package feedwatch

import (
	"context"
	"errors"
	"path/filepath"
	"strings"
	"testing"
	"time"

	"pete/internal/config"
	"pete/internal/storage"
)

func setup(t *testing.T) {
	t.Helper()
	storage.Close()
	if err := storage.Init(filepath.Join(t.TempDir(), "feedwatch.db")); err != nil {
		t.Fatal(err)
	}
	t.Cleanup(func() { storage.Close() })
}

func src(names ...string) []config.SourceConfig {
	var out []config.SourceConfig
	for _, n := range names {
		out = append(out, config.SourceConfig{Name: n, Enabled: true})
	}
	return out
}

func fail(name string, n int) {
	for range n {
		storage.RecordPollResult(name, false, 0, errors.New("feed fetch https://x/feed: status 403"))
	}
}

// setLastNew backdates a source's last new story.
func setLastNew(t *testing.T, name string, at time.Time) {
	t.Helper()
	if _, err := storage.Get().Exec(`UPDATE source_health SET last_new_at = ? WHERE source = ?`, at.Unix(), name); err != nil {
		t.Fatal(err)
	}
}

// capture is a Send that records what it was asked to deliver.
type capture struct {
	msgs []string
	err  error
}

func (c *capture) send(_ context.Context, msg string) error {
	if c.err != nil {
		return c.err
	}
	c.msgs = append(c.msgs, msg)
	return nil
}

func TestDownIsReportedOnceAndBackIsReported(t *testing.T) {
	setup(t)
	sources := src("Broken", "Fine")
	now := time.Now()

	storage.RecordPollResult("Fine", true, 10, nil)
	fail("Broken", DownAfter-1)

	c := &capture{}
	pass(context.Background(), now, sources, c.send)
	if len(c.msgs) != 0 {
		t.Fatalf("alerted below the threshold: %q", c.msgs)
	}

	fail("Broken", 1)
	pass(context.Background(), now, sources, c.send)
	if len(c.msgs) != 1 || !strings.Contains(c.msgs[0], "Broken: 5 failed polls in a row, has never fetched successfully") {
		t.Fatalf("down alert = %q", c.msgs)
	}
	if strings.Contains(c.msgs[0], "Fine") {
		t.Errorf("a healthy feed was mentioned: %q", c.msgs[0])
	}

	// Still down on the next pass: nothing new to say.
	fail("Broken", 3)
	pass(context.Background(), now.Add(Every), sources, c.send)
	if len(c.msgs) != 1 {
		t.Fatalf("down alert repeated: %q", c.msgs[1:])
	}

	// It comes back. The success has to be stamped after the alert, so step
	// past the second the alert was recorded in.
	time.Sleep(1100 * time.Millisecond)
	storage.RecordPollResult("Broken", true, 5, nil)
	pass(context.Background(), time.Now(), sources, c.send)
	if len(c.msgs) != 2 || !strings.Contains(c.msgs[1], "Broken is fetching again") {
		t.Fatalf("recovery = %q", c.msgs)
	}
	pass(context.Background(), time.Now(), sources, c.send)
	if len(c.msgs) != 2 {
		t.Fatalf("recovery repeated: %q", c.msgs[2:])
	}
}

func TestUndeliveredAlertIsRetried(t *testing.T) {
	setup(t)
	sources := src("Broken")
	fail("Broken", DownAfter)

	c := &capture{err: errors.New("homeserver unreachable")}
	pass(context.Background(), time.Now(), sources, c.send)

	c.err = nil
	pass(context.Background(), time.Now(), sources, c.send)
	if len(c.msgs) != 1 || !strings.Contains(c.msgs[0], "Broken") {
		t.Fatalf("alert after a failed send = %q, want it delivered on the retry", c.msgs)
	}
}

func TestQuietFeedIsReportedOnce(t *testing.T) {
	setup(t)
	sources := src("Sleepy", "Busy")
	now := time.Now()
	storage.RecordPollResult("Sleepy", true, 10, nil)
	storage.RecordPollResult("Busy", true, 10, nil)
	setLastNew(t, "Sleepy", now.Add(-9*24*time.Hour))

	c := &capture{}
	pass(context.Background(), now, sources, c.send)
	if len(c.msgs) != 1 || !strings.Contains(c.msgs[0], "Sleepy fetches fine but hasn't had anything new in 9 days") {
		t.Fatalf("quiet alert = %q", c.msgs)
	}
	if strings.Contains(c.msgs[0], "Busy") {
		t.Errorf("a busy feed was called quiet: %q", c.msgs[0])
	}
	pass(context.Background(), now.Add(Every), sources, c.send)
	if len(c.msgs) != 1 {
		t.Fatalf("quiet alert repeated: %q", c.msgs[1:])
	}

	// New stories end the quiet spell without a message, and a later quiet
	// spell is a new episode that gets reported again.
	storage.RecordNewStories("Sleepy", 2)
	pass(context.Background(), now, sources, c.send)
	if len(c.msgs) != 1 {
		t.Fatalf("end of a quiet spell was announced: %q", c.msgs[1:])
	}
	setLastNew(t, "Sleepy", now.Add(-8*24*time.Hour))
	pass(context.Background(), now, sources, c.send)
	if len(c.msgs) != 2 {
		t.Fatalf("second quiet spell not reported: %q", c.msgs)
	}
}

// A feed that has just been added has no history, so it must not be called
// quiet before it has had a full window to produce something.
func TestNewSourceGetsAGracePeriod(t *testing.T) {
	setup(t)
	storage.RecordPollResult("Fresh", true, 0, nil)
	r, err := Check(time.Now().Add(QuietAfter-time.Hour), src("Fresh"))
	if err != nil {
		t.Fatal(err)
	}
	if !r.Empty() {
		t.Fatalf("new source reported inside its grace period: %+v", r)
	}
}

func TestDisabledSourcesNeverAlert(t *testing.T) {
	setup(t)
	fail("Retired", DownAfter*2)
	sources := []config.SourceConfig{{Name: "Retired", Enabled: false}}
	r, err := Check(time.Now(), sources)
	if err != nil {
		t.Fatal(err)
	}
	if !r.Empty() {
		t.Fatalf("disabled source alerted: %+v", r)
	}
}