package httpapi

import (
	"context"
	"encoding/json"
	"net/http"
	"net/http/httptest"
	"strings"
	"testing"
	"text/template"
	"time"

	"gitea.maximumdirect.net/ejr/feedapi/endpoint"
	apierrors "gitea.maximumdirect.net/ejr/feedapi/errors"
	"gitea.maximumdirect.net/ejr/feedapi/render"
	"gitea.maximumdirect.net/ejr/feedapi/templates"
	"gitea.maximumdirect.net/ejr/feedapi/transport/httpx"
	"gitea.maximumdirect.net/ejr/weatherfeeder/model"
)

type fakeService struct {
	observation *model.WeatherObservation
	forecast    *model.WeatherForecastRun
	alerts      *model.WeatherAlertRun
	err         error
}

func (s *fakeService) LatestObservation(context.Context) (*model.WeatherObservation, error) {
	return s.observation, s.err
}

func (s *fakeService) LatestHourlyForecast(context.Context) (*model.WeatherForecastRun, error) {
	return s.forecast, s.err
}

func (s *fakeService) LatestActiveAlerts(context.Context) (*model.WeatherAlertRun, error) {
	return s.alerts, s.err
}

func TestObservationsRejectUnknownQueryParameter(t *testing.T) {
	h := newHandler(t, &fakeService{}, "/observations")

	w := httptest.NewRecorder()
	req := httptest.NewRequest(http.MethodGet, "/observations?bogus=1", nil)
	h.ServeHTTP(w, req)

	if w.Code != http.StatusBadRequest {
		t.Fatalf("expected 400, got %d", w.Code)
	}

	var env apierrors.Envelope
	if err := json.Unmarshal(w.Body.Bytes(), &env); err != nil {
		t.Fatalf("decode error envelope: %v", err)
	}
	if env.Error == nil || env.Error.Code != apierrors.CodeInvalidParameter {
		t.Fatalf("expected invalid_parameter code, got %+v", env.Error)
	}
}

func TestObservationsNoDataReturnsNullEnvelopeData(t *testing.T) {
	h := newHandler(t, &fakeService{}, "/observations")

	w := httptest.NewRecorder()
	req := httptest.NewRequest(http.MethodGet, "/observations", nil)
	h.ServeHTTP(w, req)

	if w.Code != http.StatusOK {
		t.Fatalf("expected 200, got %d", w.Code)
	}

	var payload struct {
		Data *json.RawMessage `json:"data"`
	}
	if err := json.Unmarshal(w.Body.Bytes(), &payload); err != nil {
		t.Fatalf("decode envelope: %v", err)
	}
	if payload.Data != nil {
		t.Fatalf("expected data null, got %s", string(*payload.Data))
	}
}

func TestObservationsPopulatedJSONEnvelope(t *testing.T) {
	now := time.Date(2026, 3, 19, 18, 0, 0, 0, time.UTC)
	h := newHandler(t, &fakeService{
		observation: &model.WeatherObservation{
			StationID:   "KSTL",
			StationName: "St. Louis",
			Timestamp:   now,
		},
	}, "/observations")

	w := httptest.NewRecorder()
	req := httptest.NewRequest(http.MethodGet, "/observations", nil)
	h.ServeHTTP(w, req)

	if w.Code != http.StatusOK {
		t.Fatalf("expected 200, got %d", w.Code)
	}

	var payload struct {
		Data struct {
			StationID string `json:"stationId"`
		} `json:"data"`
	}
	if err := json.Unmarshal(w.Body.Bytes(), &payload); err != nil {
		t.Fatalf("decode envelope: %v", err)
	}
	if payload.Data.StationID != "KSTL" {
		t.Fatalf("expected stationId KSTL, got %q", payload.Data.StationID)
	}
}

func TestFormatNegotiationXMLAndText(t *testing.T) {
	hXML := newHandler(t, &fakeService{alerts: &model.WeatherAlertRun{AsOf: time.Now().UTC()}}, "/alerts/active")

	w := httptest.NewRecorder()
	req := httptest.NewRequest(http.MethodGet, "/alerts/active", nil)
	req.Header.Set("Accept", "application/xml")
	hXML.ServeHTTP(w, req)

	if w.Code != http.StatusOK {
		t.Fatalf("expected 200 for xml request, got %d", w.Code)
	}
	if !strings.Contains(w.Header().Get("Content-Type"), "application/xml") {
		t.Fatalf("expected xml content type, got %q", w.Header().Get("Content-Type"))
	}

	hText := newHandler(t, &fakeService{forecast: &model.WeatherForecastRun{Product: model.ForecastProductHourly}}, "/forecast/hourly")
	w = httptest.NewRecorder()
	req = httptest.NewRequest(http.MethodGet, "/forecast/hourly?format=text", nil)
	hText.ServeHTTP(w, req)

	if w.Code != http.StatusOK {
		t.Fatalf("expected 200 for text request, got %d", w.Code)
	}
	if !strings.Contains(w.Header().Get("Content-Type"), "text/plain") {
		t.Fatalf("expected text/plain content type, got %q", w.Header().Get("Content-Type"))
	}
	if !strings.Contains(w.Body.String(), "Forecast text") {
		t.Fatalf("expected rendered text template body, got %q", w.Body.String())
	}
}

func newHandler(t *testing.T, svc Service, path string) http.Handler {
	t.Helper()

	def := definitionForPath(t, Definitions(svc), path)
	return httpx.Adapt(def, httpx.Dependencies{
		Renderers:     testRenderers(t),
		DefaultFormat: render.FormatJSON,
	})
}

func definitionForPath(t *testing.T, defs []endpoint.Definition, path string) endpoint.Definition {
	t.Helper()
	for _, def := range defs {
		if def.Path == path {
			return def
		}
	}
	t.Fatalf("endpoint not found: %s", path)
	return endpoint.Definition{}
}

func testRenderers(t *testing.T) *render.Registry {
	t.Helper()

	reg := render.NewRegistry()
	if err := reg.Register(render.NewJSONRenderer()); err != nil {
		t.Fatal(err)
	}
	if err := reg.Register(render.NewXMLRenderer()); err != nil {
		t.Fatal(err)
	}

	tmplReg := templates.NewRegistry()
	for name, body := range map[string]string{
		"observations.txt.tmpl":    "Observation text",
		"forecast_hourly.txt.tmpl": "Forecast text",
		"alerts_active.txt.tmpl":   "Alerts text",
	} {
		tmpl, err := template.New(name).Parse(body)
		if err != nil {
			t.Fatal(err)
		}
		if err := tmplReg.Register(name, tmpl); err != nil {
			t.Fatal(err)
		}
	}
	if err := reg.Register(templates.NewRenderer(tmplReg)); err != nil {
		t.Fatal(err)
	}

	return reg
}