package main

import (
	"fmt"
	"log"
	"math"
	"os"

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

func main() {
	toml := BuildGrammar()
	fmt.Printf("Reading TOML document from STDIN ...\n")
	result, err := toml.Match(os.Stdin)
	fmt.Printf("Completed reading document.\n")
	if err != nil {
		log.Fatalf("Error in parsing TOML: %s\n", err)
	} else {
		fmt.Printf("Result:\n")
		for i, t := range result.Tokens() {
			fmt.Printf("[%d] %v\n", i, t)
		}
	}
}

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 handler, ok := g[name]; ok {
		return handler
	}
	return func(t *tokenize.API) bool {
		if handler, ok := g[name]; ok {
			return handler(t)
		}
		panic(fmt.Sprintf("Grammar rule %q does not exist", name))
	}
}

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)
	R("minus", a.Minus)
	R("plus", a.Plus)
	R("underscore", a.Underscore)
	R("quotation-mark", a.DoubleQuote)
	R("apostrophe", a.SingleQuote)
	R("colon", a.Colon)
	R("escape", a.Backslash)
	R("hex-digit", a.HexDigit)

	// Whitespace, Newline

	R("tab", a.Tab)
	R("space", a.Space)
	R("wschar", G("tab").Or(G("space")))
	R("ws", c.ZeroOrMore(G("wschar")))
	R("newline", a.Newline)
	R("wschar-or-newline", G("wschar").Or(G("newline")))

	// Comment

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

	// Basic String

	R("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))))
	R("escaped", G("escape").Then(G("escape-seq-char")))
	R("basic-unescaped", c.Any(a.RuneRange(0x20, 0x21), a.RuneRange(0x23, 0x5B), a.RuneRange(0x5D, 0x7E), G("non-ascii")))
	R("basic-char", G("escaped").Or(G("basic-unescaped")))
	R("basic-string", c.Seq(m.Drop(G("quotation-mark")), c.ZeroOrMore(G("basic-char")), m.Drop(G("quotation-mark"))))

	// Multiline Basic String

	R("ml-basic-string-delim", G("quotation-mark").Times(3))
	R("ml-basic-unescaped", c.Any(a.RuneRange(0x20, 0x5B), a.RuneRange(0x5D, 0x7E), G("non-ascii")))
	R("ml-basic-char", G("ml-basic-unescaped").Or(G("escaped")))
	R("ml-basic-body-concat", c.Seq(G("escape"), G("ws"), G("newline"), c.ZeroOrMore(G("wschar-or-newline"))))
	R("ml-basic-body-content", c.Any(G("ml-basic-char"), G("newline"), m.Drop(G("ml-basic-body-concat"))))
	R("ml-basic-body", c.ZeroOrMore(G("ml-basic-body-content").Except(G("ml-basic-string-delim"))))
	R("ml-basic-string", c.Seq(
		m.Drop(G("ml-basic-string-delim")),
		m.Drop(c.Optional(G("newline"))),
		G("ml-basic-body"),
		m.Drop(G("ml-basic-string-delim"))))

	// Literal String
	R("literal-char", c.Any(G("tab"), a.RuneRange(0x20, 0x26), a.RuneRange(0x28, 0x7E), G("non-ascii")))
	R("literal-string", c.Seq(
		m.Drop(G("apostrophe")),
		c.ZeroOrMore(G("literal-char")),
		m.Drop(G("apostrophe"))))

	// Multiline Literal String

	R("ml-literal-string-delim", G("apostrophe").Times(3))
	R("ml-literal-char", c.Any(G("tab"), a.RuneRange(0x20, 0x7E), G("non-ascii")))
	R("ml-literal-body-content", G("ml-literal-char").Or(G("newline")))
	R("ml-literal-body", c.ZeroOrMore(G("ml-literal-body-content").Except(G("ml-literal-string-delim"))))
	R("ml-literal-string", c.Seq(
		m.Drop(G("ml-literal-string-delim")),
		G("ml-literal-body"),
		m.Drop(G("ml-literal-string-delim"))))

	// String

	R("string", c.Any(
		tok.StrInterpreted("string", G("ml-basic-string")),
		tok.StrInterpreted("string", G("basic-string")),
		tok.Str("string", G("ml-literal-string")),
		tok.Str("string", G("literal-string"))))

	// Integer

	R("digit1-9", a.DigitNotZero)
	R("underscore-int-digit", c.Any(G("digit"), m.Drop(G("underscore")).Then(G("digit"))))
	R("unsigned-dec-int", c.Any(G("digit1-9").Then(c.OneOrMore(G("underscore-int-digit"))), G("digit")))
	R("dec-int", c.Optional(G("plus").Or(G("minus"))).Then(G("unsigned-dec-int")))

	R("hex-prefix", a.Zero.Then(a.Rune('x')))
	R("underscore-hex-digit", c.Any(G("hex-digit"), m.Drop(G("underscore")).Then(G("hex-digit"))))
	R("hex-int", c.Seq(m.Drop(G("hex-prefix")), G("hex-digit"), c.ZeroOrMore(G("underscore-hex-digit"))))

	R("oct-prefix", a.Zero.Then(a.Rune('o')))
	R("digit0-7", a.RuneRange('0', '7'))
	R("underscore-oct-digit", c.Any(G("digit0-7"), m.Drop(G("underscore")).Then(G("digit0-7"))))
	R("oct-int", c.Seq(m.Drop(G("oct-prefix")), G("digit0-7"), c.ZeroOrMore(G("underscore-oct-digit"))))

	R("bin-prefix", a.Zero.Then(a.Rune('b')))
	R("digit0-1", a.Runes('0', '1'))
	R("underscore-bin-digit", c.Any(G("digit0-1"), m.Drop(G("underscore")).Then(G("digit0-1"))))
	R("bin-int", c.Seq(m.Drop(G("bin-prefix")), G("digit0-1"), c.ZeroOrMore(G("underscore-bin-digit"))))

	R("integer", c.Any(
		tok.Int64Base("integer", 16, G("hex-int")),
		tok.Int64Base("integer", 8, G("oct-int")),
		tok.Int64Base("integer", 2, G("bin-int")),
		tok.Int64("integer", G("dec-int"))))

	// Float

	R("float-int-part", G("dec-int"))
	R("exp", a.StrNoCase("e").Then(G("float-int-part")))
	R("decimal-point", a.Dot)
	R("zero-prefixable-int", c.Seq(G("digit"), m.Drop(c.ZeroOrMore(G("underscore-int-digit")))))
	R("frac", c.Seq(G("decimal-point"), G("zero-prefixable-int")))
	R("standard-float", c.Seq(G("float-int-part"), G("exp").Or(G("frac").Then(c.Optional(G("exp"))))))

	R("inf-float", c.Optional(G("plus").Or(G("minus"))).Then(a.Str("inf")))

	R("nan-float", c.Optional(G("plus").Or(G("minus"))).Then(a.Str("nan")))

	R("float", c.Any(
		tok.Float64("float", G("standard-float")),
		tok.ByCallback("float", G("inf-float"), func(t *tokenize.API) interface{} {
			if t.Result().Rune(0) == '-' {
				return math.Inf(-1)
			}
			return math.Inf(+1)
		}),
		tok.ByValue("float", G("nan-float"), math.NaN())))

	// Boolean

	R("true", a.Str("true"))
	R("false", a.Str("false"))

	R("boolean", tok.Boolean("boolean", G("true").Or(G("false"))))

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

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

	R("offset-date-time", c.Seq(G("full-date"), G("time-delim"), G("full-time")))
	R("local-date-time", c.Seq(G("full-date"), G("time-delim"), G("partial-time")))
	R("local-date", G("full-date"))
	R("local-time", G("partial-time"))

	R("date-time", c.Any(G("offset-date-time"), G("local-date-time"), G("local-date"), G("local-time")))

	// Inline Table

	R("inline-table-open", a.CurlyOpen.Then(G("ws")))
	R("inline-table-close", G("ws").Then(a.CurlyClose))
	R("inline-table-sep", c.Seq(G("ws"), a.Comma, G("ws")))
	R("inline-table-keyval", tok.Group("inline-table-keyval", c.Seq(G("key"), G("keyval-sep"), G("val"))))
	R("inline-table-keyvals", c.Seq(G("inline-table-keyval"), c.ZeroOrMore(c.Seq(G("inline-table-sep"), G("inline-table-keyval")))))

	R("inline-table", tok.Group("inline-table", c.Seq(G("inline-table-open"), G("inline-table-keyvals"), G("inline-table-close"))))

	// Array

	R("array-open", a.SquareOpen)
	R("array-close", a.SquareClose)
	R("array-sep", G("ws").Then(a.Comma))
	R("ws-comment-newline", c.ZeroOrMore(G("wschar").Or(G("comment").Optional().Then(G("newline")))))
	R("array-values", c.Any(
		c.Seq(G("ws-comment-newline"), G("val"), G("ws"), G("array-sep"), G("array-values")),
		c.Seq(G("ws-comment-newline"), G("val"), G("ws"), G("array-sep").Optional())))

	R("inline-array", tok.Group("inline-array", c.Seq(G("array-open"), G("array-values").Optional(), G("ws-comment-newline"), G("array-close"))))

	// Standard Table

	R("std-table-open", a.SquareOpen.Then(G("ws")))
	R("std-table-close", G("ws").Then(a.SquareClose))

	R("std-table", c.Seq(G("std-table-open"), tok.Group("table", G("key")), G("std-table-close")))

	// Array Table

	R("array-table", c.Seq(G("array-table-open"), tok.Group("array-of-tables", G("key")), G("array-table-close")))

	R("array-table-open", a.SquareOpen.Times(2).Then(G("ws")))
	R("array-table-close", G("ws").Then(a.SquareClose.Times(2)))

	// Table

	R("table", G("array-table").Or(G("std-table")))

	// Key-Value Pairs

	R("unquoted-key", c.OneOrMore(c.Any(G("alpha"), G("digit"), G("minus"), G("underscore"))))
	R("quoted-key", G("basic-string").Or(G("literal-string")))
	R("key-sep", c.Seq(G("ws"), a.Dot, G("ws")))
	R("simple-key", tok.Str("key-part", G("quoted-key").Or(G("unquoted-key"))))
	R("dotted-key", c.Seq(G("simple-key"), c.OneOrMore(G("key-sep").Then(G("simple-key")))))

	R("keyval-sep", c.Seq(G("ws"), a.Equal, G("ws")))

	R("key", tok.Group("key", G("dotted-key").Or(G("simple-key"))))

	R("val", tok.Group("val", c.Any(G("string"), G("boolean"), G("inline-array"), G("inline-table"), G("date-time"), G("float"), G("integer"))))

	R("keyval", tok.Group("keyval", c.Seq(G("key"), G("keyval-sep"), G("val"))))

	// Overall Structure

	R("expression", c.Any(
		c.Seq(G("ws"), G("table"), G("ws"), G("comment").Optional()),
		c.Seq(G("ws"), G("keyval"), G("ws"), G("comment").Optional()),
		c.Seq(G("ws"), G("comment").Optional()),
	))

	//R("toml", c.Seq(G("expression"), c.ZeroOrMore(G("newline").Then(G("expression"))), a.EndOfFile))
	R("toml", c.Seq(G("expression"), c.ZeroOrMore(G("newline").Then(G("expression")))))

	return G("toml")
}