/*   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 stdlib

import (
    "os"
    "fmt"
    "gitlab.com/whom/shs/ast"
    "gitlab.com/whom/shs/util"
)

/* Makes a FuncTable from all functions in the stdlib
 * add your function here if you are extending the standard library
 */
func GenFuncTable() ast.FuncTable {
    var stdlib ast.FuncTable
    stdlib = &map[string]*ast.Function{
        "if": &ast.Function{
            Function:   ShsIf,
            Name:       "if",
            NumArgs:    3,
            EvalLazy:   true,
            ArgLazy:    true,
        },

        "while": &ast.Function{
            Function:   ShsWhile,
            Name:       "while",
            NumArgs:    -1,
            EvalLazy:   true,
            ArgLazy:    true,
        },

        "progn": &ast.Function{
            Function:   ShsProgn,
            Name:       "shs_progn",
            NumArgs:    -1,
            EvalLazy:   true,
            ArgLazy:    true,
        },

        "func": &ast.Function{
            Function:   DeclFunc,
            Name:       "decl_func",
            Args:   []ast.Token_t{
                ast.STRING,
                ast.LIST,
                ast.LIST,
            },
            EvalLazy:   true,
        },

        "len": &ast.Function{
            Function:   Len,
            Name:       "len",
            NumArgs:    1,
            ArgLazy:    true,
        },

        "head": &ast.Function{
            Function:   Head,
            Name:       "head",
            Args:   []ast.Token_t{
                ast.LIST,
            },
        },

        "tail": &ast.Function{
            Function:   Tail,
            Name:       "tail",
            Args:   []ast.Token_t{
                ast.LIST,
            },
        },

        "slice": &ast.Function{
            Function:   Slice,
            Name:       "slice",
            Args:   []ast.Token_t{
                ast.NUMBER,
                ast.NUMBER,
                ast.LIST,
            },
        },

        "export": &ast.Function{
            Function:   Export,
            Name:       "export",
            EvalLazy:   true,
            Args:   []ast.Token_t{
                ast.STRING,
                ast.LIST,
            },
        },

        "input": &ast.Function{
            Function:   Input,
            Name:       "input",
            Args:   []ast.Token_t{
                ast.STRING,
            },
        },

        "load": &ast.Function{
            Function:   Load,
            Name:       "load",
            Args:   []ast.Token_t{
                ast.STRING,
            },
        },

        "bool": &ast.Function{
            Function:   BoolCast,
            Name:       "bool",
            Args:   []ast.Token_t{
                ast.STRING,
            },
        },

        "string": &ast.Function{
            Function:   StrCast,
            Name:       "string",
            NumArgs:    1,
            ArgLazy:    true,
        },

        "number": &ast.Function{
            Function:   NumCast,
            Name:       "number",
            Args:   []ast.Token_t{
                ast.NUMBER,
            },
        },

        "...": &ast.Function{
            Function:   Expand,
            Name:       "...",
            Args:   []ast.Token_t{
                ast.LIST,
            },
        },

        "append": &ast.Function{
            Function:   L_append,
            Name:       "append",
            NumArgs:    -1,
            ArgLazy:    true,
       },

        "join": &ast.Function{
            Function:   Join,
            Name:       "join",
            Args:   []ast.Token_t{
                ast.STRING,
                ast.LIST,
            },
        },

        "split": &ast.Function{
            Function:   Split,
            Name:       "split",
            Args:   []ast.Token_t{
                ast.STRING,
                ast.STRING,
            },
        },

        "substr": &ast.Function{
            Function:   Substr,
            Name:       "substr",
            Args:   []ast.Token_t{
                ast.NUMBER,
                ast.NUMBER,
                ast.STRING,
            },
        },

        "exit": &ast.Function{
            Function:   ExitShell,
            Name:       "exit",
            Args:   []ast.Token_t{},
        },

        "eq": &ast.Function{
            Function:   Eq,
            Name:       "==",
            NumArgs:       2,
            ArgLazy:    true,
        },

        "ne": &ast.Function{
            Function:   Ne,
            Name:       "!=",
            NumArgs:       2,
            ArgLazy:    true,
        },

        "<": &ast.Function{
            Function:   Lt,
            Name:       "<",
            Args:   []ast.Token_t{
                ast.NUMBER,
                ast.NUMBER,
            },
        },

        ">": &ast.Function{
            Function:   Gt,
            Name:       ">",
            Args:   []ast.Token_t{
                ast.NUMBER,
                ast.NUMBER,
            },
        },

        "<=": &ast.Function{
            Function:   Lte,
            Name:       "<=",
            Args:   []ast.Token_t{
                ast.NUMBER,
                ast.NUMBER,
            },
        },

        ">=": &ast.Function{
            Function:   Gte,
            Name:       ">=",
            Args:   []ast.Token_t{
                ast.NUMBER,
                ast.NUMBER,
            },
        },

        "!": &ast.Function{
            Function:   Not,
            Name:       "!",
            Args:   []ast.Token_t{
                ast.BOOL,
            },
        },

        "+": &ast.Function{
            Function:   Add,
            Name:       "add",
            NumArgs:    -1,
            ArgLazy:    true,
        },

        "-": &ast.Function{
            Function:   Sub,
            Name:       "sub",
            NumArgs:    -1,
            ArgLazy:    true,
        },

        "*": &ast.Function{
            Function:   Mult,
            Name:       "mult",
            NumArgs:    -1,
            ArgLazy:    true,
        },

        "/": &ast.Function{
            Function:   Div,
            Name:       "div",
            NumArgs:    -1,
            ArgLazy:    true,
        },

        "cd": &ast.Function{
            Function:   Cd,
            Name:       "changedir",
            Args:   []ast.Token_t{
                ast.STRING,
            },
        },

        "concat": &ast.Function{
            Function:   Concat,
            Name:       "concatenate",
            NumArgs:    -1,
            ArgLazy:    true,
        },

        "print": &ast.Function{
            Function:   PrintStr,
            Name:       "print",
            Args:   []ast.Token_t{
                ast.STRING,
            },
        },

        "l": &ast.Function{
            Function:   Call,
            Name:       "call",
            NumArgs:    -1,
            ArgLazy:    true,
            SymLazy:    true,
        },

        "bg": &ast.Function{
            Function:   Bgcall,
            Name:       "background call",
            NumArgs:    -1,
            ArgLazy:    true,
            SymLazy:    true,
        },

        "fg": &ast.Function{
            Function:   Fg,
            Name:       "foreground",
            Args:   []ast.Token_t{
                ast.NUMBER,
            },
        },

        "$": &ast.Function{
            Function:   ReadCmd,
            Name:       "read cmd",
            NumArgs:   -1,
            ArgLazy:    true,
            SymLazy:    true,
        },

        "?": &ast.Function{
            Function:   GetExit,
            Name:       "get exit code",
            Args:   []ast.Token_t{},
        },

        /*
        USE NATIVE KILL COMMAND.
        "kill": &ast.Function{
            Function:       kill,
            Name:     "kill job",
            Args:              1,
        },
        */

        "jobs": &ast.Function{
            Function:   Jobs,
            Name:       "list jobs",
            Args:   []ast.Token_t{},
        },

        "info": &ast.Function{
            Function:   ShInfo,
            Name:       "Shell Info",
            Args:   []ast.Token_t{
                ast.SYMBOL,
            },
        },

        "fexists": &ast.Function{
            Function:   Fexists,
            Name:       "file exists",
            Args:   []ast.Token_t{
                ast.STRING,
            },
        },

        "fread": &ast.Function{
            Function:   Fread,
            Name:       "read file",
            Args:   []ast.Token_t{
                ast.STRING,
            },
        },

        "fwrite": &ast.Function{
            Function:   Fwrite,
            Name:       "write file",
            Args:   []ast.Token_t{
                ast.STRING,
                ast.STRING,
            },
        },

        "fappend": &ast.Function{
            Function:   Fappend,
            Name:       "append to file",
            Args:   []ast.Token_t{
                ast.STRING,
                ast.STRING,
            },
        },
    }

    return stdlib
}

/* takes no args
 * exits shell when called
 *
 * Example: (exit)
 */
func ExitShell(in *ast.Token, vt ast.VarTable, ft ast.FuncTable) *ast.Token {
    os.Exit(0)
    return nil // I hope execution doesnt get here
}

/* takes one arg, doesnt evaluate it
 * returns type or metadata
 * 
 * Example: (info append)
 */
func ShInfo(in *ast.Token, vt ast.VarTable, ft ast.FuncTable) *ast.Token {
    repr := ast.GetVar(in.Value(), vt)
    if repr != nil {
        fmt.Printf("VARIABLE\nTYPE: %s\nVALUE: %s\n", ast.GetTagAsStr(repr.Tag), repr.Value())
        return nil
    }

    funct := ast.GetFunction(in.Value(), ft)
    if funct != nil {
        fmt.Printf("FUNCTION\nNAME: %s\nTIMES CALLED: %s\n\n", funct.Name, funct.TimesCalled)
        if funct.ArgLazy {
            fmt.Printf("function does not evaluate args by type\nARG COUNT: %s\n", funct.NumArgs)
        } else {
            fmt.Printf("function evaluates args by type\nARGS: ")
            for _, i := range(funct.Args) {
                fmt.Printf(ast.GetTagAsStr(i))
            }
        }

        fmt.Printf("SYMLAZY: %t\n", funct.SymLazy)
        fmt.Printf("(can undefined symbols be passed in)\n")
        fmt.Printf("EVALLAZY: %t\n", funct.EvalLazy)
        fmt.Printf("(are all forms in evaluated before function call)\n")
        return nil
    }

    fmt.Printf("UNKNOWN SYMBOL\n")
    return nil
}

/* Takes 1 arg, uses it as a prompt
 * errs if prompt is not a string or number
 * gets a line from stdin
 * returns it as a string
 *
 * Example: (print (input))
 */
func Input(in *ast.Token, vt ast.VarTable, ft ast.FuncTable) *ast.Token {
    prompt := in.Value()
    var output string

    fmt.Printf(prompt)
    fmt.Scanln(&output)

    ret := &ast.Token{Tag: ast.STRING}
    ret.Set(output)
    return ret
}

/* Takes 1 arg, returns nil
 * if arg is a valid existing file than load will execute it as a script
 *
 * Example: (load "myscript.shs")
 */
func Load(in *ast.Token, vt ast.VarTable, ft ast.FuncTable) *ast.Token {
    bp := in.Value()
    bp = AbsPath(bp)
    util.LoadScript(bp, vt, ft)
    return nil
}