package app

import (
	"bytes"
	"context"
	"encoding/csv"
	"errors"
	"fmt"
	"net"
	"net/url"
	"strconv"
	"strings"
	"time"

	"github.com/jackc/pgx/v5/pgconn"

	"github.com/geo-platform/tenant-api/internal/ops/domain"
	"github.com/geo-platform/tenant-api/internal/ops/repository"
	"github.com/geo-platform/tenant-api/internal/shared/response"
)

const (
	ActionSiteDomainMappingCreate  = "site_domain_mapping.create"
	ActionSiteDomainMappingUpdate  = "site_domain_mapping.update"
	ActionSiteDomainMappingEnable  = "site_domain_mapping.enable"
	ActionSiteDomainMappingDisable = "site_domain_mapping.disable"
	ActionSiteDomainMappingDelete  = "site_domain_mapping.delete"
	ActionSiteDomainMappingImport  = "site_domain_mapping.import"
	ActionSiteDomainMappingExport  = "site_domain_mapping.export"

	siteDomainMappingImportMaxRows   = 5000
	siteDomainMappingExportMaxRows   = 10000
	siteDomainMappingImportMaxErrors = 50
)

type SiteDomainMappingService struct {
	mappings *repository.SiteDomainMappingRepository
	audits   *AuditService
}

func NewSiteDomainMappingService(mappings *repository.SiteDomainMappingRepository, audits *AuditService) *SiteDomainMappingService {
	return &SiteDomainMappingService{mappings: mappings, audits: audits}
}

type SiteDomainMappingView struct {
	ID                int64     `json:"id"`
	RegistrableDomain string    `json:"registrable_domain"`
	SiteKey           string    `json:"site_key"`
	SiteName          string    `json:"site_name"`
	IsActive          bool      `json:"is_active"`
	CreatedAt         time.Time `json:"created_at"`
	UpdatedAt         time.Time `json:"updated_at"`
}

type SiteDomainMappingListInput struct {
	Keyword  string
	IsActive *bool
	Page     int
	Size     int
}

type SiteDomainMappingListResult struct {
	Items []SiteDomainMappingView `json:"items"`
	Total int64                   `json:"total"`
	Page  int                     `json:"page"`
	Size  int                     `json:"size"`
}

type SiteDomainMappingInput struct {
	RegistrableDomain string
	SiteKey           string
	SiteName          string
	IsActive          bool
}

type SiteDomainMappingImportInput struct {
	Content []byte
}

type SiteDomainMappingImportError struct {
	Row     int    `json:"row"`
	Message string `json:"message"`
}

type SiteDomainMappingImportResult struct {
	Total     int                            `json:"total"`
	Created   int                            `json:"created"`
	Updated   int                            `json:"updated"`
	Skipped   int                            `json:"skipped"`
	Failed    int                            `json:"failed"`
	Duplicate int                            `json:"duplicate"`
	Errors    []SiteDomainMappingImportError `json:"errors"`
}

type siteDomainMappingImportColumns struct {
	Domain int
	Key    int
	Name   int
	Active int
}

func toSiteDomainMappingView(item *domain.SiteDomainMapping) SiteDomainMappingView {
	return SiteDomainMappingView{
		ID:                item.ID,
		RegistrableDomain: item.RegistrableDomain,
		SiteKey:           item.SiteKey,
		SiteName:          item.SiteName,
		IsActive:          item.IsActive,
		CreatedAt:         item.CreatedAt,
		UpdatedAt:         item.UpdatedAt,
	}
}

func (s *SiteDomainMappingService) List(ctx context.Context, in SiteDomainMappingListInput) (*SiteDomainMappingListResult, error) {
	page := in.Page
	if page <= 0 {
		page = 1
	}
	size := in.Size
	if size <= 0 || size > 200 {
		size = 20
	}

	items, total, err := s.mappings.List(ctx, repository.SiteDomainMappingFilter{
		Keyword:  strings.TrimSpace(in.Keyword),
		IsActive: in.IsActive,
		Limit:    size,
		Offset:   (page - 1) * size,
	})
	if err != nil {
		return nil, err
	}

	views := make([]SiteDomainMappingView, 0, len(items))
	for i := range items {
		views = append(views, toSiteDomainMappingView(&items[i]))
	}
	return &SiteDomainMappingListResult{Items: views, Total: total, Page: page, Size: size}, nil
}

func (s *SiteDomainMappingService) ExportCSV(ctx context.Context, actor *Actor, in SiteDomainMappingListInput) ([]byte, error) {
	items, err := s.mappings.Export(ctx, repository.SiteDomainMappingFilter{
		Keyword:  strings.TrimSpace(in.Keyword),
		IsActive: in.IsActive,
		Limit:    siteDomainMappingExportMaxRows + 1,
	})
	if err != nil {
		return nil, err
	}
	if len(items) > siteDomainMappingExportMaxRows {
		return nil, response.ErrBadRequest(
			40059,
			"site_domain_mapping_export_too_large",
			fmt.Sprintf("单次最多导出 %d 行，请缩小筛选范围后重试", siteDomainMappingExportMaxRows),
		)
	}

	var buf bytes.Buffer
	buf.WriteString("\xEF\xBB\xBF")
	writer := csv.NewWriter(&buf)
	if err := writer.Write([]string{"registrable_domain", "site_key", "site_name", "is_active", "created_at", "updated_at"}); err != nil {
		return nil, err
	}
	for _, item := range items {
		if err := writer.Write([]string{
			item.RegistrableDomain,
			item.SiteKey,
			item.SiteName,
			strconv.FormatBool(item.IsActive),
			item.CreatedAt.Format(time.RFC3339),
			item.UpdatedAt.Format(time.RFC3339),
		}); err != nil {
			return nil, err
		}
	}
	writer.Flush()
	if err := writer.Error(); err != nil {
		return nil, err
	}

	if actor != nil && s.audits != nil {
		_ = s.audits.Append(ctx, actor.audit(ActionSiteDomainMappingExport, "site_domain_mapping", 0, map[string]any{
			"count":     len(items),
			"keyword":   strings.TrimSpace(in.Keyword),
			"is_active": in.IsActive,
		}))
	}
	return buf.Bytes(), nil
}

func (s *SiteDomainMappingService) Create(ctx context.Context, actor *Actor, in SiteDomainMappingInput) (*SiteDomainMappingView, error) {
	normalized, err := normalizeSiteDomainMappingInput(in)
	if err != nil {
		return nil, err
	}
	item, err := s.mappings.Create(ctx, repository.CreateSiteDomainMappingInput{
		RegistrableDomain: normalized.RegistrableDomain,
		SiteKey:           normalized.SiteKey,
		SiteName:          normalized.SiteName,
		IsActive:          normalized.IsActive,
	})
	if err != nil {
		if isDuplicateSiteDomainMapping(err) {
			return nil, response.ErrConflict(40920, "duplicate_site_domain_mapping", "该域名映射已存在")
		}
		return nil, err
	}
	if actor != nil && s.audits != nil {
		_ = s.audits.Append(ctx, actor.audit(ActionSiteDomainMappingCreate, "site_domain_mapping", item.ID, siteDomainMappingAuditMetadata(item)))
	}
	view := toSiteDomainMappingView(item)
	return &view, nil
}

func (s *SiteDomainMappingService) ImportCSV(ctx context.Context, actor *Actor, in SiteDomainMappingImportInput) (*SiteDomainMappingImportResult, error) {
	records, err := readSiteDomainMappingCSV(in.Content)
	if err != nil {
		return nil, err
	}
	if len(records) < 2 {
		return nil, response.ErrBadRequest(40053, "empty_site_domain_mapping_import", "CSV 至少需要表头和一行数据")
	}
	if len(records)-1 > siteDomainMappingImportMaxRows {
		return nil, response.ErrBadRequest(
			40054,
			"site_domain_mapping_import_too_large",
			fmt.Sprintf("单次最多导入 %d 行", siteDomainMappingImportMaxRows),
		)
	}

	columns, err := detectSiteDomainMappingImportColumns(records[0])
	if err != nil {
		return nil, err
	}

	result := &SiteDomainMappingImportResult{
		Total:  len(records) - 1,
		Errors: make([]SiteDomainMappingImportError, 0),
	}
	seen := map[string]int{}
	for rowIndex, record := range records[1:] {
		rowNumber := rowIndex + 2
		if isBlankCSVRecord(record) {
			result.Skipped++
			continue
		}
		input, rowErr := siteDomainMappingInputFromCSVRecord(record, columns)
		if rowErr != nil {
			appendSiteDomainMappingImportError(result, rowNumber, rowErr.Error())
			continue
		}
		normalized, rowErr := normalizeSiteDomainMappingInput(input)
		if rowErr != nil {
			appendSiteDomainMappingImportError(result, rowNumber, response.Normalize(rowErr).Detail)
			continue
		}
		if firstRow, ok := seen[normalized.RegistrableDomain]; ok {
			result.Duplicate++
			result.Skipped++
			appendSiteDomainMappingImportWarning(result, rowNumber, fmt.Sprintf("域名与第 %d 行重复，已跳过", firstRow))
			continue
		}
		seen[normalized.RegistrableDomain] = rowNumber

		upserted, rowErr := s.mappings.Upsert(ctx, repository.UpsertSiteDomainMappingInput{
			RegistrableDomain: normalized.RegistrableDomain,
			SiteKey:           normalized.SiteKey,
			SiteName:          normalized.SiteName,
			IsActive:          normalized.IsActive,
		})
		if rowErr != nil {
			appendSiteDomainMappingImportError(result, rowNumber, rowErr.Error())
			continue
		}
		if upserted.Created {
			result.Created++
		} else {
			result.Updated++
		}
	}
	if actor != nil && s.audits != nil {
		_ = s.audits.Append(ctx, actor.audit(ActionSiteDomainMappingImport, "site_domain_mapping", 0, map[string]any{
			"total":     result.Total,
			"created":   result.Created,
			"updated":   result.Updated,
			"skipped":   result.Skipped,
			"failed":    result.Failed,
			"duplicate": result.Duplicate,
		}))
	}
	return result, nil
}

func (s *SiteDomainMappingService) Update(ctx context.Context, actor *Actor, id int64, in SiteDomainMappingInput) (*SiteDomainMappingView, error) {
	normalized, err := normalizeSiteDomainMappingInput(in)
	if err != nil {
		return nil, err
	}
	item, err := s.mappings.Update(ctx, id, repository.UpdateSiteDomainMappingInput{
		RegistrableDomain: normalized.RegistrableDomain,
		SiteKey:           normalized.SiteKey,
		SiteName:          normalized.SiteName,
		IsActive:          normalized.IsActive,
	})
	if err != nil {
		if errors.Is(err, repository.ErrSiteDomainMappingNotFound) {
			return nil, response.ErrNotFound(40420, "site_domain_mapping_not_found", "域名映射不存在")
		}
		if isDuplicateSiteDomainMapping(err) {
			return nil, response.ErrConflict(40920, "duplicate_site_domain_mapping", "该域名映射已存在")
		}
		return nil, err
	}
	if actor != nil && s.audits != nil {
		_ = s.audits.Append(ctx, actor.audit(ActionSiteDomainMappingUpdate, "site_domain_mapping", item.ID, siteDomainMappingAuditMetadata(item)))
	}
	view := toSiteDomainMappingView(item)
	return &view, nil
}

func (s *SiteDomainMappingService) SetActive(ctx context.Context, actor *Actor, id int64, active bool) (*SiteDomainMappingView, error) {
	item, err := s.mappings.SetActive(ctx, id, active)
	if err != nil {
		if errors.Is(err, repository.ErrSiteDomainMappingNotFound) {
			return nil, response.ErrNotFound(40420, "site_domain_mapping_not_found", "域名映射不存在")
		}
		return nil, err
	}
	if actor != nil && s.audits != nil {
		action := ActionSiteDomainMappingEnable
		if !active {
			action = ActionSiteDomainMappingDisable
		}
		_ = s.audits.Append(ctx, actor.audit(action, "site_domain_mapping", item.ID, siteDomainMappingAuditMetadata(item)))
	}
	view := toSiteDomainMappingView(item)
	return &view, nil
}

func (s *SiteDomainMappingService) Delete(ctx context.Context, actor *Actor, id int64) error {
	item, err := s.mappings.GetByID(ctx, id)
	if err != nil {
		if errors.Is(err, repository.ErrSiteDomainMappingNotFound) {
			return response.ErrNotFound(40420, "site_domain_mapping_not_found", "域名映射不存在")
		}
		return err
	}
	if err := s.mappings.Delete(ctx, id); err != nil {
		if errors.Is(err, repository.ErrSiteDomainMappingNotFound) {
			return response.ErrNotFound(40420, "site_domain_mapping_not_found", "域名映射不存在")
		}
		return err
	}
	if actor != nil && s.audits != nil {
		_ = s.audits.Append(ctx, actor.audit(ActionSiteDomainMappingDelete, "site_domain_mapping", id, siteDomainMappingAuditMetadata(item)))
	}
	return nil
}

func normalizeSiteDomainMappingInput(in SiteDomainMappingInput) (SiteDomainMappingInput, error) {
	domainName := normalizeDomainName(in.RegistrableDomain)
	if domainName == "" || len(domainName) > 255 || strings.ContainsAny(domainName, " /\\") || !strings.Contains(domainName, ".") {
		return SiteDomainMappingInput{}, response.ErrBadRequest(40050, "invalid_registrable_domain", "请输入有效域名")
	}

	siteKey := strings.ToLower(strings.TrimSpace(in.SiteKey))
	if siteKey == "" {
		siteKey = domainName
	}
	if len(siteKey) > 255 || strings.ContainsAny(siteKey, " /\\") {
		return SiteDomainMappingInput{}, response.ErrBadRequest(40051, "invalid_site_key", "站点 Key 格式无效")
	}

	siteName := strings.TrimSpace(in.SiteName)
	if siteName == "" || len([]rune(siteName)) > 255 {
		return SiteDomainMappingInput{}, response.ErrBadRequest(40052, "invalid_site_name", "中文名不能为空且不能超过 255 个字")
	}

	return SiteDomainMappingInput{
		RegistrableDomain: domainName,
		SiteKey:           siteKey,
		SiteName:          siteName,
		IsActive:          in.IsActive,
	}, nil
}

func normalizeDomainName(raw string) string {
	value := strings.ToLower(strings.TrimSpace(raw))
	if value == "" {
		return ""
	}

	if strings.Contains(value, "://") {
		if parsed, err := url.Parse(value); err == nil && parsed.Hostname() != "" {
			value = parsed.Hostname()
		}
	} else if strings.ContainsAny(value, "/?#") {
		if parsed, err := url.Parse("https://" + value); err == nil && parsed.Hostname() != "" {
			value = parsed.Hostname()
		}
	} else if host, _, err := net.SplitHostPort(value); err == nil {
		value = host
	}

	return strings.Trim(strings.TrimSuffix(value, "."), ".")
}

func readSiteDomainMappingCSV(content []byte) ([][]string, error) {
	content = bytes.TrimPrefix(content, []byte("\xEF\xBB\xBF"))
	reader := csv.NewReader(bytes.NewReader(content))
	reader.FieldsPerRecord = -1
	reader.TrimLeadingSpace = true
	records, err := reader.ReadAll()
	if err != nil {
		return nil, response.ErrBadRequest(40055, "invalid_site_domain_mapping_csv", "CSV 文件格式无效："+err.Error())
	}
	return records, nil
}

func detectSiteDomainMappingImportColumns(header []string) (siteDomainMappingImportColumns, error) {
	columns := siteDomainMappingImportColumns{
		Domain: -1,
		Key:    -1,
		Name:   -1,
		Active: -1,
	}
	for index, raw := range header {
		switch normalizeSiteDomainMappingCSVHeader(raw) {
		case "registrable_domain":
			columns.Domain = index
		case "site_key":
			columns.Key = index
		case "site_name":
			columns.Name = index
		case "is_active":
			columns.Active = index
		}
	}
	if columns.Domain < 0 || columns.Name < 0 {
		return columns, response.ErrBadRequest(
			40056,
			"invalid_site_domain_mapping_csv_header",
			"CSV 表头至少需要 registrable_domain/site_name，或中文表头：匹配域名/中文名",
		)
	}
	return columns, nil
}

func normalizeSiteDomainMappingCSVHeader(header string) string {
	key := strings.ToLower(strings.TrimSpace(strings.TrimPrefix(header, "\ufeff")))
	key = strings.ReplaceAll(key, " ", "_")
	key = strings.ReplaceAll(key, "-", "_")
	switch key {
	case "registrable_domain", "domain", "matched_domain", "match_domain", "host", "域名", "匹配域名", "站点域名":
		return "registrable_domain"
	case "site_key", "key", "sitekey", "站点key", "站点_key":
		return "site_key"
	case "site_name", "sitename", "name", "中文名", "站点名", "站点名称", "网站名称":
		return "site_name"
	case "is_active", "active", "enabled", "status", "状态", "启用", "是否启用":
		return "is_active"
	default:
		return key
	}
}

func siteDomainMappingInputFromCSVRecord(record []string, columns siteDomainMappingImportColumns) (SiteDomainMappingInput, error) {
	active := true
	if columns.Active >= 0 {
		parsed, err := parseSiteDomainMappingActive(csvCell(record, columns.Active))
		if err != nil {
			return SiteDomainMappingInput{}, err
		}
		active = parsed
	}
	return SiteDomainMappingInput{
		RegistrableDomain: csvCell(record, columns.Domain),
		SiteKey:           csvCell(record, columns.Key),
		SiteName:          csvCell(record, columns.Name),
		IsActive:          active,
	}, nil
}

func parseSiteDomainMappingActive(value string) (bool, error) {
	normalized := strings.ToLower(strings.TrimSpace(value))
	if normalized == "" {
		return true, nil
	}
	switch normalized {
	case "true", "1", "yes", "y", "enabled", "enable", "active", "启用", "是":
		return true, nil
	case "false", "0", "no", "n", "disabled", "disable", "inactive", "停用", "否":
		return false, nil
	default:
		return false, fmt.Errorf("状态只能填写启用/停用、true/false 或 1/0")
	}
}

func csvCell(record []string, index int) string {
	if index < 0 || index >= len(record) {
		return ""
	}
	return strings.TrimSpace(record[index])
}

func isBlankCSVRecord(record []string) bool {
	for _, value := range record {
		if strings.TrimSpace(value) != "" {
			return false
		}
	}
	return true
}

func appendSiteDomainMappingImportError(result *SiteDomainMappingImportResult, row int, message string) {
	if message == "" {
		message = "导入失败"
	}
	result.Failed++
	appendSiteDomainMappingImportWarning(result, row, message)
}

func appendSiteDomainMappingImportWarning(result *SiteDomainMappingImportResult, row int, message string) {
	if message == "" {
		message = "导入失败"
	}
	if len(result.Errors) < siteDomainMappingImportMaxErrors {
		result.Errors = append(result.Errors, SiteDomainMappingImportError{Row: row, Message: message})
	}
}

func isDuplicateSiteDomainMapping(err error) bool {
	var pgErr *pgconn.PgError
	return errors.As(err, &pgErr) && pgErr.Code == "23505"
}

func siteDomainMappingAuditMetadata(item *domain.SiteDomainMapping) map[string]any {
	return map[string]any{
		"registrable_domain": item.RegistrableDomain,
		"site_key":           item.SiteKey,
		"site_name":          item.SiteName,
		"is_active":          item.IsActive,
	}
}