main.go

// Copyright (c) 2012-2014 José Carlos Nieto, https://menteslibres.net/xiam
//
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
//
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

package util

import (
	"reflect"
	"regexp"
	"strings"
	"time"

	"menteslibres.net/gosexy/to"
)

var reColumnCompareExclude = regexp.MustCompile(`[^a-zA-Z0-9]`)

var (
	durationType = reflect.TypeOf(time.Duration(0))
	timeType     = reflect.TypeOf(time.Time{})
)

type tagOptions map[string]bool

func parseTagOptions(s string) tagOptions {
	opts := make(tagOptions)
	chunks := strings.Split(s, `,`)
	for _, chunk := range chunks {
		opts[strings.TrimSpace(chunk)] = true
	}
	return opts
}

// Based on http://golang.org/src/pkg/encoding/json/tags.go
func ParseTag(tag string) (string, tagOptions) {
	if i := strings.Index(tag, `,`); i != -1 {
		return tag[:i], parseTagOptions(tag[i+1:])
	}
	return tag, parseTagOptions(``)
}

// Returns the most appropriate struct field index for a given column name.
//
// If no column matches returns nil.
func GetStructFieldIndex(t reflect.Type, columnName string) []int {

	n := t.NumField()

	for i := 0; i < n; i++ {

		field := t.Field(i)

		if field.PkgPath != "" {
			// Field is unexported.
			continue
		}

		// Attempt to use db:"column_name"
		fieldName, fieldOptions := ParseTag(field.Tag.Get("db"))

		// Deprecated "field" tag.
		if deprecatedField := field.Tag.Get("field"); deprecatedField != "" {
			fieldName = deprecatedField
		}

		// Deprecated "inline" tag.
		if deprecatedInline := field.Tag.Get("inline"); deprecatedInline != "" {
			fieldOptions["inline"] = true
		}

		// Matching fieldName
		if fieldName == "-" {
			continue
		}

		// Attempt to match field name.
		if fieldName == columnName {
			return []int{i}
		}

		if fieldName == "" {
			if NormalizeColumn(field.Name) == NormalizeColumn(columnName) {
				return []int{i}
			}
		}

		// Inline option.
		if fieldOptions["inline"] == true {
			index := GetStructFieldIndex(field.Type, columnName)
			if index != nil {
				res := append([]int{i}, index...)
				return res
			}
		}

	}

	// No match.
	return nil
}

func StringToType(src string, dstt reflect.Type) (reflect.Value, error) {
	var srcv reflect.Value
	switch dstt {
	case durationType:
		srcv = reflect.ValueOf(to.Duration(src))
	case timeType:
		// Destination is time.Time
		srcv = reflect.ValueOf(to.Time(src))
	default:
		return StringToKind(src, dstt.Kind())
	}
	return srcv, nil
}

func StringToKind(src string, dstk reflect.Kind) (reflect.Value, error) {
	var srcv reflect.Value

	// Destination type.
	switch dstk {
	case reflect.Interface:
		// Destination is interface, nuff said.
		srcv = reflect.ValueOf(src)
	default:
		cv, err := to.Convert(src, dstk)
		if err != nil {
			return srcv, nil
		}
		srcv = reflect.ValueOf(cv)
	}

	return srcv, nil
}

func NormalizeColumn(s string) string {
	return strings.ToLower(reColumnCompareExclude.ReplaceAllString(s, ""))
}