package gateway

import (
	"compress/gzip"
	"io"
	"os"
	"path/filepath"
	"reflect"
	"strings"
	"testing"
	"time"
)

func TestQualificationCatalogMatchesSection7(t *testing.T) {
	media := qualificationMediaProfiles()
	if len(media) != 3 {
		t.Fatalf("media profile count = %d, want 3", len(media))
	}
	wantMedia := []qualificationMediaProfile{
		{Name: "1080p60-h264", Codec: "h264", BitrateKbps: 20000, Duration: 10 * time.Minute, Warmup: time.Second, PacketBytes: 1179},
		{Name: "1440p120-hevc", Codec: "hevc", BitrateKbps: 50000, Duration: 10 * time.Minute, Warmup: time.Second, PacketBytes: 1179},
		{Name: "4k60-hevc", Codec: "hevc", BitrateKbps: 80000, Duration: 10 * time.Minute, Warmup: time.Second, PacketBytes: 1179},
	}
	if !reflect.DeepEqual(media, wantMedia) {
		t.Fatalf("media profiles = %#v, want %#v", media, wantMedia)
	}

	impairments := qualificationImpairmentProfiles()
	wantImpairments := []qualificationImpairmentProfile{
		{Name: "baseline", RTT: 20 * time.Millisecond},
		{Name: "latency", RTT: 150 * time.Millisecond},
		{Name: "jitter", RTT: 50 * time.Millisecond, Jitter: 30 * time.Millisecond},
		{Name: "loss", RTT: 50 * time.Millisecond, Jitter: 10 * time.Millisecond, LossPercent: 5},
		{Name: "reorder", RTT: 100 * time.Millisecond, Jitter: 10 * time.Millisecond, LossPercent: 1, Reorder: true},
		{Name: "constrained", RTT: 50 * time.Millisecond, Jitter: 10 * time.Millisecond, LossPercent: 2, Reorder: true, CapacitySteps: []int{25, 50}},
	}
	if !reflect.DeepEqual(impairments, wantImpairments) {
		t.Fatalf("impairment profiles = %#v, want %#v", impairments, wantImpairments)
	}
}

func TestQualificationOutputAndStatisticsFailClosed(t *testing.T) {
	if err := validateQualificationOutputDir("relative/evidence"); err == nil {
		t.Fatal("relative evidence directory was accepted")
	}
	if err := validateQualificationOutputDir(filepath.Join(t.TempDir(), "evidence")); err != nil {
		t.Fatalf("absolute evidence directory rejected: %v", err)
	}

	summary, err := summarizeQualificationSamples([]time.Duration{
		time.Millisecond, 2 * time.Millisecond, 3 * time.Millisecond,
		4 * time.Millisecond, 5 * time.Millisecond,
	})
	if err != nil {
		t.Fatal(err)
	}
	if summary.Count != 5 || summary.Min != time.Millisecond || summary.Median != 3*time.Millisecond ||
		summary.P90 != 5*time.Millisecond || summary.P95 != 5*time.Millisecond ||
		summary.P99 != 5*time.Millisecond || summary.Max != 5*time.Millisecond ||
		summary.Mean != 3*time.Millisecond || summary.Histogram["le_5ms"] != 5 {
		t.Fatalf("summary = %#v", summary)
	}
	if err := enforceQualificationProcessingGate(summary); err != nil {
		t.Fatalf("5 ms p95 rejected: %v", err)
	}
	summary.P95++
	if err := enforceQualificationProcessingGate(summary); err == nil {
		t.Fatal("p95 above 5 ms was accepted")
	}
}

func TestQualificationShortProcessingWritesRawArtifact(t *testing.T) {
	profile := qualificationMediaProfile{
		Name: "smoke", Codec: "h264", BitrateKbps: 1000,
		Duration: 200 * time.Millisecond, Warmup: time.Millisecond, PacketBytes: 100,
	}
	rawPath := filepath.Join(t.TempDir(), "processing.csv.gz")
	summary, err := runQualificationProcessing(profile, rawPath)
	if err != nil {
		t.Fatal(err)
	}
	if summary.Count < 1 || summary.RawSamplesSHA256 == "" || summary.RawSamplesBytes < 1 {
		t.Fatalf("processing summary = %#v", summary)
	}
	file, err := os.Open(rawPath)
	if err != nil {
		t.Fatal(err)
	}
	defer file.Close()
	reader, err := gzip.NewReader(file)
	if err != nil {
		t.Fatal(err)
	}
	raw, err := io.ReadAll(reader)
	if err != nil {
		t.Fatal(err)
	}
	if err := reader.Close(); err != nil {
		t.Fatal(err)
	}
	if !strings.HasPrefix(string(raw), "elapsed_ns,processing_ns\n") || strings.Count(string(raw), "\n") != int(summary.Count)+1 {
		t.Fatalf("raw sample rows do not match summary count: %q", raw)
	}
}

func TestQualificationProcessingPreservesPayload(t *testing.T) {
	payload := qualificationPayload(qualificationMediaProfiles()[0])
	processed, elapsed, err := processQualificationPayload(7, payload)
	if err != nil {
		t.Fatal(err)
	}
	if !reflect.DeepEqual(processed, payload) {
		t.Fatal("encoded payload mutated")
	}
	if elapsed <= 0 {
		t.Fatalf("processing duration = %s", elapsed)
	}
}

func TestQualificationImpairmentIsDeterministicAndBounded(t *testing.T) {
	profile := qualificationImpairmentProfiles()[3]
	first, err := runQualificationImpairment(profile, qualificationMediaProfiles()[0], 10_000)
	if err != nil {
		t.Fatal(err)
	}
	second, err := runQualificationImpairment(profile, qualificationMediaProfiles()[0], 10_000)
	if err != nil {
		t.Fatal(err)
	}
	if !reflect.DeepEqual(first, second) {
		t.Fatalf("impairment run is not deterministic:\n%#v\n%#v", first, second)
	}
	if first.Sent != 10_000 || first.Delivered+first.Dropped != first.Sent ||
		first.ObservedLossPercent < 4.8 || first.ObservedLossPercent > 5.2 ||
		first.MaxQueuePackets > qualificationImpairmentQueuePackets {
		t.Fatalf("impairment observation = %#v", first)
	}
	if _, err := runQualificationImpairment(profile, qualificationMediaProfiles()[0], qualificationImpairmentMaxPackets+1); err == nil {
		t.Fatal("unbounded impairment packet count was accepted")
	}
}

func TestQualificationUsesPublicQUICAndProductionPacer(t *testing.T) {
	qualificationTraverseProfiles(t, qualificationMediaProfiles())
	evidence, err := qualificationPacerEvidence()
	if err != nil {
		t.Fatal(err)
	}
	if len(evidence.PerFlowBytes) != 8 || len(evidence.CapacitySteps) != 2 || evidence.JainIndex < 0.99 {
		t.Fatalf("pacer evidence = %#v", evidence)
	}
}