From d6890360d150154236f157a718dbfffa774683a2 Mon Sep 17 00:00:00 2001
From: Tnze <cjd001113@outlook.com>
Date: Sat, 1 Jan 2022 20:45:16 +0800
Subject: [PATCH] Command parsers plan 1

---
 server/command/command.go | 95 +++++++++++++++++++++++++++++++++++++++
 server/command/parsers.go | 72 +++++++++++++++++++++++++++++
 2 files changed, 167 insertions(+)
 create mode 100644 server/command/command.go
 create mode 100644 server/command/parsers.go

diff --git a/server/command/command.go b/server/command/command.go
new file mode 100644
index 0000000..ff2c607
--- /dev/null
+++ b/server/command/command.go
@@ -0,0 +1,95 @@
+package command
+
+import (
+	"io"
+	"unsafe"
+
+	pk "github.com/Tnze/go-mc/net/packet"
+)
+
+type CmdSet struct {
+	root  int32
+	nodes []Node
+}
+
+func NewCmdSet() *CmdSet {
+	return &CmdSet{
+		root: 0,
+		nodes: []Node{
+			{
+				flags:  TypeRoot,
+				parser: nil,
+			},
+		},
+	}
+}
+
+func (c *CmdSet) AddNode(n Node) int32 {
+	c.nodes = append(c.nodes, n)
+	return int32(len(c.nodes) - 1)
+}
+
+func (c *CmdSet) WriteTo(w io.Writer) (int64, error) {
+	return pk.Tuple{
+		pk.Array(c.nodes),
+		pk.VarInt(c.root),
+	}.WriteTo(w)
+}
+
+func (c *CmdSet) Execute(cmd string) error {
+	for _, child := range c.nodes[c.root].children {
+		if node := c.nodes[child]; node.flags&0x03 == TypeLiteral {
+
+		}
+	}
+}
+
+type Node struct {
+	flags       byte
+	children    []int32
+	redirect    int32
+	name        string
+	parser      Parser
+	suggestions string
+}
+
+func (n *Node) WriteTo(w io.Writer) (int64, error) {
+	return pk.Tuple{
+		pk.Byte(n.flags),
+		pk.Array(*(*[]pk.VarInt)(unsafe.Pointer(&n.children))),
+		pk.Opt{ // Redirect
+			Has:   n.flags&HasRedirect != 0,
+			Field: pk.VarInt(n.redirect),
+		},
+		pk.Opt{ // Name
+			Has:   n.flags&0x03 == TypeLiteral || n.flags&0x03 == TypeArgument,
+			Field: pk.String(n.name),
+		},
+		pk.Opt{ // Parser & Properties
+			Has:   n.flags&0x03 == TypeArgument,
+			Field: n.parser,
+		},
+		pk.Opt{
+			Has:   n.flags&HasSuggestionsType != 0,
+			Field: pk.Identifier(n.suggestions),
+		},
+	}.WriteTo(w)
+}
+
+type Parser interface {
+	pk.FieldEncoder
+	Parse(cmd string) (token string, value interface{}, err error)
+}
+
+const (
+	TypeRoot byte = iota
+	TypeLiteral
+	TypeArgument
+	TypeUnknown
+)
+
+const (
+	IsExecutable = 1 << (iota + 2)
+	HasRedirect
+	HasSuggestionsType
+)
diff --git a/server/command/parsers.go b/server/command/parsers.go
new file mode 100644
index 0000000..aee60b9
--- /dev/null
+++ b/server/command/parsers.go
@@ -0,0 +1,72 @@
+package command
+
+import (
+	"io"
+	"strconv"
+	"strings"
+
+	pk "github.com/Tnze/go-mc/net/packet"
+)
+
+type StringParser struct {
+	Format int32
+	V      string
+}
+
+func (s StringParser) WriteTo(w io.Writer) (int64, error) {
+	return pk.Tuple{
+		pk.Identifier("brigadier:string"),
+		pk.VarInt(s.Format),
+	}.WriteTo(w)
+}
+
+func (s StringParser) Parse(cmd string) (token string, value interface{}, err error) {
+	switch s.Format {
+	case 2: // Greedy Phrase
+		return cmd, cmd, nil
+	case 1: // Quotable Phrase
+		if len(cmd) > 0 && cmd[0] == '"' {
+			var sb strings.Builder
+			var isEscaping bool
+			for i, v := range cmd[1:] {
+				if isEscaping {
+					isEscaping = false
+					switch v {
+					case '\\':
+						sb.WriteRune('\\')
+					case '"':
+						sb.WriteRune('"')
+					}
+				} else if v == '\\' {
+					isEscaping = true
+				} else if v == '"' {
+					return cmd[:i], sb.String(), nil
+				} else {
+					sb.WriteRune(v)
+				}
+			}
+			return "", nil, ParseErr{
+				Pos: len(cmd) - 1,
+				Err: "expected '\"'",
+			}
+		}
+		fallthrough
+	case 0: // Single Word
+		i := strings.IndexAny(cmd, "\t\n\v\f\r ")
+		if i == -1 {
+			return cmd, cmd, nil
+		}
+		return cmd[:i], cmd[:i], nil
+	default:
+		panic("StringParser: unknown format 0x" + strconv.FormatInt(int64(s.Format), 16))
+	}
+}
+
+type ParseErr struct {
+	Pos int
+	Err string
+}
+
+func (p ParseErr) Error() string {
+	return p.Err
+}