package main

import (
	"bytes"
	"net/http"
	"net/http/httptest"
	"os"
	"image/png"
	"strings"
	"testing"
	"time"

	"powerwatts/internal/chart"
	"powerwatts/internal/config"
	"powerwatts/internal/server"
	"powerwatts/internal/store"
)

func TestHandleIndexRendersWatts(t *testing.T) {
	srvStore := &store.Store{}
	srvStore.Set(123)
	srv := server.New("secret", 0, srvStore, embeddedStatic)
	req := httptest.NewRequest(http.MethodGet, "/", nil)
	rec := httptest.NewRecorder()

	srv.Routes().ServeHTTP(rec, req)

	if rec.Code != http.StatusOK {
		t.Fatalf("status = %d, want %d", rec.Code, http.StatusOK)
	}
	if !strings.Contains(rec.Body.String(), "123") {
		t.Fatalf("response did not contain watt value: %s", rec.Body.String())
	}
	if !strings.Contains(rec.Body.String(), "Last updated:") {
		t.Fatalf("response did not contain last updated label: %s", rec.Body.String())
	}
	if !strings.Contains(rec.Body.String(), "W") {
		t.Fatalf("response did not contain watt unit: %s", rec.Body.String())
	}
}

func TestFormatGermanNumber(t *testing.T) {
	tests := map[int]string{
		0:       "0",
		12:      "12",
		999:     "999",
		1000:    "1.000",
		10000:   "10.000",
		1234567: "1.234.567",
		-1000:   "-1.000",
	}
	for input, want := range tests {
		if got := chart.FormatGermanNumber(input); got != want {
			t.Fatalf("formatGermanNumber(%d) = %q, want %q", input, got, want)
		}
	}
}

func TestLoadConfig(t *testing.T) {
	path := t.TempDir() + "/config.json"
	if err := os.WriteFile(path, []byte(`{"write_secret":"secret","addr":":9090","chart_max_watts":750}`), 0o600); err != nil {
		t.Fatalf("write config: %v", err)
	}

	cfg, err := config.Load(path)
	if err != nil {
		t.Fatalf("Load returned error: %v", err)
	}
	if cfg.WriteSecret != "secret" {
		t.Fatalf("write_secret = %q, want %q", cfg.WriteSecret, "secret")
	}
	if cfg.Addr != ":9090" {
		t.Fatalf("addr = %q, want %q", cfg.Addr, ":9090")
	}
	if cfg.ChartMaxWatts != 750 {
		t.Fatalf("chart_max_watts = %d, want %d", cfg.ChartMaxWatts, 750)
	}
}

func TestHandleWriteRequiresSecret(t *testing.T) {
	srv := server.New("secret", 0, &store.Store{}, embeddedStatic)
	req := httptest.NewRequest(http.MethodPost, "/write", bytes.NewBufferString(`{"watts":456}`))
	req.Header.Set("Content-Type", "application/json")
	rec := httptest.NewRecorder()

	srv.Routes().ServeHTTP(rec, req)

	if rec.Code != http.StatusUnauthorized {
		t.Fatalf("status = %d, want %d", rec.Code, http.StatusUnauthorized)
	}
}

func TestHandleWriteStoresValue(t *testing.T) {
	s := &store.Store{}
	srv := server.New("secret", 0, s, embeddedStatic)
	req := httptest.NewRequest(http.MethodPost, "/write", bytes.NewBufferString(`{"watts":456}`))
	req.Header.Set("Content-Type", "application/json")
	req.Header.Set("X-Secret", "secret")
	rec := httptest.NewRecorder()

	srv.Routes().ServeHTTP(rec, req)

	if rec.Code != http.StatusOK {
		t.Fatalf("status = %d, want %d", rec.Code, http.StatusOK)
	}
	if got := s.Get(); got != 456 {
		t.Fatalf("stored watts = %d, want %d", got, 456)
	}
	if _, updatedAt, _ := s.Snapshot(); updatedAt.IsZero() {
		t.Fatal("updatedAt was not set")
	}
}

func TestBuildHistoryChart(t *testing.T) {
	history := []store.Sample{
		{At: time.Date(2026, 4, 20, 0, 0, 0, 0, time.UTC), Value: 100},
		{At: time.Date(2026, 4, 20, 6, 0, 0, 0, time.UTC), Value: 200},
		{At: time.Date(2026, 4, 20, 12, 0, 0, 0, time.UTC), Value: 150},
	}

	chartHTML := chart.BuildHistoryChart(history, 1000)
	if !strings.Contains(string(chartHTML), "<polyline") {
		t.Fatalf("chart did not contain polyline: %s", string(chartHTML))
	}
	for _, want := range []string{"1.000 W", "00:00", "06:00", "12:00"} {
		if !strings.Contains(string(chartHTML), want) {
			t.Fatalf("chart did not include %q: %s", want, string(chartHTML))
		}
	}
}

func TestLogoServedAsPng(t *testing.T) {
	srv := server.New("secret", 0, &store.Store{}, embeddedStatic)
	req := httptest.NewRequest(http.MethodGet, "/logo.png", nil)
	rec := httptest.NewRecorder()

	srv.Routes().ServeHTTP(rec, req)

	if rec.Code != http.StatusOK {
		t.Fatalf("status = %d, want %d", rec.Code, http.StatusOK)
	}
	if got := rec.Header().Get("Content-Type"); got != "image/png" {
		t.Fatalf("content-type = %q, want image/png", got)
	}
	if _, err := png.Decode(bytes.NewReader(rec.Body.Bytes())); err != nil {
		t.Fatalf("logo is not a valid png: %v", err)
	}
}