package parser

import (
	"fmt"
	"strconv"
	"strings"

	"git.jfdev.de/JonasFranzDEV/hal/hal"
)

// ParseProgram parses an program by the following specification: LINE_NUMBER INSTRUCTION OPERAND(optional)
func ParseProgram(input []string) (hal.Program, error) {
	program := make(hal.Program, len(input))
	var err error
	for index, line := range input {
		program[index], err = parseInstruction(line)
		if err != nil {
			return nil, fmt.Errorf("error while parsing line %d: %v", index+1, err)
		}
	}
	return program, nil
}

func parseInstruction(input string) (*hal.ProgrammedInstruction, error) {
	args := strings.Split(input, " ")
	if len(args) != 0 && len(args) != 1 {
		return nil, fmt.Errorf("malformated instruction '%s'", input)
	}
	instruction := hal.FindInstructionByName(args[0])
	if instruction == nil {
		return nil, fmt.Errorf("unknown instruction '%s'", args[0])
	}
	programmedInstruction := &hal.ProgrammedInstruction{
		Instruction: instruction,
	}
	if len(args) == 1 {
		operand, err := strconv.ParseInt(args[1], 10, 64)
		if err != nil {
			return nil, fmt.Errorf("error while parsing operand for instruction '%s': %v", input, err)
		}
		if instruction.ExecuteWithOperand == nil {
			return nil, fmt.Errorf("instruction '%s' has no operand, got operand %d", instruction.Name, operand)
		}
		programmedInstruction.Operand = operand
	}
	return programmedInstruction, nil
}