package stats

import (
	"context"
	"database/sql"
	"errors"
	"strings"
	"testing"
	"time"

	"lingniu-vehicle-ingest/go/vehicle-gateway/internal/envelope"
)

func TestSamplesFromEnvelopeDerivesDailyMileageSample(t *testing.T) {
	loc := time.FixedZone("Asia/Shanghai", 8*3600)
	env := envelope.FrameEnvelope{
		Protocol:    envelope.ProtocolJT808,
		VIN:         "LNBVIN00000000001",
		EventTimeMS: time.Date(2026, 7, 1, 8, 30, 0, 0, loc).UnixMilli(),
		Fields: map[string]any{
			envelope.FieldTotalMileageKM: 10241.2,
		},
	}

	samples, err := SamplesFromEnvelope(env, loc)
	if err != nil {
		t.Fatalf("SamplesFromEnvelope() error = %v", err)
	}
	if len(samples) != 1 {
		t.Fatalf("sample count = %d", len(samples))
	}
	if samples[0].VIN != "LNBVIN00000000001" {
		t.Fatalf("vin = %q", samples[0].VIN)
	}
	if samples[0].TotalMileageKM != 10241.2 {
		t.Fatalf("total mileage = %v", samples[0].TotalMileageKM)
	}
	if samples[0].StatDate != "2026-07-01" {
		t.Fatalf("stat date = %q", samples[0].StatDate)
	}
}

func TestSamplesFromEnvelopeMapsProtocolMileageFields(t *testing.T) {
	loc := time.FixedZone("Asia/Shanghai", 8*3600)
	tests := []struct {
		name     string
		protocol envelope.Protocol
		fields   map[string]any
		wantKM   float64
	}{
		{
			name:     "gb32960",
			protocol: envelope.ProtocolGB32960,
			fields:   map[string]any{"gb32960.vehicle.total_mileage_km": "38587"},
			wantKM:   38587,
		},
		{
			name:     "jt808",
			protocol: envelope.ProtocolJT808,
			fields:   map[string]any{"jt808.location.total_mileage_km": "12432.4"},
			wantKM:   12432.4,
		},
		{
			name:     "yutong mqtt meters",
			protocol: envelope.ProtocolYutongMQTT,
			fields:   map[string]any{"yutong_mqtt.data.total_mileage": "120756000"},
			wantKM:   120756,
		},
		{
			name:     "yutong mqtt root meters",
			protocol: envelope.ProtocolYutongMQTT,
			fields:   map[string]any{"yutong_mqtt.root.data.total_mileage": float64(22858000)},
			wantKM:   22858,
		},
	}
	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			samples, err := SamplesFromEnvelope(envelope.FrameEnvelope{
				Protocol:    tt.protocol,
				VIN:         "LNBVIN00000000001",
				EventTimeMS: time.Date(2026, 7, 1, 8, 30, 0, 0, loc).UnixMilli(),
				Fields:      tt.fields,
			}, loc)
			if err != nil {
				t.Fatalf("SamplesFromEnvelope() error = %v", err)
			}
			if len(samples) != 1 {
				t.Fatalf("sample count = %d", len(samples))
			}
			if samples[0].TotalMileageKM != tt.wantKM {
				t.Fatalf("total mileage = %v, want %v", samples[0].TotalMileageKM, tt.wantKM)
			}
		})
	}
}

func TestSamplesFromEnvelopeSkipsMissingVIN(t *testing.T) {
	loc := time.FixedZone("Asia/Shanghai", 8*3600)
	samples, err := SamplesFromEnvelope(envelope.FrameEnvelope{
		Protocol:    envelope.ProtocolJT808,
		Phone:       "13307811254",
		EventTimeMS: time.Date(2026, 7, 2, 0, 3, 0, 0, loc).UnixMilli(),
		Fields: map[string]any{
			envelope.FieldTotalMileageKM: 10985.7,
		},
	}, loc)
	if err != nil {
		t.Fatalf("SamplesFromEnvelope() error = %v", err)
	}
	if len(samples) != 0 {
		t.Fatalf("expected no samples without VIN, got %#v", samples)
	}
}

func TestSamplesFromEnvelopeSkipsMissingVINOrMileage(t *testing.T) {
	samples, err := SamplesFromEnvelope(envelope.FrameEnvelope{
		Protocol: envelope.ProtocolJT808,
		Fields:   map[string]any{envelope.FieldTotalMileageKM: 1.2},
	}, nil)
	if err != nil {
		t.Fatalf("SamplesFromEnvelope() error = %v", err)
	}
	if len(samples) != 0 {
		t.Fatalf("expected no samples without VIN, got %#v", samples)
	}

	samples, err = SamplesFromEnvelope(envelope.FrameEnvelope{
		Protocol: envelope.ProtocolGB32960,
		VIN:      "LNBVIN00000000002",
		Fields:   map[string]any{},
	}, nil)
	if err != nil {
		t.Fatalf("SamplesFromEnvelope() error = %v", err)
	}
	if len(samples) != 0 {
		t.Fatalf("expected no samples without mileage, got %#v", samples)
	}
}

func TestSamplesFromEnvelopeSkipsNonPositiveMileage(t *testing.T) {
	for _, value := range []any{0, 0.0, -1.0, "0"} {
		samples, err := SamplesFromEnvelope(envelope.FrameEnvelope{
			Protocol:    envelope.ProtocolJT808,
			VIN:         "LNBVIN00000000001",
			EventTimeMS: time.Date(2026, 7, 1, 9, 0, 0, 0, time.FixedZone("Asia/Shanghai", 8*3600)).UnixMilli(),
			Fields: map[string]any{
				envelope.FieldTotalMileageKM: value,
			},
		}, nil)
		if err != nil {
			t.Fatalf("SamplesFromEnvelope(%#v) error = %v", value, err)
		}
		if len(samples) != 0 {
			t.Fatalf("expected no samples for non-positive mileage %#v, got %#v", value, samples)
		}
	}
}

func TestWriterEnsuresSchemaAndUpsertsDailyMileage(t *testing.T) {
	exec := &recordingExec{}
	writer := NewWriter(exec, time.FixedZone("Asia/Shanghai", 8*3600))
	if err := writer.EnsureSchema(context.Background()); err != nil {
		t.Fatalf("EnsureSchema() error = %v", err)
	}
	if err := writer.Append(context.Background(), envelope.FrameEnvelope{
		Protocol:    envelope.ProtocolGB32960,
		VIN:         "LNBVIN00000000002",
		EventTimeMS: time.Date(2026, 7, 1, 9, 0, 0, 0, time.FixedZone("Asia/Shanghai", 8*3600)).UnixMilli(),
		Fields: map[string]any{
			envelope.FieldTotalMileageKM: "10000.0",
		},
	}); err != nil {
		t.Fatalf("Append() error = %v", err)
	}

	if !strings.Contains(exec.calls[0].query, "CREATE TABLE IF NOT EXISTS vehicle_daily_mileage") {
		t.Fatalf("unexpected schema sql: %s", exec.calls[0].query)
	}
	for _, column := range []string{"vehicle_key", "id BIGINT", "AUTO_INCREMENT", "created_at"} {
		if strings.Contains(exec.calls[0].query, column) {
			t.Fatalf("schema should not include %s: %s", column, exec.calls[0].query)
		}
	}
	if !strings.Contains(exec.calls[0].query, "PRIMARY KEY (vin, stat_date, protocol)") {
		t.Fatalf("daily mileage table should key by vin/stat_date/protocol: %s", exec.calls[0].query)
	}
	if strings.Contains(exec.calls[0].query, "KEY idx_vin (vin)") {
		t.Fatalf("daily mileage table should not keep redundant vin index covered by the primary key: %s", exec.calls[0].query)
	}
	if len(exec.calls) != 2 {
		t.Fatalf("exec calls = %d", len(exec.calls))
	}
	if !strings.Contains(exec.calls[1].query, "ON DUPLICATE KEY UPDATE") {
		t.Fatalf("unexpected upsert sql: %s", exec.calls[1].query)
	}
	if strings.Contains(exec.calls[1].query, "metric_key") || strings.Contains(exec.calls[1].query, "metric_unit") {
		t.Fatalf("daily mileage upsert should not use generic metric columns: %s", exec.calls[1].query)
	}
	if !strings.Contains(exec.calls[1].query, "first_total_mileage_km <= 0") {
		t.Fatalf("upsert should ignore legacy zero first mileage: %s", exec.calls[1].query)
	}
	if got := exec.calls[1].args[0]; got != "LNBVIN00000000002" {
		t.Fatalf("first upsert arg should be vin, got %#v", got)
	}
}

func TestWriterSkipsConsecutiveDuplicateMileageSamples(t *testing.T) {
	exec := &recordingExec{}
	writer := NewWriter(exec, time.FixedZone("Asia/Shanghai", 8*3600))
	event := envelope.FrameEnvelope{
		Protocol:    envelope.ProtocolJT808,
		VIN:         "LNBVIN00000000001",
		EventTimeMS: time.Date(2026, 7, 1, 9, 0, 0, 0, time.FixedZone("Asia/Shanghai", 8*3600)).UnixMilli(),
		Fields: map[string]any{
			envelope.FieldTotalMileageKM: 10241.2,
		},
	}

	if err := writer.Append(context.Background(), event); err != nil {
		t.Fatalf("first Append() error = %v", err)
	}
	event.ReceivedAtMS += 1000
	if err := writer.Append(context.Background(), event); err != nil {
		t.Fatalf("duplicate Append() error = %v", err)
	}

	if len(exec.calls) != 1 {
		t.Fatalf("exec calls = %d, want 1", len(exec.calls))
	}
}

func TestWriterDoesNotCacheMileageWhenUpsertFails(t *testing.T) {
	exec := &recordingExec{errs: []error{errors.New("mysql unavailable"), nil}}
	writer := NewWriter(exec, time.FixedZone("Asia/Shanghai", 8*3600))
	event := envelope.FrameEnvelope{
		Protocol:    envelope.ProtocolJT808,
		VIN:         "LNBVIN00000000001",
		EventTimeMS: time.Date(2026, 7, 1, 9, 0, 0, 0, time.FixedZone("Asia/Shanghai", 8*3600)).UnixMilli(),
		Fields: map[string]any{
			envelope.FieldTotalMileageKM: 10241.2,
		},
	}

	if err := writer.Append(context.Background(), event); err == nil {
		t.Fatalf("first Append() error = nil, want mysql error")
	}
	if err := writer.Append(context.Background(), event); err != nil {
		t.Fatalf("retry Append() error = %v", err)
	}

	if len(exec.calls) != 2 {
		t.Fatalf("exec calls = %d, want 2", len(exec.calls))
	}
}

func TestWriterKeepsOnlyLatestDateInMileageCache(t *testing.T) {
	exec := &recordingExec{}
	writer := NewWriter(exec, time.FixedZone("Asia/Shanghai", 8*3600))
	event := envelope.FrameEnvelope{
		Protocol: envelope.ProtocolJT808,
		VIN:      "LNBVIN00000000001",
		Fields: map[string]any{
			envelope.FieldTotalMileageKM: 10241.2,
		},
	}

	event.EventTimeMS = time.Date(2026, 7, 1, 23, 59, 0, 0, time.FixedZone("Asia/Shanghai", 8*3600)).UnixMilli()
	if err := writer.Append(context.Background(), event); err != nil {
		t.Fatalf("first Append() error = %v", err)
	}
	event.EventTimeMS = time.Date(2026, 7, 2, 0, 1, 0, 0, time.FixedZone("Asia/Shanghai", 8*3600)).UnixMilli()
	if err := writer.Append(context.Background(), event); err != nil {
		t.Fatalf("next-day Append() error = %v", err)
	}

	if len(exec.calls) != 2 {
		t.Fatalf("exec calls = %d, want 2", len(exec.calls))
	}
	if len(writer.lastTotalMileage) != 1 {
		t.Fatalf("cache entries = %d, want 1", len(writer.lastTotalMileage))
	}
}

type execCall struct {
	query string
	args  []any
}

type recordingExec struct {
	calls []execCall
	errs  []error
}

func (e *recordingExec) ExecContext(_ context.Context, query string, args ...any) (sql.Result, error) {
	e.calls = append(e.calls, execCall{query: query, args: args})
	if len(e.errs) > 0 {
		err := e.errs[0]
		e.errs = e.errs[1:]
		return nil, err
	}
	return nil, nil
}