package raku

import (
    "errors"
    "fmt"
    "io/ioutil"
    "os"
    "github.com/yhirose/go-peg"    
)

type Parser struct {
    *peg.Parser
}

type Result struct {
    * peg.Ast
}

func parserCheck(err error) {
    if perr, ok := err.(*peg.Error); ok {
        for _, d := range perr.Details {
            fmt.Println(d)
        }
        os.Exit(1)
    }
}

var defaultParser *Parser

/** Loads a PEG parser from the given file name. */
func LoadParser(filename string) (*Parser, error) {
    result := &Parser{}
    data, err := ioutil.ReadFile(filename)
    if err == nil {
        result.Parser, err = peg.NewParser(string(data))
        if err == nil {
            result.EnableAst()            
        }        
        return result, err
    } else {
        return nil, err
    }
}


func InitDefaultParser(peg_filename string) error {
    var err error
    defaultParser, err = LoadParser(peg_filename)
    return err
}

func wrapResult(wrapme peg.Any) *Result {
    result := &Result{};
    ast, ok := wrapme.(*peg.Ast)
    if ok {
        result.Ast = ast
        return result
    } 
    return nil    
}

func (parser Parser) Parse(source string) (*Result, error) {
    ast, err := parser.ParseAndGetValue(source, nil)
    return wrapResult(ast), err
}

func (parser Parser) ParseFile(filename string) (*Result, error) {    
    source, err := ioutil.ReadFile(filename)
    if err == nil {
        return parser.Parse(string(source))
    } else {
        return nil, err
    }
}

func parse(source string) (*Result, error) {
    if defaultParser == nil {
        return nil, errors.New("Default parser not initialized!")
    }
    return defaultParser.Parse(source)
}

func parseFile(filename string) (*Result, error) {
    if defaultParser == nil {
        return nil, errors.New("Default parser not initialized!")
    }
    return defaultParser.ParseFile(filename)
}