package core

import (
	"backea/internal/backup/models"
	"backea/internal/backup/strategy"
	"backea/internal/logging"
	"backea/internal/mail"
	"context"
	"sync"
)

// Executor handles the execution of backups for multiple services
type Executor struct {
	Config      *models.Configuration
	Factory     strategy.Factory
	Mailer      *mail.Mailer
	concurrency int
	Logger      logging.Logger
}

// NewExecutor creates a new backup executor
func NewExecutor(config *models.Configuration, factory strategy.Factory) *Executor {
	return &Executor{
		Config:  config,
		Factory: factory,
		// Mailer:      mailer,
		concurrency: 5,
		Logger:      *logging.GetLogger(),
	}
}

// SetConcurrency sets the maximum number of concurrent backups
func (e *Executor) SetConcurrency(n int) {
	if n > 0 {
		e.concurrency = n
	}
}

// PerformBackups executes backups for multiple services based on configuration
func (e *Executor) PerformBackups(ctx context.Context, serviceName string, serviceIndex string) error {
	// Process services based on parameters
	if serviceName != "" {
		// Process single service group or specific service
		if serviceIndex != "" {
			// Process specific service within a group
			return e.processSpecificService(ctx, serviceName, serviceIndex)
		} else {
			// Process all services in the specified group
			return e.processServiceGroup(ctx, serviceName)
		}
	} else {
		// Process all service groups in parallel
		return e.processAllServiceGroups(ctx)
	}
}

// processAllServiceGroups processes all service groups in parallel
func (e *Executor) processAllServiceGroups(ctx context.Context) error {
	var wg sync.WaitGroup
	errs := make(chan error, len(e.Config.Services))

	// Create a semaphore to limit concurrency
	sem := make(chan struct{}, e.concurrency)

	for groupName := range e.Config.Services {
		wg.Add(1)
		sem <- struct{}{} // Acquire semaphore
		go func(group string) {
			defer wg.Done()
			defer func() { <-sem }() // Release semaphore

			if err := e.processServiceGroup(ctx, group); err != nil {
				e.Logger.Error("Failed to backup service group %s: %v", group, err)
				errs <- NewBackupError("backup failed for group "+group, err)
			}
		}(groupName)
	}

	// Wait for all backups to complete
	wg.Wait()
	close(errs)

	// Check if any errors occurred and return the last one
	var lastErr error
	for err := range errs {
		lastErr = err
	}
	return lastErr
}

// processServiceGroup handles the backup for all services in a group
func (e *Executor) processServiceGroup(ctx context.Context, groupName string) error {
	// Get service group configuration
	serviceGroup, exists := e.Config.Services[groupName]
	if !exists {
		e.Logger.Error("Service group not found: %s", groupName)
		return NewBackupError("service group not found: "+groupName, nil)
	}

	// Create hook runner
	hooks := NewHookRunner(serviceGroup.Source.Path, serviceGroup.Hooks.BeforeHook, serviceGroup.Hooks.AfterHook)

	// Execute the before hook once for the entire group
	if err := hooks.RunBeforeHook(); err != nil {
		e.Logger.Error("Failed to execute before hook for group %s: %v", groupName, err)
		return NewBackupError("before hook failed for group "+groupName, err)
	}

	// Process all services in the group in parallel
	var wg sync.WaitGroup
	errs := make(chan error, len(serviceGroup.BackupConfigs))

	// Create a semaphore to limit concurrency within the group
	sem := make(chan struct{}, e.concurrency)

	for configIndex := range serviceGroup.BackupConfigs {
		wg.Add(1)
		sem <- struct{}{} // Acquire semaphore
		go func(group, index string) {
			defer wg.Done()
			defer func() { <-sem }() // Release semaphore

			if err := e.processSpecificService(ctx, group, index); err != nil {
				e.Logger.Error("Failed to backup service %s.%s: %v", group, index, err)
				errs <- NewBackupError("backup failed for "+group+"."+index, err)
			}
		}(groupName, configIndex)
	}

	// Wait for all backups to complete
	wg.Wait()
	close(errs)

	var lastErr error
	for err := range errs {
		lastErr = err
	}

	// Execute the after hook once for the entire group
	if err := hooks.RunAfterHook(); err != nil {
		e.Logger.Error("Failed to execute after hook for group %s: %v", groupName, err)
		// If no backup errors occurred, return the after hook error,
		// otherwise prioritize the backup errors
		if lastErr == nil {
			lastErr = NewBackupError("after hook failed for group "+groupName, err)
		}
	}

	return lastErr
}

// processSpecificService handles the backup for a specific service in a group
func (e *Executor) processSpecificService(ctx context.Context, groupName string, configIndex string) error {
	// Get service configuration
	serviceGroup, exists := e.Config.Services[groupName]
	if !exists {
		return NewBackupError("service group not found: "+groupName, nil)
	}

	// Check if the config index exists
	_, exists = serviceGroup.BackupConfigs[configIndex]
	if !exists {
		return NewBackupError("service index not found: "+groupName+"."+configIndex, nil)
	}

	// Create the appropriate backup strategy using the factory
	backupStrategy, err := e.Factory.CreateBackupStrategyForService(groupName, configIndex)
	if err != nil {
		e.Logger.Error("Failed to create backup strategy for service %s.%s: %v", groupName, configIndex, err)
		return NewBackupError("failed to create backup strategy for "+groupName+"."+configIndex, err)
	}

	// Create and run service
	service := NewService(
		groupName+"."+configIndex,
		serviceGroup.Source.Path,
		backupStrategy,
		e.Mailer,
	)

	if err := service.Backup(ctx); err != nil {
		return NewBackupError("backup execution failed for "+groupName+"."+configIndex, err)
	}

	return nil
}