package execution

import (
	"context"
	"fmt"
	"log"
	"strings"
	"time"

	"chorus/pkg/ai"
)

// TaskExecutionEngine provides AI-powered task execution with isolated sandboxes
type TaskExecutionEngine interface {
	ExecuteTask(ctx context.Context, request *TaskExecutionRequest) (*TaskExecutionResult, error)
	Initialize(ctx context.Context, config *EngineConfig) error
	Shutdown() error
	GetMetrics() *EngineMetrics
}

// TaskExecutionRequest represents a task to be executed
type TaskExecutionRequest struct {
	ID          string                 `json:"id"`
	Type        string                 `json:"type"`
	Description string                 `json:"description"`
	Context     map[string]interface{} `json:"context,omitempty"`
	Requirements *TaskRequirements     `json:"requirements,omitempty"`
	Timeout     time.Duration          `json:"timeout,omitempty"`
}

// TaskRequirements specifies execution environment needs
type TaskRequirements struct {
	AIModel         string            `json:"ai_model,omitempty"`
	SandboxType     string            `json:"sandbox_type,omitempty"`
	RequiredTools   []string          `json:"required_tools,omitempty"`
	EnvironmentVars map[string]string `json:"environment_vars,omitempty"`
	ResourceLimits  *ResourceLimits   `json:"resource_limits,omitempty"`
	SecurityPolicy  *SecurityPolicy   `json:"security_policy,omitempty"`
}

// TaskExecutionResult contains the results of task execution
type TaskExecutionResult struct {
	TaskID       string                 `json:"task_id"`
	Success      bool                   `json:"success"`
	Output       string                 `json:"output"`
	ErrorMessage string                 `json:"error_message,omitempty"`
	Artifacts    []TaskArtifact         `json:"artifacts,omitempty"`
	Metrics      *ExecutionMetrics      `json:"metrics"`
	Metadata     map[string]interface{} `json:"metadata,omitempty"`
}

// TaskArtifact represents a file or data produced during execution
type TaskArtifact struct {
	Name        string            `json:"name"`
	Type        string            `json:"type"`
	Path        string            `json:"path,omitempty"`
	Content     []byte            `json:"content,omitempty"`
	Size        int64             `json:"size"`
	CreatedAt   time.Time         `json:"created_at"`
	Metadata    map[string]string `json:"metadata,omitempty"`
}

// ExecutionMetrics tracks resource usage and performance
type ExecutionMetrics struct {
	StartTime        time.Time     `json:"start_time"`
	EndTime          time.Time     `json:"end_time"`
	Duration         time.Duration `json:"duration"`
	AIProviderTime   time.Duration `json:"ai_provider_time"`
	SandboxTime      time.Duration `json:"sandbox_time"`
	ResourceUsage    *ResourceUsage `json:"resource_usage,omitempty"`
	CommandsExecuted int           `json:"commands_executed"`
	FilesGenerated   int           `json:"files_generated"`
}

// EngineConfig configures the task execution engine
type EngineConfig struct {
	AIProviderFactory   *ai.ProviderFactory `json:"-"`
	SandboxDefaults     *SandboxConfig      `json:"sandbox_defaults"`
	DefaultTimeout      time.Duration       `json:"default_timeout"`
	MaxConcurrentTasks  int                 `json:"max_concurrent_tasks"`
	EnableMetrics       bool                `json:"enable_metrics"`
	LogLevel            string              `json:"log_level"`
}

// EngineMetrics tracks overall engine performance
type EngineMetrics struct {
	TasksExecuted     int64         `json:"tasks_executed"`
	TasksSuccessful   int64         `json:"tasks_successful"`
	TasksFailed       int64         `json:"tasks_failed"`
	AverageTime       time.Duration `json:"average_time"`
	TotalExecutionTime time.Duration `json:"total_execution_time"`
	ActiveTasks       int           `json:"active_tasks"`
}

// DefaultTaskExecutionEngine implements the TaskExecutionEngine interface
type DefaultTaskExecutionEngine struct {
	config           *EngineConfig
	aiFactory        *ai.ProviderFactory
	metrics          *EngineMetrics
	activeTasks      map[string]context.CancelFunc
	logger           *log.Logger
}

// NewTaskExecutionEngine creates a new task execution engine
func NewTaskExecutionEngine() *DefaultTaskExecutionEngine {
	return &DefaultTaskExecutionEngine{
		metrics:     &EngineMetrics{},
		activeTasks: make(map[string]context.CancelFunc),
		logger:      log.Default(),
	}
}

// Initialize configures and prepares the execution engine
func (e *DefaultTaskExecutionEngine) Initialize(ctx context.Context, config *EngineConfig) error {
	if config == nil {
		return fmt.Errorf("engine config cannot be nil")
	}

	if config.AIProviderFactory == nil {
		return fmt.Errorf("AI provider factory is required")
	}

	e.config = config
	e.aiFactory = config.AIProviderFactory

	// Set default values
	if e.config.DefaultTimeout == 0 {
		e.config.DefaultTimeout = 5 * time.Minute
	}
	if e.config.MaxConcurrentTasks == 0 {
		e.config.MaxConcurrentTasks = 10
	}

	e.logger.Printf("TaskExecutionEngine initialized with %d max concurrent tasks", e.config.MaxConcurrentTasks)
	return nil
}

// ExecuteTask executes a task using AI providers and isolated sandboxes
func (e *DefaultTaskExecutionEngine) ExecuteTask(ctx context.Context, request *TaskExecutionRequest) (*TaskExecutionResult, error) {
	if e.config == nil {
		return nil, fmt.Errorf("engine not initialized")
	}

	startTime := time.Now()

	// Create task context with timeout
	timeout := request.Timeout
	if timeout == 0 {
		timeout = e.config.DefaultTimeout
	}

	taskCtx, cancel := context.WithTimeout(ctx, timeout)
	defer cancel()

	// Track active task
	e.activeTasks[request.ID] = cancel
	defer delete(e.activeTasks, request.ID)

	e.metrics.ActiveTasks++
	defer func() { e.metrics.ActiveTasks-- }()

	result := &TaskExecutionResult{
		TaskID:  request.ID,
		Metrics: &ExecutionMetrics{StartTime: startTime},
	}

	// Execute the task
	err := e.executeTaskInternal(taskCtx, request, result)

	// Update metrics
	result.Metrics.EndTime = time.Now()
	result.Metrics.Duration = result.Metrics.EndTime.Sub(result.Metrics.StartTime)

	e.metrics.TasksExecuted++
	e.metrics.TotalExecutionTime += result.Metrics.Duration

	if err != nil {
		result.Success = false
		result.ErrorMessage = err.Error()
		e.metrics.TasksFailed++
		e.logger.Printf("Task %s failed: %v", request.ID, err)
	} else {
		result.Success = true
		e.metrics.TasksSuccessful++
		e.logger.Printf("Task %s completed successfully in %v", request.ID, result.Metrics.Duration)
	}

	e.metrics.AverageTime = e.metrics.TotalExecutionTime / time.Duration(e.metrics.TasksExecuted)

	return result, err
}

// executeTaskInternal performs the actual task execution
func (e *DefaultTaskExecutionEngine) executeTaskInternal(ctx context.Context, request *TaskExecutionRequest, result *TaskExecutionResult) error {
	// Step 1: Determine AI model and get provider
	aiStartTime := time.Now()

	role := e.determineRoleFromTask(request)
	provider, providerConfig, err := e.aiFactory.GetProviderForRole(role)
	if err != nil {
		return fmt.Errorf("failed to get AI provider for role %s: %w", role, err)
	}

	// Step 2: Create AI request
	aiRequest := &ai.TaskRequest{
		TaskID:          request.ID,
		TaskTitle:       request.Type,
		TaskDescription: request.Description,
		Context:         request.Context,
		ModelName:       providerConfig.DefaultModel,
		AgentRole:       role,
	}

	// Step 3: Get AI response
	aiResponse, err := provider.ExecuteTask(ctx, aiRequest)
	if err != nil {
		return fmt.Errorf("AI provider execution failed: %w", err)
	}

	result.Metrics.AIProviderTime = time.Since(aiStartTime)

	// Step 4: Parse AI response for executable commands
	commands, artifacts, err := e.parseAIResponse(aiResponse)
	if err != nil {
		return fmt.Errorf("failed to parse AI response: %w", err)
	}

	// Step 5: Execute commands in sandbox if needed
	if len(commands) > 0 {
		sandboxStartTime := time.Now()

		sandboxResult, err := e.executeSandboxCommands(ctx, request, commands)
		if err != nil {
			return fmt.Errorf("sandbox execution failed: %w", err)
		}

		result.Metrics.SandboxTime = time.Since(sandboxStartTime)
		result.Metrics.CommandsExecuted = len(commands)
		result.Metrics.ResourceUsage = sandboxResult.ResourceUsage

		// Merge sandbox artifacts
		artifacts = append(artifacts, sandboxResult.Artifacts...)
	}

	// Step 6: Process results and artifacts
	result.Output = e.formatOutput(aiResponse, artifacts)
	result.Artifacts = artifacts
	result.Metrics.FilesGenerated = len(artifacts)

	// Add metadata
	result.Metadata = map[string]interface{}{
		"ai_provider": providerConfig.Type,
		"ai_model":    providerConfig.DefaultModel,
		"role":        role,
		"commands":    len(commands),
	}

	return nil
}

// determineRoleFromTask analyzes the task to determine appropriate AI role
func (e *DefaultTaskExecutionEngine) determineRoleFromTask(request *TaskExecutionRequest) string {
	taskType := strings.ToLower(request.Type)
	description := strings.ToLower(request.Description)

	// Determine role based on task type and description keywords
	if strings.Contains(taskType, "code") || strings.Contains(description, "program") ||
	   strings.Contains(description, "script") || strings.Contains(description, "function") {
		return "developer"
	}

	if strings.Contains(taskType, "analysis") || strings.Contains(description, "analyze") ||
	   strings.Contains(description, "review") {
		return "analyst"
	}

	if strings.Contains(taskType, "test") || strings.Contains(description, "test") {
		return "tester"
	}

	// Default to general purpose
	return "general"
}

// parseAIResponse extracts executable commands and artifacts from AI response
func (e *DefaultTaskExecutionEngine) parseAIResponse(response *ai.TaskResponse) ([]string, []TaskArtifact, error) {
	var commands []string
	var artifacts []TaskArtifact

	// Parse response content for commands and files
	// This is a simplified parser - in reality would need more sophisticated parsing

	if len(response.Actions) > 0 {
		for _, action := range response.Actions {
			switch action.Type {
			case "command", "command_run":
				// Extract command from content or target
				if action.Content != "" {
					commands = append(commands, action.Content)
				} else if action.Target != "" {
					commands = append(commands, action.Target)
				}
			case "file", "file_create", "file_edit":
				// Create artifact from file action
				if action.Target != "" && action.Content != "" {
					artifact := TaskArtifact{
						Name:      action.Target,
						Type:      "file",
						Content:   []byte(action.Content),
						Size:      int64(len(action.Content)),
						CreatedAt: time.Now(),
					}
					artifacts = append(artifacts, artifact)
				}
			}
		}
	}

	return commands, artifacts, nil
}

// SandboxExecutionResult contains results from sandbox command execution
type SandboxExecutionResult struct {
	Output        string
	Artifacts     []TaskArtifact
	ResourceUsage *ResourceUsage
}

// executeSandboxCommands runs commands in an isolated sandbox
func (e *DefaultTaskExecutionEngine) executeSandboxCommands(ctx context.Context, request *TaskExecutionRequest, commands []string) (*SandboxExecutionResult, error) {
	// Create sandbox configuration
	sandboxConfig := e.createSandboxConfig(request)

	// Initialize sandbox
	sandbox := NewDockerSandbox()
	err := sandbox.Initialize(ctx, sandboxConfig)
	if err != nil {
		return nil, fmt.Errorf("failed to initialize sandbox: %w", err)
	}
	defer sandbox.Cleanup()

	var outputs []string
	var artifacts []TaskArtifact

	// Execute each command
	for _, cmdStr := range commands {
		cmd := &Command{
			Executable: "/bin/sh",
			Args:       []string{"-c", cmdStr},
			WorkingDir: "/workspace",
			Timeout:    30 * time.Second,
		}

		cmdResult, err := sandbox.ExecuteCommand(ctx, cmd)
		if err != nil {
			return nil, fmt.Errorf("command execution failed: %w", err)
		}

		outputs = append(outputs, fmt.Sprintf("$ %s\n%s", cmdStr, cmdResult.Stdout))

		if cmdResult.ExitCode != 0 {
			outputs = append(outputs, fmt.Sprintf("Error (exit %d): %s", cmdResult.ExitCode, cmdResult.Stderr))
		}
	}

	// Get resource usage
	resourceUsage, _ := sandbox.GetResourceUsage(ctx)

	// Collect any generated files as artifacts
	files, err := sandbox.ListFiles(ctx, "/workspace")
	if err == nil {
		for _, file := range files {
			if !file.IsDir && file.Size > 0 {
				content, err := sandbox.ReadFile(ctx, "/workspace/"+file.Name)
				if err == nil {
					artifact := TaskArtifact{
						Name:      file.Name,
						Type:      "generated_file",
						Content:   content,
						Size:      file.Size,
						CreatedAt: file.ModTime,
					}
					artifacts = append(artifacts, artifact)
				}
			}
		}
	}

	return &SandboxExecutionResult{
		Output:        strings.Join(outputs, "\n"),
		Artifacts:     artifacts,
		ResourceUsage: resourceUsage,
	}, nil
}

// createSandboxConfig creates a sandbox configuration from task requirements
func (e *DefaultTaskExecutionEngine) createSandboxConfig(request *TaskExecutionRequest) *SandboxConfig {
	config := &SandboxConfig{
		Type:         "docker",
		Image:        "alpine:latest",
		Architecture: "amd64",
		WorkingDir:   "/workspace",
		Timeout:      5 * time.Minute,
		Environment:  make(map[string]string),
	}

	// Apply defaults from engine config
	if e.config.SandboxDefaults != nil {
		if e.config.SandboxDefaults.Image != "" {
			config.Image = e.config.SandboxDefaults.Image
		}
		if e.config.SandboxDefaults.Resources.MemoryLimit > 0 {
			config.Resources = e.config.SandboxDefaults.Resources
		}
		if e.config.SandboxDefaults.Security.NoNewPrivileges {
			config.Security = e.config.SandboxDefaults.Security
		}
	}

	// Apply task-specific requirements
	if request.Requirements != nil {
		if request.Requirements.SandboxType != "" {
			config.Type = request.Requirements.SandboxType
		}

		if request.Requirements.EnvironmentVars != nil {
			for k, v := range request.Requirements.EnvironmentVars {
				config.Environment[k] = v
			}
		}

		if request.Requirements.ResourceLimits != nil {
			config.Resources = *request.Requirements.ResourceLimits
		}

		if request.Requirements.SecurityPolicy != nil {
			config.Security = *request.Requirements.SecurityPolicy
		}
	}

	return config
}

// formatOutput creates a formatted output string from AI response and artifacts
func (e *DefaultTaskExecutionEngine) formatOutput(aiResponse *ai.TaskResponse, artifacts []TaskArtifact) string {
	var output strings.Builder

	output.WriteString("AI Response:\n")
	output.WriteString(aiResponse.Response)
	output.WriteString("\n\n")

	if len(artifacts) > 0 {
		output.WriteString("Generated Artifacts:\n")
		for _, artifact := range artifacts {
			output.WriteString(fmt.Sprintf("- %s (%s, %d bytes)\n",
				artifact.Name, artifact.Type, artifact.Size))
		}
	}

	return output.String()
}

// GetMetrics returns current engine metrics
func (e *DefaultTaskExecutionEngine) GetMetrics() *EngineMetrics {
	return e.metrics
}

// Shutdown gracefully shuts down the execution engine
func (e *DefaultTaskExecutionEngine) Shutdown() error {
	e.logger.Printf("Shutting down TaskExecutionEngine...")

	// Cancel all active tasks
	for taskID, cancel := range e.activeTasks {
		e.logger.Printf("Canceling active task: %s", taskID)
		cancel()
	}

	// Wait for tasks to finish (with timeout)
	shutdownCtx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
	defer cancel()

	for len(e.activeTasks) > 0 {
		select {
		case <-shutdownCtx.Done():
			e.logger.Printf("Shutdown timeout reached, %d tasks may still be active", len(e.activeTasks))
			return nil
		case <-time.After(100 * time.Millisecond):
			// Continue waiting
		}
	}

	e.logger.Printf("TaskExecutionEngine shutdown complete")
	return nil
}