package asnresolve

import (
	"compress/gzip"
	"context"
	"errors"
	"io"
	"net/http"
	"net/http/httptest"
	"strings"
	"testing"
	"time"

	"evobgp/internal/httpclient"
)

type ripeRoundTrip func(*http.Request) (*http.Response, error)

func (f ripeRoundTrip) RoundTrip(r *http.Request) (*http.Response, error) { return f(r) }

type ripeCountingBody struct {
	io.Reader
	read   int
	closed bool
}

func (b *ripeCountingBody) Read(p []byte) (int, error) {
	n, e := b.Reader.Read(p)
	b.read += n
	return n, e
}
func (b *ripeCountingBody) Close() error { b.closed = true; return nil }

func TestRIPECompleteResponseLimits(t *testing.T) {
	cases := []struct {
		name   string
		limit  int
		prefix string
		call   func(context.Context, *http.Client) error
	}{
		{"announced", 32 << 20, `{"status":"ok","data":{"prefixes":[]}}`, func(ctx context.Context, hc *http.Client) error { _, e := AnnouncedPrefixes(ctx, hc, 64496); return e }},
		{"holder", 4 << 20, `{"status":"ok","data":{"holder":"Example"}}`, func(ctx context.Context, hc *http.Client) error { _, e := ASHolderName(ctx, hc, 64496); return e }},
	}
	for _, tc := range cases {
		t.Run(tc.name, func(t *testing.T) {
			for _, known := range []bool{true, false} {
				for _, extra := range []int{0, 1} {
					body := &ripeCountingBody{Reader: strings.NewReader(tc.prefix + strings.Repeat(" ", tc.limit-len(tc.prefix)+extra))}
					hc := &http.Client{Transport: ripeRoundTrip(func(r *http.Request) (*http.Response, error) {
						if _, ok := r.Context().Deadline(); !ok {
							t.Error("missing request deadline")
						}
						length := int64(-1)
						if known {
							length = int64(tc.limit + extra)
						}
						return &http.Response{StatusCode: 200, Body: body, ContentLength: length, Header: make(http.Header)}, nil
					})}
					err := tc.call(context.Background(), hc)
					if extra == 0 && err != nil {
						t.Fatalf("exact limit rejected known=%v: %v", known, err)
					}
					if extra == 1 && !errors.Is(err, httpclient.ErrResponseTooLarge) {
						t.Fatalf("oversized valid prefix accepted known=%v: %v", known, err)
					}
					if body.read > tc.limit+1 || !body.closed {
						t.Fatalf("read=%d closed=%v", body.read, body.closed)
					}
				}
			}
		})
	}
}

func TestRIPEErrorBodySmallAndContextPreserved(t *testing.T) {
	body := &ripeCountingBody{Reader: strings.NewReader(strings.Repeat("x", 1<<20))}
	hc := &http.Client{Transport: ripeRoundTrip(func(*http.Request) (*http.Response, error) {
		return &http.Response{StatusCode: 400, Status: "400 Bad Request", Body: body, Header: make(http.Header)}, nil
	})}
	if _, err := AnnouncedPrefixes(context.Background(), hc, 1); err == nil || body.read > 4<<10 || !body.closed {
		t.Fatalf("non200 unbounded read=%d close=%v err=%v", body.read, body.closed, err)
	}
	ctx, cancel := context.WithTimeout(context.Background(), 20*time.Millisecond)
	defer cancel()
	hc.Transport = ripeRoundTrip(func(r *http.Request) (*http.Response, error) { <-r.Context().Done(); return nil, r.Context().Err() })
	if _, err := ASHolderName(ctx, hc, 1); !errors.Is(err, context.DeadlineExceeded) {
		t.Fatalf("caller deadline lost: %v", err)
	}
}

func TestRIPEGzipExpandedLimit(t *testing.T) {
	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("Content-Encoding", "gzip")
		gz := gzip.NewWriter(w)
		_, _ = io.WriteString(gz, `{"status":"ok","data":{"holder":"Example"}}`+strings.Repeat(" ", 4<<20))
		_ = gz.Close()
	}))
	defer server.Close()
	t.Setenv("EVOBGP_RIPESTAT_AS_OVERVIEW_URL", server.URL)
	if _, err := ASHolderName(context.Background(), server.Client(), 1); !errors.Is(err, httpclient.ErrResponseTooLarge) {
		t.Fatalf("gzip bypassed decoded limit: %v", err)
	}
}