// Copyright (c) 2022 Alibaba Group Holding Ltd.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//	http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package server

import (
	"encoding/json"
	"testing"

	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
)

// MockHttpContext is a mock implementation for testing - skipping interface implementation for now
// Tests that require full HttpContext will be tested in integration tests with real host
type MockHttpContext struct {
	responseBody   []byte
	responseStatus int
	headers        map[string]string
}

// TestMcpProtocolInitialization tests the MCP protocol initialization flow
func TestMcpProtocolInitialization(t *testing.T) {
	// Create proxy server
	server := NewMcpProxyServer("test-proxy")

	// Set server fields directly
	server.SetMcpServerURL("http://mock-backend.example.com/mcp")
	server.SetTimeout(5000)

	// Create proxy tool
	toolConfig := McpProxyToolConfig{
		Name:        "test-tool",
		Description: "Test tool for initialization",
		Args: []ToolArg{
			{
				Name:        "input",
				Description: "Test input",
				Type:        "string",
				Required:    true,
			},
		},
	}

	err := server.AddProxyTool(toolConfig)
	require.NoError(t, err)

	tool, exists := server.GetMCPTools()["test-tool"]
	require.True(t, exists)

	// Create tool instance with parameters
	params := map[string]interface{}{
		"input": "test value",
	}
	paramsBytes, err := json.Marshal(params)
	require.NoError(t, err)

	toolInstance := tool.Create(paramsBytes)
	require.NotNil(t, toolInstance)

	// Skip HttpContext-dependent test for now - will be tested in integration
	// mockCtx := &MockHttpContext{}
	// err = toolInstance.Call(mockCtx, server)
	// assert.NoError(t, err)

	// Test the tool creation was successful
	assert.NotNil(t, toolInstance)
}

// TestMcpSessionManagement tests temporary session creation and cleanup
func TestMcpSessionManagement(t *testing.T) {
	_ = NewMcpProxyServer("session-test")

	// Skip session management test until implemented
	t.Skip("Session management not implemented yet")

	// Test session creation
	sessionManager := NewMcpSessionManager()
	sessionID, err := sessionManager.CreateSession("http://backend.example.com/mcp")

	// This will fail until session management is implemented
	assert.NoError(t, err)
	assert.NotEmpty(t, sessionID)

	// Test session retrieval
	session, exists := sessionManager.GetSession(sessionID)
	assert.True(t, exists)
	assert.NotNil(t, session)

	// Test session cleanup
	sessionManager.CleanupSession(sessionID)
	_, exists = sessionManager.GetSession(sessionID)
	assert.False(t, exists)
}

// TestMcpProtocolVersionNegotiation tests protocol version handling
func TestMcpProtocolVersionNegotiation(t *testing.T) {
	tests := []struct {
		name              string
		requestedVersion  string
		supportedVersions []string
		shouldSucceed     bool
		expectedVersion   string
	}{
		{
			name:              "supported version 2025-03-26",
			requestedVersion:  "2025-03-26",
			supportedVersions: []string{"2024-11-05", "2025-03-26"},
			shouldSucceed:     true,
			expectedVersion:   "2025-03-26",
		},
		{
			name:              "unsupported version",
			requestedVersion:  "2026-01-01",
			supportedVersions: []string{"2024-11-05", "2025-03-26"},
			shouldSucceed:     false,
			expectedVersion:   "",
		},
		{
			name:              "fallback to supported version",
			requestedVersion:  "2025-06-18",
			supportedVersions: []string{"2024-11-05", "2025-03-26"},
			shouldSucceed:     false,
			expectedVersion:   "",
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			// Skip until NewMcpVersionNegotiator is implemented
			t.Skip("Version negotiation not implemented yet")

			negotiator := NewMcpVersionNegotiator(tt.supportedVersions)
			version, err := negotiator.NegotiateVersion(tt.requestedVersion)

			if tt.shouldSucceed {
				assert.NoError(t, err)
				assert.Equal(t, tt.expectedVersion, version)
			} else {
				assert.Error(t, err)
			}
		})
	}
}

// TestMcpInitializeRequest tests the initialize request format and handling
func TestMcpInitializeRequest(t *testing.T) {
	_ = NewMcpProxyServer("init-test")

	// Skip until CreateInitializeRequest is implemented
	t.Skip("MCP protocol initialization not implemented yet")

	// Test initialize request creation
	initRequest := CreateInitializeRequest()

	assert.Equal(t, "2.0", initRequest.JsonRPC)
	assert.Equal(t, "initialize", initRequest.Method)
	assert.NotNil(t, initRequest.Params)

	// Validate client info
	params := initRequest.Params.(map[string]interface{})
	clientInfo := params["clientInfo"].(map[string]interface{})
	assert.Equal(t, "Higress-mcp-proxy", clientInfo["name"])
	assert.Equal(t, "1.0.0", clientInfo["version"])

	// Test protocol version
	assert.Equal(t, "2025-03-26", params["protocolVersion"])
}

// TestMcpNotificationsInitialized tests the notifications/initialized message
func TestMcpNotificationsInitialized(t *testing.T) {
	// Skip until CreateInitializedNotification is implemented
	t.Skip("MCP notifications not implemented yet")

	// Test notifications/initialized request creation
	notification := CreateInitializedNotification()

	assert.Equal(t, "2.0", notification.JsonRPC)
	assert.Equal(t, "notifications/initialized", notification.Method)
	assert.Nil(t, notification.ID) // Notifications don't have IDs
}

// TestMcpErrorHandling tests error response handling and source identification
func TestMcpErrorHandling(t *testing.T) {
	tests := []struct {
		name           string
		errorType      string
		originalError  error
		expectedSource string
		expectedCode   int
	}{
		{
			name:           "backend connection error",
			errorType:      "connection",
			originalError:  assert.AnError,
			expectedSource: "mcp-proxy",
			expectedCode:   -32603,
		},
		{
			name:           "backend timeout error",
			errorType:      "timeout",
			originalError:  assert.AnError,
			expectedSource: "mcp-proxy",
			expectedCode:   -32000,
		},
		{
			name:           "protocol version error",
			errorType:      "version",
			originalError:  assert.AnError,
			expectedSource: "mcp-proxy",
			expectedCode:   -32602,
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			// Skip until CreateMcpErrorResponse is implemented
			t.Skip("MCP error handling not implemented yet")

			errorResponse := CreateMcpErrorResponse(tt.errorType, tt.originalError, "http://backend.example.com/mcp")

			assert.Equal(t, "2.0", errorResponse.JsonRPC)
			assert.NotNil(t, errorResponse.Error)
			assert.Equal(t, tt.expectedCode, errorResponse.Error.Code)
			assert.Equal(t, tt.expectedSource, errorResponse.Error.Data["source"])
		})
	}
}

// Helper types and functions that will fail until implemented

type McpSessionManager struct{}

func NewMcpSessionManager() *McpSessionManager {
	panic("McpSessionManager not implemented yet")
}

func (m *McpSessionManager) CreateSession(backendURL string) (string, error) {
	panic("CreateSession not implemented yet")
}

func (m *McpSessionManager) GetSession(sessionID string) (interface{}, bool) {
	panic("GetSession not implemented yet")
}

func (m *McpSessionManager) CleanupSession(sessionID string) {
	panic("CleanupSession not implemented yet")
}

type McpVersionNegotiator struct {
	supportedVersions []string
}

func NewMcpVersionNegotiator(versions []string) *McpVersionNegotiator {
	panic("McpVersionNegotiator not implemented yet")
}

func (n *McpVersionNegotiator) NegotiateVersion(requested string) (string, error) {
	panic("NegotiateVersion not implemented yet")
}

type McpRequest struct {
	JsonRPC string      `json:"jsonrpc"`
	ID      interface{} `json:"id,omitempty"`
	Method  string      `json:"method"`
	Params  interface{} `json:"params,omitempty"`
}

type McpErrorResponse struct {
	JsonRPC string      `json:"jsonrpc"`
	ID      interface{} `json:"id,omitempty"`
	Error   *McpError   `json:"error"`
}

type McpError struct {
	Code    int                    `json:"code"`
	Message string                 `json:"message"`
	Data    map[string]interface{} `json:"data,omitempty"`
}

func CreateInitializeRequest() *McpRequest {
	panic("CreateInitializeRequest not implemented yet")
}

func CreateInitializedNotification() *McpRequest {
	panic("CreateInitializedNotification not implemented yet")
}

func CreateMcpErrorResponse(errorType string, originalError error, backendURL string) *McpErrorResponse {
	panic("CreateMcpErrorResponse not implemented yet")
}