package crud

import (
	"errors"
	"github.com/labstack/echo/v4"
	"net/http"
	"reflect"
	"sorbet/pkg/db"
	"sorbet/pkg/rsp"
	"strconv"
	"strings"
)

type (
	// RequestGuarder 参数守卫函数签名
	RequestGuarder func(c echo.Context, req any) error

	// BodyBinder 将请求体绑定到结构体上
	BodyBinder interface {
		BindBody(c echo.Context, i any) (err error)
	}
)

// 使用内置数据绑定函数
// 默认使用 echo.DefaultBinder
var binder BodyBinder

// Validate 验证数据
func Validate(c echo.Context, t any, guards ...RequestGuarder) error {
	err := c.Validate(t)
	if err != nil && !errors.Is(err, echo.ErrValidatorNotRegistered) {
		return err
	}
	if v, ok := t.(interface{ Validate() error }); ok {
		err = v.Validate()
		if err != nil {
			return err
		}
	}
	for _, guard := range guards {
		err = guard(c, t)
		if err != nil {
			return err
		}
	}
	return nil
}

// Bind 将提交的参数绑定到泛型 T 的实例上
func Bind[T any](c echo.Context, guards ...RequestGuarder) (*T, error) {
	var req T
	if err := c.Bind(&req); err != nil {
		return nil, err
	}
	if err := Validate(c, &req, guards...); err != nil {
		return nil, err
	}
	return &req, nil
}

// BindBody 将提交请求体绑定到泛型 T 的实例上
func BindBody[T any](c echo.Context, guards ...RequestGuarder) (*T, error) {
	b, ok := c.Echo().Binder.(BodyBinder)
	if !ok || b == nil {
		if binder == nil {
			binder = &echo.DefaultBinder{}
		}
		b = binder
	}
	var req T
	if err := b.BindBody(c, &req); err != nil {
		return nil, err
	}
	if err := Validate(c, &req, guards...); err != nil {
		return nil, err
	}
	return &req, nil
}

type identifier struct {
	ID any `json:"id" xml:"id"`
}

// BindID 自请求中获取需要的数据编号
// 查找的是名称为 `id` 的数据，查找顺序如下
// 1. 查看路由中是否定义，比如：`/configs/:id`
// 2. 查看查询字符串中是否存在，比如：`?id=123`
// 3. 查看请求体中是否存在，支持 json 和 xml 两种格式。
func BindID(c echo.Context) (id any, err error) {
	defer func() {
		if recovered := recover(); recovered != nil {
			c.Logger().Debugf("%#v", recovered)
			id = nil
			err = rsp.ErrBadParams
		}
	}()
	for i, name := range c.ParamNames() {
		if name == "id" {
			id = c.ParamValues()[i]
			if id != "" {
				return
			}
			break
		}
	}
	switch c.Request().Method {
	case http.MethodGet, http.MethodDelete, http.MethodHead:
		for key, values := range c.QueryParams() {
			if key == "id" {
				id = values[0]
				if id != "" {
					return
				}
				break
			}
		}
	}
	if c.Request().ContentLength == 0 {
		err = rsp.ErrBadParams
		return
	}
	var data *identifier
	data, err = BindBody[identifier](c)
	if err != nil {
		return nil, err
	}
	if data.ID == nil {
		return nil, rsp.ErrBadParams
	}
	rv := reflect.ValueOf(data.ID)
	if rv.IsZero() || rv.IsNil() {
		return nil, rsp.ErrBadParams
	}
	return data.ID, nil
}

func BindQuery[T any](c echo.Context, qb *db.QueryBuilder[T]) (page, limit int, err error) {
	query := c.QueryParams()
	var paginating bool
	for key, values := range query {
		switch key {
		case "sortby":
			for _, s := range values {
				if s[0] == '+' {
					qb.AscentBy(s[1:])
				} else if s[0] == '-' {
					qb.DescentBy(s[1:])
				} else {
					qb.AscentBy(s)
				}
			}
		case "limit", "page":
			var v int
			if values[0] != "" {
				v, err = strconv.Atoi(values[0])
				if err != nil {
					return
				}
			}
			if v <= 0 {
				err = rsp.ErrInternal
				return
			}
			if key == "limit" {
				qb.Limit(v)
				limit = v
			} else {
				paginating = true
				page = max(v, 1)
			}
		default:
			v := values[0]
			i := strings.IndexByte(key, '#')
			if i == -1 {
				qb.Eq(key, v)
				continue
			}
			switch k, op := key[:i], key[i+1:]; op {
			case "=":
				qb.Eq(k, v)
			case "!=":
				qb.Neq(k, v)
			case "<":
				qb.Lt(k, v)
			case "<=":
				qb.Lte(k, v)
			case ">":
				qb.Gt(k, v)
			case ">=":
				qb.Gte(k, v)
			case "<>", "><":
				var less, more any
				switch len(values) {
				case 2:
					less, more = values[0], values[1]
				case 1:
					vs := strings.Split(v, ",")
					if len(vs) != 2 || vs[0] == "" || vs[1] == "" {
						err = rsp.ErrBadParams
						return
					}
					less, more = vs[0], vs[1]
				default:
					err = rsp.ErrBadParams
					return
				}
				if op == "<>" {
					qb.Between(k, less, more)
				} else {
					qb.NotBetween(k, key, more)
				}
			case "nil":
				qb.IsNull(k)
			case "!nil":
				qb.NotNull(k)
			case "~":
				qb.Like(k, v)
			case "!~":
				qb.NotLike(k, v)
			case "in", "!in":
				if len(values) == 1 {
					values = strings.Split(v, ",")
				}
				vs := make([]any, len(values))
				for i, value := range values {
					vs[i] = value
				}
				if op == "in" {
					qb.In(k, vs...)
				} else {
					qb.NotIn(k, vs...)
				}
			default:
				qb.Eq(key, v)
			}
		}
	}
	if paginating {
		if limit == 0 {
			limit = 30
			qb.Limit(limit)
		}
		qb.Offset((page - 1) * limit)
	}
	return
}