package mcp

import (
	"bytes"
	"encoding/json"
	"io"
	"log"
	"net/http"
	"net/http/httptest"
	"strings"
	"testing"
	"time"
)

// testHTTPTransport creates a transport with a test server
func testHTTPTransport(t *testing.T, config HTTPConfig) (*HTTPTransport, *httptest.Server) {
	// Use a mock store
	server := NewServer(nil, log.New(io.Discard, "", 0))

	if config.SessionTTL == 0 {
		config.SessionTTL = 30 * time.Minute
	}
	transport := NewHTTPTransport(server, config)

	// Create test server
	mux := http.NewServeMux()
	endpoint := config.Endpoint
	if endpoint == "" {
		endpoint = "/mcp"
	}
	mux.HandleFunc(endpoint, transport.handleMCP)

	ts := httptest.NewServer(mux)
	t.Cleanup(func() {
		ts.Close()
		transport.sessions.Stop()
	})

	return transport, ts
}

func TestHTTPTransportInitialize(t *testing.T) {
	_, ts := testHTTPTransport(t, HTTPConfig{})

	// Send initialize request
	initReq := Request{
		JSONRPC: "2.0",
		ID:      1,
		Method:  MethodInitialize,
		Params:  json.RawMessage(`{"protocolVersion":"2024-11-05","capabilities":{},"clientInfo":{"name":"test","version":"1.0"}}`),
	}
	body, _ := json.Marshal(initReq)

	req, _ := http.NewRequest("POST", ts.URL+"/mcp", bytes.NewReader(body))
	req.Header.Set("Content-Type", "application/json")
	req.Header.Set("Accept", "application/json")

	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		t.Fatalf("Request failed: %v", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		t.Errorf("Expected 200, got %d", resp.StatusCode)
	}

	// Check session ID header
	sessionID := resp.Header.Get("Mcp-Session-Id")
	if sessionID == "" {
		t.Error("Expected Mcp-Session-Id header")
	}
	if len(sessionID) != 32 {
		t.Errorf("Session ID should be 32 chars, got %d", len(sessionID))
	}

	// Check response body
	var initResp Response
	if err := json.NewDecoder(resp.Body).Decode(&initResp); err != nil {
		t.Fatalf("Failed to decode response: %v", err)
	}

	if initResp.Error != nil {
		t.Errorf("Initialize failed: %v", initResp.Error)
	}
}

func TestHTTPTransportSessionRequired(t *testing.T) {
	_, ts := testHTTPTransport(t, HTTPConfig{})

	// Send tools/list without session
	listReq := Request{
		JSONRPC: "2.0",
		ID:      1,
		Method:  MethodToolsList,
	}
	body, _ := json.Marshal(listReq)

	req, _ := http.NewRequest("POST", ts.URL+"/mcp", bytes.NewReader(body))
	req.Header.Set("Content-Type", "application/json")

	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		t.Fatalf("Request failed: %v", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusBadRequest {
		t.Errorf("Expected 400 without session, got %d", resp.StatusCode)
	}
}

func TestHTTPTransportInvalidSession(t *testing.T) {
	_, ts := testHTTPTransport(t, HTTPConfig{})

	// Send request with invalid session
	listReq := Request{
		JSONRPC: "2.0",
		ID:      1,
		Method:  MethodToolsList,
	}
	body, _ := json.Marshal(listReq)

	req, _ := http.NewRequest("POST", ts.URL+"/mcp", bytes.NewReader(body))
	req.Header.Set("Content-Type", "application/json")
	req.Header.Set("Mcp-Session-Id", "invalid-session-id")

	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		t.Fatalf("Request failed: %v", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusNotFound {
		t.Errorf("Expected 404 for invalid session, got %d", resp.StatusCode)
	}
}

func TestHTTPTransportValidSession(t *testing.T) {
	transport, ts := testHTTPTransport(t, HTTPConfig{})

	// Create session manually
	session, _ := transport.sessions.Create()

	// Send tools/list with valid session
	listReq := Request{
		JSONRPC: "2.0",
		ID:      1,
		Method:  MethodToolsList,
	}
	body, _ := json.Marshal(listReq)

	req, _ := http.NewRequest("POST", ts.URL+"/mcp", bytes.NewReader(body))
	req.Header.Set("Content-Type", "application/json")
	req.Header.Set("Mcp-Session-Id", session.ID)

	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		t.Fatalf("Request failed: %v", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		t.Errorf("Expected 200 with valid session, got %d", resp.StatusCode)
	}
}

func TestHTTPTransportNotificationAccepted(t *testing.T) {
	transport, ts := testHTTPTransport(t, HTTPConfig{})

	session, _ := transport.sessions.Create()

	// Send notification (no ID)
	notification := Request{
		JSONRPC: "2.0",
		Method:  MethodInitialized,
	}
	body, _ := json.Marshal(notification)

	req, _ := http.NewRequest("POST", ts.URL+"/mcp", bytes.NewReader(body))
	req.Header.Set("Content-Type", "application/json")
	req.Header.Set("Mcp-Session-Id", session.ID)

	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		t.Fatalf("Request failed: %v", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusAccepted {
		t.Errorf("Expected 202 for notification, got %d", resp.StatusCode)
	}

	// Verify session is marked as initialized
	if !session.IsInitialized() {
		t.Error("Session should be marked as initialized")
	}
}

func TestHTTPTransportDeleteSession(t *testing.T) {
	transport, ts := testHTTPTransport(t, HTTPConfig{})

	session, _ := transport.sessions.Create()

	// Delete session
	req, _ := http.NewRequest("DELETE", ts.URL+"/mcp", nil)
	req.Header.Set("Mcp-Session-Id", session.ID)

	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		t.Fatalf("Request failed: %v", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusNoContent {
		t.Errorf("Expected 204 for delete, got %d", resp.StatusCode)
	}

	// Verify session is gone
	if transport.sessions.Get(session.ID) != nil {
		t.Error("Session should be deleted")
	}
}

func TestHTTPTransportDeleteNonexistentSession(t *testing.T) {
	_, ts := testHTTPTransport(t, HTTPConfig{})

	req, _ := http.NewRequest("DELETE", ts.URL+"/mcp", nil)
	req.Header.Set("Mcp-Session-Id", "nonexistent")

	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		t.Fatalf("Request failed: %v", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusNotFound {
		t.Errorf("Expected 404 for nonexistent session, got %d", resp.StatusCode)
	}
}

func TestHTTPTransportOriginValidation(t *testing.T) {
	tests := []struct {
		name           string
		allowedOrigins []string
		origin         string
		expectAllowed  bool
	}{
		{
			name:           "no origin header",
			allowedOrigins: nil,
			origin:         "",
			expectAllowed:  true,
		},
		{
			name:           "localhost allowed by default",
			allowedOrigins: nil,
			origin:         "http://localhost:3000",
			expectAllowed:  true,
		},
		{
			name:           "127.0.0.1 allowed by default",
			allowedOrigins: nil,
			origin:         "http://127.0.0.1:8080",
			expectAllowed:  true,
		},
		{
			name:           "external origin blocked by default",
			allowedOrigins: nil,
			origin:         "http://evil.com",
			expectAllowed:  false,
		},
		{
			name:           "explicit allow",
			allowedOrigins: []string{"http://example.com"},
			origin:         "http://example.com",
			expectAllowed:  true,
		},
		{
			name:           "explicit allow wildcard",
			allowedOrigins: []string{"*"},
			origin:         "http://anything.com",
			expectAllowed:  true,
		},
		{
			name:           "not in allowed list",
			allowedOrigins: []string{"http://example.com"},
			origin:         "http://other.com",
			expectAllowed:  false,
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			_, ts := testHTTPTransport(t, HTTPConfig{
				AllowedOrigins: tt.allowedOrigins,
			})

			// Use initialize since it doesn't require a session
			initReq := Request{
				JSONRPC: "2.0",
				ID:      1,
				Method:  MethodInitialize,
				Params:  json.RawMessage(`{"protocolVersion":"2024-11-05","capabilities":{},"clientInfo":{"name":"test","version":"1.0"}}`),
			}
			body, _ := json.Marshal(initReq)

			req, _ := http.NewRequest("POST", ts.URL+"/mcp", bytes.NewReader(body))
			req.Header.Set("Content-Type", "application/json")
			if tt.origin != "" {
				req.Header.Set("Origin", tt.origin)
			}

			resp, err := http.DefaultClient.Do(req)
			if err != nil {
				t.Fatalf("Request failed: %v", err)
			}
			defer resp.Body.Close()

			if tt.expectAllowed && resp.StatusCode == http.StatusForbidden {
				t.Error("Expected request to be allowed but was forbidden")
			}
			if !tt.expectAllowed && resp.StatusCode != http.StatusForbidden {
				t.Errorf("Expected request to be forbidden but got status %d", resp.StatusCode)
			}
		})
	}
}

func TestHTTPTransportSSERequiresAcceptHeader(t *testing.T) {
	transport, ts := testHTTPTransport(t, HTTPConfig{})

	session, _ := transport.sessions.Create()

	// GET without Accept: text/event-stream
	req, _ := http.NewRequest("GET", ts.URL+"/mcp", nil)
	req.Header.Set("Mcp-Session-Id", session.ID)

	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		t.Fatalf("Request failed: %v", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusNotAcceptable {
		t.Errorf("Expected 406 without Accept header, got %d", resp.StatusCode)
	}
}

func TestHTTPTransportSSEStream(t *testing.T) {
	transport, ts := testHTTPTransport(t, HTTPConfig{})

	session, _ := transport.sessions.Create()

	// Start SSE stream in goroutine
	req, _ := http.NewRequest("GET", ts.URL+"/mcp", nil)
	req.Header.Set("Mcp-Session-Id", session.ID)
	req.Header.Set("Accept", "text/event-stream")

	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		t.Fatalf("Request failed: %v", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		t.Fatalf("Expected 200, got %d", resp.StatusCode)
	}

	contentType := resp.Header.Get("Content-Type")
	if contentType != "text/event-stream" {
		t.Errorf("Expected Content-Type text/event-stream, got %s", contentType)
	}

	// Send a notification
	notification := &Response{
		JSONRPC: "2.0",
		ID:      42,
		Result:  map[string]string{"test": "data"},
	}
	session.SendNotification(notification)

	// Read the SSE event
	buf := make([]byte, 1024)
	n, err := resp.Body.Read(buf)
	if err != nil && err != io.EOF {
		t.Fatalf("Failed to read SSE event: %v", err)
	}

	data := string(buf[:n])
	if !strings.HasPrefix(data, "data: ") {
		t.Errorf("Expected SSE data event, got: %s", data)
	}

	// Parse the JSON from the SSE event
	jsonData := strings.TrimPrefix(strings.TrimSuffix(data, "\n\n"), "data: ")
	var received Response
	if err := json.Unmarshal([]byte(jsonData), &received); err != nil {
		t.Fatalf("Failed to parse notification JSON: %v", err)
	}

	// JSON unmarshal converts numbers to float64, so compare as float64
	receivedID, ok := received.ID.(float64)
	if !ok {
		t.Fatalf("Expected numeric ID, got %T", received.ID)
	}
	if int(receivedID) != 42 {
		t.Errorf("Expected notification ID 42, got %v", receivedID)
	}
}

func TestHTTPTransportParseError(t *testing.T) {
	_, ts := testHTTPTransport(t, HTTPConfig{})

	// Send invalid JSON
	req, _ := http.NewRequest("POST", ts.URL+"/mcp", bytes.NewReader([]byte("not json")))
	req.Header.Set("Content-Type", "application/json")

	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		t.Fatalf("Request failed: %v", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		t.Errorf("Expected 200 (with JSON-RPC error), got %d", resp.StatusCode)
	}

	var jsonResp Response
	if err := json.NewDecoder(resp.Body).Decode(&jsonResp); err != nil {
		t.Fatalf("Failed to decode response: %v", err)
	}

	if jsonResp.Error == nil {
		t.Error("Expected JSON-RPC error for parse error")
	}
	if jsonResp.Error != nil && jsonResp.Error.Code != ParseError {
		t.Errorf("Expected parse error code %d, got %d", ParseError, jsonResp.Error.Code)
	}
}

func TestHTTPTransportMethodNotAllowed(t *testing.T) {
	_, ts := testHTTPTransport(t, HTTPConfig{})

	req, _ := http.NewRequest("PUT", ts.URL+"/mcp", nil)

	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		t.Fatalf("Request failed: %v", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusMethodNotAllowed {
		t.Errorf("Expected 405, got %d", resp.StatusCode)
	}
}

func TestHTTPTransportOptionsRequest(t *testing.T) {
	_, ts := testHTTPTransport(t, HTTPConfig{
		AllowedOrigins: []string{"http://example.com"},
	})

	req, _ := http.NewRequest("OPTIONS", ts.URL+"/mcp", nil)
	req.Header.Set("Origin", "http://example.com")

	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		t.Fatalf("Request failed: %v", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusNoContent {
		t.Errorf("Expected 204, got %d", resp.StatusCode)
	}

	if resp.Header.Get("Access-Control-Allow-Origin") != "http://example.com" {
		t.Error("Expected CORS origin header")
	}
	if resp.Header.Get("Access-Control-Allow-Methods") == "" {
		t.Error("Expected CORS methods header")
	}
}

func TestHTTPTransportDefaultConfig(t *testing.T) {
	server := NewServer(nil, log.New(io.Discard, "", 0))
	transport := NewHTTPTransport(server, HTTPConfig{})

	// Verify defaults are applied
	if transport.config.Address != "127.0.0.1:8080" {
		t.Errorf("Expected default address 127.0.0.1:8080, got %s", transport.config.Address)
	}
	if transport.config.Endpoint != "/mcp" {
		t.Errorf("Expected default endpoint /mcp, got %s", transport.config.Endpoint)
	}
	if transport.config.SessionTTL != 30*time.Minute {
		t.Errorf("Expected default session TTL 30m, got %v", transport.config.SessionTTL)
	}
	if transport.config.MaxRequestSize != DefaultMaxRequestSize {
		t.Errorf("Expected default max request size %d, got %d", DefaultMaxRequestSize, transport.config.MaxRequestSize)
	}
	if transport.config.ReadTimeout != DefaultReadTimeout {
		t.Errorf("Expected default read timeout %v, got %v", DefaultReadTimeout, transport.config.ReadTimeout)
	}
	if transport.config.WriteTimeout != DefaultWriteTimeout {
		t.Errorf("Expected default write timeout %v, got %v", DefaultWriteTimeout, transport.config.WriteTimeout)
	}
	if transport.config.IdleTimeout != DefaultIdleTimeout {
		t.Errorf("Expected default idle timeout %v, got %v", DefaultIdleTimeout, transport.config.IdleTimeout)
	}
	if transport.config.ReadHeaderTimeout != DefaultReadHeaderTimeout {
		t.Errorf("Expected default read header timeout %v, got %v", DefaultReadHeaderTimeout, transport.config.ReadHeaderTimeout)
	}

	transport.sessions.Stop()
}

func TestHTTPTransportCustomConfig(t *testing.T) {
	server := NewServer(nil, log.New(io.Discard, "", 0))
	config := HTTPConfig{
		Address:           "0.0.0.0:9090",
		Endpoint:          "/api/mcp",
		SessionTTL:        1 * time.Hour,
		MaxRequestSize:    5 << 20, // 5MB
		ReadTimeout:       60 * time.Second,
		WriteTimeout:      60 * time.Second,
		IdleTimeout:       300 * time.Second,
		ReadHeaderTimeout: 20 * time.Second,
	}
	transport := NewHTTPTransport(server, config)

	// Verify custom values are preserved
	if transport.config.Address != "0.0.0.0:9090" {
		t.Errorf("Expected custom address, got %s", transport.config.Address)
	}
	if transport.config.Endpoint != "/api/mcp" {
		t.Errorf("Expected custom endpoint, got %s", transport.config.Endpoint)
	}
	if transport.config.SessionTTL != 1*time.Hour {
		t.Errorf("Expected custom session TTL, got %v", transport.config.SessionTTL)
	}
	if transport.config.MaxRequestSize != 5<<20 {
		t.Errorf("Expected custom max request size, got %d", transport.config.MaxRequestSize)
	}
	if transport.config.ReadTimeout != 60*time.Second {
		t.Errorf("Expected custom read timeout, got %v", transport.config.ReadTimeout)
	}
	if transport.config.WriteTimeout != 60*time.Second {
		t.Errorf("Expected custom write timeout, got %v", transport.config.WriteTimeout)
	}
	if transport.config.IdleTimeout != 300*time.Second {
		t.Errorf("Expected custom idle timeout, got %v", transport.config.IdleTimeout)
	}
	if transport.config.ReadHeaderTimeout != 20*time.Second {
		t.Errorf("Expected custom read header timeout, got %v", transport.config.ReadHeaderTimeout)
	}

	transport.sessions.Stop()
}

func TestHTTPTransportRequestBodyTooLarge(t *testing.T) {
	_, ts := testHTTPTransport(t, HTTPConfig{
		MaxRequestSize: 100, // Very small limit for testing
	})

	// Create a request body larger than the limit
	largeBody := make([]byte, 200)
	for i := range largeBody {
		largeBody[i] = 'x'
	}

	req, _ := http.NewRequest("POST", ts.URL+"/mcp", bytes.NewReader(largeBody))
	req.Header.Set("Content-Type", "application/json")

	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		t.Fatalf("Request failed: %v", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusRequestEntityTooLarge {
		t.Errorf("Expected 413 for oversized request, got %d", resp.StatusCode)
	}
}

func TestHTTPTransportRequestBodyWithinLimit(t *testing.T) {
	_, ts := testHTTPTransport(t, HTTPConfig{
		MaxRequestSize: 10000, // Reasonable limit
	})

	// Send initialize request (should be well within limit)
	initReq := Request{
		JSONRPC: "2.0",
		ID:      1,
		Method:  MethodInitialize,
		Params:  json.RawMessage(`{"protocolVersion":"2024-11-05","capabilities":{},"clientInfo":{"name":"test","version":"1.0"}}`),
	}
	body, _ := json.Marshal(initReq)

	req, _ := http.NewRequest("POST", ts.URL+"/mcp", bytes.NewReader(body))
	req.Header.Set("Content-Type", "application/json")

	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		t.Fatalf("Request failed: %v", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		t.Errorf("Expected 200 for valid request within limit, got %d", resp.StatusCode)
	}
}

func TestIsLocalhostOrigin(t *testing.T) {
	tests := []struct {
		origin   string
		expected bool
	}{
		{"http://localhost", true},
		{"http://localhost:3000", true},
		{"https://localhost", true},
		{"https://localhost:8443", true},
		{"http://127.0.0.1", true},
		{"http://127.0.0.1:8080", true},
		{"https://127.0.0.1", true},
		{"http://[::1]", true},
		{"http://[::1]:8080", true},
		{"https://[::1]", true},
		{"http://example.com", false},
		{"https://example.com", false},
		{"http://localhost.evil.com", false},
		{"http://192.168.1.1", false},
	}

	for _, tt := range tests {
		t.Run(tt.origin, func(t *testing.T) {
			result := isLocalhostOrigin(tt.origin)
			if result != tt.expected {
				t.Errorf("isLocalhostOrigin(%q) = %v, want %v", tt.origin, result, tt.expected)
			}
		})
	}
}