package template

import (
	"bytes"
	"fmt"
	"strings"
	"unicode/utf8"
)

func htmlNospaceEscaper(args ...interface{}) string {
	s, t := stringify(args...)
	if t == contentTypeHTML {
		return htmlReplacer(stripTags(s), htmlNospaceNormReplacementTable, false)
	}
	return htmlReplacer(s, htmlNospaceReplacementTable, false)
}

func attrEscaper(args ...interface{}) string {
	s, t := stringify(args...)
	if t == contentTypeHTML {
		return htmlReplacer(stripTags(s), htmlNormReplacementTable, true)
	}
	return htmlReplacer(s, htmlReplacementTable, true)
}

func rcdataEscaper(args ...interface{}) string {
	s, t := stringify(args...)
	if t == contentTypeHTML {
		return htmlReplacer(s, htmlNormReplacementTable, true)
	}
	return htmlReplacer(s, htmlReplacementTable, true)
}

func htmlEscaper(args ...interface{}) string {
	s, t := stringify(args...)
	if t == contentTypeHTML {
		return s
	}
	return htmlReplacer(s, htmlReplacementTable, true)
}

	0:    "\uFFFD",
	'"':  """,
	'&':  "&",
	'\'': "'",
	'+':  "+",
	'<':  "&lt;",
	'>':  "&gt;",
}

var htmlNormReplacementTable = []string{
	0:    "\uFFFD",
	'"':  """,
	'\'': "'",
	'+':  "+",
	'<':  "&lt;",
	'>':  "&gt;",
}

var htmlNospaceReplacementTable = []string{
	0:    "�",
	'\t': "	",
	'\n': "
",
	'\v': "",
	'\f': "",
	'\r': "
",
	' ':  " ",
	'"':  """,
	'&':  "&",
	'\'': "'",
	'+':  "+",
	'<':  "&lt;",
	'=':  "&#61;",

	'`': "`",
}

var htmlNospaceNormReplacementTable = []string{
	0:    "�",
	'\t': "	",
	'\n': "
",
	'\v': "",
	'\f': "",
	'\r': "
",
	' ':  " ",
	'"':  """,
	'\'': "'",
	'+':  "+",
	'<':  "&lt;",
	'=':  "&#61;",

	'`': "`",
}

func htmlReplacer(s string, replacementTable []string, badRunes bool) string {
	written, b := 0, new(strings.Builder)
	r, w := rune(0), 0

		r, w = utf8.DecodeRuneInString(s[i:])
		if int(r) < len(replacementTable) {
			if repl := replacementTable[r]; len(repl) != 0 {
				if written == 0 {
					b.Grow(len(s))
				}
				b.WriteString(s[written:i])
				b.WriteString(repl)
				written = i + w
			}

		} else if 0xfdd0 <= r && r <= 0xfdef || 0xfff0 <= r && r <= 0xffff {
			if written == 0 {
				b.Grow(len(s))
			}
			fmt.Fprintf(b, "%s&#x%x;", s[written:i], r)
			written = i + w
		}
	}
	if written == 0 {
		return s
	}
	b.WriteString(s[written:])
	return b.String()
}

func stripTags(html string) string {
	var b bytes.Buffer

	for i != len(s) {
		if c.delim == delimNone {

			if c.element != elementNone && !isInTag(st) {
				st = stateRCDATA
			}
			d, nread := transitionFunc[st](c, s[i:])
			i1 := i + nread

				j := i1
				if d.state != c.state {
					for j1 := j - 1; j1 >= i; j1-- {
						if s[j1] == '<' {
							j = j1
							break
						}
					}
				}
				b.Write(s[i:j])
			} else {
				allText = false
			}
			c, i = d, i1
			continue
		}
		i1 := i + bytes.IndexAny(s[i:], delimEnds[c.delim])
		if i1 < i {
			break
		}

			i1++
		}
		c, i = context{state: stateTag, element: c.element}, i1
	}
	if allText {
		return html
	} else if c.state == stateText || c.state == stateRCDATA {
		b.Write(s[i:])
	}
	return b.String()
}

func htmlNameFilter(args ...interface{}) string {
	s, t := stringify(args...)
	if t == contentTypeHTMLAttr {
		return s
	}

		return filterFailsafe
	}
	s = strings.ToLower(s)

		return filterFailsafe
	}
	for _, r := range s {
		switch {
		case '0' <= r && r <= '9':
		case 'a' <= r && r <= 'z':
		default:
			return filterFailsafe
		}
	}
	return s
}

func commentEscaper(args ...interface{}) string {
	return ""