package monitor

import (
	"context"
	"fmt"
	"sync"
	"testing"
	"time"

	"gitea.dooplex.hu/admin/felhom-hub/internal/tenantsync"
)

// fakeUsage is a usageReader for tests: it returns a scripted usage/err and counts calls.
type fakeUsage struct {
	mu    sync.Mutex
	usage tenantsync.BoxUsage
	err   error
	calls int
}

func (f *fakeUsage) Usage(_ context.Context) (tenantsync.BoxUsage, error) {
	f.mu.Lock()
	defer f.mu.Unlock()
	f.calls++
	return f.usage, f.err
}
func (f *fakeUsage) set(u tenantsync.BoxUsage, err error) {
	f.mu.Lock()
	f.usage, f.err = u, err
	f.mu.Unlock()
}
func (f *fakeUsage) nCalls() int { f.mu.Lock(); defer f.mu.Unlock(); return f.calls }

func usageBytes(totalGiB, usedGiB int64) tenantsync.BoxUsage {
	return tenantsync.BoxUsage{Total: totalGiB * gib, Used: usedGiB * gib, Avail: (totalGiB - usedGiB) * gib}
}

// C1 — throttle: ≤1 ep0 usage call per 15-min window across an hour of 60 s sweeps (≈4, not ≈60).
func TestPBSDRBox_Throttle(t *testing.T) {
	f := &fakeUsage{usage: usageBytes(40, 8)}
	var cur time.Time
	c := NewPBSDRBoxChecker(f, 80, 90, noEvent, quietLog())
	c.now = func() time.Time { return cur }
	base := time.Now().UTC()
	for i := 0; i < 60; i++ {
		cur = base.Add(time.Duration(i) * 60 * time.Second)
		c.Check()
	}
	if f.nCalls() < 3 || f.nCalls() > 5 {
		t.Fatalf("usage op called %d times over an hour of 60 s sweeps, want ≈4 (throttled to 15 min)", f.nCalls())
	}
	snap, ok := c.Snapshot()
	if !ok || snap.State != PBSStateOK || snap.CapacityBytes != 40*gib {
		t.Fatalf("snapshot wrong: %+v ok=%v", snap, ok)
	}
}

// C2/C3 — fill bands: escalation-only, in-band no re-emit, recovery re-arm, pbsdr-box scope.
// Red-proof (esc): remove the escalation-only guard → the C3 same-band case re-emits → fails.
func TestPBSDRBox_FillBands(t *testing.T) {
	f := &fakeUsage{usage: usageBytes(1000, 750)} // 75%
	ev := &capturedBox{}
	var cur time.Time
	c := NewPBSDRBoxChecker(f, 80, 90, ev.fn, quietLog())
	c.now = func() time.Time { return cur }
	base := time.Now().UTC()
	cur = base
	step := func(usedGiB int64) {
		cur = cur.Add(16 * time.Minute)
		f.set(usageBytes(1000, usedGiB), nil)
		c.Check()
	}

	c.Check() // 75% → no emit
	if len(ev.typ) != 0 {
		t.Fatalf("75%% must not emit, got %v", ev.typ)
	}
	step(820) // 82% → one warning
	if count(ev.typ, "pbsdr_box_fill") != 1 || ev.sev[0] != "warning" {
		t.Fatalf("82%% must warn once, got typ=%v sev=%v", ev.typ, ev.sev)
	}
	step(850) // 85% same band → no re-emit
	if count(ev.typ, "pbsdr_box_fill") != 1 {
		t.Fatalf("same-band must NOT re-emit, got %d", count(ev.typ, "pbsdr_box_fill"))
	}
	step(920) // 92% → critical
	if count(ev.typ, "pbsdr_box_fill") != 2 || ev.sev[len(ev.sev)-1] != "critical" {
		t.Fatalf("92%% must escalate to critical, got typ=%v sev=%v", ev.typ, ev.sev)
	}
	step(700) // 70% → recovery re-arm (silent)
	if c.FillState() != bandOK {
		t.Fatalf("recovery must re-arm to ok, got %s", c.FillState())
	}
	if count(ev.typ, "pbsdr_box_fill") != 2 {
		t.Fatalf("recovery must be silent, got %d", count(ev.typ, "pbsdr_box_fill"))
	}
	step(920) // re-breach → emits again
	if count(ev.typ, "pbsdr_box_fill") != 3 {
		t.Fatalf("re-breach after recovery must emit again, got %d", count(ev.typ, "pbsdr_box_fill"))
	}
	for _, cust := range ev.cust {
		if cust != "pbsdr-box" {
			t.Fatalf("every emit must carry the pbsdr-box scope, got %q", cust)
		}
	}
}

// C4 — usage-unsupported (ErrUsageUnsupported) → the distinct "unavailable" state, NOT degraded, NO
// alert, NO band transition. Red-proof (unavail-band): let unavailable drive a band → alert fires → fails.
func TestPBSDRBox_Unavailable(t *testing.T) {
	f := &fakeUsage{err: tenantsync.ErrUsageUnsupported}
	ev := &capturedBox{}
	c := NewPBSDRBoxChecker(f, 80, 90, ev.fn, quietLog())
	c.Check()
	snap, ok := c.Snapshot()
	if !ok || snap.State != PBSStateUnavailable {
		t.Fatalf("ErrUsageUnsupported must yield the 'unavailable' state, got %+v", snap)
	}
	if len(ev.typ) != 0 {
		t.Fatalf("unavailable must NOT alert, got %v", ev.typ)
	}
	if c.FillState() != "unknown" {
		t.Fatalf("unavailable must not set a fill band, got %s", c.FillState())
	}
}

// C5 — exec error/timeout → last snapshot kept, marked degraded, NO band transition (missing ≠ 0%).
func TestPBSDRBox_DegradedKeepsLast(t *testing.T) {
	f := &fakeUsage{usage: usageBytes(1000, 920)} // 92% critical
	ev := &capturedBox{}
	var cur time.Time
	c := NewPBSDRBoxChecker(f, 80, 90, ev.fn, quietLog())
	c.now = func() time.Time { return cur }
	cur = time.Now().UTC()

	c.Check() // establish 92% critical + emit
	if count(ev.typ, "pbsdr_box_fill") != 1 {
		t.Fatalf("setup: want one critical emit, got %v", ev.typ)
	}
	before, _ := c.Snapshot()

	f.set(tenantsync.BoxUsage{}, fmt.Errorf("ssh timeout"))
	cur = cur.Add(16 * time.Minute)
	c.Check()

	after, ok := c.Snapshot()
	if !ok || after.State != PBSStateDegraded {
		t.Fatalf("a failed poll must mark degraded (keeping last), got %+v", after)
	}
	if after.UsedBytes != before.UsedBytes || after.CapacityBytes != before.CapacityBytes {
		t.Fatalf("a failed poll must keep the last-known values (before %d/%d, after %d/%d)",
			before.UsedBytes, before.CapacityBytes, after.UsedBytes, after.CapacityBytes)
	}
	if c.FillState() != bandCritical {
		t.Fatalf("a failed poll must NOT transition the band, got %s", c.FillState())
	}
	if count(ev.typ, "pbsdr_box_fill") != 1 {
		t.Fatalf("a failed poll must not emit, got %d", count(ev.typ, "pbsdr_box_fill"))
	}
}