package httpx

import (
	"context"
	"encoding/json"
	"log/slog"
	"net"
	"net/http"
	"net/http/httptest"
	"strings"
	"testing"
)

func TestWriteErrorUsesEnvelope(t *testing.T) {
	rec := httptest.NewRecorder()
	WriteError(rec, NewError(CodeNotFound, "no such resource"))

	if rec.Code != http.StatusNotFound {
		t.Fatalf("status = %d, want 404", rec.Code)
	}
	if got := rec.Header().Get("Content-Type"); got != "application/json; charset=utf-8" {
		t.Errorf("Content-Type = %q", got)
	}
	var body struct {
		Error Error `json:"error"`
	}
	if err := json.Unmarshal(rec.Body.Bytes(), &body); err != nil {
		t.Fatalf("decode envelope: %v", err)
	}
	if body.Error.Code != CodeNotFound || body.Error.Message == "" {
		t.Errorf("unexpected error payload: %+v", body.Error)
	}
}

func TestHTTPStatusMapping(t *testing.T) {
	cases := map[ErrorCode]int{
		CodeInternalError:         http.StatusInternalServerError,
		CodeNotFound:              http.StatusNotFound,
		CodeBadRequest:            http.StatusBadRequest,
		CodeRateLimited:           http.StatusTooManyRequests,
		CodeNotReady:              http.StatusServiceUnavailable,
		ErrorCode("unknown.code"): http.StatusInternalServerError,
	}
	for code, want := range cases {
		if got := NewError(code, "").HTTPStatus(); got != want {
			t.Errorf("status for %q = %d, want %d", code, got, want)
		}
	}
}

func TestRequestIDIsGeneratedAndPropagated(t *testing.T) {
	var seen string
	handler := RequestID(http.HandlerFunc(func(_ http.ResponseWriter, r *http.Request) {
		seen = RequestIDFrom(r.Context())
	}))

	rec := httptest.NewRecorder()
	handler.ServeHTTP(rec, httptest.NewRequestWithContext(context.Background(), http.MethodGet, "/", nil))

	if seen == "" {
		t.Fatal("request id is empty inside the handler")
	}
	if rec.Header().Get("X-Request-Id") != seen {
		t.Errorf("header %q does not match context value %q", rec.Header().Get("X-Request-Id"), seen)
	}
}

func TestRequestIDIsReusedFromHeader(t *testing.T) {
	req := httptest.NewRequestWithContext(context.Background(), http.MethodGet, "/", nil)
	req.Header.Set("X-Request-Id", "client-supplied-id")

	rec := httptest.NewRecorder()
	var seen string
	RequestID(http.HandlerFunc(func(_ http.ResponseWriter, r *http.Request) {
		seen = RequestIDFrom(r.Context())
	})).ServeHTTP(rec, req)

	if seen != "client-supplied-id" {
		t.Errorf("request id = %q, want client-supplied-id", seen)
	}
}

func TestRecovererTurnsPanicIntoError(t *testing.T) {
	logger := slog.New(slog.DiscardHandler)
	handler := Recoverer(logger)(http.HandlerFunc(func(http.ResponseWriter, *http.Request) {
		panic("boom")
	}))

	rec := httptest.NewRecorder()
	handler.ServeHTTP(rec, httptest.NewRequestWithContext(context.Background(), http.MethodGet, "/", nil))

	if rec.Code != http.StatusInternalServerError {
		t.Fatalf("status = %d, want 500", rec.Code)
	}
	if !json.Valid(rec.Body.Bytes()) {
		t.Errorf("panic response is not json: %s", rec.Body.String())
	}
}

func TestSecurityHeaders(t *testing.T) {
	rec := httptest.NewRecorder()
	SecurityHeaders("files.example.com")(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
		w.WriteHeader(http.StatusOK)
	})).ServeHTTP(rec, httptest.NewRequestWithContext(context.Background(), http.MethodGet, "/", nil))

	headers := rec.Header()
	for _, name := range []string{"Content-Security-Policy", "Referrer-Policy", "X-Content-Type-Options", "X-Frame-Options", "Cross-Origin-Resource-Policy"} {
		if headers.Get(name) == "" {
			t.Errorf("header %s is missing", name)
		}
	}
	if headers.Get("Strict-Transport-Security") != "" {
		t.Error("HSTS must not be sent over plain http")
	}
}

func TestSecurityHeadersAddHSTSBehindProxy(t *testing.T) {
	req := httptest.NewRequestWithContext(context.Background(), http.MethodGet, "/", nil)
	req.Header.Set("X-Forwarded-Proto", "https")

	rec := httptest.NewRecorder()
	SecurityHeaders("files.example.com")(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
		w.WriteHeader(http.StatusOK)
	})).ServeHTTP(rec, req)

	if rec.Header().Get("Strict-Transport-Security") == "" {
		t.Error("HSTS header is missing for a proxied https request")
	}
}

func TestJSONBodyLimitRejectsOversizedBody(t *testing.T) {
	handler := JSONBodyLimit(16)(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		buf := make([]byte, 64)
		if _, err := r.Body.Read(buf); err != nil {
			WriteErrorStatus(w, http.StatusRequestEntityTooLarge, CodeBadRequest, "too large")
			return
		}
		w.WriteHeader(http.StatusOK)
	}))

	req := httptest.NewRequestWithContext(context.Background(), http.MethodPost, "/", strings.NewReader(strings.Repeat("a", 128)))
	rec := httptest.NewRecorder()
	handler.ServeHTTP(rec, req)

	if rec.Code != http.StatusRequestEntityTooLarge {
		t.Fatalf("status = %d, want 413", rec.Code)
	}
}

func TestClientIPPrefersForwardedForFromTrustedProxy(t *testing.T) {
	_, network, err := net.ParseCIDR("10.0.0.0/8")
	if err != nil {
		t.Fatalf("parse cidr: %v", err)
	}

	req := httptest.NewRequestWithContext(context.Background(), http.MethodGet, "/", nil)
	req.RemoteAddr = "10.0.0.5:1234"
	// Единственный доверенный прокси (Caddy) дописывает клиента в конец цепочки.
	req.Header.Set("X-Forwarded-For", "203.0.113.9, 198.51.100.7")

	if got := ClientIP(req, []*net.IPNet{network}); got != "198.51.100.7" {
		t.Errorf("ClientIP() = %q, want the last hop appended by the trusted proxy", got)
	}
}

func TestClientIPIgnoresForwardedForFromUntrustedPeer(t *testing.T) {
	_, network, err := net.ParseCIDR("10.0.0.0/8")
	if err != nil {
		t.Fatalf("parse cidr: %v", err)
	}

	req := httptest.NewRequestWithContext(context.Background(), http.MethodGet, "/", nil)
	req.RemoteAddr = "198.51.100.7:1234"
	req.Header.Set("X-Forwarded-For", "203.0.113.9")

	if got := ClientIP(req, []*net.IPNet{network}); got != "198.51.100.7" {
		t.Errorf("ClientIP() = %q, want the peer address", got)
	}
}