package main

import (
	"bufio"
	"fmt"
	"io"
	"strconv"
	"strings"
)

func parseRESP(reader *bufio.Reader) ([]string, error) {
	line, err := reader.ReadString('\n')
	if err != nil {
		return nil, err
	}

	if len(line) == 0 {
		return nil, fmt.Errorf("empty line")
	}

	switch line[0] {
	case '*':
		var args []string
		argC, _ := strconv.Atoi(strings.TrimSpace(line[1:]))

		for i := 0; i < argC; i++ {
			nestedArgs, err := parseRESP(reader)
			if err != nil {
				return nil, err
			}

			args = append(args, nestedArgs...)
		}
		return args, nil
	case '$':
		strLen, _ := strconv.Atoi(strings.TrimSpace(line[1:]))

		if strLen == -1 {
			return []string{""}, nil
		}

		buf := make([]byte, strLen)

		_, err = io.ReadFull(reader, buf)
		if err != nil {
			return nil, err
		}

		_, err = reader.Discard(2)
		if err != nil {
			return nil, err
		}

		return []string{string(buf)}, nil
	case '+':
		cleanStr := strings.TrimSpace(line[1:])
		return []string{cleanStr}, nil
	case ':':
		return []string{strings.TrimSpace(line[1:])}, nil
	default:
		return nil, fmt.Errorf("unknown command type: %c", line[0])
	}
}