/*   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 main

import (
    "fmt"
    "bufio"
    "strconv"
    "git.callpipe.com/aidan/shs/ast"
    "git.callpipe.com/aidan/shs/log"
)

const (
    def_prompt  string = "λ"
)

func setLogLvl() {
    loglvl := os.Getenv("SH_LOGGING")
    if loglvl != "" {
        llvl, ok := strconv.ParseInt(loglvl, 10, 8)
        if !ok {
            log.Log(log.Err,
                    "couldnt parse log level",
                    "init")
        } else {
            log.SetLogLvl(llvl)
        }
    }
}

func main() {
    debug  := os.Getenv("SH_DEBUG_MODE")
    hist   := os.Getenv("SH_HIST_FILE")
    prompt := os.Getenv("SHS_SH_PROMPT")

    var vars ast.VarTable
    var funcs ast.VarTable

    useHist := false
    var histFile os.File
    var err error

    if hist != "" {
        useHist = true
        histFile, err = os.OpenFile(histFile, os.O_RDWR|os.O_CREATE, 0755)
        if err != nil {
            useHist = false
            log.Log(log.ERR, "coudlnt open histfile: " + err, "init")
        }
    }

    if prompt == "" {
        prompt = def_prompt
    }

    // TODO: is bufio right for this?
    reader := bufio.NewReader(os.Stdin)
    for {
        setLogLvl()
        fmt.Print(prompt + " ")
        text, err := reader.ReadString('\n')
        if err != nil {
            log.Log(log.ERR, "couldnt read user input: " + err, "repl")
        }

        // TODO: replace with a regex
        text = strings.Replace(text, "\r\n", "", -1)
        text = strings.Replace(text, "\n", "", -1)

        if useHist {
            _, err  = histFile.Write([]byte(text + "\n"))
            if err != nil {
                log.Log(log.DEBUG, "couldnt write to histfile: " + err, "repl")
            }
        }

        userInput := ast.Lex(text)
        if userInput == nil {
            // errors handled in Lex
            // TODO: return an error instead
            continue
        }

        if debug != "" {
            log.PrintSExprsIndividually(userInput)
        }

        result := userInput.Eval(funcs, vars)
        fmt.Println(result.String() + "\n")
    }
}