package service

import (
	"context"
	"errors"
	"fmt"
	"time"

	"github.com/muyuqingfeng/iloom/textile-service/internal/model"
	"github.com/muyuqingfeng/iloom/textile-service/internal/repository"
)

type ProcessService struct {
	stepRepo      *repository.StepRepo
	inventoryRepo *repository.InventoryRepo
}

func NewProcessService(stepRepo *repository.StepRepo, inventoryRepo *repository.InventoryRepo) *ProcessService {
	return &ProcessService{
		stepRepo:      stepRepo,
		inventoryRepo: inventoryRepo,
	}
}

func (s *ProcessService) CompleteStep(ctx context.Context, planID, stepID, companyID, userID, notes string) error {
	step, err := s.stepRepo.GetByID(ctx, stepID)
	if err != nil {
		return fmt.Errorf("step not found: %w", err)
	}

	if step.PlanID != planID {
		return errors.New("step does not belong to this plan")
	}

	if step.Status != "pending" && step.Status != "active" {
		return fmt.Errorf("step status is %s, cannot complete", step.Status)
	}

	// Validate prerequisite steps are completed
	allSteps, err := s.stepRepo.GetByPlan(ctx, planID)
	if err != nil {
		return fmt.Errorf("failed to get plan steps: %w", err)
	}

	if err := s.validatePrerequisites(step.StepType, allSteps); err != nil {
		return err
	}

	var notePtr *string
	if notes != "" {
		notePtr = &notes
	}

	if err := s.stepRepo.UpdateStatus(ctx, stepID, "completed", userID, notePtr); err != nil {
		return fmt.Errorf("failed to update step: %w", err)
	}

	// Check if this is the last step (fabric_warehouse)
	if step.StepType == "fabric_warehouse" {
		// All steps completed - plan production is done at textile side
		// Purchaser service can be notified via event/HTTP if needed
		_ = companyID // available for future cross-service notification
	}

	return nil
}

func (s *ProcessService) RejectStep(ctx context.Context, planID, stepID, companyID, userID, reason string) error {
	step, err := s.stepRepo.GetByID(ctx, stepID)
	if err != nil {
		return fmt.Errorf("step not found: %w", err)
	}

	if step.PlanID != planID {
		return errors.New("step does not belong to this plan")
	}

	if step.Status != "pending" && step.Status != "active" {
		return fmt.Errorf("step status is %s, cannot reject", step.Status)
	}

	return s.stepRepo.UpdateStatus(ctx, stepID, "rejected", userID, &reason)
}

func (s *ProcessService) validatePrerequisites(currentType string, allSteps []model.ProcessStep) error {
	currentIdx := -1
	for i, st := range model.StepOrder {
		if st == currentType {
			currentIdx = i
			break
		}
	}
	if currentIdx < 0 {
		return fmt.Errorf("unknown step type: %s", currentType)
	}

	// Build a map of step type -> status
	statusMap := make(map[string]string, len(allSteps))
	for _, step := range allSteps {
		statusMap[step.StepType] = step.Status
	}

	// All preceding steps must be completed
	for i := 0; i < currentIdx; i++ {
		prevType := model.StepOrder[i]
		if statusMap[prevType] != "completed" {
			return fmt.Errorf("prerequisite step %s is not completed (status: %s)", prevType, statusMap[prevType])
		}
	}

	return nil
}

// StepTimestamp returns the completion timestamp for a step, if available.
func StepTimestamp(step *model.ProcessStep) *time.Time {
	return step.Timestamp
}