package parse2

import (
	"fmt"

	"git.makaay.nl/mauricem/go-parsekit/tokenize"
)

type Grammar map[string]tokenize.Handler

func (g Grammar) Rule(name string, definition tokenize.Handler) {
	if _, ok := g[name]; ok {
		panic(fmt.Sprintf("Grammar rule %q already exists", name))
	}
	g[name] = definition
}

func (g Grammar) Get(name string) tokenize.Handler {
	if h, ok := g[name]; ok {
		return g[name]
	}
	return func(t *tokenize.API) bool {
		return g[name](t)
	}
}

func BuildGrammar() tokenize.Handler {

	c, a, m, tok := tokenize.C, tokenize.A, tokenize.M, tokenize.T

	g := make(Grammar)
	R := g.Rule
	G := g.Get

	R("alpha", a.Letter)
	R("digit", a.Digit)
	g["minus"] = a.Minus
	g["plus"] = a.Plus
	g["underscore"] = a.Underscore
	g["quotation-mark"] = a.DoubleQuote
	g["apostrophe"] = a.SingleQuote
	g["colon"] = a.Colon
	g["escape"] = a.Backslash
	g["hex-digit"] = a.HexDigit

	// Whitespace, Newline

	g["tab"] = a.Tab
	g["space"] = a.Space
	g["wschar"] = g["tab"].Or(g["space"])
	g["ws"] = c.ZeroOrMore(g["wschar"])
	g["newline"] = a.Newline
	g["ws-or-newline"] = g["ws"].Or(g["newline"])

	// Comment

	g["comment-start-symbol"] = a.Hash
	g["printable-ascii"] = a.RuneRange(0x20, 0x7E)
	g["non-ascii"] = a.RuneRange(0x80, 0xD7FF).Or(a.RuneRange(0xE000, 0x10FFFF))
	g["non-eol"] = c.Any(a.Rune(0x09), g["printable-ascii"], g["non-ascii"])
	g["comment"] = g["comment-start-symbol"].Then(c.ZeroOrMore(g["non-eol"]))

	// Basic String

	g["escape-seq-char"] = c.Any(
		a.Runes('"', '\\', 'b', 'f', 'n', 'r', 't'),
		a.Rune('u').Then(g["hex-digit"].Times(4)),
		a.Rune('U').Then(g["hex-digit"].Times(8)))
	g["escaped"] = g["escape"].Then(g["escape-seq-char"])
	g["basic-unescaped"] = c.Any(g["printable-ascii"].Except(g["quotation-mark"].Or(g["escape"])), g["non-ascii"])
	g["basic-char"] = g["escaped"].Or(g["basic-unescaped"])
	g["basic-string"] = c.Seq(g["quotation-mark"], c.ZeroOrMore(g["basic-char"]), g["quotation-mark"])

	// Multiline Basic String

	g["ml-basic-string-delim"] = g["quotation-mark"].Times(3)
	g["ml-basic-unescaped"] = c.Any(g["printable-ascii"].Except(g["backslash"]), g["non-ascii"])
	g["ml-basic-char"] = g["ml-basic-unescaped"].Or(g["escaped"])
	g["ml-basic-body-concat"] = c.Seq(g["escape"], g["ws"], g["newline"], c.ZeroOrMore(g["ws-or-newline"]))
	g["ml-basic-body"] = c.ZeroOrMore(c.Any(g["ml-basic-char"], g["newline"], g["ml-basic-body-concat"]))
	g["ml-basic-strinct"] = c.Seq(g["ml-basic-string-delim"], g["ml-basic-body"], g["ml-basic-string-delim"])

	// Literal String

	g["literal-char"] = c.Any(g["tab"], g["printable-ascii"].Except(g["apostrophe"]), g["non-ascii"])
	g["literal-string"] = c.Seq(g["apostrophe"], c.ZeroOrMore(g["literal-char"]), g["apostrophe"])

	// Multiline Literal String

	g["ml-literal-string-delim"] = g["apostrophe"].Times(3)
	g["ml-literal-char"] = c.Any(g["tab"], g["printable-ascii"], g["non-ascii"])
	g["ml-literal-body"] = c.ZeroOrMore(g["ml-literal-char"].Or(g["newline"]))
	g["ml-literal-string"] = c.Seq(g["ml-literal-string-delim"], g["ml-literal-body"], g["ml-literal-string-delim"])

	// String

	g["string"] = c.Any(g["ml-basic-string"], g["basic-string"], g["ml-literal-string"], g["literal-string"])

	// Integer

	g["digit1-9"] = a.DigitNotZero
	g["underscore-int-digit"] = c.Any(g["digit"], g["underscore"].Then(g["digit"]))
	g["unsiged-dec-int"] = c.Any(g["digit"], g["digit1-9"].Then(c.OneOrMore(g["underscore-int-digit"])))
	g["dec-int"] = c.Optional(g["plus"].Or(g["minus"])).Then(g["unsigned-dec-int"])

	g["hex-prefix"] = a.Zero.Then(a.Rune('x'))
	g["underscore-hex-digit"] = c.Any(g["hex-digit"], g["underscore"].Then(g["hex-digit"]))
	g["hex-int"] = c.Seq(g["hex-prefix"], g["hex-digit"], c.ZeroOrMore(g["underscore-hex-digit"]))

	g["oct-prefix"] = a.Zero.Then(a.Rune('o'))
	g["digit0-7"] = a.RuneRange('0', '7')
	g["underscore-oct-digit"] = c.Any(g["digit0-7"], g["underscore"].Then(g["digit0-7"]))
	g["oct-int"] = c.Seq(g["oct-prefix"], g["digit0-7"], c.ZeroOrMore(g["underscore-oct-digit"]))

	g["bin-prefix"] = a.Zero.Then(a.Rune('b'))
	g["digit0-1"] = a.Runes('0', '1')
	g["underscore-bin-digit"] = c.Any(g["digit0-1"], g["underscore"].Then(g["digit0-1"]))
	g["bin-int"] = c.Seq(g["bin-prefix"], g["digit0-1"], c.ZeroOrMore(g["underscore-bin-digit"]))

	g["integer"] = c.Any(g["dec-int"], g["hex-int"], g["oct-int"], g["bin-int"])

	// Float

	g["float-int-part"] = g["dec-int"]
	g["exp"] = a.StrNoCase("e").Then(g["float-int-part"])
	g["decimal-point"] = a.Dot
	g["zero-prefixable-int"] = c.Seq(g["digit"], c.ZeroOrMore(g["underscore-int-digit"]))
	g["frac"] = c.Seq(g["decimal-point"], g["zero-prefixable-int"])
	g["standard-float"] = c.Seq(g["float-int-part"], g["exp"].Or(g["frac"].Then(c.Optional(g["exp"]))))

	g["inf"] = a.Str("inf")
	g["nan"] = a.Str("nan")
	g["special-float"] = c.Optional(g["plus"].Or(g["minus"])).Then(g["inf"].Or(g["nan"]))

	g["float"] = g["standard-float"].Or(g["special-float"])

	// Boolean

	g["true"] = a.Str("true")
	g["false"] = a.Str("false")

	g["boolean"] = g["true"].Or(g["false"])

	// Date and time (as defined in RFC 3339)

	g["date-full-year"] = g["digit"].Times(4)
	g["date-month"] = g["digit"].Times(2)
	g["date-mday"] = g["digit"].Times(2)
	g["time-delim"] = a.Runes('T', 't', ' ')
	g["time-hour"] = g["digit"].Times(2)
	g["time-minute"] = g["digit"].Times(2)
	g["time-second"] = g["digit"].Times(2)
	g["time-sec-frac"] = g["decimal-point"].Then(c.OneOrMore(g["digit"]))
	g["time-num-offset"] = c.Seq(g["plus"].Or(g["minus"]), g["time-hour"], g["colon"], g["time-minute"])
	g["time-offset"] = c.Any(a.Runes('Z', 'z'), g["time-num-offset"])
	g["partial-time"] = c.Seq(g["time-hour"], g["colon"], g["time-minute"], g["colon"], g["time-second"], g["time-sec-frac"].Optional())
	g["full-time"] = c.Seq(g["partial-time"], g["time-offset"])
	g["full-date"] = c.Seq(g["date-full-year"], g["minus"], g["date-month"], g["minus"], g["date-mday"])

	g["offset-date-time"] = c.Seq(g["full-date"], g["time-delim"], g["full-time"])
	g["local-date-time"] = c.Seq(g["full-date"], g["time-delim"], g["parial-time"])
	g["local-date"] = g["full-date"]
	g["local-time"] = g["parial-time"]

	g["date-time"] = c.Any(g["offset-date-time"], g["local-date-time"], g["local-date"], g["local-time"])

	// Array

	g["array-open"] = a.SquareOpen
	g["array-close"] = a.SquareClose
	g["ws-comment-newline"] = c.ZeroOrMore(g["wschar"].Or(g["comment"].Optional().Then(g["newline"])))
	g["array-value"] = g["ws-comment-newline"].Then(g.Recursive("val"))
	g["array-values"] = c.Seq(g["array-value"], c.ZeroOrMore(c.Seq(g["array-sep"], g["array-value"])), g["array-sep"].Optional())
	g["array-sep"] = g["ws"].Then(a.Comma)

	g["array"] = c.Seq(g["array-open"], g["array-values"].Optional(), g["ws-comment-newline"], g["array-close"])

	// Table

	g["table"] = g["std-table"].Or(g["array-table"])

	// Standard Table

	g["std-table"] = c.Seq(g["std-table-open"], g.Recursive("key"), g["std-table-close"])

	g["std-table-open"] = a.SquareOpen.Then(g["ws"])
	g["std-table-close"] = g["ws"].Then(a.SquareClose)

	// Inline Table

	g["inline-table"] = c.Seq(g["inline-table-open"], g["inline-table-keyvals"], g["inline-table-close"])

	g["inline-table-open"] = a.CurlyOpen.Then(g["ws"])
	g["inline-table-close"] = g["ws"].Then(a.CurlyClose)
	g["inline-table-sep"] = c.Seq(g["ws"], a.Comma, g["ws"])
	g["inline-table-keyval"] = c.Seq(g.Recursive("key"), g.Recursive("keyval-sep"), g.Recursive("val"))
	g["inline-table-keyvals"] = c.Seq(g["inline-table-keyval"], c.ZeroOrMore(c.Seq(g["inline-table-sep"], g["inline-table-keyval"])))

	// Array Table

	g["array-table"] = c.Seq(g["array-table-open"], g.Recursive("key"), g["array-table-close"])

	g["array-table-open"] = a.SquareOpen.Times(2).Then(g["ws"])
	g["array-table-close"] = g["ws"].Then(a.SquareClose.Times(2))

	// Key-Value Pairs

	g["unquoted-key"] = c.OneOrMore(c.Any(g["alpha"], g["digit"], g["minus"], g["underscore"]))
	g["quoted-key"] = g["basic-string"].Or(g["literal-string"])
	g["dot-sep"] = c.Seq(g["ws"], a.Dot, g["ws"])
	g["simple-key"] = g["quoted-key"].Or(g["unquoted-key"])
	g["dotted-key"] = c.Seq(g["simple-key"], c.OneOrMore(g["dot-sep"].Then(g["simple_key"])))

	g["key-val-sep"] = c.Seq(g["ws"], a.Equal, g["ws"])

	g["val"] = c.Any(g["string"], g["boolean"], g["array"], g["inlineTable"], g["dateTime"], g["float"], g["integer"])

	g["key"] = g["simple-key"].Or(g["dotted-key"])

	g["keyval"] = c.Seq(g["key"], g["keyval-sep"], g["val"])

	// Overall Structure

	g["expression"] = c.Any(
		c.Seq(g["ws"], g["comment"].Optional()),
		c.Seq(g["ws"], g["keyval"], g["ws"], g["comment"].Optional()),
		c.Seq(g["ws"], g["table"], g["ws"], g["comment"].Optional()))

	g["toml"] = c.Seq(g["expression"], c.ZeroOrMore(g["newline"].Then(g["expression"])))

	return g["toml"]
}