// Package task provides unified task type definitions and interfaces
package task

import (
	"context"
	"fmt"

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

// UnifiedTaskType defines all async task types in a single location
type UnifiedTaskType string

const (
	// TaskTypeTopologyAnalysis represents topology analysis task
	TaskTypeTopologyAnalysis UnifiedTaskType = "TOPOLOGY_ANALYSIS"
	// TaskTypePerformanceAnalysis represents performance analysis task
	TaskTypePerformanceAnalysis UnifiedTaskType = "PERFORMANCE_ANALYSIS"
	// TaskTypeEventAnalysis represents event analysis task
	TaskTypeEventAnalysis UnifiedTaskType = "EVENT_ANALYSIS"
	// TaskTypeBatchImport represents batch import task
	TaskTypeBatchImport UnifiedTaskType = "BATCH_IMPORT"
	// TaskTypeTest represents test task for system verification
	TaskTypeTest UnifiedTaskType = "TEST"
)

// UnifiedTaskStatus defines task status constants
type UnifiedTaskStatus string

const (
	// TaskStatusPending represents task waiting to be processed
	TaskStatusPending UnifiedTaskStatus = "PENDING"
	// TaskStatusRunning represents task currently executing
	TaskStatusRunning UnifiedTaskStatus = "RUNNING"
	// TaskStatusCompleted represents task finished successfully
	TaskStatusCompleted UnifiedTaskStatus = "COMPLETED"
	// TaskStatusFailed represents task failed with error
	TaskStatusFailed UnifiedTaskStatus = "FAILED"
)

// TaskParams defines the interface for task-specific parameters
// All task types must implement this interface to provide their parameter structure
type TaskParams interface {
	// Validate checks if the parameters are valid for this task type
	Validate() error
	// GetType returns the task type these parameters are for
	GetType() UnifiedTaskType
	// ToMap converts parameters to map for database storage
	ToMap() map[string]interface{}
	// FromMap populates parameters from map (for database retrieval)
	FromMap(params map[string]interface{}) error
}

// UnifiedTask defines the base interface that all tasks must implement
// This provides a clean abstraction for task execution and management
type UnifiedTask interface {
	// GetType returns the task type
	GetType() UnifiedTaskType

	// GetParams returns the task parameters
	GetParams() TaskParams

	// Execute performs the actual task logic
	Execute(ctx context.Context, taskID uuid.UUID, db *gorm.DB) error

	// GetName returns a human-readable task name for logging
	GetName() string

	// Validate checks if the task is valid before execution
	Validate() error
}

// BaseTask provides common functionality for all task implementations
type BaseTask struct {
	taskType UnifiedTaskType
	params   TaskParams
	name     string
}

// NewBaseTask creates a new BaseTask instance
func NewBaseTask(taskType UnifiedTaskType, params TaskParams, name string) *BaseTask {
	return &BaseTask{
		taskType: taskType,
		params:   params,
		name:     name,
	}
}

// GetType returns the task type
func (t *BaseTask) GetType() UnifiedTaskType {
	return t.taskType
}

// GetParams returns the task parameters
func (t *BaseTask) GetParams() TaskParams {
	return t.params
}

// GetName returns the task name
func (t *BaseTask) GetName() string {
	return t.name
}

// Validate checks if the task is valid
func (t *BaseTask) Validate() error {
	if t.params == nil {
		return fmt.Errorf("task parameters cannot be nil")
	}

	if t.taskType != t.params.GetType() {
		return fmt.Errorf("task type mismatch: expected %s, got %s", t.taskType, t.params.GetType())
	}

	return t.params.Validate()
}

// IsTaskType checks if a task type string is valid
func IsTaskType(taskType string) bool {
	switch UnifiedTaskType(taskType) {
	case TaskTypeTopologyAnalysis, TaskTypePerformanceAnalysis,
		TaskTypeEventAnalysis, TaskTypeBatchImport, TaskTypeTest:
		return true
	default:
		return false
	}
}

// GetTaskTypes returns all registered task types
func GetTaskTypes() []UnifiedTaskType {
	return []UnifiedTaskType{
		TaskTypeTopologyAnalysis,
		TaskTypePerformanceAnalysis,
		TaskTypeEventAnalysis,
		TaskTypeBatchImport,
		TaskTypeTest,
	}
}