/*
Copyright 2024 The K8sGPT Authors.
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 (
	"context"
	"encoding/json"
	"fmt"
	"regexp"

	schemav1 "buf.build/gen/go/k8sgpt-ai/k8sgpt/protocolbuffers/go/schema/v1"
	"github.com/k8sgpt-ai/k8sgpt/pkg/ai"
	"github.com/k8sgpt-ai/k8sgpt/pkg/analysis"
	"github.com/k8sgpt-ai/k8sgpt/pkg/kubernetes"
	"github.com/k8sgpt-ai/k8sgpt/pkg/server/config"
	"github.com/mark3labs/mcp-go/mcp"
	"github.com/mark3labs/mcp-go/server"
	"github.com/spf13/viper"
	"go.uber.org/zap"
)

// K8sGptMCPServer represents an MCP server for k8sgpt
type K8sGptMCPServer struct {
	server      *server.MCPServer
	port        string
	aiProvider  *ai.AIProvider
	useHTTP     bool
	logger      *zap.Logger
	httpServer  *server.StreamableHTTPServer
	stdioServer *server.StdioServer
}

func NewMCPServer(port string, aiProvider *ai.AIProvider, useHTTP bool, logger *zap.Logger) (*K8sGptMCPServer, error) {
	opts := []server.ServerOption{
		server.WithToolCapabilities(true),
		server.WithResourceCapabilities(true, false),
		server.WithPromptCapabilities(false),
	}

	// Create the MCP server
	mcpServer := server.NewMCPServer("k8sgpt", "1.0.0", opts...)
	var k8sGptMCPServer = &K8sGptMCPServer{
		server:     mcpServer,
		port:       port,
		aiProvider: aiProvider,
		useHTTP:    useHTTP,
		logger:     logger,
	}

	// Register tools and resources immediately
	if err := k8sGptMCPServer.registerToolsAndResources(); err != nil {
		return nil, fmt.Errorf("failed to register tools and resources: %v", err)
	}

	if useHTTP {
		// Create HTTP server with streamable transport
		httpOpts := []server.StreamableHTTPOption{
			server.WithLogger(&zapLoggerAdapter{logger: logger}),
		}

		httpServer := server.NewStreamableHTTPServer(mcpServer, httpOpts...)

		// Launch the HTTP server directly
		go func() {
			logger.Info("Starting MCP HTTP server", zap.String("port", port))
			if err := httpServer.Start(":" + port); err != nil {
				logger.Fatal("MCP HTTP server failed", zap.Error(err))
			}
		}()

		return &K8sGptMCPServer{
			server:     mcpServer,
			port:       port,
			aiProvider: aiProvider,
			useHTTP:    useHTTP,
			logger:     logger,
			httpServer: httpServer,
		}, nil
	} else {
		// Create stdio server
		stdioServer := server.NewStdioServer(mcpServer)

		return &K8sGptMCPServer{
			server:      mcpServer,
			port:        port,
			aiProvider:  aiProvider,
			useHTTP:     useHTTP,
			logger:      logger,
			stdioServer: stdioServer,
		}, nil
	}
}

// Start starts the MCP server
func (s *K8sGptMCPServer) Start() error {
	if s.server == nil {
		return fmt.Errorf("server not initialized")
	}
	// Register prompts
	if err := s.registerPrompts(); err != nil {
		return fmt.Errorf("failed to register prompts: %v", err)
	}
	// Register resources
	if err := s.registerResources(); err != nil {
		return fmt.Errorf("failed to register resources: %v", err)
	}

	// Start the server based on transport type
	if s.useHTTP {
		// HTTP server is already running in a goroutine
		return nil
	} else {
		// Start stdio server (this will block)
		return server.ServeStdio(s.server)
	}
}

func (s *K8sGptMCPServer) registerToolsAndResources() error {
	// Register analyze tool with proper JSON schema
	analyzeTool := mcp.NewTool("analyze",
		mcp.WithDescription("Analyze Kubernetes resources for issues and problems"),
		mcp.WithString("namespace",
			mcp.Description("Kubernetes namespace to analyze (empty for all namespaces)"),
		),
		mcp.WithString("backend",
			mcp.Description("AI backend to use for analysis (e.g., openai, azure, localai)"),
		),
		mcp.WithBoolean("explain",
			mcp.Description("Provide detailed explanations for issues"),
		),
		mcp.WithArray("filters",
			mcp.Description("Provide filters to narrow down the analysis (e.g. ['Pods', 'Deployments'])"),
			// without below line MCP server fails with Google Agent Development Kit (ADK), interestingly works fine with mcpinspector
			mcp.WithStringItems(),
		),
	)
	s.server.AddTool(analyzeTool, s.handleAnalyze)

	// Register cluster info tool (no parameters needed)
	clusterInfoTool := mcp.NewTool("cluster-info",
		mcp.WithDescription("Get Kubernetes cluster information and version"),
	)
	s.server.AddTool(clusterInfoTool, s.handleClusterInfo)

	// Register config tool with proper JSON schema
	configTool := mcp.NewTool("config",
		mcp.WithDescription("Configure K8sGPT settings including custom analyzers and cache"),
		mcp.WithObject("customAnalyzers",
			mcp.Description("Custom analyzer configurations"),
			mcp.Properties(map[string]any{
				"name": map[string]any{
					"type":        "string",
					"description": "Name of the custom analyzer",
				},
				"connection": map[string]any{
					"type": "object",
					"properties": map[string]any{
						"url": map[string]any{
							"type":        "string",
							"description": "URL of the custom analyzer service",
						},
						"port": map[string]any{
							"type":        "integer",
							"description": "Port of the custom analyzer service",
						},
					},
				},
			}),
		),
		mcp.WithObject("cache",
			mcp.Description("Cache configuration"),
			mcp.Properties(map[string]any{
				"type": map[string]any{
					"type":        "string",
					"description": "Cache type (s3, azure, gcs)",
					"enum":        []string{"s3", "azure", "gcs"},
				},
				"bucketName": map[string]any{
					"type":        "string",
					"description": "Bucket name for S3/GCS cache",
				},
				"region": map[string]any{
					"type":        "string",
					"description": "Region for S3/GCS cache",
				},
				"endpoint": map[string]any{
					"type":        "string",
					"description": "Custom endpoint for S3 cache",
				},
				"insecure": map[string]any{
					"type":        "boolean",
					"description": "Use insecure connection for cache",
				},
				"storageAccount": map[string]any{
					"type":        "string",
					"description": "Storage account for Azure cache",
				},
				"containerName": map[string]any{
					"type":        "string",
					"description": "Container name for Azure cache",
				},
				"projectId": map[string]any{
					"type":        "string",
					"description": "Project ID for GCS cache",
				},
			}),
		),
	)
	s.server.AddTool(configTool, s.handleConfig)
	return nil
}

// AnalyzeRequest represents the input parameters for the analyze tool
type AnalyzeRequest struct {
	Namespace       string   `json:"namespace,omitempty"`
	Backend         string   `json:"backend,omitempty"`
	Language        string   `json:"language,omitempty"`
	Filters         []string `json:"filters,omitempty"`
	LabelSelector   string   `json:"labelSelector,omitempty"`
	NoCache         bool     `json:"noCache,omitempty"`
	Explain         bool     `json:"explain,omitempty"`
	MaxConcurrency  int      `json:"maxConcurrency,omitempty"`
	WithDoc         bool     `json:"withDoc,omitempty"`
	InteractiveMode bool     `json:"interactiveMode,omitempty"`
	CustomHeaders   []string `json:"customHeaders,omitempty"`
	WithStats       bool     `json:"withStats,omitempty"`
	Anonymize       bool     `json:"anonymize,omitempty"`
}

// AnalyzeResponse represents the output of the analyze tool
type AnalyzeResponse struct {
	Results string `json:"results"`
}

// ClusterInfoRequest represents the input parameters for the cluster-info tool
type ClusterInfoRequest struct {
	// Empty struct as we don't need any input parameters
}

// ClusterInfoResponse represents the output of the cluster-info tool
type ClusterInfoResponse struct {
	Info string `json:"info"`
}

// ConfigRequest represents the input parameters for the config tool
type ConfigRequest struct {
	CustomAnalyzers []struct {
		Name       string `json:"name"`
		Connection struct {
			Url  string `json:"url"`
			Port int    `json:"port"`
		} `json:"connection"`
	} `json:"customAnalyzers,omitempty"`
	Cache struct {
		Type string `json:"type"`
		// S3 specific fields
		BucketName string `json:"bucketName,omitempty"`
		Region     string `json:"region,omitempty"`
		Endpoint   string `json:"endpoint,omitempty"`
		Insecure   bool   `json:"insecure,omitempty"`
		// Azure specific fields
		StorageAccount string `json:"storageAccount,omitempty"`
		ContainerName  string `json:"containerName,omitempty"`
		// GCS specific fields
		ProjectId string `json:"projectId,omitempty"`
	} `json:"cache,omitempty"`
}

// ConfigResponse represents the output of the config tool
type ConfigResponse struct {
	Status string `json:"status"`
}

// handleAnalyze handles the analyze tool
func (s *K8sGptMCPServer) handleAnalyze(ctx context.Context, request mcp.CallToolRequest) (*mcp.CallToolResult, error) {

	var req AnalyzeRequest
	if err := request.BindArguments(&req); err != nil {
		return mcp.NewToolResultErrorf("Failed to parse request arguments: %v", err), nil
	}

	if req.Backend == "" {
		if s.aiProvider.Name != "" {
			req.Backend = s.aiProvider.Name
		} else {
			req.Backend = "openai" // fallback default
		}
	}

	// Get stored filters if not specified
	if len(req.Filters) == 0 {
		req.Filters = viper.GetStringSlice("active_filters")
	}

	// Validate MaxConcurrency to prevent excessive memory allocation
	req.MaxConcurrency = validateMaxConcurrency(req.MaxConcurrency)

	// Create a new analysis with the request parameters
	analysis, err := analysis.NewAnalysis(
		req.Backend,
		req.Language,
		req.Filters,
		req.Namespace,
		req.LabelSelector,
		req.NoCache,
		req.Explain,
		req.MaxConcurrency,
		req.WithDoc,
		req.InteractiveMode,
		req.CustomHeaders,
		req.WithStats,
	)
	if err != nil {
		return mcp.NewToolResultErrorf("Failed to create analysis: %v", err), nil
	}
	defer analysis.Close()

	// Run the analysis
	analysis.RunAnalysis()
	if req.Explain {

		var output string
		err := analysis.GetAIResults(output, req.Anonymize)
		if err != nil {
			return mcp.NewToolResultErrorf("Failed to get results from AI: %v", err), nil
		}

		// Convert results to JSON string using PrintOutput
		outputBytes, err := analysis.PrintOutput("text")
		if err != nil {
			return mcp.NewToolResultErrorf("Failed to convert results to string: %v", err), nil
		}
		plainText := stripANSI(string(outputBytes))
		return mcp.NewToolResultText(plainText), nil
	} else {
		// Get the output
		output, err := analysis.PrintOutput("json")
		if err != nil {
			return mcp.NewToolResultErrorf("Failed to print output: %v", err), nil
		}
		return mcp.NewToolResultText(string(output)), nil
	}
}

// validateMaxConcurrency validates and bounds the MaxConcurrency parameter
func validateMaxConcurrency(maxConcurrency int) int {
	const maxAllowedConcurrency = 100
	if maxConcurrency <= 0 {
		return 10 // Default value if not set
	} else if maxConcurrency > maxAllowedConcurrency {
		return maxAllowedConcurrency // Cap at a reasonable maximum
	}
	return maxConcurrency
}

// handleClusterInfo handles the cluster-info tool
func (s *K8sGptMCPServer) handleClusterInfo(ctx context.Context, request mcp.CallToolRequest) (*mcp.CallToolResult, error) {
	// Create a new Kubernetes client
	client, err := kubernetes.NewClient("", "")
	if err != nil {
		return mcp.NewToolResultErrorf("failed to create Kubernetes client: %v", err), nil
	}

	// Get cluster info from the client
	version, err := client.Client.Discovery().ServerVersion()
	if err != nil {
		return mcp.NewToolResultErrorf("failed to get cluster version: %v", err), nil
	}

	info := fmt.Sprintf("Kubernetes %s", version.GitVersion)
	return mcp.NewToolResultText(info), nil
}

// handleConfig handles the config tool
func (s *K8sGptMCPServer) handleConfig(ctx context.Context, request mcp.CallToolRequest) (*mcp.CallToolResult, error) {
	// Parse request arguments
	var req ConfigRequest
	if err := request.BindArguments(&req); err != nil {
		return mcp.NewToolResultErrorf("Failed to parse request arguments: %v", err), nil
	}

	// Create a new config handler
	handler := &config.Handler{}

	// Convert request to AddConfigRequest
	addConfigReq := &schemav1.AddConfigRequest{
		CustomAnalyzers: make([]*schemav1.CustomAnalyzer, 0),
	}

	// Add custom analyzers if present
	if len(req.CustomAnalyzers) > 0 {
		for _, ca := range req.CustomAnalyzers {
			addConfigReq.CustomAnalyzers = append(addConfigReq.CustomAnalyzers, &schemav1.CustomAnalyzer{
				Name: ca.Name,
				Connection: &schemav1.Connection{
					Url:  ca.Connection.Url,
					Port: fmt.Sprintf("%d", ca.Connection.Port),
				},
			})
		}
	}

	// Add cache configuration if present
	if req.Cache.Type != "" {
		cacheConfig := &schemav1.Cache{}
		switch req.Cache.Type {
		case "s3":
			cacheConfig.CacheType = &schemav1.Cache_S3Cache{
				S3Cache: &schemav1.S3Cache{
					BucketName: req.Cache.BucketName,
					Region:     req.Cache.Region,
					Endpoint:   req.Cache.Endpoint,
					Insecure:   req.Cache.Insecure,
				},
			}
		case "azure":
			cacheConfig.CacheType = &schemav1.Cache_AzureCache{
				AzureCache: &schemav1.AzureCache{
					StorageAccount: req.Cache.StorageAccount,
					ContainerName:  req.Cache.ContainerName,
				},
			}
		case "gcs":
			cacheConfig.CacheType = &schemav1.Cache_GcsCache{
				GcsCache: &schemav1.GCSCache{
					BucketName: req.Cache.BucketName,
					Region:     req.Cache.Region,
					ProjectId:  req.Cache.ProjectId,
				},
			}
		}
		addConfigReq.Cache = cacheConfig
	}

	// Apply the configuration using the shared function
	if err := handler.ApplyConfig(ctx, addConfigReq); err != nil {
		return mcp.NewToolResultErrorf("Failed to add config: %v", err), nil
	}

	return mcp.NewToolResultText("Successfully added configuration"), nil
}

// registerPrompts registers the prompts for the MCP server
func (s *K8sGptMCPServer) registerPrompts() error {
	// Register any prompts needed for the MCP server
	return nil
}

// registerResources registers the resources for the MCP server
func (s *K8sGptMCPServer) registerResources() error {
	clusterInfoResource := mcp.NewResource("cluster-info", "cluster-info",
		mcp.WithResourceDescription("Get information about the Kubernetes cluster"),
		mcp.WithMIMEType("application/json"),
	)

	s.server.AddResource(clusterInfoResource, s.getClusterInfo)
	return nil
}

func (s *K8sGptMCPServer) getClusterInfo(ctx context.Context, request mcp.ReadResourceRequest) ([]mcp.ResourceContents, error) {
	// Create a new Kubernetes client
	client, err := kubernetes.NewClient("", "")
	if err != nil {
		return nil, fmt.Errorf("failed to create Kubernetes client: %v", err)
	}

	// Get cluster info from the client
	version, err := client.Client.Discovery().ServerVersion()
	if err != nil {
		return nil, fmt.Errorf("failed to get cluster version: %v", err)
	}

	data, err := json.Marshal(map[string]string{
		"version":    version.String(),
		"platform":   version.Platform,
		"gitVersion": version.GitVersion,
	})
	if err != nil {
		return []mcp.ResourceContents{
			&mcp.TextResourceContents{
				URI:      "cluster-info",
				MIMEType: "text/plain",
				Text:     "Failed to marshal cluster info",
			},
		}, nil
	}

	return []mcp.ResourceContents{
		&mcp.TextResourceContents{
			URI:      "cluster-info",
			MIMEType: "application/json",
			Text:     string(data),
		},
	}, nil
}

// Close closes the MCP server and releases resources
func (s *K8sGptMCPServer) Close() error {
	return nil
}

// zapLoggerAdapter adapts zap.Logger to the interface expected by mark3labs/mcp-go
type zapLoggerAdapter struct {
	logger *zap.Logger
}

func (z *zapLoggerAdapter) Infof(format string, v ...any) {
	z.logger.Info(fmt.Sprintf(format, v...))
}

func (z *zapLoggerAdapter) Errorf(format string, v ...any) {
	z.logger.Error(fmt.Sprintf(format, v...))
}

// stripANSI removes ANSI escape sequences from a string
func stripANSI(input string) string {
	re := regexp.MustCompile(`\x1b\[[0-9;]*m`)
	return re.ReplaceAllString(input, "")
}