package system

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"kra/internal/biz/system"
	"strconv"
	"strings"
	"time"

	"gorm.io/gorm"
)

type exportTemplatePO struct {
	ID           uint `gorm:"primaryKey"`
	CreatedAt    time.Time
	UpdatedAt    time.Time
	DeletedAt    gorm.DeletedAt `gorm:"index"`
	DBName       string
	Name         string
	DBTableName  string `gorm:"column:table_name"`
	TemplateID   string
	TemplateInfo string `gorm:"type:text"`
	SQL          string `gorm:"type:text"`
	ImportSQL    string `gorm:"type:text"`
	Limit        *int
	Order        string
}

func (exportTemplatePO) TableName() string { return "sys_export_templates" }

type exportConditionPO struct {
	ID         uint `gorm:"primaryKey"`
	CreatedAt  time.Time
	UpdatedAt  time.Time
	DeletedAt  gorm.DeletedAt `gorm:"index"`
	TemplateID string         `gorm:"index"`
	From       string
	Column     string
	Operator   string
}

func (exportConditionPO) TableName() string { return "sys_export_template_condition" }

type exportJoinPO struct {
	ID         uint `gorm:"primaryKey"`
	CreatedAt  time.Time
	UpdatedAt  time.Time
	DeletedAt  gorm.DeletedAt `gorm:"index"`
	TemplateID string         `gorm:"index"`
	Join       string         `gorm:"column:joins"`
	Table      string
	On         string `gorm:"column:on"`
}

func (exportJoinPO) TableName() string { return "sys_export_template_join" }

type exportRepo struct{ data Provider }

func NewExportRepo(data Provider) system.ExportRepo { return &exportRepo{data: data} }
func exportFromPO(po exportTemplatePO, conditions []exportConditionPO, joins []exportJoinPO) *system.ExportTemplate {
	v := &system.ExportTemplate{ID: po.ID, CreatedAt: po.CreatedAt, UpdatedAt: po.UpdatedAt, DBName: po.DBName, Name: po.Name, TableName: po.DBTableName, TemplateID: po.TemplateID, TemplateInfo: po.TemplateInfo, SQL: po.SQL, ImportSQL: po.ImportSQL, Limit: po.Limit, Order: po.Order}
	if conditions != nil {
		v.Conditions = make([]system.ExportCondition, 0, len(conditions))
	}
	for _, x := range conditions {
		v.Conditions = append(v.Conditions, system.ExportCondition{ID: x.ID, CreatedAt: x.CreatedAt, UpdatedAt: x.UpdatedAt, TemplateID: x.TemplateID, From: x.From, Column: x.Column, Operator: x.Operator})
	}
	if joins != nil {
		v.Joins = make([]system.ExportJoin, 0, len(joins))
	}
	for _, x := range joins {
		v.Joins = append(v.Joins, system.ExportJoin{ID: x.ID, CreatedAt: x.CreatedAt, UpdatedAt: x.UpdatedAt, TemplateID: x.TemplateID, Join: x.Join, Table: x.Table, On: x.On})
	}
	return v
}
func exportToPO(v *system.ExportTemplate) exportTemplatePO {
	return exportTemplatePO{DBName: v.DBName, Name: v.Name, DBTableName: v.TableName, TemplateID: v.TemplateID, TemplateInfo: v.TemplateInfo, SQL: v.SQL, ImportSQL: v.ImportSQL, Limit: v.Limit, Order: v.Order}
}
func (r *exportRepo) saveRelations(tx *gorm.DB, v *system.ExportTemplate, replace bool) error {
	if replace {
		if err := tx.Where("template_id = ?", v.TemplateID).Delete(&exportConditionPO{}).Error; err != nil {
			return err
		}
		if err := tx.Where("template_id = ?", v.TemplateID).Delete(&exportJoinPO{}).Error; err != nil {
			return err
		}
	}
	conditions := make([]exportConditionPO, 0, len(v.Conditions))
	for _, x := range v.Conditions {
		conditions = append(conditions, exportConditionPO{TemplateID: v.TemplateID, From: x.From, Column: x.Column, Operator: x.Operator})
	}
	if len(conditions) > 0 {
		if err := tx.Create(&conditions).Error; err != nil {
			return err
		}
	}
	joins := make([]exportJoinPO, 0, len(v.Joins))
	for _, x := range v.Joins {
		joins = append(joins, exportJoinPO{TemplateID: v.TemplateID, Join: x.Join, Table: x.Table, On: x.On})
	}
	if len(joins) > 0 {
		return tx.Create(&joins).Error
	}
	return nil
}
func (r *exportRepo) CreateExportTemplate(ctx context.Context, v *system.ExportTemplate) error {
	return r.data.DB().WithContext(ctx).Transaction(func(tx *gorm.DB) error {
		po := exportToPO(v)
		if err := tx.Create(&po).Error; err != nil {
			return err
		}
		v.ID = po.ID
		return r.saveRelations(tx, v, false)
	})
}
func (r *exportRepo) UpdateExportTemplate(ctx context.Context, v *system.ExportTemplate) error {
	return r.data.DB().WithContext(ctx).Transaction(func(tx *gorm.DB) error {
		po := exportToPO(v)
		if err := tx.Model(&exportTemplatePO{}).Where("id = ?", v.ID).Updates(&po).Error; err != nil {
			return err
		}
		return r.saveRelations(tx, v, true)
	})
}
func (r *exportRepo) DeleteExportTemplates(ctx context.Context, ids []uint) error {
	return r.data.DB().WithContext(ctx).Delete(&[]exportTemplatePO{}, "id IN ?", ids).Error
}
func (r *exportRepo) FindExportTemplate(ctx context.Context, id uint, tid string) (*system.ExportTemplate, error) {
	var po exportTemplatePO
	db := r.data.DB().WithContext(ctx)
	var err error
	if tid != "" {
		err = db.Where("template_id = ?", tid).First(&po).Error
	} else {
		err = db.Where("id = ?", id).First(&po).Error
	}
	if err != nil {
		return nil, err
	}
	var conditions []exportConditionPO
	var joins []exportJoinPO
	if err = db.Where("template_id = ?", po.TemplateID).Find(&conditions).Error; err != nil {
		return nil, err
	}
	if err = db.Where("template_id = ?", po.TemplateID).Find(&joins).Error; err != nil {
		return nil, err
	}
	return exportFromPO(po, conditions, joins), nil
}
func (r *exportRepo) ListExportTemplates(ctx context.Context, page, size int, q *system.ExportTemplate) ([]*system.ExportTemplate, int64, error) {
	db := r.data.DB().WithContext(ctx).Model(&exportTemplatePO{})
	if q != nil {
		if q.StartCreatedAt != nil && q.EndCreatedAt != nil {
			db = db.Where("created_at BETWEEN ? AND ?", q.StartCreatedAt, q.EndCreatedAt)
		}
		if q.Name != "" {
			db = db.Where("name LIKE ?", "%"+q.Name+"%")
		}
		if q.TableName != "" {
			db = db.Where("table_name = ?", q.TableName)
		}
		if q.TemplateID != "" {
			db = db.Where("template_id = ?", q.TemplateID)
		}
	}
	var total int64
	if err := db.Count(&total).Error; err != nil {
		return nil, 0, err
	}
	var pos []exportTemplatePO
	// This module applies pageSize and its raw offset formula verbatim instead
	// of using the shared PageInfo normalization.
	if size != 0 {
		db = db.Limit(size).Offset(size * (page - 1))
	}
	if err := db.Find(&pos).Error; err != nil {
		return nil, 0, err
	}
	out := make([]*system.ExportTemplate, 0, len(pos))
	for _, po := range pos {
		out = append(out, exportFromPO(po, nil, nil))
	}
	return out, total, nil
}

func (r *exportRepo) QueryExport(ctx context.Context, t *system.ExportTemplate, params map[string]string) ([]map[string]any, string, error) {
	query, err := r.buildExportQuery(ctx, t, params)
	if err != nil {
		return nil, "", err
	}
	var rows []map[string]any
	preview := query.ToSQL(func(tx *gorm.DB) *gorm.DB { return tx.Find(&[]map[string]any{}) })
	err = query.Find(&rows).Error
	return rows, preview, err
}

func exportColumns(raw string) ([]string, error) {
	columns := make([]string, 0)
	decoder := json.NewDecoder(strings.NewReader(raw))
	if token, err := decoder.Token(); err != nil || token != json.Delim('{') {
		return nil, errors.New("导出模板列定义必须是 JSON 对象")
	}
	for decoder.More() {
		key, err := decoder.Token()
		if err != nil {
			return nil, err
		}
		column, ok := key.(string)
		if !ok {
			return nil, errors.New("导出模板列名无效")
		}
		columns = append(columns, column)
		var ignored any
		if err = decoder.Decode(&ignored); err != nil {
			return nil, err
		}
	}
	if len(columns) == 0 {
		return nil, errors.New("模板列为空")
	}
	return columns, nil
}

func (r *exportRepo) buildExportQuery(ctx context.Context, t *system.ExportTemplate, params map[string]string) (*gorm.DB, error) {
	if err := system.ValidateExportTemplate(t); err != nil {
		return nil, err
	}
	selected, err := r.data.Database(t.DBName)
	if err != nil {
		return nil, err
	}
	db := selected.WithContext(ctx)
	columns, err := exportColumns(t.TemplateInfo)
	if err != nil {
		return nil, err
	}
	query := db.Table(t.TableName).Select(strings.Join(columns, ","))
	for _, j := range t.Joins {
		query = query.Joins(strings.ToUpper(strings.Join(strings.Fields(j.Join), " ")) + " " + j.Table + " ON " + j.On)
	}
	if params["filterDeleted"] == "true" {
		query = query.Where(t.TableName + ".deleted_at IS NULL")
		for _, join := range t.Joins {
			if db.Migrator().HasColumn(join.Table, "deleted_at") {
				query = query.Where(join.Table + ".deleted_at IS NULL")
			}
		}
	}
	for _, condition := range t.Conditions {
		operator := strings.ToUpper(strings.Join(strings.Fields(condition.Operator), " "))
		value := params[condition.From]
		switch operator {
		case "LIKE":
			if value != "" {
				query = query.Where(condition.Column+" LIKE ?", "%"+value+"%")
			}
		case "IN", "NOT IN":
			if value != "" {
				values := strings.Split(value, ",")
				for index := range values {
					values[index] = strings.TrimSpace(values[index])
				}
				query = query.Where(condition.Column+" "+operator+" ?", values)
			}
		case "BETWEEN":
			start, end := params["start"+condition.From], params["end"+condition.From]
			if start != "" && end != "" {
				query = query.Where(condition.Column+" BETWEEN ? AND ?", start, end)
			}
		default:
			if value != "" {
				query = query.Where(condition.Column+" "+operator+" ?", value)
			}
		}
	}
	limit := 0
	if raw := params["limit"]; raw != "" {
		limit, err = strconv.Atoi(raw)
		if err != nil || limit < 0 || limit > 100000 {
			return nil, errors.New("导出行数限制不合法")
		}
	} else if t.Limit != nil {
		limit = *t.Limit
	}
	if limit > 0 {
		query = query.Limit(limit)
	}
	if raw := params["offset"]; raw != "" {
		offset, parseErr := strconv.Atoi(raw)
		if parseErr != nil || offset < 0 {
			return nil, errors.New("导出偏移量不合法")
		}
		query = query.Offset(offset)
	}
	order := params["order"]
	if order == "" {
		order = t.Order
	}
	if order != "" {
		parts := strings.Fields(order)
		if len(parts) > 2 {
			return nil, errors.New("导出排序不合法")
		}
		fields := map[string]bool{}
		columnTypes, columnErr := db.Migrator().ColumnTypes(t.TableName)
		if columnErr != nil {
			return nil, columnErr
		}
		for _, column := range columnTypes {
			fields[column.Name()] = true
		}
		columnName := parts[0]
		if dot := strings.LastIndex(columnName, "."); dot >= 0 {
			columnName = columnName[dot+1:]
		}
		if !fields[columnName] {
			return nil, fmt.Errorf("order by %s is not in the fields", order)
		}
		orderSQL := parts[0]
		if len(parts) > 1 {
			if !strings.EqualFold(parts[1], "asc") && !strings.EqualFold(parts[1], "desc") {
				return nil, fmt.Errorf("order by %s is not secure", order)
			}
			orderSQL += " " + strings.ToUpper(parts[1])
		}
		query = query.Order(orderSQL)
	}
	return query, nil
}

func (r *exportRepo) PreviewExport(ctx context.Context, t *system.ExportTemplate, params map[string]string) (string, error) {
	query, err := r.buildExportQuery(ctx, t, params)
	if err != nil {
		return "", err
	}
	return query.ToSQL(func(tx *gorm.DB) *gorm.DB { return tx.Find(&[]map[string]any{}) }), nil
}
func parseTemplateColumns(raw string) map[string]string {
	out := map[string]string{}
	parts := strings.Split(strings.Trim(strings.TrimSpace(raw), "{}"), ",")
	for _, part := range parts {
		pair := strings.SplitN(part, ":", 2)
		if len(pair) == 2 {
			out[strings.Trim(strings.TrimSpace(pair[0]), `"`)] = strings.Trim(strings.TrimSpace(pair[1]), `"`)
		}
	}
	return out
}
func (r *exportRepo) ImportExportRows(ctx context.Context, t *system.ExportTemplate, rows []map[string]any) error {
	if err := system.ValidateExportTemplate(t); err != nil {
		return err
	}
	selected, err := r.data.Database(t.DBName)
	if err != nil {
		return err
	}
	return selected.WithContext(ctx).Transaction(func(tx *gorm.DB) error {
		needCreated := tx.Migrator().HasColumn(t.TableName, "created_at")
		needUpdated := tx.Migrator().HasColumn(t.TableName, "updated_at")
		for _, row := range rows {
			if row["created_at"] == nil && needCreated {
				row["created_at"] = time.Now()
			}
			if row["updated_at"] == nil && needUpdated {
				row["updated_at"] = time.Now()
			}
		}
		return tx.Table(t.TableName).CreateInBatches(&rows, 1000).Error
	})
}