package warningnotify

import (
	"sort"
	"strings"
)

type groupKey struct {
	Business   string
	TenantID   string
	DeptID     int64
	CreatedBy  int64
	Method     string
	Recipients string
	Category   string
}

func BuildBatches(events []Event) []Batch {
	if len(events) == 0 {
		return nil
	}

	grouped := make(map[groupKey]*Batch)
	for _, event := range events {
		event = normalizeEvent(event)
		for _, method := range methodsForEvent(event) {
			for _, recipients := range recipientGroupsForMethod(method, event) {
				if methodRequiresRecipient(method) && len(recipients) == 0 {
					continue
				}
				key := groupKeyForEvent(method, recipients, event)
				batch := grouped[key]
				if batch == nil {
					batch = &Batch{
						Business:   event.Business,
						Method:     method,
						TenantID:   event.TenantID,
						DeptID:     event.DeptID,
						DeptName:   event.DeptName,
						CreatedBy:  event.CreatedBy,
						Category:   event.Category,
						Recipients: recipients,
						Items:      make([]Event, 0),
					}
					grouped[key] = batch
				} else if strings.TrimSpace(batch.DeptName) == "" {
					batch.DeptName = event.DeptName
				}
				batch.Items = append(batch.Items, event)
			}
		}
	}

	keys := make([]groupKey, 0, len(grouped))
	for key := range grouped {
		keys = append(keys, key)
	}
	sort.Slice(keys, func(i, j int) bool {
		return compareGroupKey(keys[i], keys[j]) < 0
	})

	batches := make([]Batch, 0, len(keys))
	for _, key := range keys {
		batch := grouped[key]
		sort.SliceStable(batch.Items, func(i, j int) bool {
			if batch.Items[i].WarnStage != batch.Items[j].WarnStage {
				return batch.Items[i].WarnStage > batch.Items[j].WarnStage
			}
			if batch.Items[i].ItemCode != batch.Items[j].ItemCode {
				return batch.Items[i].ItemCode < batch.Items[j].ItemCode
			}
			return batch.Items[i].EventID < batch.Items[j].EventID
		})
		batch.WarnStage = highestStage(batch.Items)
		applyContent(batch)
		batches = append(batches, *batch)
	}
	return batches
}

func groupKeyForEvent(method string, recipients []string, event Event) groupKey {
	key := groupKey{
		Business:   event.Business,
		TenantID:   event.TenantID,
		DeptID:     event.DeptID,
		CreatedBy:  event.CreatedBy,
		Method:     method,
		Recipients: strings.Join(recipients, ","),
		Category:   event.Category,
	}
	if method == MethodSMS || method == MethodEmail {
		key.DeptID = 0
		key.CreatedBy = 0
	}
	if method == MethodWechat {
		key.DeptID = 0
		key.CreatedBy = 0
		key.Recipients = ""
	}
	return key
}

func compareGroupKey(left, right groupKey) int {
	leftParts := []string{left.TenantID, left.Business, left.Method, left.Recipients, left.Category}
	rightParts := []string{right.TenantID, right.Business, right.Method, right.Recipients, right.Category}
	for i := range leftParts {
		if leftParts[i] < rightParts[i] {
			return -1
		}
		if leftParts[i] > rightParts[i] {
			return 1
		}
	}
	if left.DeptID != right.DeptID {
		if left.DeptID < right.DeptID {
			return -1
		}
		return 1
	}
	if left.CreatedBy != right.CreatedBy {
		if left.CreatedBy < right.CreatedBy {
			return -1
		}
		return 1
	}
	return 0
}

func normalizeEvent(event Event) Event {
	event.Business = strings.TrimSpace(event.Business)
	if event.Business == "" {
		event.Business = BusinessSimWarning
	}
	event.TenantID = strings.TrimSpace(event.TenantID)
	event.DeptName = strings.TrimSpace(event.DeptName)
	event.Category = strings.TrimSpace(event.Category)
	if event.Category == "" {
		event.Category = "预警"
	}
	event.Kind = strings.TrimSpace(event.Kind)
	event.ItemCode = strings.TrimSpace(event.ItemCode)
	event.MSISDN = strings.TrimSpace(event.MSISDN)
	event.WarnMethods = strings.TrimSpace(event.WarnMethods)
	event.WarnPhones = strings.TrimSpace(event.WarnPhones)
	event.WarnEmails = strings.TrimSpace(event.WarnEmails)
	event.UnitText = strings.TrimSpace(event.UnitText)
	event.Remark = strings.TrimSpace(event.Remark)
	event.OperationText = strings.TrimSpace(event.OperationText)
	event.BatchNo = strings.TrimSpace(event.BatchNo)
	return event
}

func methodsForEvent(event Event) []string {
	values := splitList(event.WarnMethods)
	seen := map[string]struct{}{MethodPlatform: {}}
	result := []string{MethodPlatform}
	for _, value := range values {
		switch value {
		case MethodSMS, MethodEmail, MethodPhone, MethodPlatform:
		default:
			continue
		}
		if _, exists := seen[value]; exists {
			continue
		}
		seen[value] = struct{}{}
		result = append(result, value)
	}
	sort.SliceStable(result, func(i, j int) bool {
		return methodOrder(result[i]) < methodOrder(result[j])
	})
	return result
}

func methodOrder(method string) int {
	switch method {
	case MethodPlatform:
		return 1
	case MethodEmail:
		return 2
	case MethodSMS:
		return 3
	case MethodPhone:
		return 4
	case MethodWechat:
		return 5
	default:
		return 99
	}
}

func recipientGroupsForMethod(method string, event Event) [][]string {
	switch method {
	case MethodSMS:
		return singleRecipientGroups(splitList(event.WarnPhones))
	case MethodEmail:
		return singleRecipientGroups(splitList(event.WarnEmails))
	default:
		return [][]string{{}}
	}
}

func methodRequiresRecipient(method string) bool {
	return method == MethodSMS || method == MethodEmail
}

func singleRecipientGroups(recipients []string) [][]string {
	groups := make([][]string, 0, len(recipients))
	for _, recipient := range recipients {
		recipient = strings.TrimSpace(recipient)
		if recipient == "" {
			continue
		}
		groups = append(groups, []string{recipient})
	}
	return groups
}

func splitList(value string) []string {
	parts := strings.FieldsFunc(value, func(r rune) bool {
		switch r {
		case ',', ';', '，', '；', '|', '\n', '\r', '\t', ' ':
			return true
		default:
			return false
		}
	})
	seen := make(map[string]struct{}, len(parts))
	result := make([]string, 0, len(parts))
	for _, part := range parts {
		part = strings.TrimSpace(part)
		if part == "" {
			continue
		}
		if _, exists := seen[part]; exists {
			continue
		}
		seen[part] = struct{}{}
		result = append(result, part)
	}
	sort.Strings(result)
	return result
}

func highestStage(items []Event) int {
	stage := 0
	for _, item := range items {
		if item.WarnStage > stage {
			stage = item.WarnStage
		}
	}
	return stage
}