func Delimit(seq, delimiter interface{}, last ...interface{}) (template.HTML, error) {
	d, err := cast.ToStringE(delimiter)
	if err != nil {
		return "", err
	}

	var dLast *string
	for _, l := range last {
		dStr, err := cast.ToStringE(l)
		if err != nil {
			dLast = nil
		}
		dLast = &dStr
		break
	}

	seqv := reflect.ValueOf(seq)
	seqv, isNil := indirect(seqv)
	if isNil {
		return "", errors.New("can't iterate over a nil value")
	}

	var str string
	switch seqv.Kind() {
	case reflect.Map:
		sortSeq, err := Sort(seq)
		if err != nil {
			return "", err
		}
		seqv = reflect.ValueOf(sortSeq)
		fallthrough
	case reflect.Array, reflect.Slice, reflect.String:
		for i := 0; i < seqv.Len(); i++ {
			val := seqv.Index(i).Interface()
			valStr, err := cast.ToStringE(val)
			if err != nil {
				continue
			}
			switch {
			case i == seqv.Len()-2 && dLast != nil:
				str += valStr + *dLast
			case i == seqv.Len()-1:
				str += valStr
			default:
				str += valStr + d
			}
		}

	default:
		return "", errors.New("can't iterate over " + reflect.ValueOf(seq).Type().String())
	}

	return template.HTML(str), nil
}

// Replace all occurences of b with c in a
func Replace(a, b, c interface{}) (string, error) {
	aStr, err := cast.ToStringE(a)
	if err != nil {
		return "", err
	}
	bStr, err := cast.ToStringE(b)
	if err != nil {
		return "", err
	}
	cStr, err := cast.ToStringE(c)
	if err != nil {
		return "", err
	}
	return strings.Replace(aStr, bStr, cStr, -1), nil
}

func (self *Options) String(key string) string {
	value, err := cast.ToStringE(self.Interface(key))
	if err != nil {
		self.log.Printf("%s for key '%s'", err.Error(), key)
	}
	return value
}

// singularize returns the singular form of a single word.
func singularize(in interface{}) (string, error) {
	word, err := cast.ToStringE(in)
	if err != nil {
		return "", err
	}
	return inflect.Singularize(word), nil
}

// substr extracts parts of a string, beginning at the character at the specified
// position, and returns the specified number of characters.
//
// It normally takes two parameters: start and length.
// It can also take one parameter: start, i.e. length is omitted, in which case
// the substring starting from start until the end of the string will be returned.
//
// To extract characters from the end of the string, use a negative start number.
//
// In addition, borrowing from the extended behavior described at http://php.net/substr,
// if length is given and is negative, then that many characters will be omitted from
// the end of string.
func substr(a interface{}, nums ...interface{}) (string, error) {
	aStr, err := cast.ToStringE(a)
	if err != nil {
		return "", err
	}

	var start, length int

	asRunes := []rune(aStr)

	switch len(nums) {
	case 0:
		return "", errors.New("too less arguments")
	case 1:
		if start, err = cast.ToIntE(nums[0]); err != nil {
			return "", errors.New("start argument must be integer")
		}
		length = len(asRunes)
	case 2:
		if start, err = cast.ToIntE(nums[0]); err != nil {
			return "", errors.New("start argument must be integer")
		}
		if length, err = cast.ToIntE(nums[1]); err != nil {
			return "", errors.New("length argument must be integer")
		}
	default:
		return "", errors.New("too many arguments")
	}

	if start < -len(asRunes) {
		start = 0
	}
	if start > len(asRunes) {
		return "", fmt.Errorf("start position out of bounds for %d-byte string", len(aStr))
	}

	var s, e int
	if start >= 0 && length >= 0 {
		s = start
		e = start + length
	} else if start < 0 && length >= 0 {
		s = len(asRunes) + start - length + 1
		e = len(asRunes) + start + 1
	} else if start >= 0 && length < 0 {
		s = start
		e = len(asRunes) + length
	} else {
		s = len(asRunes) + start
		e = len(asRunes) + length
	}

	if s > e {
		return "", fmt.Errorf("calculated start position greater than end position: %d > %d", s, e)
	}
	if e > len(asRunes) {
		e = len(asRunes)
	}

	return string(asRunes[s:e]), nil
}

// Param is a convenience method to do lookups in Site's Params map.
//
// This method is also implemented on Page.
func (n *Node) Param(key interface{}) (interface{}, error) {
	keyStr, err := cast.ToStringE(key)
	if err != nil {
		return nil, err
	}
	return n.Site.Params[keyStr], err
}

// Trim leading/trailing characters defined by b from a
func Trim(a interface{}, b string) (string, error) {
	aStr, err := cast.ToStringE(a)
	if err != nil {
		return "", err
	}
	return strings.Trim(aStr, b), nil
}

func htmlUnescape(in interface{}) (string, error) {
	conv, err := cast.ToStringE(in)
	if err != nil {
		return "", err
	}
	return html.UnescapeString(conv), nil
}

// Slicing in Slicestr is done by specifying a half-open range with
// two indices, start and end. 1 and 4 creates a slice including elements 1 through 3.
// The end index can be omitted, it defaults to the string's length.
func Slicestr(a interface{}, startEnd ...int) (string, error) {
	aStr, err := cast.ToStringE(a)
	if err != nil {
		return "", err
	}

	if len(startEnd) > 2 {
		return "", errors.New("too many arguments")
	}

	asRunes := []rune(aStr)

	if len(startEnd) > 0 && (startEnd[0] < 0 || startEnd[0] >= len(asRunes)) {
		return "", errors.New("slice bounds out of range")
	}

	if len(startEnd) == 2 {
		if startEnd[1] < 0 || startEnd[1] > len(asRunes) {
			return "", errors.New("slice bounds out of range")
		}
		return string(asRunes[startEnd[0]:startEnd[1]]), nil
	} else if len(startEnd) == 1 {
		return string(asRunes[startEnd[0]:]), nil
	} else {
		return string(asRunes[:]), nil
	}

}

func Split(a interface{}, delimiter string) ([]string, error) {
	aStr, err := cast.ToStringE(a)
	if err != nil {
		return []string{}, err
	}
	return strings.Split(aStr, delimiter), nil
}

func (c *Configr) String(key string) (string, error) {
	val, err := c.Get(key)
	if err != nil {
		return "", err
	}
	return cast.ToStringE(val)
}

// emojify "emojifies" the given string.
//
// See http://www.emoji-cheat-sheet.com/
func emojify(in interface{}) (template.HTML, error) {
	str, err := cast.ToStringE(in)

	if err != nil {
		return "", err
	}
	return template.HTML(helpers.Emojify([]byte(str))), nil
}

func Chomp(text interface{}) (string, error) {
	s, err := cast.ToStringE(text)
	if err != nil {
		return "", err
	}

	return strings.TrimRight(s, "\r\n"), nil
}

// chomp removes trailing newline characters from a string.
func chomp(text interface{}) (template.HTML, error) {
	s, err := cast.ToStringE(text)
	if err != nil {
		return "", err
	}

	return template.HTML(strings.TrimRight(s, "\r\n")), nil
}

// sha1 hashes the given input and returns its SHA1 checksum
func sha1(in interface{}) (string, error) {
	conv, err := cast.ToStringE(in)
	if err != nil {
		return "", err
	}

	hash := _sha1.Sum([]byte(conv))
	return hex.EncodeToString(hash[:]), nil
}

// highlight returns an HTML string with syntax highlighting applied.
func highlight(in interface{}, lang, opts string) (template.HTML, error) {
	str, err := cast.ToStringE(in)

	if err != nil {
		return "", err
	}

	return template.HTML(helpers.Highlight(html.UnescapeString(str), lang, opts)), nil
}

// plainify strips any HTML and returns the plain text version.
func plainify(in interface{}) (string, error) {
	s, err := cast.ToStringE(in)

	if err != nil {
		return "", err
	}

	return helpers.StripHTML(s), nil
}

// base64Encode returns the base64 encoding of the given content.
func base64Encode(content interface{}) (string, error) {
	conv, err := cast.ToStringE(content)

	if err != nil {
		return "", err
	}

	return base64.StdEncoding.EncodeToString([]byte(conv)), nil
}

// Param is a convenience method to do lookups in Page's and Site's Params map,
// in that order.
//
// This method is also implemented on Node.
func (p *Page) Param(key interface{}) (interface{}, error) {
	keyStr, err := cast.ToStringE(key)
	if err != nil {
		return nil, err
	}
	if val, ok := p.Params[keyStr]; ok {
		return val, nil
	}
	return p.Site.Params[keyStr], nil
}

func (p *Page) Menus() PageMenus {
	p.pageMenusInit.Do(func() {
		p.pageMenus = PageMenus{}

		if ms, ok := p.Params["menu"]; ok {
			link, _ := p.RelPermalink()

			me := MenuEntry{Name: p.LinkTitle(), Weight: p.Weight, URL: link}

			// Could be the name of the menu to attach it to
			mname, err := cast.ToStringE(ms)

			if err == nil {
				me.Menu = mname
				p.pageMenus[mname] = &me
				return
			}

			// Could be a slice of strings
			mnames, err := cast.ToStringSliceE(ms)

			if err == nil {
				for _, mname := range mnames {
					me.Menu = mname
					p.pageMenus[mname] = &me
				}
				return
			}

			// Could be a structured menu entry
			menus, err := cast.ToStringMapE(ms)

			if err != nil {
				jww.ERROR.Printf("unable to process menus for %q\n", p.Title)
			}

			for name, menu := range menus {
				menuEntry := MenuEntry{Name: p.LinkTitle(), URL: link, Weight: p.Weight, Menu: name}
				if menu != nil {
					jww.DEBUG.Printf("found menu: %q, in %q\n", name, p.Title)
					ime, err := cast.ToStringMapE(menu)
					if err != nil {
						jww.ERROR.Printf("unable to process menus for %q: %s", p.Title, err)
					}

					menuEntry.marshallMap(ime)
				}
				p.pageMenus[name] = &menuEntry

			}
		}
	})

	return p.pageMenus
}