package upwatch

import (
	"context"
	"encoding/json"
	"sync"
	"testing"
	"time"
)

type memStore struct {
	mu  sync.Mutex
	raw json.RawMessage
}

func (m *memStore) GetUpwatch() json.RawMessage { m.mu.Lock(); defer m.mu.Unlock(); return m.raw }
func (m *memStore) UpdateUpwatch(fn func(json.RawMessage) (json.RawMessage, error)) error {
	m.mu.Lock()
	defer m.mu.Unlock()
	n, err := fn(m.raw)
	if err == nil {
		m.raw = n
	}
	return err
}

// D41 (operator 2026-10-24): qBittorrent gets 50 % of the host's TESTED line — never of the push floor, which read
// 10 Mbit/s on demo-hp's 90 Mbit/s line. The watch judges against the higher of the two.
// RED-PROOF: let QBLimitNow use s.Line() → the push floor alone sets a limit → fails; let line() ignore the test →
// Line() stays at the floor → fails.
func TestService_QBLimitFromTheTestedLineOnly(t *testing.T) {
	logins, expire, limit := 0, false, int64(0)
	srv := fakeQBServer(t, "pw-canary", &logins, &expire, &limit)
	defer srv.Close()
	st := &memStore{}
	floor := LineRecord{Peak10Mbps: 10, Counts: true}
	if err := st.UpdateUpwatch(func(json.RawMessage) (json.RawMessage, error) { return json.Marshal(State{Line: []LineRecord{floor}}) }); err != nil {
		t.Fatal(err)
	}
	var tested float64
	at := time.Date(2026, 10, 24, 6, 31, 0, 0, time.UTC)
	svc := &Service{Store: st, QB: &QBittorrent{Box: envBox{"qbittorrent/QBT_ADMIN_PASSWORD": "pw-canary"}, URL: srv.URL},
		QBShare: 0.5, Measured: func(context.Context) (float64, time.Time, bool) { return tested, at, tested > 0 }}

	svc.QBLimitNow(context.Background())
	if limit != 0 {
		t.Fatalf("no test yet, push floor 10 Mbit/s: qBittorrent limited to %d B/s — the floor must not set a limit", limit)
	}
	if l, ok := svc.Line(); !ok || l != 10 {
		t.Fatalf("watch line before a test = %.1f %v, want the push floor 10", l, ok)
	}
	if v := svc.View(); !v.LineKnown || v.LineTested || v.LineMbps != 10 {
		t.Fatalf("view before a test = %+v", v)
	}

	tested = 90.7
	svc.QBLimitNow(context.Background())
	if want := int64(5668750) / 1024 * 1024; limit != want {
		t.Fatalf("tested 90.7 Mbit/s: limit %d B/s, want 50 %% = %d (stored in KiB/s)", limit, want)
	}
	if l, ok := svc.Line(); !ok || l != 90.7 {
		t.Fatalf("watch line after the test = %.1f %v, want 90.7", l, ok)
	}
	if v := svc.View(); !v.LineTested || v.LineMbps != 90.7 || v.QBLimitBps != limit {
		t.Fatalf("view after the test = %+v", v)
	}

	// The agent stops answering: the last tested value stays (an agent restart must not drop the limit).
	tested = 0
	svc.RefreshMeasured(context.Background())
	if l, ok := svc.MeasuredLine(); !ok || l != 90.7 {
		t.Fatalf("after a failed read: %.1f %v, want the last value kept", l, ok)
	}
}