cyber-realm/world.go

package main

import (
	"encoding/json"
	"errors"
	"fmt"
	"os"
	"path"
	"strconv"
	"strings"
)

type World struct {
	Name      string     `json:"name"`
	Width     uint64     `json:"width"`
	Height    uint64     `json:"height"`
	TileIndex *TileIndex `json:"-"`
	Map       []uint64   `json:"-"`
}

func LoadWorld(worlddir string) (*World, error) {
	var (
		w   *World = &World{}
		err error
	)
	payload, err := os.ReadFile(path.Join(worlddir, "world.json"))
	if err != nil {
		return nil, err
	}
	err = json.Unmarshal(payload, &w)
	if err != nil {
		return nil, err
	}
	w.Map = make([]uint64, 0, w.Width*w.Height)
	ti, err := ParseTileIndex(path.Join(worlddir, "tiles.txt"))
	if err != nil {
		return nil, err
	}
	w.TileIndex = ti
	payload, err = os.ReadFile(path.Join(worlddir, "map.dat"))
	if err != nil {
		return nil, err
	}
	var (
		line    string = ""
		linenum int    = 0
	)
	for _, b := range payload {
		if b == '\n' {
			linenum += 1
			parts := strings.Split(line, " ")
			if len(parts) != int(w.Width) {
				return nil, fmt.Errorf("%d]: Failed parsing Map Data, not enough parts (expected=%d, got=%d), '%s'", linenum, w.Width, len(parts), line)
			}
			for segnum, p := range parts {
				t, err := strconv.ParseUint(p, 10, 64)
				if err != nil {
					return nil, fmt.Errorf("%d]: Failed parsing Map Data, line segment #%d errored %v, '%s'", linenum, segnum, err, line)
				}
				w.Map = append(w.Map, t)
			}
			line = ""
		} else {
			line += string(b)
		}
	}
	return w, nil
}

func (w *World) Save(dirname string) error {
	stat, err := os.Stat(dirname)
	if err != nil {
		if errors.Is(err, os.ErrNotExist) {
			err1 := os.MkdirAll(dirname, 0775)
			if err1 != nil {
				return fmt.Errorf("%v >> %v", err, err1)
			}
		} else {
			return err
		}
	}
	if stat != nil {
		if !stat.IsDir() {
			err = os.Remove(dirname)
			if err != nil {
				return err
			}
			err := os.MkdirAll(dirname, 0775)
			if err != nil {
				return err
			}
		}
	}
	payload, err := json.Marshal(w)
	if err != nil {
		return err
	}
	err = os.WriteFile(path.Join(dirname, "world.json"), payload, 0666)
	if err != nil {
		return err
	}
	err = w.TileIndex.Save(path.Join(dirname, "tiles.txt"))
	if err != nil {
		return err
	}
	f, err := os.Create(path.Join(dirname, "map.dat"))
	if err != nil {
		return err
	}
	defer f.Close()
	var idx int = 0
	for _, t := range w.Map {
		if idx >= int(w.Width) {
			_, err = f.WriteString("\n")
			if err != nil {
				return err
			}
			idx -= int(w.Width)
		}
		_, err = f.WriteString(fmt.Sprintf("%d ", t))
		if err != nil {
			return err
		}
		idx += 1
	}
	return nil
}

func (w *World) Get(x, y uint64) uint64 {
	idx := (y * w.Width) + x
	max := w.Width * w.Height
	if idx >= max {
		return 0
	}
	return w.Map[idx]
}