// Parsen der Lump aus wad.go zu go structs
package mapfmt

import (
	"encoding/binary"
	"fmt"
)

type Vertex struct {
	X int16
	Y int16
}

type Linedef struct {
	V1, V2    uint16
	Flags     uint16
	Special   uint16
	Tag       uint16
	RightSide int16
	LeftSide  int16
}

type MapData struct {
	Vertices []Vertex
	Linedefs []Linedef
}

// Parsen der Vertices Lumps
func ParseVertices(data []byte) ([]Vertex, error) {
	if len(data)%4 != 0 {
		return nil, fmt.Errorf("VERTEXES size %d not multiple of 4", len(data))
	}
	n := len(data) / 4
	verts := make([]Vertex, n)
	for i := 0; i < n; i++ {
		verts[i].X = int16(binary.LittleEndian.Uint16(data[i*4:]))
		verts[i].Y = int16(binary.LittleEndian.Uint16(data[i*4+2:]))
	}
	return verts, nil
}

// Parsen der Linedef Lumps
func ParseLinedefs(data []byte) ([]Linedef, error) {
	if len(data)%14 != 0 {
		return nil, fmt.Errorf("LINEDEFS size %d not multiple of 14", len(data))
	}
	n := len(data) / 14
	lines := make([]Linedef, n)
	for i := 0; i < n; i++ {
		base := i * 14
		lines[i].V1 = binary.LittleEndian.Uint16(data[base:])
		lines[i].V2 = binary.LittleEndian.Uint16(data[base+2:])
		lines[i].Flags = binary.LittleEndian.Uint16(data[base+4:])
		lines[i].Special = binary.LittleEndian.Uint16(data[base+6:])
		lines[i].Tag = binary.LittleEndian.Uint16(data[base+8:])
		lines[i].RightSide = int16(binary.LittleEndian.Uint16(data[base+10:]))
		lines[i].LeftSide = int16(binary.LittleEndian.Uint16(data[base+12:]))
	}
	return lines, nil
}

// Generieren der MapData aus den von LoadMapLumps geliferten Daten und Parsen per funcs
func LoadMap(raw map[string][]byte) (*MapData, error) {
	v, err := ParseVertices(raw["VERTEXES"])
	if err != nil {
		return nil, err
	}
	l, err := ParseLinedefs(raw["LINEDEFS"])
	if err != nil {
		return nil, err
	}
	return &MapData{Vertices: v, Linedefs: l}, nil
}