package scheduler

import (
	"path/filepath"
	"testing"

	"pete/internal/poster"
	"pete/internal/storage"
)

type fakeQueue struct {
	items []poster.QueueItem
}

func (f *fakeQueue) Enqueue(item poster.QueueItem) {
	f.items = append(f.items, item)
}

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

func insertPostable(t *testing.T, guid, source, channel string, seenAt int64) {
	t.Helper()
	if err := storage.InsertStory(&storage.Story{
		GUID:       guid,
		Headline:   "Headline for " + guid,
		Lede:       "Lede for " + guid,
		ArticleURL: "https://example.com/" + guid,
		Source:     source,
		SeenAt:     seenAt,
	}); err != nil {
		t.Fatalf("InsertStory(%s): %v", guid, err)
	}
	storage.MarkClassified(guid, channel, "[]")
}

func TestNew_EmptyChannels_ReturnsNil(t *testing.T) {
	if New(nil, 4, &fakeQueue{}) != nil {
		t.Error("expected nil when no channels are given")
	}
}

func TestNew_SortsChannels(t *testing.T) {
	rr := New([]string{"tech", "gaming", "politics"}, 4, &fakeQueue{})
	if rr == nil {
		t.Fatal("expected non-nil RoundRobin")
	}
	want := []string{"gaming", "politics", "tech"}
	for i, ch := range rr.channels {
		if ch != want[i] {
			t.Errorf("channel[%d]=%s, want %s", i, ch, want[i])
		}
	}
}

func TestTick_PicksNewestPostableFromFirstChannel(t *testing.T) {
	setupTestDB(t)
	insertPostable(t, "g-old", "TimeExt", "gaming", 100)
	insertPostable(t, "g-new", "TimeExt", "gaming", 200)
	insertPostable(t, "p-1", "GuardianPolitics", "politics", 150)

	fq := &fakeQueue{}
	rr := New([]string{"gaming", "politics"}, 4, fq)
	rr.tick()

	if len(fq.items) != 1 {
		t.Fatalf("expected 1 enqueued, got %d", len(fq.items))
	}
	if fq.items[0].GUID != "g-new" {
		t.Errorf("expected newest from gaming (g-new), got %s", fq.items[0].GUID)
	}
	lastChannel, _, _ := storage.GetRoundRobinState()
	if lastChannel != "gaming" {
		t.Errorf("expected last_channel=gaming, got %s", lastChannel)
	}
}

func TestTick_SkipsEmptyAndAdvancesPointer(t *testing.T) {
	setupTestDB(t)
	// Pretend we just posted in gaming; next tick should start at politics, which
	// is empty, so it should skip to tech.
	storage.SetRoundRobinState("gaming", 0)
	insertPostable(t, "t-1", "GuardianTech", "tech", 100)

	fq := &fakeQueue{}
	rr := New([]string{"gaming", "politics", "tech"}, 4, fq)
	rr.tick()

	if len(fq.items) != 1 || fq.items[0].GUID != "t-1" {
		t.Fatalf("expected t-1 to be enqueued, got %+v", fq.items)
	}
	lastChannel, _, _ := storage.GetRoundRobinState()
	if lastChannel != "tech" {
		t.Errorf("expected last_channel=tech after skipping politics, got %s", lastChannel)
	}
}

func TestTick_NothingPostable_LeavesPointerUnchanged(t *testing.T) {
	setupTestDB(t)
	storage.SetRoundRobinState("gaming", 1000)

	fq := &fakeQueue{}
	rr := New([]string{"gaming", "tech"}, 4, fq)
	rr.tick()

	if len(fq.items) != 0 {
		t.Fatalf("expected 0 enqueued, got %d", len(fq.items))
	}
	lastChannel, lastTickAt, _ := storage.GetRoundRobinState()
	if lastChannel != "gaming" {
		t.Errorf("expected last_channel unchanged=gaming, got %s", lastChannel)
	}
	if lastTickAt <= 1000 {
		t.Errorf("expected last_tick_at to advance past 1000, got %d", lastTickAt)
	}
}

func TestTick_WrapsAroundFromLastChannel(t *testing.T) {
	setupTestDB(t)
	// Sorted order is [gaming, politics, tech]. last_channel=tech wraps to gaming.
	storage.SetRoundRobinState("tech", 0)
	insertPostable(t, "g-1", "TimeExt", "gaming", 100)
	insertPostable(t, "t-1", "GuardianTech", "tech", 200) // tech is newer, but rotation must pick gaming

	fq := &fakeQueue{}
	rr := New([]string{"gaming", "politics", "tech"}, 4, fq)
	rr.tick()

	if len(fq.items) != 1 || fq.items[0].GUID != "g-1" {
		t.Fatalf("expected g-1 (wraparound), got %+v", fq.items)
	}
}

func TestTick_DiscardedAndDuplicateExcluded(t *testing.T) {
	setupTestDB(t)
	insertPostable(t, "t-discard", "GuardianTech", "_discarded", 200)
	insertPostable(t, "t-dup", "GuardianTech", "_duplicate", 150)
	insertPostable(t, "t-real", "GuardianTech", "tech", 100)

	fq := &fakeQueue{}
	rr := New([]string{"tech"}, 4, fq)
	rr.tick()

	if len(fq.items) != 1 || fq.items[0].GUID != "t-real" {
		t.Fatalf("expected t-real (sentinels excluded), got %+v", fq.items)
	}
}

func TestTick_AlreadyPostedExcluded(t *testing.T) {
	setupTestDB(t)
	insertPostable(t, "t-posted", "GuardianTech", "tech", 200)
	insertPostable(t, "t-fresh", "GuardianTech", "tech", 100)
	storage.InsertPostLog("t-posted", "tech", "$evt1", "https://example.com/t-posted")

	fq := &fakeQueue{}
	rr := New([]string{"tech"}, 4, fq)
	rr.tick()

	if len(fq.items) != 1 || fq.items[0].GUID != "t-fresh" {
		t.Fatalf("expected t-fresh (t-posted already in post_log), got %+v", fq.items)
	}
}

func TestTick_UnknownLastChannel_StartsAtIndexZero(t *testing.T) {
	setupTestDB(t)
	// Stale state pointing at a channel no longer in config.
	storage.SetRoundRobinState("retired", 0)
	insertPostable(t, "g-1", "TimeExt", "gaming", 100)
	insertPostable(t, "t-1", "GuardianTech", "tech", 200)

	fq := &fakeQueue{}
	rr := New([]string{"gaming", "tech"}, 4, fq)
	rr.tick()

	if len(fq.items) != 1 || fq.items[0].GUID != "g-1" {
		t.Fatalf("expected g-1 (start at idx 0 when last_channel unknown), got %+v", fq.items)
	}
}