testing.T) {
	mins := []int{360, 720, 1080} // min gap 6h => half = 3h
	now := time.Date(2024, 3, 2, 12, 0, 0, 0, time.UTC)
	dir := t.TempDir()
	runs := filepath.Join(dir, "runs.jsonl")

	// No log yet: first boot polls immediately.
	if due, err := catchUpDue(runs, mins, now); err != nil || !due {
		t.Errorf("no runs: due=%v err=%v, want true", due, err)
	}
	recent := core.RunRow{RanAt: now.Add(-time.Hour), EntriesSeen: 3}
	if err := core.AppendRun(runs, recent); err != nil {
		t.Fatalf("AppendRun: %v", err)
	}
	if due, _ := catchUpDue(runs, mins, now); due {
		t.Error("last run 1h ago: due=true, want false (next slot will cover it)")
	}
	old := core.RunRow{RanAt: now.Add(-5 * time.Hour), EntriesSeen: 3}
	if err := core.AppendRun(runs, old); err != nil {
		t.Fatalf("AppendRun: %v", err)
	}
	if due, _ := catchUpDue(runs, mins, now); !due {
		t.Error("last run 5h ago: due=false, want true (downtime across slots)")
	}
}

func TestServeRoutes(t *testing.T) {
	dir := t.TempDir()
	runsPath := filepath.Join(dir, "runs.jsonl")
	row := core.RunRow{
		RanAt:       time.Date(2024, 3, 1, 6, 0, 0, 0, time.UTC),
		EntriesSeen: 42,
		Kept: []core.KeptItem{
			{EntryID: 101, URL: "https://example.com/a", Title: "Alpha", FeedTitle: "Feed A",
				PublishedAt: time.Date(2024, 3, 1, 5, 0, 0, 0, time.UTC), Content: "body a", Score: 0.9, Kind: core.KindRanked},
			{EntryID: 102, URL: "https://example.com/b", Title: "Beta", FeedTitle: "Feed B",
				PublishedAt: time.Date(2024, 3, 1, 5, 30, 0, 0, time.UTC), Content: "body b", Score: 0.2, Kind: core.KindRandom},
		},
	}
	if err := core.AppendRun(runsPath, row); err != nil {
		t.Fatalf("AppendRun: %v", err)
	}

	cmd := &ServeCommand{Runs: runsPath, RSSBatches: 21}
	handler := cmd.routes([]int{360, 720, 1080}, time.Now().Add(-48*time.Hour))

	rec := httptest.NewRecorder()
	handler.ServeHTTP(rec, httptest.NewRequest(http.MethodGet, "/recommendations.xml", nil))
	if rec.Code != http.StatusOK {
		t.Fatalf("RSS status = %d", rec.Code)
	}
	if ct := rec.Header().Get("Content-Type"); !strings.Contains(ct, "application/rss+xml") {
		t.Errorf("RSS content-type = %q", ct)
	}
	body := rec.Body.String()
	if !strings.Contains(body, "<guid isPermaLink=\"false\">mf:101</guid>") {
		t.Error("RSS missing mf:101 guid")
	}
	if strings.Count(body, "<item>") != 2 {
		t.Errorf("RSS item count = %d, want 2", strings.Count(body, "<item>"))
	}

	rec = httptest.NewRecorder()
	handler.ServeHTTP(rec, httptest.NewRequest(http.MethodGet, "/api/status", nil))
	if rec.Code != http.StatusOK {
		t.Fatalf("status = %d", rec.Code)
	}
	var status map[string]any
	if err := json.Unmarshal(rec.Body.Bytes(), &status); err != nil {
		t.Fatalf("status not JSON: %v", err)
	}
	last, ok := status["last_run"].(map[string]any)
	if !ok {
		t.Fatalf("status last_run missing: %v", status)
	}
	if last["entries_seen"].(float64) != 42 || last["kept"].(float64) != 2 {
		t.Errorf("last_run = %v, want entries_seen=42 kept=2", last)
	}
	if status["model_age_hours"].(float64) <= 0 {
		t.Errorf("model_age_hours = %v, want positive", status["model_age_hours"])
	}
}