package handlers_test

import (
	"bytes"
	"encoding/json"
	"errors"
	"io"
	"log/slog"
	"net/http"
	"net/http/httptest"
	"strings"
	"testing"

	"sneak.berlin/go/netwatch/internal/handlers"
	"sneak.berlin/go/netwatch/internal/logger"
	"sneak.berlin/go/netwatch/internal/middleware"
	"sneak.berlin/go/netwatch/internal/reportbuf"
)

var errStorageFailed = errors.New("storage failed")

// stubAppender drives the storage success/failure path without a
// real buffer or disk.
type stubAppender struct {
	err error
}

func (s stubAppender) Append(any) error { return s.err }

func newTestHandlers(buf stubAppender, out io.Writer) *handlers.Handlers {
	return handlers.NewForTest(buf, slog.New(slog.NewJSONHandler(out, nil)))
}

func decodeStatus(t *testing.T, body []byte) string {
	t.Helper()

	var resp struct {
		Status string `json:"status"`
	}

	err := json.Unmarshal(body, &resp)
	if err != nil {
		t.Fatalf("response body not JSON: %v (%q)", err, body)
	}

	return resp.Status
}

func TestHandleReportStorageFailureIsNon2xx(t *testing.T) {
	t.Parallel()

	h := newTestHandlers(stubAppender{err: errStorageFailed}, io.Discard)

	rec := httptest.NewRecorder()
	req := httptest.NewRequestWithContext(t.Context(),
		http.MethodPost, "/api/v1/reports",
		strings.NewReader(`{"clientId":"c1","hosts":[]}`),
	)

	h.HandleReport().ServeHTTP(rec, req)

	if rec.Code < 500 {
		t.Fatalf("storage failure status = %d, want a 5xx", rec.Code)
	}

	if got := decodeStatus(t, rec.Body.Bytes()); got != "error" {
		t.Fatalf("status field = %q, want %q", got, "error")
	}
}

// TestHandleReportFullIs507 checks the answer when the report files
// are at their size cap: 507 and the usual error body, which tells
// the client nothing more.
func TestHandleReportFullIs507(t *testing.T) {
	t.Parallel()

	h := newTestHandlers(stubAppender{err: reportbuf.ErrFull}, io.Discard)

	rec := httptest.NewRecorder()
	req := httptest.NewRequestWithContext(t.Context(),
		http.MethodPost, "/api/v1/reports",
		strings.NewReader(`{"clientId":"c1","hosts":[]}`),
	)

	h.HandleReport().ServeHTTP(rec, req)

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

	if got := rec.Body.String(); got != "{\"status\":\"error\"}\n" {
		t.Errorf("body = %q, want %q", got, "{\"status\":\"error\"}\n")
	}
}

func TestHandleReportMalformedJSONIs400(t *testing.T) {
	t.Parallel()

	h := newTestHandlers(stubAppender{}, io.Discard)

	rec := httptest.NewRecorder()
	req := httptest.NewRequestWithContext(t.Context(),
		http.MethodPost, "/api/v1/reports",
		strings.NewReader(`{not json`),
	)

	h.HandleReport().ServeHTTP(rec, req)

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

func TestHandleReportOversizeIs413(t *testing.T) {
	t.Parallel()

	const limit = 32

	h := newTestHandlers(stubAppender{}, io.Discard)
	handler := (&middleware.Middleware{}).MaxBodyBytes(limit)(
		h.HandleReport(),
	)

	rec := httptest.NewRecorder()
	req := httptest.NewRequestWithContext(t.Context(),
		http.MethodPost, "/api/v1/reports",
		strings.NewReader(`{"clientId":"`+strings.Repeat("x", 200)+`"}`),
	)
	// No declared length, so only the middleware's read cap can
	// stop this body.
	req.ContentLength = -1

	handler.ServeHTTP(rec, req)

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

func TestHandleReportDoesNotLogRawGeo(t *testing.T) {
	t.Parallel()

	const sentinel = "SENSITIVE-GEO-BLOB"

	var logbuf bytes.Buffer

	h := newTestHandlers(stubAppender{}, &logbuf)

	rec := httptest.NewRecorder()
	req := httptest.NewRequestWithContext(t.Context(),
		http.MethodPost, "/api/v1/reports",
		strings.NewReader(
			`{"clientId":"c1","geo":{"raw":"`+sentinel+`"},"hosts":[]}`,
		),
	)

	h.HandleReport().ServeHTTP(rec, req)

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

	if strings.Contains(logbuf.String(), sentinel) {
		t.Fatal("raw geo bytes were written to the log")
	}

	if !strings.Contains(logbuf.String(), "geo_bytes") {
		t.Fatal("expected a bounded geo_bytes field in the log")
	}
}

func TestHandleReportLogsClientIDCutToBound(t *testing.T) {
	t.Parallel()

	long := strings.Repeat("c", 2*logger.MaxLoggedFieldBytes)

	var logbuf bytes.Buffer

	h := newTestHandlers(stubAppender{}, &logbuf)

	rec := httptest.NewRecorder()
	req := httptest.NewRequestWithContext(t.Context(),
		http.MethodPost, "/api/v1/reports",
		strings.NewReader(
			`{"clientId":"`+long+`","timestamp":"`+long+`","hosts":[]}`,
		),
	)

	h.HandleReport().ServeHTTP(rec, req)

	var logged map[string]any

	err := json.Unmarshal(logbuf.Bytes(), &logged)
	if err != nil {
		t.Fatalf("log line not JSON: %v (%q)", err, logbuf.String())
	}

	want := long[:logger.MaxLoggedFieldBytes]

	if logged["client_id"] != want {
		t.Fatalf("logged client_id not cut to %d bytes: %q",
			logger.MaxLoggedFieldBytes, logged["client_id"])
	}

	if logged["timestamp"] != want {
		t.Fatalf("logged timestamp not cut to %d bytes: %q",
			logger.MaxLoggedFieldBytes, logged["timestamp"])
	}
}

func TestHandleReportDecodeErrorLogIsBounded(t *testing.T) {
	t.Parallel()

	// A number too large for its int64 field makes the decoder's
	// error text quote the whole number.
	huge := strings.Repeat("9", 2*logger.MaxLoggedFieldBytes)

	var logbuf bytes.Buffer

	h := newTestHandlers(stubAppender{}, &logbuf)

	rec := httptest.NewRecorder()
	req := httptest.NewRequestWithContext(t.Context(),
		http.MethodPost, "/api/v1/reports",
		strings.NewReader(`{"hosts":[{"history":[{"t":`+huge+`}]}]}`),
	)

	h.HandleReport().ServeHTTP(rec, req)

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

	if strings.Contains(logbuf.String(), huge) {
		t.Fatal("the whole oversized number was written to the log")
	}
}