/*   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

type Operation func(*Token) *Token

type Function struct {
    function    Operation
    name        string
    timesCalled int
    args        int // TODO: Make this a list of expected types (TAGs)
}

type FuncTable map[string]*Function

// TODO: Currently only checks arg list length
func (f Function) ParseFunction(args *Token) bool {
    // HANDLE EXEC
    if f.args < 0 {
        return true
    }

    i := f.args
    for iter := args; iter != nil; iter = iter.Next {
        i -= 1
    }

    if i != 0 {
        log.Log(log.ERR, 
                "Incorrect number of arguments",
                "eval")
        return false
    }

    return true
}

func (f Function) CallFunction(args *Token) *Token {
    if !f.ParseFunction(args) {
        log.Log(log.Err,
                "Couldnt call " + f.name,
                "eval")
        return nil
    }

    f.timesCalled += 1
    return f.function(args)
}

func (table FuncTable) GetFunction(arg string) *Function {
    target, ok := table[arg]
    if !ok {
        log.Log(log.DEBUG,
                "function " + arg + " not found",
                "eval")
        return nil
    }

    return target
}