// Package task provides asynchronous task processing with handler factory pattern
package task

import (
	"context"
	"fmt"
	"sync"

	"modelRT/logger"

	"github.com/gofrs/uuid"
	"gorm.io/gorm"
)

// TaskHandler defines the interface for task processors
type TaskHandler interface {
	// Execute processes a task with the given ID and type
	Execute(ctx context.Context, taskID uuid.UUID, taskType TaskType, db *gorm.DB) error
	// CanHandle returns true if this handler can process the given task type
	CanHandle(taskType TaskType) bool
	// Name returns the name of the handler for logging and metrics
	Name() string
}

// HandlerFactory creates task handlers based on task type
type HandlerFactory struct {
	handlers map[TaskType]TaskHandler
	mu       sync.RWMutex
}

// NewHandlerFactory creates a new HandlerFactory
func NewHandlerFactory() *HandlerFactory {
	return &HandlerFactory{
		handlers: make(map[TaskType]TaskHandler),
	}
}

// RegisterHandler registers a handler for a specific task type
func (f *HandlerFactory) RegisterHandler(taskType TaskType, handler TaskHandler) {
	f.mu.Lock()
	defer f.mu.Unlock()

	f.handlers[taskType] = handler
	logger.Info(context.Background(), "Handler registered",
		"task_type", taskType,
		"handler_name", handler.Name(),
	)
}

// GetHandler returns a handler for the given task type
func (f *HandlerFactory) GetHandler(taskType TaskType) (TaskHandler, error) {
	f.mu.RLock()
	handler, exists := f.handlers[taskType]
	f.mu.RUnlock()

	if !exists {
		return nil, fmt.Errorf("no handler registered for task type: %s", taskType)
	}

	return handler, nil
}

// CreateDefaultHandlers registers all default task handlers
func (f *HandlerFactory) CreateDefaultHandlers() {
	f.RegisterHandler(TypeTopologyAnalysis, &TopologyAnalysisHandler{})
	f.RegisterHandler(TypeEventAnalysis, &EventAnalysisHandler{})
	f.RegisterHandler(TypeBatchImport, &BatchImportHandler{})
}

// BaseHandler provides common functionality for all task handlers
type BaseHandler struct {
	name string
}

// NewBaseHandler creates a new BaseHandler
func NewBaseHandler(name string) *BaseHandler {
	return &BaseHandler{name: name}
}

// Name returns the handler name
func (h *BaseHandler) Name() string {
	return h.name
}

// TopologyAnalysisHandler handles topology analysis tasks
type TopologyAnalysisHandler struct {
	BaseHandler
}

// NewTopologyAnalysisHandler creates a new TopologyAnalysisHandler
func NewTopologyAnalysisHandler() *TopologyAnalysisHandler {
	return &TopologyAnalysisHandler{
		BaseHandler: *NewBaseHandler("topology_analysis_handler"),
	}
}

// Execute processes a topology analysis task
func (h *TopologyAnalysisHandler) Execute(ctx context.Context, taskID uuid.UUID, taskType TaskType, db *gorm.DB) error {
	logger.Info(ctx, "Starting topology analysis",
		"task_id", taskID,
		"task_type", taskType,
	)

	// TODO: Implement actual topology analysis logic
	// This would typically involve:
	// 1. Fetching task parameters from database
	// 2. Performing topology analysis (checking for islands, shorts, etc.)
	// 3. Storing results in database
	// 4. Updating task status

	// Simulate work
	logger.Info(ctx, "Topology analysis completed",
		"task_id", taskID,
		"task_type", taskType,
	)

	return nil
}

// CanHandle returns true for topology analysis tasks
func (h *TopologyAnalysisHandler) CanHandle(taskType TaskType) bool {
	return taskType == TypeTopologyAnalysis
}

// EventAnalysisHandler handles event analysis tasks
type EventAnalysisHandler struct {
	BaseHandler
}

// NewEventAnalysisHandler creates a new EventAnalysisHandler
func NewEventAnalysisHandler() *EventAnalysisHandler {
	return &EventAnalysisHandler{
		BaseHandler: *NewBaseHandler("event_analysis_handler"),
	}
}

// Execute processes an event analysis task
func (h *EventAnalysisHandler) Execute(ctx context.Context, taskID uuid.UUID, taskType TaskType, db *gorm.DB) error {
	logger.Info(ctx, "Starting event analysis",
		"task_id", taskID,
		"task_type", taskType,
	)

	// TODO: Implement actual event analysis logic
	// This would typically involve:
	// 1. Fetching motor and trigger information
	// 2. Analyzing events within the specified duration
	// 3. Generating analysis report
	// 4. Storing results in database

	// Simulate work
	logger.Info(ctx, "Event analysis completed",
		"task_id", taskID,
		"task_type", taskType,
	)

	return nil
}

// CanHandle returns true for event analysis tasks
func (h *EventAnalysisHandler) CanHandle(taskType TaskType) bool {
	return taskType == TypeEventAnalysis
}

// BatchImportHandler handles batch import tasks
type BatchImportHandler struct {
	BaseHandler
}

// NewBatchImportHandler creates a new BatchImportHandler
func NewBatchImportHandler() *BatchImportHandler {
	return &BatchImportHandler{
		BaseHandler: *NewBaseHandler("batch_import_handler"),
	}
}

// Execute processes a batch import task
func (h *BatchImportHandler) Execute(ctx context.Context, taskID uuid.UUID, taskType TaskType, db *gorm.DB) error {
	logger.Info(ctx, "Starting batch import",
		"task_id", taskID,
		"task_type", taskType,
	)

	// TODO: Implement actual batch import logic
	// This would typically involve:
	// 1. Reading file from specified path
	// 2. Parsing file content (CSV, Excel, etc.)
	// 3. Validating and importing data into database
	// 4. Generating import report

	// Simulate work
	logger.Info(ctx, "Batch import completed",
		"task_id", taskID,
		"task_type", taskType,
	)

	return nil
}

// CanHandle returns true for batch import tasks
func (h *BatchImportHandler) CanHandle(taskType TaskType) bool {
	return taskType == TypeBatchImport
}

// CompositeHandler can handle multiple task types by delegating to appropriate handlers
type CompositeHandler struct {
	factory *HandlerFactory
}

// NewCompositeHandler creates a new CompositeHandler
func NewCompositeHandler(factory *HandlerFactory) *CompositeHandler {
	return &CompositeHandler{factory: factory}
}

// Execute delegates task execution to the appropriate handler
func (h *CompositeHandler) Execute(ctx context.Context, taskID uuid.UUID, taskType TaskType, db *gorm.DB) error {
	handler, err := h.factory.GetHandler(taskType)
	if err != nil {
		return fmt.Errorf("failed to get handler for task type %s: %w", taskType, err)
	}

	return handler.Execute(ctx, taskID, taskType, db)
}

// CanHandle returns true if any registered handler can handle the task type
func (h *CompositeHandler) CanHandle(taskType TaskType) bool {
	_, err := h.factory.GetHandler(taskType)
	return err == nil
}

// Name returns the composite handler name
func (h *CompositeHandler) Name() string {
	return "composite_handler"
}

// DefaultHandlerFactory returns a HandlerFactory with all default handlers registered
func DefaultHandlerFactory() *HandlerFactory {
	factory := NewHandlerFactory()
	factory.CreateDefaultHandlers()
	return factory
}

// DefaultCompositeHandler returns a CompositeHandler with all default handlers
func DefaultCompositeHandler() TaskHandler {
	factory := DefaultHandlerFactory()
	return NewCompositeHandler(factory)
}