package api

import (
	"context"
	"encoding/json"
	"net/http"
	"net/http/httptest"
	"os"
	"testing"
	"time"

	"github.com/go-chi/chi/v5"
	"github.com/jackc/pgx/v5/pgtype"
)

func newMetricsRouter(h *handlers) chi.Router {
	r := chi.NewRouter()
	r.Get("/api/me/recommendation-metrics", h.handleGetRecommendationMetrics)
	return r
}

// seedSourcedPlay inserts a play_event with an explicit source + completion +
// skip flag. A nil source inserts NULL (library/radio play).
func seedSourcedPlay(
	t *testing.T, h *handlers, userID, trackID, sessionID pgtype.UUID,
	source *string, completion float64, skipped bool,
) {
	t.Helper()
	if _, err := h.pool.Exec(context.Background(),
		`INSERT INTO play_events
		   (user_id, track_id, session_id, started_at, source, completion_ratio, was_skipped)
		 VALUES ($1, $2, $3, now(), $4, $5, $6)`,
		userID, trackID, sessionID, source, completion, skipped); err != nil {
		t.Fatalf("seed sourced play: %v", err)
	}
}

func TestRecommendationMetrics_NoSession401(t *testing.T) {
	h, _ := testHandlers(t)
	req := httptest.NewRequest(http.MethodGet, "/api/me/recommendation-metrics", nil)
	rec := httptest.NewRecorder()
	newMetricsRouter(h).ServeHTTP(rec, req)
	if rec.Code != http.StatusUnauthorized {
		t.Errorf("status = %d, want 401", rec.Code)
	}
}

func TestRecommendationMetrics_AggregatesBySourceExcludingNull(t *testing.T) {
	if os.Getenv("MINSTREL_TEST_DATABASE_URL") == "" {
		t.Skip("MINSTREL_TEST_DATABASE_URL not set")
	}
	h, pool := testHandlers(t)
	user := seedUser(t, pool, "metrics", "pw", false)
	artist := seedArtist(t, pool, "MetricArtist")
	album := seedAlbum(t, pool, artist.ID, "MetricAlbum", 2020)
	tk := seedTrack(t, pool, album.ID, artist.ID, "MetricTrack", 1, 200000)
	session := seedPlaySession(t, pool, user.ID, time.Now())

	forYou := "for_you"
	discover := "discover"
	// for_you: 3 plays, 1 skipped; completions 1.0, 0.95, 0.05 → mean 0.6667.
	seedSourcedPlay(t, h, user.ID, tk.ID, session, &forYou, 1.0, false)
	seedSourcedPlay(t, h, user.ID, tk.ID, session, &forYou, 0.95, false)
	seedSourcedPlay(t, h, user.ID, tk.ID, session, &forYou, 0.05, true)
	// discover: 1 play.
	seedSourcedPlay(t, h, user.ID, tk.ID, session, &discover, 0.8, false)
	// library play (NULL source) — must be excluded.
	seedSourcedPlay(t, h, user.ID, tk.ID, session, nil, 1.0, false)

	req := httptest.NewRequest(http.MethodGet, "/api/me/recommendation-metrics", nil)
	req = withUser(req, user)
	rec := httptest.NewRecorder()
	newMetricsRouter(h).ServeHTTP(rec, req)
	if rec.Code != http.StatusOK {
		t.Fatalf("status = %d, want 200", rec.Code)
	}

	var resp recommendationMetricsResp
	if err := json.Unmarshal(rec.Body.Bytes(), &resp); err != nil {
		t.Fatalf("decode: %v", err)
	}
	if resp.WindowDays != recMetricsDefaultDays {
		t.Errorf("window_days = %d, want %d", resp.WindowDays, recMetricsDefaultDays)
	}
	bySource := map[string]recommendationMetric{}
	for _, m := range resp.Sources {
		bySource[m.Source] = m
	}
	if _, present := bySource[""]; present {
		t.Error("NULL-source (library) plays should be excluded")
	}
	fy, ok := bySource["for_you"]
	if !ok {
		t.Fatal("for_you metrics missing")
	}
	if fy.Plays != 3 || fy.Skips != 1 {
		t.Errorf("for_you plays/skips = %d/%d, want 3/1", fy.Plays, fy.Skips)
	}
	if fy.SkipRate < 0.32 || fy.SkipRate > 0.34 {
		t.Errorf("for_you skip_rate = %.3f, want ~0.333", fy.SkipRate)
	}
	if fy.AvgCompletion < 0.66 || fy.AvgCompletion > 0.67 {
		t.Errorf("for_you avg_completion = %.4f, want ~0.6667", fy.AvgCompletion)
	}
	if d, ok := bySource["discover"]; !ok || d.Plays != 1 || d.Skips != 0 {
		t.Errorf("discover metrics = %+v, want plays=1 skips=0", d)
	}
}