//go:build generate
// +build generate

// gen_blocks.go generates block information.
package main

import (
	"encoding/json"
	"fmt"
	"net/http"
	"os"
	"text/template"

	"github.com/iancoleman/strcase"
)

const (
	version = "1.17"
	infoURL = "https://raw.githubusercontent.com/PrismarineJS/minecraft-data/master/data/pc/" + version + "/blocks.json"
	//language=gohtml
	blockTmpl = `// Code generated by gen_block.go; DO NOT EDIT.

// Package block stores information about blocks in Minecraft.
package block

import (
	"math"
)

// BitsPerBlock indicates how many bits are needed to represent all possible
// block states. This value is used to determine the size of the global palette.
var BitsPerBlock = int(math.Ceil(math.Log2(float64(len(StateID)))))

// ID describes the numeric ID of a block.
type ID uint32

// Block describes information about a type of block.
type Block struct {
	ID          ID
	DisplayName string
	Name        string

	Hardness   float64
	Diggable   bool
	DropIDs    []uint32
	NeedsTools map[uint32]bool

	MinStateID uint32
	MaxStateID uint32

	Transparent      bool
	FilterLightLevel int
	EmitLightLevel   int
}

var (
	{{- range .}}
	{{.CamelName}} = Block{
		ID: {{.ID}}, 
		DisplayName: "{{.DisplayName}}", 
		Name: "{{.Name}}", 
		Hardness: {{.Hardness}}, 
		Diggable: {{.Diggable}}, 
		DropIDs: []uint32{ {{- range .DropIDs}}{{.}},{{end -}} }, 
		NeedsTools: map[uint32]bool{ {{- range $key, $val := .NeedsTools}}{{$key}}: {{$val}},{{end -}} }, 
		MinStateID: {{.MinStateID}}, 
		MaxStateID: {{.MaxStateID}}, 
		Transparent: {{.Transparent}}, 
		FilterLightLevel: {{.FilterLightLevel}}, 
		EmitLightLevel: {{.EmitLightLevel}}, 
	}{{end}}
)

// ByID is an index of minecraft blocks by their ID.
var ByID = map[ID]*Block{ {{range .}}
	{{.ID}}: &{{.CamelName}},{{end}}
}

// StateID maps all possible state IDs to a corresponding block ID.
var StateID = map[uint32]ID{ {{range $block := .}}
	{{- range .States}}
	{{.}}: {{$block.ID}},
	{{- end}}{{end}}
}`
)

type Block struct {
	ID          uint32 `json:"id"`
	CamelName   string `json:"-"`
	DisplayName string `json:"displayName"`
	Name        string `json:"name"`

	Hardness   float64         `json:"hardness"`
	Diggable   bool            `json:"diggable"`
	DropIDs    []uint32        `json:"drops"`
	NeedsTools map[uint32]bool `json:"harvestTools"`

	MinStateID uint32 `json:"minStateId"`
	MaxStateID uint32 `json:"maxStateId"`

	Transparent      bool `json:"transparent"`
	FilterLightLevel int  `json:"filterLight"`
	EmitLightLevel   int  `json:"emitLight"`
}

func (b Block) States() []uint32 {
	if b.MinStateID == b.MaxStateID {
		return []uint32{b.MinStateID}
	}
	states := make([]uint32, 0)
	for i := b.MinStateID; i <= b.MaxStateID; i++ {
		states = append(states, i)
	}
	return states
}

func downloadInfo() ([]*Block, error) {
	resp, err := http.Get(infoURL)
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()

	var data []*Block
	if err := json.NewDecoder(resp.Body).Decode(&data); err != nil {
		return nil, err
	}
	for _, d := range data {
		d.CamelName = strcase.ToCamel(d.Name)
	}
	return data, nil
}

//go:generate go run $GOFILE
//go:generate go fmt block.go
func main() {
	fmt.Println("generating block.go")
	blocks, err := downloadInfo()
	if err != nil {
		panic(err)
	}

	f, err := os.Create("block.go")
	if err != nil {
		panic(err)
	}
	defer f.Close()

	if err := template.Must(template.New("").Parse(blockTmpl)).Execute(f, blocks); err != nil {
		panic(err)
	}
}
