/*   SHS: Syntactically Homogeneous Shell
 *   Copyright (C) 2019  Aidan Hahn
 *
 *   This program is free software: you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation, either version 3 of the License, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */

package ast

import (
    "strings"
    "fmt"
)

/* Print function which is better suited for repl.
 * This one prints the SEXPRs as one would write them.
 */
func (t *Token) String() string {
    switch t.Tag {
    case STRING:
        return "\"" + t.Inner.(string) + "\""

    case NUMBER:
        return t.Inner.(string)

    case LIST:
        repr := "("
        if t.Inner.(*Token) == nil {
            return repr + ")"
        }

        for i := t.Inner.(*Token); i != nil; i = i.Next {
            repr = repr + i.String() + " "
        }
        // remove trailing space
        return repr[:len(repr)-1] + ")"

    case SYMBOL:
        return "<" + t.Inner.(string) + ">"
    }

    return "[UNKNOWN CELL TYPE]"
}

/* Print function which breaks each embedded list out on individual lines.
 * Used in the print_ast debug tool. not too useful for repl applications.
 * Very useful for debugging syntax though.
 * TODO: Add numbers to denote embedded scope?
 */
func PrintSExprsIndividually(arg *Token) {
    if arg == nil {
        return //TODO: Handle error here?
    }

    var lists TokenStack;
    lists.Push(arg)

loop:
    var constructor strings.Builder
    i := lists.Pop()
    if i == nil {
        return
    }

    for iter := i; iter != nil; iter = iter.Next {
        if iter.Tag == LIST {
            lists.Push(iter.Inner.(*Token))
        }

        constructor.WriteString(FmtToken(iter))
    }

    println(constructor.String())
    goto loop
}

func FmtToken(arg *Token) string {
    suffix := "->"
    if arg.Next == nil {
        suffix = ""
    }

    switch arg.Tag {
    case LIST:
        return fmt.Sprintf("(%s, [List])%s", "LIST", suffix)

    default:
        return fmt.Sprintf("(%s, %s)%s", GetTagAsStr(arg.Tag), arg.Inner, suffix)
    }
}

func GetTagAsStr(tag Token_t) string {
    switch tag {
    case LIST:
        return "LIST"
    case STRING:
        return "STRING"
    case NUMBER:
        return "NUMBER"
    case SYMBOL:
        return "SYMBOL"
    }
    return "UNKNOWN"
}