package save

import (
	"bytes"
	"compress/gzip"
	"compress/zlib"
	"errors"
	"io"

	"github.com/Tnze/go-mc/nbt"
)

// Chunk is 16* chunk
type Chunk struct {
	BlockEntities  []nbt.RawMessage `nbt:"block_entities"`
	BlockTicks     nbt.RawMessage   `nbt:"block_ticks"`
	CarvingMasks   map[string][]uint64
	DataVersion    int32
	Entities       []nbt.RawMessage    `nbt:"entities"`
	FluidTicks     nbt.RawMessage      `nbt:"fluid_ticks"`
	Heightmaps     map[string][]uint64 // keys: "WORLD_SURFACE_WG", "WORLD_SURFACE", "WORLD_SURFACE_IGNORE_SNOW", "OCEAN_FLOOR_WG", "OCEAN_FLOOR", "MOTION_BLOCKING", "MOTION_BLOCKING_NO_LEAVES"
	InhabitedTime  int64
	IsLightOn      byte `nbt:"isLightOn"`
	LastUpdate     int64
	Lights         []nbt.RawMessage
	PostProcessing nbt.RawMessage
	Sections       []Section `nbt:"sections"`
	Status         string
	Structures     nbt.RawMessage `nbt:"structures"`
	XPos           int32          `nbt:"xPos"`
	YPos           int32          `nbt:"yPos"`
	ZPos           int32          `nbt:"zPos"`
}

type Section struct {
	Y           int8
	BlockStates PaletteContainer[BlockState] `nbt:"block_states"`
	Biomes      PaletteContainer[BiomeState] `nbt:"biomes"`
	SkyLight    []byte
	BlockLight  []byte
}

type PaletteContainer[T any] struct {
	Palette []T      `nbt:"palette"`
	Data    []uint64 `nbt:"data"`
}

type BlockState struct {
	Name       string
	Properties nbt.RawMessage
}

type BiomeState string

// Load read column data from []byte
func (c *Chunk) Load(data []byte) (err error) {
	var r io.Reader = bytes.NewReader(data[1:])

	switch data[0] {
	default:
		err = errors.New("unknown compression")
	case 1:
		r, err = gzip.NewReader(r)
	case 2:
		r, err = zlib.NewReader(r)
	case 3:
		// none compression
	}
	if err != nil {
		return err
	}

	d := nbt.NewDecoder(r)
	// d.DisallowUnknownFields()
	_, err = d.Decode(c)
	return
}

func (c *Chunk) Data(compressingType byte) ([]byte, error) {
	var buff bytes.Buffer

	buff.WriteByte(compressingType)
	var w io.Writer
	switch compressingType {
	default:
		return nil, errors.New("unknown compression")
	case 1:
		w = gzip.NewWriter(&buff)
	case 2:
		w = zlib.NewWriter(&buff)
	case 3:
		w = &buff
	}
	err := nbt.NewEncoder(w).Encode(c, "")
	return buff.Bytes(), err
}