package data

import (
	"bufio"
	"bytes"
	"io"
	"io/ioutil"
	"strconv"
)

var hashComment = []byte("#")

type CompassPoints struct {
	N  int
	NE int
	E  int
	SE int
	S  int
	SW int
	W  int
	NW int
}

type Range struct {
	Start int
	End   int
}

func fileToScanner(filename string) (*bufio.Scanner, error) {
	data, err := ioutil.ReadFile(filename)
	if err != nil {
		return nil, err
	}

	return bufio.NewScanner(bytes.NewReader(data)), nil
}

func consumeString(scanner *bufio.Scanner) (string, error) {
	for scanner.Scan() {
		line := scanner.Bytes()

		if len(line) == 0 || line[0] == hashComment[0] { // Most .dat files use # for comments
			continue
		}

		comment := bytes.Index(line, hashComment)
		if comment > 0 {
			line = line[0:comment]
		}

		return string(bytes.TrimRight(line, "\r\n\t ")), nil
	}

	err := scanner.Err()
	if err == nil {
		return "", io.EOF
	}

	return "", err
}

func consumeInt(scanner *bufio.Scanner) (int, error) {
	str, err := consumeString(scanner)
	if err != nil {
		return 0, err
	}

	return strconv.Atoi(str)
}

func consumeIntPtr(to *int, scanner *bufio.Scanner) error {
	val, err := consumeInt(scanner)
	if err != nil {
		return err
	}

	*to = val
	return nil
}

func consumeIntPtrs(scanner *bufio.Scanner, ptrs ...*int) error {
	for _, ptr := range ptrs {
		if err := consumeIntPtr(ptr, scanner); err != nil {
			return err
		}
	}

	return nil
}

func consumeRange(scanner *bufio.Scanner) (Range, error) {
	var out Range

	err := consumeIntPtrs(scanner, &out.Start, &out.End)
	return out, err
}

func consumeCompassPoints(scanner *bufio.Scanner) (CompassPoints, error) {
	var out CompassPoints

	err := consumeIntPtrs(
		scanner,
		&out.N, &out.NE, &out.E, &out.SE, &out.S, &out.SW, &out.W, &out.NW,
	)

	return out, err
}