package main

import (
	"errors"
	"strings"
	"testing"
	"time"
)

const (
	testInstallation = "6f1a2b3c-4d5e-4f60-8a9b-0c1d2e3f4a5b"
	testSession      = "11111111-2222-4333-8444-555555555555"
	testNowS         = 1_790_000_000
)

// testNow is the sample time the telemetry tests send, as "now" for the clock-ahead check.
var testNow = time.Unix(testNowS, 0)

func isValidationError(err error) bool {
	var v *ValidationError
	return errors.As(err, &v)
}

func TestConsumptionAcceptsAWellFormedChunk(t *testing.T) {
	c, err := validateConsumption([]byte(`{"installationId":"` + testInstallation + `","date":"2026-10-07",
		"recordedAt":1760000000000,"day":{"km":42.5,"kwh":7.25,"hours":0.9,"socDrop":11.5},
		"lifetime":{"km":12000,"kwh":2100,"hours":240,"socDrop":3400},"sohPercent":97.5}`))
	if err != nil {
		t.Fatal(err)
	}
	if c.Date != "2026-10-07" || c.Day.Kwh != 7.25 || c.RecordedAt.UnixMilli() != 1760000000000 || *c.SohPercent != 97.5 {
		t.Fatalf("unexpected chunk %+v", c)
	}
}

func TestConsumptionMissingSohIsOmittedNotDefaulted(t *testing.T) {
	// The car omits a field it could not read. Writing 0 would be a battery at nothing.
	c, err := validateConsumption([]byte(`{"installationId":"` + testInstallation + `","date":"2026-10-07",
		"recordedAt":1,"day":{"km":1,"kwh":1,"hours":1,"socDrop":1}}`))
	if err != nil {
		t.Fatal(err)
	}
	if c.SohPercent != nil {
		t.Fatalf("SoH should be absent, got %v", *c.SohPercent)
	}
}

func TestConsumptionRejectsBadInput(t *testing.T) {
	base := map[string]string{
		"installationId": `"` + testInstallation + `"`, "date": `"2026-10-07"`, "recordedAt": "1",
		"day": `{"km":1,"kwh":1,"hours":1,"socDrop":1}`,
	}
	cases := map[string][2]string{
		"bad id":             {"installationId", `"nope"`},
		"german date":        {"date", `"07.10.2026"`},
		"negative timestamp": {"recordedAt", "-5"},
		"fractional time":    {"recordedAt", "1.5"},
		"string number":      {"day", `{"km":"1","kwh":1,"hours":1,"socDrop":1}`},
		"huge totals":        {"day", `{"km":1e9,"kwh":1,"hours":1,"socDrop":1}`},
		"missing field":      {"day", `{"km":1,"kwh":1,"hours":1}`},
		"bad lifetime":       {"lifetime", `{"km":1}`},
		"soh above 100":      {"sohPercent", "101"},
	}
	for name, change := range cases {
		fields := map[string]string{}
		for k, v := range base {
			fields[k] = v
		}
		fields[change[0]] = change[1]
		var parts []string
		for k, v := range fields {
			parts = append(parts, `"`+k+`":`+v)
		}
		if _, err := validateConsumption([]byte("{" + strings.Join(parts, ",") + "}")); !isValidationError(err) {
			t.Errorf("%s: want ValidationError, got %v", name, err)
		}
	}
	for _, body := range []string{"", "[]", "null", "{", `{"a":1}{"b":2}`} {
		if _, err := validateConsumption([]byte(body)); !isValidationError(err) {
			t.Errorf("body %q: want ValidationError, got %v", body, err)
		}
	}
}

func chargingBody(overrides string) []byte {
	return []byte(`{"installationId":"` + testInstallation + `","sessionId":"` + testSession + `",
		"startedAt":1760500000000,"endedAt":1760501800000,"durationSeconds":1800,"energyKwh":30,
		"pricePerKwh":0.59,"startSocPercent":20,"endSocPercent":80,
		"curve":[{"timestampMs":1760500060000,"powerKw":95,"socPercent":21},{"timestampMs":1760500120000,"powerKw":110}]` +
		overrides + `}`)
}

func TestChargingSessionAppliesTheServersLossAndCost(t *testing.T) {
	// The car's own grid and cost figures are not trusted; the server applies 10 % loss.
	s, err := validateChargingSession(chargingBody(`,"gridEnergyKwh":1,"totalCost":1`), testSession)
	if err != nil {
		t.Fatal(err)
	}
	if s.GridEnergyKwh != 33 || s.TotalCost != 33*0.59 || s.ChargingLossPercent != 10 {
		t.Fatalf("grid %v cost %v loss %v", s.GridEnergyKwh, s.TotalCost, s.ChargingLossPercent)
	}
	if len(s.Curve) != 2 || s.Curve[1].SocPercent != nil || *s.Curve[0].SocPercent != 21 {
		t.Fatalf("curve not kept as sent: %+v", s.Curve)
	}
}

func TestChargingSessionMustMatchItsPath(t *testing.T) {
	if _, err := validateChargingSession(chargingBody(""), "22222222-2222-4333-8444-555555555555"); !isValidationError(err) {
		t.Fatalf("want ValidationError, got %v", err)
	}
}

func TestChargingSessionRejectsOversizedCurvesAndBadPoints(t *testing.T) {
	points := strings.Repeat(`{"timestampMs":1,"powerKw":1},`, 721)
	long := []byte(`{"installationId":"` + testInstallation + `","sessionId":"` + testSession + `","curve":[` +
		strings.TrimSuffix(points, ",") + `]}`)
	if _, err := validateChargingSession(long, testSession); !isValidationError(err) {
		t.Errorf("721 points: want ValidationError, got %v", err)
	}
	bad := []byte(strings.Replace(string(chargingBody("")), `"powerKw":95`, `"powerKw":-5`, 1))
	if _, err := validateChargingSession(bad, testSession); !isValidationError(err) {
		t.Errorf("negative power: want ValidationError, got %v", err)
	}
}

func telemetryBody(samples string) []byte {
	return []byte(`{"installationId":"` + testInstallation + `","samples":[` + samples + `]}`)
}

func TestTelemetryKeepsOnlyWhatWasSent(t *testing.T) {
	b, err := validateTelemetryBatch(telemetryBody(
		`{"utc":1790000000,"soc":81,"power":-12.5,"speed":0,"lat":52.1,"lon":7.6,"is_charging":1,"is_dcfc":false}`), testNow)
	if err != nil {
		t.Fatal(err)
	}
	s := b.Samples[0]
	if s.UTC != testNowS || s.Numbers["soc"] != 81 || s.Numbers["power"] != -12.5 || s.Numbers["lat"] != 52.1 {
		t.Fatalf("numbers %+v", s.Numbers)
	}
	if v, ok := s.Numbers["speed"]; !ok || v != 0 {
		t.Fatal("a real 0 must be kept")
	}
	if s.Flags["is_charging"] != true || s.Flags["is_dcfc"] != false || len(s.Flags) != 2 {
		t.Fatalf("flags %+v", s.Flags)
	}
	// An unread signal stays absent: a missing SOC must never become 0.
	if _, ok := s.Numbers["est_battery_range"]; ok {
		t.Fatal("absent field invented")
	}
}

func TestTelemetryDropsUnknownFields(t *testing.T) {
	b, err := validateTelemetryBatch(telemetryBody(`{"utc":1790000000,"future_field":3}`), testNow)
	if err != nil {
		t.Fatal(err)
	}
	if len(b.Samples[0].Numbers) != 0 || len(b.Samples[0].Flags) != 0 {
		t.Fatalf("unknown field kept: %+v", b.Samples[0])
	}
}

func TestTelemetryDropsBadValuesAndKeepsTheRest(t *testing.T) {
	for name, c := range map[string]struct {
		sample  string
		dropped string
		kept    bool // the sample itself survives
	}{
		"milliseconds":      {`{"utc":1790000000000,"soc":5}`, "samples[0].utc", false},
		"fractional utc":    {`{"utc":1790000000.5,"soc":5}`, "samples[0].utc", false},
		"clock unset":       {`{"utc":0,"soc":5}`, "samples[0].utc", false},
		"clock a day ahead": {`{"utc":1790086400,"soc":5}`, "samples[0].utc", false},
		"not an object":     {`5`, "samples[0]", false},
		"soc above 100":     {`{"utc":1790000000,"soc":101,"speed":20}`, "samples[0].soc", true},
		"reversing":         {`{"utc":1790000000,"soc":5,"speed":-4}`, "samples[0].speed", true},
		"string speed":      {`{"utc":1790000000,"soc":5,"speed":"fast"}`, "samples[0].speed", true},
		"flag 2":            {`{"utc":1790000000,"soc":5,"is_parked":2}`, "samples[0].is_parked", true},
		"half position":     {`{"utc":1790000000,"soc":5,"lat":52.1}`, "samples[0].lat/lon", true},
	} {
		b, err := validateTelemetryBatch(telemetryBody(c.sample), testNow)
		if err != nil {
			t.Errorf("%s: the batch was rejected: %v", name, err)
			continue
		}
		if len(b.Dropped) != 1 || b.Dropped[0] != c.dropped {
			t.Errorf("%s: dropped %v, want %s", name, b.Dropped, c.dropped)
		}
		if (len(b.Samples) == 1) != c.kept {
			t.Errorf("%s: %d samples kept", name, len(b.Samples))
		}
		if c.kept && b.Samples[0].Numbers["soc"] != 5 && name != "soc above 100" {
			t.Errorf("%s: the valid soc was lost", name)
		}
	}
}

func TestTelemetryRejectsEmptyAndOversizedBatches(t *testing.T) {
	if _, err := validateTelemetryBatch(telemetryBody(""), testNow); !isValidationError(err) {
		t.Error("empty batch accepted")
	}
	many := strings.TrimSuffix(strings.Repeat(`{"utc":1790000000},`, 501), ",")
	if _, err := validateTelemetryBatch(telemetryBody(many), testNow); !isValidationError(err) {
		t.Error("501 samples accepted")
	}
	if _, err := validateTelemetryBatch([]byte(`{"installationId":"nope","samples":[{"utc":1790000000}]}`), testNow); !isValidationError(err) {
		t.Error("bad installation id accepted")
	}
}