package ratelimit

import (
	"errors"
	"net/http"
	"net/http/httptest"
	"testing"
	"time"

	"github.com/labstack/echo/v4"
)

func TestAllowsRequestsWithinWindow(t *testing.T) {
	e := echo.New()
	now := time.Date(2026, 4, 13, 12, 0, 0, 0, time.UTC)

	mw := WithConfig(Config{
		Limit:      2,
		Window:     time.Minute,
		SetHeaders: true,
		now: func() time.Time {
			return now
		},
	})

	handler := mw(func(c echo.Context) error {
		return c.String(http.StatusOK, "ok")
	})

	rec1 := performRequest(e, handler, "203.0.113.1")
	if rec1.Code != http.StatusOK {
		t.Fatalf("first request status = %d", rec1.Code)
	}
	if got := rec1.Header().Get("X-RateLimit-Remaining"); got != "1" {
		t.Fatalf("first remaining = %q", got)
	}

	rec2 := performRequest(e, handler, "203.0.113.1")
	if rec2.Code != http.StatusOK {
		t.Fatalf("second request status = %d", rec2.Code)
	}
	if got := rec2.Header().Get("X-RateLimit-Remaining"); got != "0" {
		t.Fatalf("second remaining = %q", got)
	}
}

func TestHeadersEnabledByDefault(t *testing.T) {
	e := echo.New()
	now := time.Date(2026, 4, 13, 12, 0, 0, 0, time.UTC)

	mw := WithConfig(Config{
		Limit:  1,
		Window: time.Minute,
		now: func() time.Time {
			return now
		},
	})

	handler := mw(func(c echo.Context) error {
		return c.NoContent(http.StatusOK)
	})

	rec := performRequest(e, handler, "203.0.113.20")
	if got := rec.Header().Get("X-RateLimit-Limit"); got != "1" {
		t.Fatalf("limit header = %q", got)
	}
}

func TestDeniesRequestsOverLimit(t *testing.T) {
	e := echo.New()
	now := time.Date(2026, 4, 13, 12, 0, 0, 0, time.UTC)

	mw := WithConfig(Config{
		Limit:      1,
		Window:     30 * time.Second,
		SetHeaders: true,
		now: func() time.Time {
			return now
		},
	})

	handler := mw(func(c echo.Context) error {
		return c.NoContent(http.StatusOK)
	})

	_ = performRequest(e, handler, "203.0.113.10")
	rec := performRequest(e, handler, "203.0.113.10")

	if rec.Code != http.StatusTooManyRequests {
		t.Fatalf("status = %d", rec.Code)
	}
	if got := rec.Header().Get("Retry-After"); got != "30" {
		t.Fatalf("retry-after = %q", got)
	}
}

func TestWindowResets(t *testing.T) {
	e := echo.New()
	now := time.Date(2026, 4, 13, 12, 0, 0, 0, time.UTC)

	mw := WithConfig(Config{
		Limit:  1,
		Window: 10 * time.Second,
		now: func() time.Time {
			return now
		},
	})

	handler := mw(func(c echo.Context) error {
		return c.NoContent(http.StatusOK)
	})

	rec1 := performRequest(e, handler, "198.51.100.1")
	if rec1.Code != http.StatusOK {
		t.Fatalf("first status = %d", rec1.Code)
	}

	rec2 := performRequest(e, handler, "198.51.100.1")
	if rec2.Code != http.StatusTooManyRequests {
		t.Fatalf("second status = %d", rec2.Code)
	}

	now = now.Add(11 * time.Second)
	rec3 := performRequest(e, handler, "198.51.100.1")
	if rec3.Code != http.StatusOK {
		t.Fatalf("third status = %d", rec3.Code)
	}
}

func TestSkipperBypassesLimiter(t *testing.T) {
	e := echo.New()
	mw := WithConfig(Config{
		Limit:  1,
		Window: time.Minute,
		Skipper: func(c echo.Context) bool {
			return c.Path() == "/health"
		},
	})

	handler := mw(func(c echo.Context) error {
		return c.NoContent(http.StatusOK)
	})

	rec1 := performRequestWithPath(e, handler, "203.0.113.5", "/health")
	rec2 := performRequestWithPath(e, handler, "203.0.113.5", "/health")
	if rec1.Code != http.StatusOK || rec2.Code != http.StatusOK {
		t.Fatalf("skipped requests should both pass: %d %d", rec1.Code, rec2.Code)
	}
}

func TestRealIPErrorsPropagate(t *testing.T) {
	e := echo.New()
	expected := errors.New("boom")

	mw := WithConfig(Config{
		Limit:  1,
		Window: time.Minute,
		ErrorHandler: func(_ echo.Context, err error) error {
			if err == nil {
				t.Fatal("expected error")
			}
			return expected
		},
	})

	handler := mw(func(c echo.Context) error {
		return c.NoContent(http.StatusOK)
	})

	req := httptest.NewRequest(http.MethodGet, "/", nil)
	req.RemoteAddr = ":1234"
	rec := httptest.NewRecorder()
	c := e.NewContext(req, rec)

	err := handler(c)
	if !errors.Is(err, expected) {
		t.Fatalf("error = %v", err)
	}
}

func performRequest(e *echo.Echo, h echo.HandlerFunc, ip string) *httptest.ResponseRecorder {
	return performRequestWithPath(e, h, ip, "/")
}

func performRequestWithPath(e *echo.Echo, h echo.HandlerFunc, ip, path string) *httptest.ResponseRecorder {
	req := httptest.NewRequest(http.MethodGet, path, nil)
	req.RemoteAddr = ip + ":1234"
	rec := httptest.NewRecorder()
	c := e.NewContext(req, rec)
	c.SetPath(path)

	err := h(c)
	if err != nil {
		e.HTTPErrorHandler(err, c)
	}

	return rec
}