package main

import (
	"context"
	"encoding/json"
	"errors"
	"net/http"
	"net/http/httptest"
	"strings"
	"sync"
	"testing"
)

type fakeStore struct {
	mu        sync.Mutex
	telemetry []TelemetrySample
	chunks    []ConsumptionChunk
	sessions  []ChargingSession
	devices   []Device
	fail      error
}

func (f *fakeStore) WriteTelemetry(_ context.Context, _ string, s []TelemetrySample) error {
	f.mu.Lock()
	defer f.mu.Unlock()
	if f.fail != nil {
		return f.fail
	}
	f.telemetry = append(f.telemetry, s...)
	return nil
}

func (f *fakeStore) WriteConsumptionChunk(_ context.Context, c ConsumptionChunk) error {
	f.mu.Lock()
	defer f.mu.Unlock()
	if f.fail != nil {
		return f.fail
	}
	f.chunks = append(f.chunks, c)
	return nil
}

func (f *fakeStore) WriteChargingSession(_ context.Context, s ChargingSession) error {
	f.mu.Lock()
	defer f.mu.Unlock()
	f.sessions = append(f.sessions, s)
	return f.fail
}

func (f *fakeStore) SaveDevice(_ context.Context, d Device) error {
	f.mu.Lock()
	defer f.mu.Unlock()
	if f.fail != nil {
		return f.fail
	}
	f.devices = append(f.devices, d)
	return nil
}

func (f *fakeStore) LoadDevices(context.Context) ([]Device, error) {
	f.mu.Lock()
	defer f.mu.Unlock()
	return f.devices, f.fail
}

func (f *fakeStore) ReadConsumptionChunks(context.Context, string) ([]ConsumptionChunk, error) {
	f.mu.Lock()
	defer f.mu.Unlock()
	return f.chunks, f.fail
}

const (
	testToken            = "ingest-test-token-0123456789abcdef"
	testApprovalPassword = "approval-password-123"
)

func newTestAPI() (*API, *fakeStore) {
	store := &fakeStore{}
	return &API{Store: store, IngestToken: testToken, Forwarder: &Forwarder{},
		Pairing: NewPairing(testApprovalPassword, nil), PublicURL: "https://car.example.com"}, store
}

func do(t *testing.T, h http.Handler, method, path, token, body string) *httptest.ResponseRecorder {
	t.Helper()
	req := httptest.NewRequest(method, path, strings.NewReader(body))
	if token != "" {
		req.Header.Set("Authorization", "Bearer "+token)
	}
	rec := httptest.NewRecorder()
	h.ServeHTTP(rec, req)
	return rec
}

func TestHealthNeedsNoToken(t *testing.T) {
	api, _ := newTestAPI()
	rec := do(t, api.Routes(), "GET", "/v1/health", "", "")
	if rec.Code != 200 || strings.TrimSpace(rec.Body.String()) != `{"status":"ok"}` {
		t.Fatalf("%d %s", rec.Code, rec.Body)
	}
}

func TestEveryOtherEndpointNeedsTheIngestToken(t *testing.T) {
	api, _ := newTestAPI()
	h := api.Routes()
	for _, c := range []struct{ method, path string }{
		{"POST", "/v1/telemetry"},
		{"PUT", "/v1/consumption/daily"},
		{"PUT", "/v1/charging-sessions/" + testSession},
		{"GET", "/v1/consumption/history/" + testInstallation},
	} {
		for _, token := range []string{"", "wrong-token-0123456789abcdef", testToken + "x"} {
			if rec := do(t, h, c.method, c.path, token, "{}"); rec.Code != 401 {
				t.Errorf("%s %s with %q: want 401, got %d", c.method, c.path, token, rec.Code)
			}
		}
	}
}

func TestTelemetryIsStoredAndBadInputIsA400(t *testing.T) {
	api, store := newTestAPI()
	h := api.Routes()
	rec := do(t, h, "POST", "/v1/telemetry", testToken, string(telemetryBody(`{"utc":1790000000,"soc":80}`)))
	if rec.Code != 204 || len(store.telemetry) != 1 {
		t.Fatalf("%d, stored %d", rec.Code, len(store.telemetry))
	}
	rec = do(t, h, "POST", "/v1/telemetry", testToken, string(telemetryBody(`{"utc":1790000000,"soc":120}`)))
	if rec.Code != 400 || !strings.Contains(rec.Body.String(), "samples[0].soc is invalid") {
		t.Fatalf("%d %s", rec.Code, rec.Body)
	}
	if rec := do(t, h, "GET", "/v1/telemetry", testToken, ""); rec.Code != 405 {
		t.Fatalf("GET on a POST route: want 405, got %d", rec.Code)
	}
}

func TestAFailedWriteIsA500WithoutDetail(t *testing.T) {
	api, store := newTestAPI()
	store.fail = errors.New("influx says: token xyz rejected")
	rec := do(t, api.Routes(), "POST", "/v1/telemetry", testToken, string(telemetryBody(`{"utc":1790000000,"soc":80}`)))
	if rec.Code != 500 || strings.Contains(rec.Body.String(), "xyz") {
		t.Fatalf("%d %s", rec.Code, rec.Body)
	}
}

func TestOversizedBodiesAreRejected(t *testing.T) {
	api, _ := newTestAPI()
	big := `{"x":"` + strings.Repeat("a", maxBodyBytes) + `"}`
	if rec := do(t, api.Routes(), "PUT", "/v1/consumption/daily", testToken, big); rec.Code != 400 {
		t.Fatalf("want 400, got %d", rec.Code)
	}
}

func TestHistoryReturnsDaysNewestFirstAndTheLifetime(t *testing.T) {
	api, _ := newTestAPI()
	h := api.Routes()
	day := func(date string, at int64) string {
		return `{"installationId":"` + testInstallation + `","date":"` + date + `","recordedAt":` +
			jsonInt(at) + `,"day":{"km":2.5,"kwh":0.4,"hours":0.03,"socDrop":0.6}}`
	}
	// Two chunks on one day and one on the next. Retry dedupe is InfluxDB's overwrite and is
	// covered by the end-to-end check, not this fake.
	for _, body := range []string{day("2026-10-16", 1000), day("2026-10-16", 2000), day("2026-10-17", 3000)} {
		if rec := do(t, h, "PUT", "/v1/consumption/daily", testToken, body); rec.Code != 204 {
			t.Fatalf("chunk: %d %s", rec.Code, rec.Body)
		}
	}
	rec := do(t, h, "GET", "/v1/consumption/history/"+testInstallation, testToken, "")
	if rec.Code != 200 {
		t.Fatalf("%d %s", rec.Code, rec.Body)
	}
	var got struct {
		Records []struct {
			Date string `json:"date"`
			Day  Totals `json:"day"`
		} `json:"records"`
		Lifetime Totals `json:"lifetime"`
	}
	if err := json.Unmarshal(rec.Body.Bytes(), &got); err != nil {
		t.Fatal(err)
	}
	if len(got.Records) != 2 || got.Records[0].Date != "2026-10-17" || got.Records[1].Day.Km != 5 || got.Lifetime.Km != 7.5 {
		t.Fatalf("%s", rec.Body)
	}
	if rec := do(t, h, "GET", "/v1/consumption/history/not-a-uuid", testToken, ""); rec.Code != 400 {
		t.Fatalf("bad id: want 400, got %d", rec.Code)
	}
}

func jsonInt(v int64) string {
	b, _ := json.Marshal(v)
	return string(b)
}