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"

	"git.fabledsword.com/bvandeusen/minstrel/internal/db/dbq"
)

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 (manual library play → baseline).
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)
	}
}

// findSurface returns the named family from any group, or nil.
func findSurface(resp recommendationMetricsResp, key string) *surfaceMetric {
	for _, g := range resp.Groups {
		for i := range g.Surfaces {
			if g.Surfaces[i].Key == key {
				return &g.Surfaces[i]
			}
		}
	}
	return nil
}

func TestBucketMetricsResponse_FamiliesGroupsBaseline(t *testing.T) {
	src := func(s string) *string { return &s }
	rows := []dbq.RecommendationSourceMetricsForUserRow{
		{Source: src("for_you"), Plays: 3, Skips: 1, CompletionN: 3, AvgCompletion: 2.0 / 3},
		// Two radio sessions collapse into one "radio" family; weighted
		// completion = (0.2*1 + 0.8*1) / 2 = 0.5.
		{Source: src("radio:aaaa"), Plays: 1, Skips: 1, CompletionN: 1, AvgCompletion: 0.2},
		{Source: src("radio:bbbb"), Plays: 1, Skips: 0, CompletionN: 1, AvgCompletion: 0.8},
		{Source: src("album:cccc"), Plays: 1, Skips: 0, CompletionN: 0, AvgCompletion: 0},
		{Source: src("discover"), Plays: 1, Skips: 0, CompletionN: 1, AvgCompletion: 0.8},
		// NULL source = manual plays → baseline, not a group row.
		{Source: nil, Plays: 25, Skips: 5, CompletionN: 20, AvgCompletion: 0.9},
	}
	resp := bucketMetricsResponse(recMetricsDefaultDays, rows)

	if resp.Baseline == nil {
		t.Fatal("baseline missing")
	}
	if resp.Baseline.Plays != 25 || resp.Baseline.SkipRate != 0.2 {
		t.Errorf("baseline = %+v, want plays=25 skip_rate=0.2", resp.Baseline)
	}
	if resp.Baseline.LowConfidence {
		t.Error("baseline with 25 plays should not be low-confidence")
	}

	radio := findSurface(resp, "radio")
	if radio == nil {
		t.Fatal("radio family missing")
	}
	if radio.Plays != 2 || radio.Skips != 1 {
		t.Errorf("radio plays/skips = %d/%d, want 2/1", radio.Plays, radio.Skips)
	}
	if radio.AvgCompletion < 0.49 || radio.AvgCompletion > 0.51 {
		t.Errorf("radio avg_completion = %.3f, want 0.5 (play-weighted merge)", radio.AvgCompletion)
	}
	if !radio.LowConfidence {
		t.Error("radio with 2 plays should be low-confidence")
	}

	if s := findSurface(resp, "direct_album"); s == nil || s.Plays != 1 {
		t.Errorf("direct_album = %+v, want plays=1", s)
	}
	if s := findSurface(resp, ""); s != nil {
		t.Error("NULL source must not appear as a surface family")
	}

	// Group ordering is intent-banded: go_to before discovery before direct.
	wantOrder := []string{intentGoTo, intentDiscovery, intentDirect}
	if len(resp.Groups) != len(wantOrder) {
		t.Fatalf("groups = %d, want %d", len(resp.Groups), len(wantOrder))
	}
	for i, g := range resp.Groups {
		if g.Intent != wantOrder[i] {
			t.Errorf("group[%d].intent = %s, want %s", i, g.Intent, wantOrder[i])
		}
	}
}

func TestRecommendationMetrics_BucketsWithBaseline(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"
	radioA := "radio:11111111-1111-1111-1111-111111111111"
	// 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)
	// A radio session play collapses into the "radio" family.
	seedSourcedPlay(t, h, user.ID, tk.ID, session, &radioA, 0.8, false)
	// Manual play (NULL source) — the baseline row.
	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)
	}
	if resp.Baseline == nil || resp.Baseline.Plays != 1 {
		t.Fatalf("baseline = %+v, want plays=1", resp.Baseline)
	}
	fy := findSurface(resp, "for_you")
	if fy == nil {
		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 radio := findSurface(resp, "radio"); radio == nil || radio.Plays != 1 {
		t.Errorf("radio family = %+v, want plays=1 (collapsed from radio:<uuid>)", radio)
	}
}