package parser

import (
	"eq2emu/internal/common"
	"fmt"
	"strconv"
	"strings"
	"unicode"
)

// Parser is a single-pass recursive descent parser for packet definitions
type Parser struct {
	input      string
	pos        int
	line       int
	col        int
	substructs map[string]*PacketDef
	templates  map[string]*PacketDef
	tagStack   []string
}

// NewParser creates a new string-based parser
func NewParser(input string) *Parser {
	return &Parser{
		input:      input,
		line:       1,
		col:        1,
		substructs: make(map[string]*PacketDef),
		templates:  make(map[string]*PacketDef),
		tagStack:   make([]string, 0, 16),
	}
}

// peek returns the current character without advancing
func (p *Parser) peek() rune {
	if p.pos >= len(p.input) {
		return 0
	}
	return rune(p.input[p.pos])
}

// peekN looks ahead n characters
func (p *Parser) peekN(n int) rune {
	pos := p.pos + n
	if pos >= len(p.input) {
		return 0
	}
	return rune(p.input[pos])
}

// advance moves to the next character and returns it
func (p *Parser) advance() rune {
	if p.pos >= len(p.input) {
		return 0
	}

	ch := rune(p.input[p.pos])
	p.pos++

	if ch == '\n' {
		p.line++
		p.col = 1
	} else {
		p.col++
	}

	return ch
}

// skipWhitespace skips whitespace characters
func (p *Parser) skipWhitespace() {
	for p.pos < len(p.input) && unicode.IsSpace(p.peek()) {
		p.advance()
	}
}

// consumeChar consumes the expected character, returns true if found
func (p *Parser) consumeChar(expected rune) bool {
	if p.peek() == expected {
		p.advance()
		return true
	}
	return false
}

// consumeString consumes the expected string, returns true if found
func (p *Parser) consumeString(expected string) bool {
	if p.pos+len(expected) > len(p.input) {
		return false
	}

	if p.input[p.pos:p.pos+len(expected)] == expected {
		for range expected {
			p.advance()
		}
		return true
	}
	return false
}

// parseIdentifier parses an identifier (alphanumeric + underscore)
func (p *Parser) parseIdentifier() (string, error) {
	start := p.pos

	if p.pos >= len(p.input) || (!unicode.IsLetter(p.peek()) && p.peek() != '_') {
		return "", fmt.Errorf("expected identifier at line %d, col %d", p.line, p.col)
	}

	for p.pos < len(p.input) {
		ch := p.peek()
		if unicode.IsLetter(ch) || unicode.IsDigit(ch) || ch == '_' || ch == '-' {
			p.advance()
		} else {
			break
		}
	}

	return p.input[start:p.pos], nil
}

// parseQuotedString parses a quoted string value
func (p *Parser) parseQuotedString() (string, error) {
	quote := p.peek()
	if quote != '"' && quote != '\'' {
		return "", fmt.Errorf("expected quoted string at line %d, col %d", p.line, p.col)
	}

	p.advance() // consume opening quote
	start := p.pos

	for p.pos < len(p.input) && p.peek() != quote {
		if p.peek() == '\\' {
			p.advance() // consume backslash
			if p.pos < len(p.input) {
				p.advance() // consume escaped character
			}
		} else {
			p.advance()
		}
	}

	if p.pos >= len(p.input) {
		return "", fmt.Errorf("unclosed quoted string at line %d", p.line)
	}

	value := p.input[start:p.pos]
	p.advance() // consume closing quote
	return value, nil
}

// parseAttributes parses tag attributes
func (p *Parser) parseAttributes() (map[string]string, error) {
	attrs := make(map[string]string)

	for {
		p.skipWhitespace()

		// Check for end of tag
		if p.pos >= len(p.input) || p.peek() == '>' || (p.peek() == '/' && p.peekN(1) == '>') {
			break
		}

		// Parse attribute name
		name, err := p.parseIdentifier()
		if err != nil {
			return nil, err
		}

		p.skipWhitespace()
		if !p.consumeChar('=') {
			return nil, fmt.Errorf("expected '=' after attribute name '%s' at line %d", name, p.line)
		}

		p.skipWhitespace()

		// Parse attribute value
		value, err := p.parseQuotedString()
		if err != nil {
			return nil, err
		}

		attrs[name] = strings.TrimSpace(value)
	}

	return attrs, nil
}

// parseComment skips over comment content
func (p *Parser) parseComment() error {
	// We're at the start of <!--
	if !p.consumeString("<!--") {
		return fmt.Errorf("expected '<!--' at line %d", p.line)
	}

	// Find closing -->
	for p.pos+2 < len(p.input) {
		if p.consumeString("-->") {
			return nil
		}
		p.advance()
	}

	return fmt.Errorf("unclosed comment at line %d", p.line)
}

// Tag represents a parsed XML tag
type Tag struct {
	Name        string
	Attributes  map[string]string
	SelfClosing bool
	IsClosing   bool
}

// parseTag parses an opening, closing, or self-closing tag
func (p *Parser) parseTag() (*Tag, error) {
	if !p.consumeChar('<') {
		return nil, fmt.Errorf("expected '<' at line %d", p.line)
	}

	// Check for comment
	if p.peek() == '!' && p.peekN(1) == '-' && p.peekN(2) == '-' {
		// We already consumed the '<', so parse comment from here
		if !p.consumeString("!--") {
			return nil, fmt.Errorf("expected '<!--' at line %d", p.line)
		}

		// Find closing -->
		for p.pos+2 < len(p.input) {
			if p.consumeString("-->") {
				return p.parseTag() // recursively get the next tag
			}
			p.advance()
		}

		return nil, fmt.Errorf("unclosed comment at line %d", p.line)
	}

	tag := &Tag{}

	// Check for closing tag
	if p.consumeChar('/') {
		tag.IsClosing = true
		name, err := p.parseIdentifier()
		if err != nil {
			return nil, err
		}
		tag.Name = name

		p.skipWhitespace()
		if !p.consumeChar('>') {
			return nil, fmt.Errorf("expected '>' after closing tag '%s' at line %d", name, p.line)
		}
		return tag, nil
	}

	// Parse tag name
	name, err := p.parseIdentifier()
	if err != nil {
		return nil, err
	}
	tag.Name = name

	// Parse attributes
	attrs, err := p.parseAttributes()
	if err != nil {
		return nil, err
	}
	tag.Attributes = attrs

	p.skipWhitespace()

	// Check for self-closing
	if p.consumeString("/>") {
		tag.SelfClosing = true
	} else if p.consumeChar('>') {
		// Regular opening tag
	} else {
		return nil, fmt.Errorf("expected '>' or '/>' after tag '%s' at line %d", name, p.line)
	}

	return tag, nil
}

// pushTag pushes a tag name onto the stack for validation
func (p *Parser) pushTag(tag string) {
	p.tagStack = append(p.tagStack, tag)
}

// popTag pops and validates the closing tag
func (p *Parser) popTag(expectedTag string) error {
	if len(p.tagStack) == 0 {
		return fmt.Errorf("unexpected closing tag '%s' at line %d", expectedTag, p.line)
	}

	lastTag := p.tagStack[len(p.tagStack)-1]
	if lastTag != expectedTag {
		return fmt.Errorf("mismatched closing tag: expected '%s', got '%s' at line %d", lastTag, expectedTag, p.line)
	}

	p.tagStack = p.tagStack[:len(p.tagStack)-1]
	return nil
}

// validateAllTagsClosed checks for unclosed tags
func (p *Parser) validateAllTagsClosed() error {
	if len(p.tagStack) > 0 {
		return fmt.Errorf("unclosed tag '%s'", p.tagStack[len(p.tagStack)-1])
	}
	return nil
}

// Helper functions for robust attribute parsing
func (p *Parser) parseIntAttribute(value string, attributeName string) (int, error) {
	if value == "" {
		return 0, fmt.Errorf("empty %s attribute at line %d", attributeName, p.line)
	}

	cleanValue := strings.TrimSpace(value)
	if cleanValue == "" {
		return 0, fmt.Errorf("empty %s attribute value '%s' at line %d", attributeName, value, p.line)
	}

	result, err := strconv.Atoi(cleanValue)
	if err != nil {
		return 0, fmt.Errorf("invalid %s value '%s' at line %d: %v", attributeName, value, p.line, err)
	}

	return result, nil
}

func (p *Parser) parseUintAttribute(value string, attributeName string) (uint32, error) {
	if value == "" {
		return 0, fmt.Errorf("empty %s attribute at line %d", attributeName, p.line)
	}

	cleanValue := strings.TrimSpace(value)
	if cleanValue == "" {
		return 0, fmt.Errorf("empty %s attribute value '%s' at line %d", attributeName, value, p.line)
	}

	result, err := strconv.ParseUint(cleanValue, 10, 32)
	if err != nil {
		return 0, fmt.Errorf("invalid %s value '%s' at line %d: %v", attributeName, value, p.line, err)
	}

	return uint32(result), nil
}

func (p *Parser) parseInt8Attribute(value string, attributeName string) (int8, error) {
	if value == "" {
		return 0, fmt.Errorf("empty %s attribute at line %d", attributeName, p.line)
	}

	cleanValue := strings.TrimSpace(value)
	if cleanValue == "" {
		return 0, fmt.Errorf("empty %s attribute value '%s' at line %d", attributeName, value, p.line)
	}

	result, err := strconv.ParseInt(cleanValue, 10, 8)
	if err != nil {
		return 0, fmt.Errorf("invalid %s value '%s' at line %d: %v", attributeName, value, p.line, err)
	}

	return int8(result), nil
}

// parseFieldNames parses comma-separated field names
func (p *Parser) parseFieldNames(nameAttr string) []string {
	if nameAttr == "" {
		return nil
	}

	// Fast path for single name
	if !strings.Contains(nameAttr, ",") {
		name := strings.TrimSpace(nameAttr)
		if name != "" {
			return []string{name}
		}
		return nil
	}

	// Parse multiple names
	names := strings.Split(nameAttr, ",")
	result := make([]string, 0, len(names))
	for _, name := range names {
		if trimmed := strings.TrimSpace(name); trimmed != "" {
			result = append(result, trimmed)
		}
	}

	return result
}

// Parse parses the entire packet definition document
func (p *Parser) Parse() (map[string]*PacketDef, error) {
	packets := make(map[string]*PacketDef)

	for p.pos < len(p.input) {
		p.skipWhitespace()
		if p.pos >= len(p.input) {
			break
		}

		if p.peek() != '<' {
			return nil, fmt.Errorf("expected '<' at line %d", p.line)
		}

		// Handle comments at the top level
		if p.peek() == '<' && p.peekN(1) == '!' && p.peekN(2) == '-' && p.peekN(3) == '-' {
			err := p.parseComment()
			if err != nil {
				return nil, err
			}
			continue
		}

		tag, err := p.parseTag()
		if err != nil {
			return nil, err
		}

		switch tag.Name {
		case "packet":
			name := tag.Attributes["name"]
			packet, err := p.parsePacket(tag)
			if err != nil {
				return nil, err
			}
			if name != "" {
				packets[name] = packet
			}

		case "substruct":
			name := tag.Attributes["name"]
			substruct, err := p.parseSubstruct(tag)
			if err != nil {
				return nil, err
			}
			if name != "" {
				p.substructs[name] = substruct
			}

		case "template":
			name := tag.Attributes["name"]
			if name != "" {
				err := p.parseTemplateDefinition(tag, name)
				if err != nil {
					return nil, err
				}
			}

		default:
			return nil, fmt.Errorf("unexpected top-level tag '%s' at line %d", tag.Name, p.line)
		}
	}

	if err := p.validateAllTagsClosed(); err != nil {
		return nil, err
	}

	return packets, nil
}

// parsePacket parses a packet element
func (p *Parser) parsePacket(openTag *Tag) (*PacketDef, error) {
	packetDef := NewPacketDef(16)

	if openTag.SelfClosing {
		return packetDef, nil
	}

	p.pushTag("packet")

	for {
		p.skipWhitespace()
		if p.pos >= len(p.input) {
			return nil, fmt.Errorf("unexpected end of input in packet")
		}

		if p.peek() != '<' {
			return nil, fmt.Errorf("expected '<' at line %d", p.line)
		}

		// Handle comments
		if p.peek() == '<' && p.peekN(1) == '!' && p.peekN(2) == '-' && p.peekN(3) == '-' {
			err := p.parseComment()
			if err != nil {
				return nil, err
			}
			continue
		}

		tag, err := p.parseTag()
		if err != nil {
			return nil, err
		}

		if tag.IsClosing {
			if tag.Name != "packet" {
				return nil, fmt.Errorf("expected closing tag 'packet', got '%s' at line %d", tag.Name, p.line)
			}
			if err := p.popTag("packet"); err != nil {
				return nil, err
			}
			break
		}

		if tag.Name == "version" {
			err := p.parseVersion(tag, packetDef)
			if err != nil {
				return nil, err
			}
		} else {
			return nil, fmt.Errorf("unexpected tag '%s' in packet at line %d", tag.Name, p.line)
		}
	}

	return packetDef, nil
}

// parseSubstruct parses a substruct element
func (p *Parser) parseSubstruct(openTag *Tag) (*PacketDef, error) {
	packetDef := NewPacketDef(16)

	if openTag.SelfClosing {
		return packetDef, nil
	}

	p.pushTag("substruct")

	// Check if this substruct contains version elements
	hasVersions := false
	for {
		p.skipWhitespace()
		if p.pos >= len(p.input) {
			return nil, fmt.Errorf("unexpected end of input in substruct")
		}

		if p.peek() != '<' {
			return nil, fmt.Errorf("expected '<' at line %d", p.line)
		}

		tag, err := p.parseTag()
		if err != nil {
			return nil, err
		}

		if tag.IsClosing {
			if tag.Name != "substruct" {
				return nil, fmt.Errorf("expected closing tag 'substruct', got '%s' at line %d", tag.Name, p.line)
			}
			if err := p.popTag("substruct"); err != nil {
				return nil, err
			}
			break
		}

		if tag.Name == "version" {
			hasVersions = true
			err := p.parseVersion(tag, packetDef)
			if err != nil {
				return nil, err
			}
		} else if hasVersions {
			return nil, fmt.Errorf("unexpected tag '%s' after version in substruct at line %d", tag.Name, p.line)
		} else {
			// No versions found, parse as direct elements
			fieldOrder := make([]string, 0)
			err := p.parseElement(tag, packetDef, &fieldOrder, "")
			if err != nil {
				return nil, err
			}

			// Continue parsing remaining elements
			for {
				p.skipWhitespace()
				if p.pos >= len(p.input) || p.peek() != '<' {
					break
				}

				nextTag, err := p.parseTag()
				if err != nil {
					return nil, err
				}

				if nextTag.IsClosing {
					if nextTag.Name != "substruct" {
						return nil, fmt.Errorf("expected closing tag 'substruct', got '%s' at line %d", nextTag.Name, p.line)
					}
					if err := p.popTag("substruct"); err != nil {
						return nil, err
					}
					break
				}

				err = p.parseElement(nextTag, packetDef, &fieldOrder, "")
				if err != nil {
					return nil, err
				}
			}

			// Set field order for version 1
			packetDef.Orders[1] = make([]string, len(fieldOrder))
			copy(packetDef.Orders[1], fieldOrder)
			break
		}
	}

	return packetDef, nil
}

// parseVersion parses a version element
func (p *Parser) parseVersion(openTag *Tag, packetDef *PacketDef) error {
	version := uint32(1)
	if v := openTag.Attributes["number"]; v != "" {
		if parsed, err := p.parseUintAttribute(v, "number"); err == nil {
			version = parsed
		}
		// Don't fail on invalid version numbers, just use default
	}

	fieldOrder := make([]string, 0)

	if openTag.SelfClosing {
		packetDef.Orders[version] = fieldOrder
		return nil
	}

	p.pushTag("version")

	for {
		p.skipWhitespace()
		if p.pos >= len(p.input) {
			return fmt.Errorf("unexpected end of input in version")
		}

		if p.peek() != '<' {
			return fmt.Errorf("expected '<' at line %d", p.line)
		}

		// Handle comments
		if p.peek() == '<' && p.peekN(1) == '!' && p.peekN(2) == '-' && p.peekN(3) == '-' {
			err := p.parseComment()
			if err != nil {
				return err
			}
			continue
		}

		tag, err := p.parseTag()
		if err != nil {
			return err
		}

		if tag.IsClosing {
			if tag.Name != "version" {
				return fmt.Errorf("expected closing tag 'version', got '%s' at line %d", tag.Name, p.line)
			}
			if err := p.popTag("version"); err != nil {
				return err
			}
			break
		}

		err = p.parseElement(tag, packetDef, &fieldOrder, "")
		if err != nil {
			return err
		}
	}

	packetDef.Orders[version] = make([]string, len(fieldOrder))
	copy(packetDef.Orders[version], fieldOrder)
	return nil
}

// parseElement parses any element (field, array, group, template, substruct reference)
func (p *Parser) parseElement(tag *Tag, packetDef *PacketDef, fieldOrder *[]string, prefix string) error {
	switch tag.Name {
	case "group":
		return p.parseGroup(tag, packetDef, fieldOrder, prefix)
	case "array":
		return p.parseArray(tag, packetDef, fieldOrder, prefix)
	case "template":
		return p.parseTemplateUsage(tag, packetDef, fieldOrder, prefix)
	case "substruct":
		return p.parseSubstructReference(tag, packetDef, fieldOrder, prefix)
	case "item":
		return p.parseItemField(tag, packetDef, fieldOrder, prefix)
	default:
		// Try to parse as a field
		return p.parseField(tag, packetDef, fieldOrder, prefix)
	}
}

// parseGroup parses a group element
func (p *Parser) parseGroup(openTag *Tag, packetDef *PacketDef, fieldOrder *[]string, prefix string) error {
	groupPrefix := prefix
	if name := openTag.Attributes["name"]; name != "" {
		if prefix == "" {
			groupPrefix = name + "_"
		} else {
			groupPrefix = prefix + name + "_"
		}
	}

	if openTag.SelfClosing {
		return nil
	}

	p.pushTag("group")

	for {
		p.skipWhitespace()
		if p.pos >= len(p.input) {
			return fmt.Errorf("unexpected end of input in group")
		}

		if p.peek() != '<' {
			return fmt.Errorf("expected '<' at line %d", p.line)
		}

		tag, err := p.parseTag()
		if err != nil {
			return err
		}

		if tag.IsClosing {
			if tag.Name != "group" {
				return fmt.Errorf("expected closing tag 'group', got '%s' at line %d", tag.Name, p.line)
			}
			if err := p.popTag("group"); err != nil {
				return err
			}
			break
		}

		err = p.parseElement(tag, packetDef, fieldOrder, groupPrefix)
		if err != nil {
			return err
		}
	}

	return nil
}

// parseArray parses an array element
func (p *Parser) parseArray(openTag *Tag, packetDef *PacketDef, fieldOrder *[]string, prefix string) error {
	var arrayName string
	if prefix == "" {
		arrayName = openTag.Attributes["name"]
	} else {
		arrayName = prefix + openTag.Attributes["name"]
	}

	fieldDesc := FieldDesc{
		Type:        common.TypeArray,
		Condition:   openTag.Attributes["count"],
		AddToStruct: true, // Default to true
	}

	if ifCond := openTag.Attributes["if"]; ifCond != "" {
		fieldDesc.Condition = combineConditions(fieldDesc.Condition, ifCond)
	}

	// Parse additional attributes
	if maxSize := openTag.Attributes["max_size"]; maxSize != "" {
		if m, err := p.parseIntAttribute(maxSize, "max_size"); err == nil {
			fieldDesc.MaxArraySize = m
		} else {
			return err
		}
	}

	if optional := openTag.Attributes["optional"]; optional == "true" {
		fieldDesc.Optional = true
	}

	if addToStruct := openTag.Attributes["add_to_struct"]; addToStruct == "false" {
		fieldDesc.AddToStruct = false
	}

	// Handle substruct reference
	if substruct := openTag.Attributes["substruct"]; substruct != "" {
		if subDef, exists := p.substructs[substruct]; exists {
			fieldDesc.SubDef = subDef
		}
	}

	// Arrays with substruct references or explicit self-closing syntax are self-closing
	if openTag.SelfClosing || fieldDesc.SubDef != nil {
		packetDef.Fields[arrayName] = fieldDesc
		*fieldOrder = append(*fieldOrder, arrayName)
		return nil
	}

	p.pushTag("array")

	// Handle direct child elements as substruct fields
	if fieldDesc.SubDef == nil {
		subDef := NewPacketDef(16)
		subOrder := make([]string, 0)

		for {
			p.skipWhitespace()
			if p.pos >= len(p.input) {
				return fmt.Errorf("unexpected end of input in array")
			}

			if p.peek() != '<' {
				return fmt.Errorf("expected '<' at line %d", p.line)
			}

			tag, err := p.parseTag()
			if err != nil {
				return err
			}

			if tag.IsClosing {
				if tag.Name != "array" {
					return fmt.Errorf("expected closing tag 'array', got '%s' at line %d", tag.Name, p.line)
				}
				if err := p.popTag("array"); err != nil {
					return err
				}
				break
			}

			err = p.parseElement(tag, subDef, &subOrder, "")
			if err != nil {
				return err
			}
		}

		// Only create substruct if we actually have fields
		if len(subOrder) > 0 {
			subDef.Orders[1] = make([]string, len(subOrder))
			copy(subDef.Orders[1], subOrder)
			fieldDesc.SubDef = subDef
		}
	}

	packetDef.Fields[arrayName] = fieldDesc
	*fieldOrder = append(*fieldOrder, arrayName)
	return nil
}

// combineConditions combines two conditions with AND logic - using existing function

// parseField parses a field element
func (p *Parser) parseField(openTag *Tag, packetDef *PacketDef, fieldOrder *[]string, prefix string) error {
	dataType, exists := getDataType(openTag.Name)
	if !exists {
		return fmt.Errorf("unknown field type '%s' at line %d", openTag.Name, p.line)
	}

	nameAttr := openTag.Attributes["name"]
	if nameAttr == "" {
		return fmt.Errorf("field missing name attribute at line %d", p.line)
	}

	names := p.parseFieldNames(nameAttr)
	for _, name := range names {
		var fullName string
		if prefix == "" {
			fullName = name
		} else {
			fullName = prefix + name
		}

		fieldDesc := FieldDesc{
			Type:        dataType,
			Condition:   openTag.Attributes["if"],
			AddToStruct: true, // Default to true
			AddType:     dataType,
		}

		// Parse size attribute
		if size := openTag.Attributes["size"]; size != "" {
			if s, err := p.parseIntAttribute(size, "size"); err == nil {
				fieldDesc.Length = s
			} else {
				return err
			}
		}

		// Parse oversized attribute
		if oversized := openTag.Attributes["oversized"]; oversized != "" {
			if o, err := p.parseIntAttribute(oversized, "oversized"); err == nil {
				fieldDesc.Oversized = o
			} else {
				return err
			}
		}

		// Parse type2 attributes
		if type2 := openTag.Attributes["type2"]; type2 != "" {
			if t2, exists := getDataType(type2); exists {
				fieldDesc.Type2 = t2
				fieldDesc.Type2Cond = openTag.Attributes["type2_if"]
			}
		}

		// Parse default value
		if defaultVal := openTag.Attributes["default"]; defaultVal != "" {
			if d, err := p.parseInt8Attribute(defaultVal, "default"); err == nil {
				fieldDesc.DefaultValue = d
			} else {
				return err
			}
		}

		// Parse max_size
		if maxSize := openTag.Attributes["max_size"]; maxSize != "" {
			if m, err := p.parseIntAttribute(maxSize, "max_size"); err == nil {
				fieldDesc.MaxArraySize = m
			} else {
				return err
			}
		}

		// Parse optional
		if optional := openTag.Attributes["optional"]; optional == "true" {
			fieldDesc.Optional = true
		}

		// Parse add_to_struct
		if addToStruct := openTag.Attributes["add_to_struct"]; addToStruct == "false" {
			fieldDesc.AddToStruct = false
		}

		// Parse add_type
		if addType := openTag.Attributes["add_type"]; addType != "" {
			if at, exists := getDataType(addType); exists {
				fieldDesc.AddType = at
			}
		}

		packetDef.Fields[fullName] = fieldDesc
		*fieldOrder = append(*fieldOrder, fullName)
	}

	return nil
}

// parseTemplateDefinition parses a template definition
func (p *Parser) parseTemplateDefinition(openTag *Tag, templateName string) error {
	templateDef := NewPacketDef(16)
	fieldOrder := make([]string, 0)

	if openTag.SelfClosing {
		templateDef.Orders[1] = fieldOrder
		p.templates[templateName] = templateDef
		return nil
	}

	p.pushTag("template")

	for {
		p.skipWhitespace()
		if p.pos >= len(p.input) {
			return fmt.Errorf("unexpected end of input in template")
		}

		if p.peek() != '<' {
			return fmt.Errorf("expected '<' at line %d", p.line)
		}

		tag, err := p.parseTag()
		if err != nil {
			return err
		}

		if tag.IsClosing {
			if tag.Name != "template" {
				return fmt.Errorf("expected closing tag 'template', got '%s' at line %d", tag.Name, p.line)
			}
			if err := p.popTag("template"); err != nil {
				return err
			}
			break
		}

		err = p.parseElement(tag, templateDef, &fieldOrder, "")
		if err != nil {
			return err
		}
	}

	templateDef.Orders[1] = make([]string, len(fieldOrder))
	copy(templateDef.Orders[1], fieldOrder)
	p.templates[templateName] = templateDef
	return nil
}

// parseTemplateUsage parses template usage
func (p *Parser) parseTemplateUsage(tag *Tag, packetDef *PacketDef, fieldOrder *[]string, prefix string) error {
	// Template usage: <template use="foo">
	if templateUse := tag.Attributes["use"]; templateUse != "" {
		template, exists := p.templates[templateUse]
		if !exists {
			return fmt.Errorf("undefined template '%s' at line %d", templateUse, p.line)
		}

		// Inject all template fields into current packet
		if templateOrder, exists := template.Orders[1]; exists {
			for _, fieldName := range templateOrder {
				if fieldDesc, exists := template.Fields[fieldName]; exists {
					// Apply prefix if provided
					fullName := fieldName
					if prefix != "" {
						fullName = prefix + fieldName
					}

					packetDef.Fields[fullName] = fieldDesc
					*fieldOrder = append(*fieldOrder, fullName)
				}
			}
		}

		return nil
	}

	return fmt.Errorf("template missing 'use' attribute at line %d", p.line)
}

// parseSubstructReference parses a substruct reference like <substruct name="header" use="ItemDescription">
func (p *Parser) parseSubstructReference(tag *Tag, packetDef *PacketDef, fieldOrder *[]string, prefix string) error {
	nameAttr := tag.Attributes["name"]
	useAttr := tag.Attributes["use"]

	if nameAttr == "" {
		return fmt.Errorf("substruct reference missing 'name' attribute at line %d", p.line)
	}

	var fullName string
	if prefix == "" {
		fullName = nameAttr
	} else {
		fullName = prefix + nameAttr
	}

	fieldDesc := FieldDesc{
		Type:        common.TypeArray, // Substructs are treated as arrays
		AddToStruct: true,
	}

	// Handle substruct reference with 'use' attribute
	if useAttr != "" {
		if subDef, exists := p.substructs[useAttr]; exists {
			fieldDesc.SubDef = subDef
		} else {
			// If substruct doesn't exist yet, it might be defined later
			// For now, we'll create a placeholder
		}
	}

	packetDef.Fields[fullName] = fieldDesc
	*fieldOrder = append(*fieldOrder, fullName)
	return nil
}

// parseItemField parses an item field like <item name="item">
func (p *Parser) parseItemField(tag *Tag, packetDef *PacketDef, fieldOrder *[]string, prefix string) error {
	nameAttr := tag.Attributes["name"]
	if nameAttr == "" {
		return fmt.Errorf("item field missing 'name' attribute at line %d", p.line)
	}

	var fullName string
	if prefix == "" {
		fullName = nameAttr
	} else {
		fullName = prefix + nameAttr
	}

	fieldDesc := FieldDesc{
		Type:        common.TypeItem,
		Condition:   tag.Attributes["if"],
		AddToStruct: true,
		AddType:     common.TypeItem,
	}

	packetDef.Fields[fullName] = fieldDesc
	*fieldOrder = append(*fieldOrder, fullName)
	return nil
}

// Parse function that uses the new string parser
func Parse(content string) (map[string]*PacketDef, error) {
	parser := NewParser(content)
	return parser.Parse()
}

// Type mapping using corrected type constants
var typeMap = map[string]common.EQ2DataType{
	"u8":     common.TypeInt8,
	"u16":    common.TypeInt16,
	"u32":    common.TypeInt32,
	"u64":    common.TypeInt64,
	"i8":     common.TypeSInt8,
	"i16":    common.TypeSInt16,
	"i32":    common.TypeSInt32,
	"i64":    common.TypeSInt64,
	"f32":    common.TypeFloat,
	"f64":    common.TypeDouble,
	"double": common.TypeDouble,
	"str8":   common.TypeString8,
	"str16":  common.TypeString16,
	"str32":  common.TypeString32,
	"char":   common.TypeChar,
	"color":  common.TypeColor,
	"equip":  common.TypeEquipment,
	"array":  common.TypeArray,
}

// combineConditions combines two conditions with AND logic
func combineConditions(cond1, cond2 string) string {
	if cond1 == "" {
		return cond2
	}
	if cond2 == "" {
		return cond1
	}
	return cond1 + "&" + cond2
}

// Fast type lookup using first character
func getDataType(tag string) (common.EQ2DataType, bool) {
	if len(tag) == 0 {
		return 0, false
	}

	switch tag[0] {
	case 'u':
		switch tag {
		case "u8":
			return common.TypeInt8, true
		case "u16":
			return common.TypeInt16, true
		case "u32":
			return common.TypeInt32, true
		case "u64":
			return common.TypeInt64, true
		}
	case 'i':
		switch tag {
		case "i8":
			return common.TypeSInt8, true
		case "i16":
			return common.TypeSInt16, true
		case "i32":
			return common.TypeSInt32, true
		case "i64":
			return common.TypeSInt64, true
		}
	case 's':
		switch tag {
		case "str8":
			return common.TypeString8, true
		case "str16":
			return common.TypeString16, true
		case "str32":
			return common.TypeString32, true
		}
	case 'f':
		switch tag {
		case "f32":
			return common.TypeFloat, true
		case "f64":
			return common.TypeDouble, true
		}
	case 'd':
		if tag == "double" {
			return common.TypeDouble, true
		}
	case 'c':
		switch tag {
		case "char":
			return common.TypeChar, true
		case "color":
			return common.TypeColor, true
		}
	case 'e':
		if tag == "equip" {
			return common.TypeEquipment, true
		}
	case 'a':
		if tag == "array" {
			return common.TypeArray, true
		}
	}

	// Fallback to map lookup
	if dataType, exists := typeMap[tag]; exists {
		return dataType, true
	}

	return 0, false
}