// Copyright 2021 The Tint Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

// Package tok defines tokens that are produced by the Tint intrinsic definition
// lexer
package tok

import "fmt"

// Kind is an enumerator of token kinds
type Kind string

// Token enumerator types
const (
	InvalidToken Kind = "<invalid>"
	Identifier   Kind = "ident"
	Integer      Kind = "integer"
	String       Kind = "string"
	Match        Kind = "match"
	Function     Kind = "fn"
	Operator     Kind = "op"
	Type         Kind = "type"
	Enum         Kind = "enum"
	Colon        Kind = ":"
	Comma        Kind = ","
	Shl          Kind = "<<"
	Shr          Kind = ">>"
	Lt           Kind = "<"
	Le           Kind = "<="
	Gt           Kind = ">"
	Ge           Kind = ">="
	Lbrace       Kind = "{"
	Rbrace       Kind = "}"
	Ldeco        Kind = "[["
	Rdeco        Kind = "]]"
	Lparen       Kind = "("
	Rparen       Kind = ")"
	Or           Kind = "|"
	Arrow        Kind = "->"
	Star         Kind = "*"
	Divide       Kind = "/"
	Modulo       Kind = "%"
	Xor          Kind = "^"
	Plus         Kind = "+"
	Minus        Kind = "-"
	And          Kind = "&"
	AndAnd       Kind = "&&"
	OrOr         Kind = "||"
	NotEqual     Kind = "!="
	Equal        Kind = "=="
	Assign       Kind = "="
)

// Invalid represents an invalid token
var Invalid = Token{Kind: InvalidToken}

// Location describes a rune location in the source code
type Location struct {
	// 1-based line index
	Line int
	// 1-based column index
	Column int
	// 0-based rune index
	Rune int
	// Optional file path
	Filepath string
}

// Format implements the fmt.Formatter interface
func (l Location) Format(w fmt.State, verb rune) {
	if w.Flag('+') {
		if l.Filepath != "" {
			fmt.Fprintf(w, "%v:%v:%v[%v]", l.Filepath, l.Line, l.Column, l.Rune)
		} else {
			fmt.Fprintf(w, "%v:%v[%v]", l.Line, l.Column, l.Rune)
		}
	} else {
		if l.Filepath != "" {
			fmt.Fprintf(w, "%v:%v:%v", l.Filepath, l.Line, l.Column)
		} else {
			fmt.Fprintf(w, "%v:%v", l.Line, l.Column)
		}
	}
}

// Source describes a start and end range in the source code
type Source struct {
	S, E Location
}

// IsValid returns true if the source is valid
func (s Source) IsValid() bool {
	return s.S.Line != 0 && s.S.Column != 0 && s.E.Line != 0 && s.E.Column != 0
}

// Format implements the fmt.Formatter interface
func (s Source) Format(w fmt.State, verb rune) {
	if w.Flag('+') {
		fmt.Fprint(w, "[")
		s.S.Format(w, verb)
		fmt.Fprint(w, " - ")
		s.E.Format(w, verb)
		fmt.Fprint(w, "]")
	} else {
		s.S.Format(w, verb)
	}
}

// Token describes a parsed token
type Token struct {
	Kind   Kind
	Runes  []rune
	Source Source
}

// Format implements the fmt.Formatter interface
func (t Token) Format(w fmt.State, verb rune) {
	fmt.Fprint(w, "[")
	t.Source.Format(w, verb)
	fmt.Fprint(w, " ")
	fmt.Fprint(w, t.Kind)
	fmt.Fprint(w, " ")
	fmt.Fprint(w, string(t.Runes))
	fmt.Fprint(w, "]")
}