package tableDB

import (
	"fmt"
	"strings"
	"time"

	"apigo.cc/go/cast"
	"apigo.cc/go/db"
	"apigo.cc/go/log"
)

const SystemUserID = "_system"

const SystemSchema = `
== System ==
_Table SD // 核心表：存储所有表的元数据
  id c10 PK
  name v64 U // 表名
  memo t // 备注
  createTime bi // 创建时间
  creator v64 // 创建者

_Field SD // 核心表：存储所有字段的元数据
  id c10 PK
  tableId c10 I // 所属表 ID
  name v64 // 字段名
  type v32 // 字段类型
  isIndex b // 是否索引
  memo t // 备注
  createTime bi // 创建时间
  creator v64 // 创建者

_Policy SD // 核心表：访问策略
  subject v64 I // 主体 (UserID 或 Role)
  action v32 I // 动作
  resource v128 I // 资源 (Table 或 Record ID)
  effect v16 // allow 或 deny
  creator v64 // 创建者
`

type Hooks struct {
	OnCreatedTable func(tableName string, record map[string]any)
	OnRemovedTable func(tableName string)
	OnUpdatedField func(tableId, fieldName string, record map[string]any)
	OnRemovedField func(tableId, fieldName string)
	OnUpdatingRow  func(tableName string, row map[string]any) error
	OnUpdatedRows  func(tableName string, count int)
	OnRemovedRows  func(tableName string, ids []string)
}

// TableDB wraps the base go/db implementation to provide high-level abstractions.
type TableDB struct {
	base   *db.DB
	userID string
	Hooks  *Hooks
}

type App = TableDB

// GetDB retrieves a configured database instance.
func GetDB(name string, logger *log.Logger) *TableDB {
	baseDB := db.GetDB(name, logger)
	return &TableDB{
		base:   baseDB,
		userID: SystemUserID,
		Hooks:  &Hooks{},
	}
}

// Auth creates a new instance with the specified userID context.
func (d *TableDB) Auth(userID string) *App {
	return &TableDB{
		base:   d.base,
		userID: userID,
		Hooks:  d.Hooks,
	}
}

// SyncSchema automatically applies the DSL schema to the underlying database.
func (d *TableDB) SyncSchema(schemaDSL string) error {
	// 1. Sync to actual DB
	// Underground rules (autoIndex, id normalization) are now handled internally by d.base.Sync
	
	finalDSL := schemaDSL
	if !strings.Contains(schemaDSL, "_Table") {
		finalDSL = SystemSchema + "\n" + schemaDSL
	}

	err := d.base.Sync(finalDSL)
	if err != nil {
		return err
	}

	// 2. Update _Table and _Field metadata
	res := d.base.Query("SELECT name FROM sqlite_master WHERE type='table' AND name='_Table'")
	if d.base.Config.Type == "mysql" {
		res = d.base.Query("SELECT TABLE_NAME name FROM information_schema.TABLES WHERE TABLE_SCHEMA=? AND TABLE_NAME='_Table'", d.base.Config.DB)
	}
	if res.Error == nil && res.MapOnR1()["name"] != nil {
		groups := db.ParseSchema(finalDSL)
		for _, group := range groups {
			for _, table := range group.Tables {
				// Upsert _Table
				tRecord := map[string]any{
					"name":       table.Name,
					"memo":       table.Comment,
					"createTime": time.Now().UnixMilli(),
				}
				existingTable, _ := d.Table("_Table").List(map[string]any{"name": table.Name})
				var tid string
				if len(existingTable) > 0 {
					tid = cast.String(existingTable[0]["id"])
					tRecord["id"] = tid
				}
				_ = d.Table("_Table").Set(tRecord)
				if tid == "" {
					newTable, _ := d.Table("_Table").List(map[string]any{"name": table.Name})
					if len(newTable) > 0 {
						tid = cast.String(newTable[0]["id"])
					}
				}

				if tid != "" {
					// Update _Field
					for _, field := range table.Fields {
						fRecord := map[string]any{
							"tableId":    tid,
							"name":       field.Name,
							"type":       field.Type,
							"isIndex":    cast.If(field.Index != "", 1, 0),
							"memo":       field.Comment,
							"createTime": time.Now().UnixMilli(),
						}
						existingField, _ := d.Table("_Field").List(map[string]any{"tableId": tid, "name": field.Name})
						if len(existingField) > 0 {
							fRecord["id"] = existingField[0]["id"]
						}
						_ = d.Table("_Field").Set(fRecord)
					}
				}
			}
		}
	}

	// 3. Reload cache
	return GlobalCache.Load(d)
}

// Table returns an AI-friendly interface for multi-dimensional operations on a specific table.
func (d *TableDB) Table(name string) *Table {
	return NewTable(name, d)
}

// Base returns the underlying apigo.cc/go/db.DB for raw queries if needed.
func (d *TableDB) Base() *db.DB {
	return d.base
}

// Query performs a structured query.
func (d *TableDB) Query(req QueryRequest) ([]map[string]any, error) {
	sql, args, err := d.BuildQuery(req)
	if err != nil {
		return nil, err
	}
	res := d.base.Query(sql, args...)
	if res.Error != nil {
		return nil, res.Error
	}
	return res.MapResults(), nil
}

// BuildQuery constructs a SQL query from a QueryRequest with strict identifier validation.
func (d *TableDB) BuildQuery(req QueryRequest) (string, []any, error) {
	if GlobalCache.GetTable(req.Table) == nil {
		return "", nil, fmt.Errorf("invalid table: %s", req.Table)
	}

	fields := "*"
	if len(req.Select) > 0 {
		validFields := GlobalCache.GetValidFields(req.Table)
		fieldMap := make(map[string]bool)
		for _, f := range validFields {
			fieldMap[f] = true
		}

		var validatedSelect []string
		for _, s := range req.Select {
			if !fieldMap[s] {
				return "", nil, fmt.Errorf("invalid field %s in table %s", s, req.Table)
			}
			validatedSelect = append(validatedSelect, "`"+s+"`")
		}
		fields = strings.Join(validatedSelect, ", ")
	}

	var sql strings.Builder
	fmt.Fprintf(&sql, "SELECT %s FROM `%s` ", fields, req.Table)

	for _, join := range req.Joins {
		if GlobalCache.GetTable(join.Table) == nil {
			return "", nil, fmt.Errorf("invalid join table: %s", join.Table)
		}
		joinType := join.Type
		if joinType == "" {
			joinType = "LEFT"
		}
		jt := strings.ToUpper(joinType)
		if jt != "LEFT" && jt != "INNER" && jt != "RIGHT" && jt != "FULL" && jt != "CROSS" {
			return "", nil, fmt.Errorf("invalid join type: %s", joinType)
		}
		fmt.Fprintf(&sql, "%s JOIN `%s` ON %s ", jt, join.Table, join.On)
	}

	args := req.Args
	if req.Where != "" {
		sql.WriteString(" WHERE ")
		sql.WriteString(req.Where)
	}

	if req.OrderBy != "" {
		parts := strings.Fields(req.OrderBy)
		if len(parts) > 0 {
			fieldName := parts[0]
			validFields := GlobalCache.GetValidFields(req.Table)
			found := false
			for _, f := range validFields {
				if f == fieldName {
					found = true
					break
				}
			}
			if !found {
				return "", nil, fmt.Errorf("invalid order by field: %s", fieldName)
			}

			direction := ""
			if len(parts) > 1 {
				dir := strings.ToUpper(parts[1])
				if dir == "ASC" || dir == "DESC" {
					direction = " " + dir
				} else {
					return "", nil, fmt.Errorf("invalid order by direction: %s", parts[1])
				}
			}
			fmt.Fprintf(&sql, " ORDER BY `%s` %s", fieldName, direction)
		}
	}

	if req.Limit > 0 {
		fmt.Fprintf(&sql, " LIMIT %d", req.Limit)
	}
	if req.Offset > 0 {
		fmt.Fprintf(&sql, " OFFSET %d", req.Offset)
	}

	return sql.String(), args, nil
}

// BuildWhere is a helper to convert a map of conditions into a SQL WHERE clause and args.
func buildWhere(filter map[string]any) (string, []any) {
	if len(filter) == 0 {
		return "", nil
	}

	var builder strings.Builder
	var args []any
	first := true

	for k, v := range filter {
		if !first {
			builder.WriteString(" AND ")
		}
		first = false

		k = strings.TrimSpace(k)
		operator := "="
		parts := strings.Split(k, " ")
		if len(parts) > 1 {
			k = parts[0]
			operator = strings.Join(parts[1:], " ")
		}

		builder.WriteString(k)
		builder.WriteString(" ")
		builder.WriteString(operator)
		builder.WriteString(" ?")
		args = append(args, v)
	}

	return builder.String(), args
}