package query

import (
	"strconv"

	"github.com/gin-gonic/gin"
	"gorm.io/gorm"
)

type Params struct {
	Page     int
	PageSize int
	SortBy   string
	SortDir  string
	Filters  map[string]string
}

func ParseParams(c *gin.Context) Params {
	page, _ := strconv.Atoi(c.DefaultQuery("page", "1"))
	pageSize, _ := strconv.Atoi(c.DefaultQuery("page_size", "20"))

	if page < 1 {
		page = 1
	}
	if pageSize < 1 {
		pageSize = 20
	}
	if pageSize > 100 {
		pageSize = 100
	}

	sortBy := c.Query("sort_by")
	sortDir := c.DefaultQuery("sort_dir", "asc")
	if sortDir != "asc" && sortDir != "desc" {
		sortDir = "asc"
	}

	filters := make(map[string]string)
	for key, values := range c.Request.URL.Query() {
		if key != "page" && key != "page_size" && key != "sort_by" && key != "sort_dir" {
			filters[key] = values[0]
		}
	}

	return Params{
		Page:     page,
		PageSize: pageSize,
		SortBy:   sortBy,
		SortDir:  sortDir,
		Filters:  filters,
	}
}

func Paginate(p Params) func(db *gorm.DB) *gorm.DB {
	return func(db *gorm.DB) *gorm.DB {
		offset := (p.Page - 1) * p.PageSize
		return db.Offset(offset).Limit(p.PageSize)
	}
}

func Sort(p Params) func(db *gorm.DB) *gorm.DB {
	return func(db *gorm.DB) *gorm.DB {
		if p.SortBy == "" {
			return db
		}
		return db.Order(p.SortBy + " " + p.SortDir)
	}
}

func Filter(p Params, allowed map[string]string) func(db *gorm.DB) *gorm.DB {
	return func(db *gorm.DB) *gorm.DB {
		for key, value := range p.Filters {
			if col, ok := allowed[key]; ok && value != "" {
				db = db.Where(col+" = ?", value)
			}
		}
		return db
	}
}

type PageResult[T any] struct {
	Items    []T   `json:"items"`
	Total    int64 `json:"total"`
	Page     int   `json:"page"`
	PageSize int   `json:"page_size"`
}