package main

import (
	"flag"
	"fmt"
	"io"
	"log"
	"monkey/compiler"
	"monkey/lexer"
	"monkey/object"
	"monkey/parser"
	"monkey/repl"
	"os"
	"os/user"
	"path"
	"strings"
)

var (
	engine      string
	interactive bool
	compile     bool
	version     bool
	debug       bool
)

func init() {
	flag.Usage = func() {
		fmt.Fprintf(flag.CommandLine.Output(), "Usage: %s [options] [<filename>]\n", path.Base(os.Args[0]))
		flag.PrintDefaults()
		os.Exit(0)
	}

	flag.BoolVar(&version, "v", false, "display version information")
	flag.BoolVar(&debug, "d", false, "enable debug mode")
	flag.BoolVar(&compile, "c", false, "compile input to bytecode")

	flag.BoolVar(&interactive, "i", false, "enable interactive mode")
	flag.StringVar(&engine, "e", "vm", "engine to use (eval or vm)")
}

// Indent indents a block of text with an indent string
func Indent(text, indent string) string {
	if text[len(text)-1:] == "\n" {
		result := ""
		for _, j := range strings.Split(text[:len(text)-1], "\n") {
			result += indent + j + "\n"
		}
		return result
	}
	result := ""
	for _, j := range strings.Split(strings.TrimRight(text, "\n"), "\n") {
		result += indent + j + "\n"
	}
	return result[:len(result)-1]
}

func main() {
	flag.Parse()

	if version {
		fmt.Printf("%s %s", path.Base(os.Args[0]), FullVersion())
		os.Exit(0)
	}

	user, err := user.Current()
	if err != nil {
		log.Fatalf("could not determine current user: %s", err)
	}

	args := flag.Args()

	if compile {
		if len(args) < 1 {
			log.Fatal("no source file given to compile")
		}
		f, err := os.Open(args[0])
		defer f.Close()

		b, err := io.ReadAll(f)
		if err != nil {
			log.Fatal(err)
		}

		l := lexer.New(string(b))
		p := parser.New(l)

		program := p.ParseProgram()
		if len(p.Errors()) != 0 {
			log.Fatal(p.Errors())
		}

		c := compiler.New()
		err = c.Compile(program)
		if err != nil {
			log.Fatal(err)
		}

		code := c.Bytecode()
		fmt.Printf("Main:\n%s\n", code.Instructions)

		fmt.Print("Constants:\n")
		for i, constant := range code.Constants {
			fmt.Printf("%04d %s\n", i, constant.Inspect())
			if fn, ok := constant.(*object.CompiledFunction); ok {
				fmt.Printf("%s\n", Indent(fn.Instructions.String(), "     "))
			}
		}
	} else {
		opts := &repl.Options{
			Debug:       debug,
			Engine:      engine,
			Interactive: interactive,
		}
		repl := repl.New(user.Username, args, opts)
		repl.Run()
	}
}