package sets

import (
	"fmt"
	"io"
	"io/ioutil"
	"path/filepath"
	"strconv"
	"strings"

	"ur.gs/chaos-gate/internal/util/asciiscan"
)

type MapSet struct {
	Description string
	Defs        [4]byte // TODO: work out what these are for

	// TODO: is there any more structure than this? Should I preserve empty lines?
	Palette []string
}

func LoadSets(dir string) (map[string]*MapSet, error) {
	fis, err := ioutil.ReadDir(dir)
	if err != nil {
		return nil, err
	}

	out := make(map[string]*MapSet, len(fis))

	for _, fi := range fis {
		filename := filepath.Join(dir, fi.Name())
		basename := filepath.Base(filename)
		extname := filepath.Ext(filename)

		// Don't try to load non-.obj files
		if !strings.EqualFold(extname, ".set") {
			continue
		}

		obj, err := LoadSet(filename)
		if err != nil {
			return nil, fmt.Errorf("%s: %v", filename, err)
		}

		out[basename] = obj
	}

	return out, nil
}

func LoadSet(filename string) (*MapSet, error) {
	out := &MapSet{}

	s, err := asciiscan.New(filename)
	if err != nil {
		return nil, err
	}

	defer s.Close()

	out.Description, err = s.ConsumeString()
	if err != nil {
		return nil, err
	}

	out.Defs, err = consumeDefs(s)
	if err != nil {
		return nil, err
	}

	for {
		str, err := s.ConsumeString()
		if err != nil {
			if err == io.EOF {
				return out, nil
			}

			return nil, err
		}

		out.Palette = append(out.Palette, str)
	}

	return out, nil
}

func consumeDefs(scanner *asciiscan.Scanner) ([4]byte, error) {
	var out [4]byte

	expectDefs, err := scanner.ConsumeString()
	if err != nil {
		return out, err
	}

	if expectDefs != "Defs" {
		return out, fmt.Errorf("Couldn't find Defs section")
	}

	defs, err := scanner.ConsumeString()
	if err != nil {
		return out, err
	}

	parts := strings.SplitN(defs, " ", -1)
	if len(parts) != 4 {
		return out, fmt.Errorf("Defs section did not have 4 components")
	}

	for i, part := range parts {
		n, err := strconv.ParseInt(part, 10, 8)
		if err != nil {
			return out, err
		}

		out[i] = byte(n) // safe as we specify 8 bits to ParseInt
	}

	return out, nil
}