package probe

import (
	"context"
	"errors"
	"net/http"
	"net/http/httptest"
	"strings"
	"testing"
	"time"
)

// mockHTTPClient records requests and returns configurable responses
type mockHTTPClient struct {
	Resp *http.Response
	Err  error
}

func (m *mockHTTPClient) Do(req *http.Request) (*http.Response, error) {
	// Simulate context cancellation: if the request context is done, return context error
	select {
	case <-req.Context().Done():
		return nil, req.Context().Err()
	default:
	}
	return m.Resp, m.Err
}

func TestProbeExecutor_ExecuteProbe_Success(t *testing.T) {
	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.WriteHeader(http.StatusOK)
		w.Write([]byte(`{"status":"ok"}`))
	}))
	defer server.Close()

	executor := NewProbeExecutor(nil) // nil → uses real http.Client

	outcome, err := executor.ExecuteProbe(context.Background(), ProbeTarget{
		AccountID:   1,
		Platform:   "openai",
		Endpoint:   server.URL,
		AuthHeader: "Bearer test-key",
	})

	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
	if outcome.StatusCode != http.StatusOK {
		t.Fatalf("expected 200, got: %d", outcome.StatusCode)
	}
	if outcome.LatencyMs < 0 {
		t.Fatalf("expected latency >= 0, got: %d", outcome.LatencyMs)
	}
	if outcome.RequestID == "" {
		t.Fatal("expected request_id to be set")
	}
}

func TestProbeExecutor_ExecuteProbe_ExplicitFailure(t *testing.T) {
	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.WriteHeader(http.StatusUnauthorized)
	}))
	defer server.Close()

	executor := NewProbeExecutor(nil)

	outcome, err := executor.ExecuteProbe(context.Background(), ProbeTarget{
		AccountID: 2,
		Platform: "openai",
		Endpoint: server.URL,
	})

	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
	if outcome.StatusCode != http.StatusUnauthorized {
		t.Fatalf("expected 401, got: %d", outcome.StatusCode)
	}
}

func TestProbeExecutor_ExecuteProbe_Inconclusive_429(t *testing.T) {
	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.WriteHeader(http.StatusTooManyRequests)
	}))
	defer server.Close()

	executor := NewProbeExecutor(nil)

	outcome, err := executor.ExecuteProbe(context.Background(), ProbeTarget{
		AccountID: 3,
		Platform: "openai",
		Endpoint: server.URL,
	})

	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
	if outcome.StatusCode != http.StatusTooManyRequests {
		t.Fatalf("expected 429, got: %d", outcome.StatusCode)
	}
}

func TestProbeExecutor_ExecuteProbe_TransportError(t *testing.T) {
	client := &mockHTTPClient{
		Err: errors.New("connection refused"),
	}
	executor := NewProbeExecutor(client)

	outcome, err := executor.ExecuteProbe(context.Background(), ProbeTarget{
		AccountID: 4,
		Platform: "openai",
		Endpoint: "http://localhost:9999",
	})

	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
	if outcome.TransportError == nil {
		t.Fatal("expected transport error to be set")
	}
	if outcome.StatusCode != 0 {
		t.Fatalf("expected status 0 on transport error, got: %d", outcome.StatusCode)
	}
}

func TestProbeExecutor_ExecuteProbe_InvalidTarget(t *testing.T) {
	executor := NewProbeExecutor(nil)

	_, err := executor.ExecuteProbe(context.Background(), ProbeTarget{
		AccountID: 5,
		Platform: "openai",
		Endpoint: "", // empty endpoint
	})

	if err == nil {
		t.Fatal("expected error for empty endpoint")
	}
}

func TestProbeExecutor_ExecuteProbe_ContextCanceled(t *testing.T) {
	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		time.Sleep(5 * time.Second) // delay longer than context
		w.WriteHeader(http.StatusOK)
	}))
	defer server.Close()

	executor := NewProbeExecutor(nil)

	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Millisecond)
	defer cancel()

	outcome, err := executor.ExecuteProbe(ctx, ProbeTarget{
		AccountID: 6,
		Platform: "openai",
		Endpoint: server.URL,
	})

	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
	if outcome.TransportError == nil {
		t.Fatal("expected context deadline exceeded transport error")
	}
}

func TestProbeExecutor_ExecuteProbe_ResponseBodyTruncated(t *testing.T) {
	largeBody := strings.Repeat("x", 10*1024) // 10KB
	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.WriteHeader(http.StatusOK)
		w.Write([]byte(largeBody))
	}))
	defer server.Close()

	executor := NewProbeExecutor(nil)

	outcome, err := executor.ExecuteProbe(context.Background(), ProbeTarget{
		AccountID: 7,
		Platform: "openai",
		Endpoint: server.URL,
	})

	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
	if len(outcome.ResponseBody) > 1024 {
		t.Fatalf("expected body truncated to <=1024, got: %d", len(outcome.ResponseBody))
	}
}

func TestProbeExecutor_SetsUserAgentAndAcceptHeader(t *testing.T) {
	var receivedHeaders http.Header
	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		receivedHeaders = r.Header.Clone()
		w.WriteHeader(http.StatusOK)
	}))
	defer server.Close()

	executor := NewProbeExecutor(nil)

	_, _ = executor.ExecuteProbe(context.Background(), ProbeTarget{
		AccountID:   8,
		Platform:   "openai",
		Endpoint:   server.URL,
		AuthHeader: "Bearer my-key",
	})

	if receivedHeaders == nil {
		t.Fatal("server handler was not called — check test setup")
	}
	if receivedHeaders.Get("User-Agent") == "" {
		t.Fatal("expected User-Agent header to be set")
	}
	if receivedHeaders.Get("Accept") != "application/json" {
		t.Fatalf("expected Accept: application/json, got: %s", receivedHeaders.Get("Accept"))
	}
	if receivedHeaders.Get("Authorization") != "Bearer my-key" {
		t.Fatalf("expected Authorization header to be set")
	}
}