package main

import (
	"os"
	"bufio"
	"main/walk"
)

type Program []Command

type ProgramState struct {
	path, value, xreg []walk.Atom
	in chan walk.WalkItem
	out chan walk.WalkItem
	program []Command
}

func main() {
	quiet := false
	var input string
	hasInput := false
	
	for i := 1; i < len(os.Args); i += 1 {
		switch os.Args[i] {
			case "-n":
				quiet = true
				continue
		}
		if i < len(os.Args) - 1 {
			panic("Unexpected arguments after program")
		}
		input = os.Args[i]
		hasInput = true
	}
	if !hasInput {
		panic("Missing program")
	}

	tokens := Lex(input)
	program := Parse(tokens)

	stdin := bufio.NewReader(os.Stdin)
	dataStream := walk.Json(stdin)

	state := ProgramState {
		in: dataStream,
		out: make(chan walk.WalkItem),
		program: program,
	}
	
	go func () {
		for walkItem := range dataStream {
			state.value = walk.Atomise([]walk.WalkValue{walkItem.Value})
			state.path = walk.Atomise(walkItem.Path.ToWalkValues())
			for _, cmd := range state.program {
				cmd.exec(&state)
			}
			if !quiet {
				pathValues, err := walk.Compound(state.path)
				if err != nil {
					panic("Tried to convert invalid atoms to values")
				}
				path := walk.PathFromWalkValues(pathValues)
				values, err := walk.Compound(state.value)
				if err != nil {
					panic("Tried to convert invalid atoms to values")
				}
				for _, value := range values {
					state.out <- walk.WalkItem {
						Value: value,
						Path: path,
					}
				}
			}
		}
		close(state.out)
	}()
	
	walk.JsonOut(state.out)
}