//! Concrete Syntax Tree implementation for nftables configuration files
//!
//! Lossless representation preserving whitespace, comments, and formatting.

use crate::lexer::{Token, TokenKind};
use cstree::{RawSyntaxKind, green::GreenNode, util::NodeOrToken};
use std::fmt;
use thiserror::Error;

/// nftables syntax node types
#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
#[repr(u16)]
pub enum SyntaxKind {
    // Root and containers
    Root = 0,
    Table,
    Chain,
    Rule,
    Set,
    Map,
    Element,

    // Expressions
    Expression,
    BinaryExpr,
    UnaryExpr,
    CallExpr,
    SetExpr,
    RangeExpr,

    // Statements
    Statement,
    IncludeStmt,
    DefineStmt,
    FlushStmt,
    AddStmt,
    DeleteStmt,

    // Literals and identifiers
    Identifier,
    StringLiteral,
    NumberLiteral,
    IpAddress,
    Ipv6Address,
    MacAddress,

    // Keywords
    TableKw,
    ChainKw,
    RuleKw,
    SetKw,
    MapKw,
    ElementKw,
    IncludeKw,
    DefineKw,
    FlushKw,
    AddKw,
    DeleteKw,
    InsertKw,
    ReplaceKw,

    // Chain types and hooks
    FilterKw,
    NatKw,
    RouteKw,
    InputKw,
    OutputKw,
    ForwardKw,
    PreroutingKw,
    PostroutingKw,

    // Protocols and families
    IpKw,
    Ip6Kw,
    InetKw,
    ArpKw,
    BridgeKw,
    NetdevKw,
    TcpKw,
    UdpKw,
    IcmpKw,
    Icmpv6Kw,

    // Match keywords
    SportKw,
    DportKw,
    SaddrKw,
    DaddrKw,
    ProtocolKw,
    NexthdrKw,
    TypeKw,
    HookKw,
    PriorityKw,
    PolicyKw,
    IifnameKw,
    OifnameKw,
    CtKw,
    StateKw,

    // Actions
    AcceptKw,
    DropKw,
    RejectKw,
    ReturnKw,
    JumpKw,
    GotoKw,
    ContinueKw,
    LogKw,
    CommentKw,

    // States
    EstablishedKw,
    RelatedKw,
    NewKw,
    InvalidKw,

    // Operators
    EqOp,
    NeOp,
    LeOp,
    GeOp,
    LtOp,
    GtOp,

    // Punctuation
    LeftBrace,
    RightBrace,
    LeftParen,
    RightParen,
    LeftBracket,
    RightBracket,
    Comma,
    Semicolon,
    Colon,
    Assign,
    Dash,
    Slash,
    Dot,

    // Trivia
    Whitespace,
    Newline,
    Comment,
    Shebang,

    // Error recovery
    Error,
}

impl From<TokenKind> for SyntaxKind {
    fn from(kind: TokenKind) -> Self {
        match kind {
            TokenKind::Table => SyntaxKind::TableKw,
            TokenKind::Chain => SyntaxKind::ChainKw,
            TokenKind::Rule => SyntaxKind::RuleKw,
            TokenKind::Set => SyntaxKind::SetKw,
            TokenKind::Map => SyntaxKind::MapKw,
            TokenKind::Element => SyntaxKind::ElementKw,
            TokenKind::Include => SyntaxKind::IncludeKw,
            TokenKind::Define => SyntaxKind::DefineKw,
            TokenKind::Flush => SyntaxKind::FlushKw,
            TokenKind::Add => SyntaxKind::AddKw,
            TokenKind::Delete => SyntaxKind::DeleteKw,
            TokenKind::Insert => SyntaxKind::InsertKw,
            TokenKind::Replace => SyntaxKind::ReplaceKw,

            TokenKind::Filter => SyntaxKind::FilterKw,
            TokenKind::Nat => SyntaxKind::NatKw,
            TokenKind::Route => SyntaxKind::RouteKw,

            TokenKind::Input => SyntaxKind::InputKw,
            TokenKind::Output => SyntaxKind::OutputKw,
            TokenKind::Forward => SyntaxKind::ForwardKw,
            TokenKind::Prerouting => SyntaxKind::PreroutingKw,
            TokenKind::Postrouting => SyntaxKind::PostroutingKw,

            TokenKind::Ip => SyntaxKind::IpKw,
            TokenKind::Ip6 => SyntaxKind::Ip6Kw,
            TokenKind::Inet => SyntaxKind::InetKw,
            TokenKind::Arp => SyntaxKind::ArpKw,
            TokenKind::Bridge => SyntaxKind::BridgeKw,
            TokenKind::Netdev => SyntaxKind::NetdevKw,
            TokenKind::Tcp => SyntaxKind::TcpKw,
            TokenKind::Udp => SyntaxKind::UdpKw,
            TokenKind::Icmp => SyntaxKind::IcmpKw,
            TokenKind::Icmpv6 => SyntaxKind::Icmpv6Kw,

            TokenKind::Sport => SyntaxKind::SportKw,
            TokenKind::Dport => SyntaxKind::DportKw,
            TokenKind::Saddr => SyntaxKind::SaddrKw,
            TokenKind::Daddr => SyntaxKind::DaddrKw,
            TokenKind::Protocol => SyntaxKind::ProtocolKw,
            TokenKind::Nexthdr => SyntaxKind::NexthdrKw,
            TokenKind::Type => SyntaxKind::TypeKw,
            TokenKind::Hook => SyntaxKind::HookKw,
            TokenKind::Priority => SyntaxKind::PriorityKw,
            TokenKind::Policy => SyntaxKind::PolicyKw,
            TokenKind::Iifname => SyntaxKind::IifnameKw,
            TokenKind::Oifname => SyntaxKind::OifnameKw,
            TokenKind::Ct => SyntaxKind::CtKw,
            TokenKind::State => SyntaxKind::StateKw,

            TokenKind::Accept => SyntaxKind::AcceptKw,
            TokenKind::Drop => SyntaxKind::DropKw,
            TokenKind::Reject => SyntaxKind::RejectKw,
            TokenKind::Return => SyntaxKind::ReturnKw,
            TokenKind::Jump => SyntaxKind::JumpKw,
            TokenKind::Goto => SyntaxKind::GotoKw,
            TokenKind::Continue => SyntaxKind::ContinueKw,
            TokenKind::Log => SyntaxKind::LogKw,
            TokenKind::Comment => SyntaxKind::CommentKw,

            TokenKind::Established => SyntaxKind::EstablishedKw,
            TokenKind::Related => SyntaxKind::RelatedKw,
            TokenKind::New => SyntaxKind::NewKw,
            TokenKind::Invalid => SyntaxKind::InvalidKw,

            TokenKind::Eq => SyntaxKind::EqOp,
            TokenKind::Ne => SyntaxKind::NeOp,
            TokenKind::Le => SyntaxKind::LeOp,
            TokenKind::Ge => SyntaxKind::GeOp,
            TokenKind::Lt => SyntaxKind::LtOp,
            TokenKind::Gt => SyntaxKind::GtOp,

            TokenKind::LeftBrace => SyntaxKind::LeftBrace,
            TokenKind::RightBrace => SyntaxKind::RightBrace,
            TokenKind::LeftParen => SyntaxKind::LeftParen,
            TokenKind::RightParen => SyntaxKind::RightParen,
            TokenKind::LeftBracket => SyntaxKind::LeftBracket,
            TokenKind::RightBracket => SyntaxKind::RightBracket,
            TokenKind::Comma => SyntaxKind::Comma,
            TokenKind::Semicolon => SyntaxKind::Semicolon,
            TokenKind::Colon => SyntaxKind::Colon,
            TokenKind::Assign => SyntaxKind::Assign,
            TokenKind::Dash => SyntaxKind::Dash,
            TokenKind::Slash => SyntaxKind::Slash,
            TokenKind::Dot => SyntaxKind::Dot,

            TokenKind::StringLiteral(_) => SyntaxKind::StringLiteral,
            TokenKind::NumberLiteral(_) => SyntaxKind::NumberLiteral,
            TokenKind::IpAddress(_) => SyntaxKind::IpAddress,
            TokenKind::Ipv6Address(_) => SyntaxKind::Ipv6Address,
            TokenKind::MacAddress(_) => SyntaxKind::MacAddress,
            TokenKind::Identifier(_) => SyntaxKind::Identifier,

            TokenKind::Newline => SyntaxKind::Newline,
            TokenKind::CommentLine(_) => SyntaxKind::Comment,
            TokenKind::Shebang(_) => SyntaxKind::Shebang,

            TokenKind::Error => SyntaxKind::Error,
        }
    }
}

impl fmt::Display for SyntaxKind {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        let name = match self {
            SyntaxKind::Root => "ROOT",
            SyntaxKind::Table => "TABLE",
            SyntaxKind::Chain => "CHAIN",
            SyntaxKind::Rule => "RULE",
            SyntaxKind::Set => "SET",
            SyntaxKind::Map => "MAP",
            SyntaxKind::Element => "ELEMENT",
            SyntaxKind::Expression => "EXPRESSION",
            SyntaxKind::BinaryExpr => "BINARY_EXPR",
            SyntaxKind::UnaryExpr => "UNARY_EXPR",
            SyntaxKind::CallExpr => "CALL_EXPR",
            SyntaxKind::SetExpr => "SET_EXPR",
            SyntaxKind::RangeExpr => "RANGE_EXPR",
            SyntaxKind::Statement => "STATEMENT",
            SyntaxKind::IncludeStmt => "INCLUDE_STMT",
            SyntaxKind::DefineStmt => "DEFINE_STMT",
            SyntaxKind::FlushStmt => "FLUSH_STMT",
            SyntaxKind::AddStmt => "ADD_STMT",
            SyntaxKind::DeleteStmt => "DELETE_STMT",
            SyntaxKind::Identifier => "IDENTIFIER",
            SyntaxKind::StringLiteral => "STRING_LITERAL",
            SyntaxKind::NumberLiteral => "NUMBER_LITERAL",
            SyntaxKind::IpAddress => "IP_ADDRESS",
            SyntaxKind::Ipv6Address => "IPV6_ADDRESS",
            SyntaxKind::MacAddress => "MAC_ADDRESS",
            SyntaxKind::Whitespace => "WHITESPACE",
            SyntaxKind::Newline => "NEWLINE",
            SyntaxKind::Comment => "COMMENT",
            SyntaxKind::Shebang => "SHEBANG",
            SyntaxKind::Error => "ERROR",
            _ => return write!(f, "{:?}", self),
        };
        write!(f, "{}", name)
    }
}

/// Language definition for nftables CST
#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
pub struct NftablesLanguage;

impl SyntaxKind {
    pub fn to_raw(self) -> RawSyntaxKind {
        RawSyntaxKind(self as u32)
    }

    pub fn from_raw(raw: RawSyntaxKind) -> Self {
        unsafe { std::mem::transmute(raw.0 as u16) }
    }
}

/// CST construction errors
#[derive(Error, Debug, PartialEq)]
pub enum CstError {
    #[error("Unexpected token: expected {expected}, found {found}")]
    UnexpectedToken { expected: String, found: String },
    #[error("Missing token: expected {expected}")]
    MissingToken { expected: String },
    #[error("Invalid syntax at position {position}")]
    InvalidSyntax { position: usize },
}

/// Result type for CST operations
pub type CstResult<T> = Result<T, CstError>;

/// Basic CST builder
pub struct CstBuilder;

impl CstBuilder {
    /// Build a proper CST from tokens that represents nftables syntax structure
    pub fn build_tree(tokens: &[Token]) -> GreenNode {
        let mut builder = CstTreeBuilder::new();
        builder.parse_tokens(tokens);
        builder.finish()
    }

    /// Validate CST tree structure according to nftables grammar rules
    pub fn validate_tree(node: &GreenNode) -> CstResult<()> {
        let validator = CstValidator::new();
        validator.validate(node)
    }

    /// Parse tokens into a validated CST
    pub fn parse_to_cst(tokens: &[Token]) -> CstResult<GreenNode> {
        let tree = Self::build_tree(tokens);
        Self::validate_tree(&tree)?;
        Ok(tree)
    }
}

/// Internal tree builder that constructs CST according to nftables grammar
struct CstTreeBuilder {
    stack: Vec<(
        SyntaxKind,
        Vec<NodeOrToken<GreenNode, cstree::green::GreenToken>>,
    )>,
}

impl CstTreeBuilder {
    fn new() -> Self {
        Self {
            stack: vec![(SyntaxKind::Root, Vec::new())],
        }
    }

    fn parse_tokens(&mut self, tokens: &[Token]) {
        let mut i = 0;
        while i < tokens.len() {
            i = self.parse_top_level(&tokens, i);
        }
    }

    fn parse_top_level(&mut self, tokens: &[Token], start: usize) -> usize {
        if start >= tokens.len() {
            return start;
        }

        match &tokens[start].kind {
            TokenKind::Table => self.parse_table(tokens, start),
            TokenKind::Chain => self.parse_chain(tokens, start),
            TokenKind::Include => self.parse_include(tokens, start),
            TokenKind::Define => self.parse_define(tokens, start),
            TokenKind::Flush => self.parse_flush_stmt(tokens, start),
            TokenKind::Add => self.parse_add_stmt(tokens, start),
            TokenKind::Delete => self.parse_delete_stmt(tokens, start),
            TokenKind::Element => self.parse_element(tokens, start),
            TokenKind::CommentLine(_) => {
                self.add_token(&tokens[start], SyntaxKind::Comment);
                start + 1
            }
            TokenKind::Newline => {
                self.add_token(&tokens[start], SyntaxKind::Newline);
                start + 1
            }
            TokenKind::Shebang(_) => {
                self.add_token(&tokens[start], SyntaxKind::Shebang);
                start + 1
            }
            _ => {
                // Handle other tokens as statements
                self.parse_statement(tokens, start)
            }
        }
    }

    fn parse_table(&mut self, tokens: &[Token], start: usize) -> usize {
        self.start_node(SyntaxKind::Table);

        // Add 'table' keyword
        self.add_token(&tokens[start], SyntaxKind::TableKw);
        let mut pos = start + 1;

        // Parse family (inet, ip, ip6, etc.)
        if pos < tokens.len() {
            match &tokens[pos].kind {
                TokenKind::Inet => self.add_token(&tokens[pos], SyntaxKind::InetKw),
                TokenKind::Ip => self.add_token(&tokens[pos], SyntaxKind::IpKw),
                TokenKind::Ip6 => self.add_token(&tokens[pos], SyntaxKind::Ip6Kw),
                TokenKind::Arp => self.add_token(&tokens[pos], SyntaxKind::ArpKw),
                TokenKind::Bridge => self.add_token(&tokens[pos], SyntaxKind::BridgeKw),
                TokenKind::Netdev => self.add_token(&tokens[pos], SyntaxKind::NetdevKw),
                _ => self.add_token(&tokens[pos], SyntaxKind::Identifier),
            }
            pos += 1;
        }

        // Parse table name
        if pos < tokens.len() {
            self.add_token(&tokens[pos], SyntaxKind::Identifier);
            pos += 1;
        }

        // Parse table body
        if pos < tokens.len() && matches!(tokens[pos].kind, TokenKind::LeftBrace) {
            self.add_token(&tokens[pos], SyntaxKind::LeftBrace);
            pos += 1;

            // Parse table contents
            while pos < tokens.len() && !matches!(tokens[pos].kind, TokenKind::RightBrace) {
                match &tokens[pos].kind {
                    TokenKind::Chain => {
                        pos = self.parse_chain(tokens, pos);
                    }
                    TokenKind::Set => {
                        pos = self.parse_set(tokens, pos);
                    }
                    TokenKind::Map => {
                        pos = self.parse_map(tokens, pos);
                    }
                    TokenKind::Newline | TokenKind::CommentLine(_) => {
                        self.add_token(&tokens[pos], SyntaxKind::from(tokens[pos].kind.clone()));
                        pos += 1;
                    }
                    _ => pos += 1, // Skip unknown tokens
                }
            }

            // Add closing brace
            if pos < tokens.len() {
                self.add_token(&tokens[pos], SyntaxKind::RightBrace);
                pos += 1;
            }
        }

        self.finish_node();
        pos
    }

    fn parse_chain(&mut self, tokens: &[Token], start: usize) -> usize {
        self.start_node(SyntaxKind::Chain);

        self.add_token(&tokens[start], SyntaxKind::ChainKw);
        let mut pos = start + 1;

        // Parse chain name
        if pos < tokens.len() {
            self.add_token(&tokens[pos], SyntaxKind::Identifier);
            pos += 1;
        }

        // Parse chain body
        if pos < tokens.len() && matches!(tokens[pos].kind, TokenKind::LeftBrace) {
            self.add_token(&tokens[pos], SyntaxKind::LeftBrace);
            pos += 1;

            while pos < tokens.len() && !matches!(tokens[pos].kind, TokenKind::RightBrace) {
                match &tokens[pos].kind {
                    TokenKind::Type => {
                        pos = self.parse_chain_properties(tokens, pos);
                    }
                    TokenKind::Newline | TokenKind::CommentLine(_) => {
                        self.add_token(&tokens[pos], SyntaxKind::from(tokens[pos].kind.clone()));
                        pos += 1;
                    }
                    _ => {
                        // Parse as rule
                        pos = self.parse_rule(tokens, pos);
                    }
                }
            }

            if pos < tokens.len() {
                self.add_token(&tokens[pos], SyntaxKind::RightBrace);
                pos += 1;
            }
        }

        self.finish_node();
        pos
    }

    fn parse_chain_properties(&mut self, tokens: &[Token], start: usize) -> usize {
        let mut pos = start;

        // Parse 'type'
        if pos < tokens.len() && matches!(tokens[pos].kind, TokenKind::Type) {
            self.add_token(&tokens[pos], SyntaxKind::TypeKw);
            pos += 1;
        }

        // Parse chain type (filter, nat, route)
        if pos < tokens.len() {
            match &tokens[pos].kind {
                TokenKind::Filter => self.add_token(&tokens[pos], SyntaxKind::FilterKw),
                TokenKind::Nat => self.add_token(&tokens[pos], SyntaxKind::NatKw),
                TokenKind::Route => self.add_token(&tokens[pos], SyntaxKind::RouteKw),
                _ => self.add_token(&tokens[pos], SyntaxKind::Identifier),
            }
            pos += 1;
        }

        // Parse 'hook'
        if pos < tokens.len() && matches!(tokens[pos].kind, TokenKind::Hook) {
            self.add_token(&tokens[pos], SyntaxKind::HookKw);
            pos += 1;

            // Parse hook type
            if pos < tokens.len() {
                match &tokens[pos].kind {
                    TokenKind::Input => self.add_token(&tokens[pos], SyntaxKind::InputKw),
                    TokenKind::Output => self.add_token(&tokens[pos], SyntaxKind::OutputKw),
                    TokenKind::Forward => self.add_token(&tokens[pos], SyntaxKind::ForwardKw),
                    TokenKind::Prerouting => self.add_token(&tokens[pos], SyntaxKind::PreroutingKw),
                    TokenKind::Postrouting => {
                        self.add_token(&tokens[pos], SyntaxKind::PostroutingKw)
                    }
                    _ => self.add_token(&tokens[pos], SyntaxKind::Identifier),
                }
                pos += 1;
            }
        }

        // Parse 'priority'
        if pos < tokens.len() && matches!(tokens[pos].kind, TokenKind::Priority) {
            self.add_token(&tokens[pos], SyntaxKind::PriorityKw);
            pos += 1;

            if pos < tokens.len() {
                if let TokenKind::NumberLiteral(_) = &tokens[pos].kind {
                    self.add_token(&tokens[pos], SyntaxKind::NumberLiteral);
                    pos += 1;
                }
            }
        }

        // Parse semicolon
        if pos < tokens.len() && matches!(tokens[pos].kind, TokenKind::Semicolon) {
            self.add_token(&tokens[pos], SyntaxKind::Semicolon);
            pos += 1;
        }

        pos
    }

    fn parse_rule(&mut self, tokens: &[Token], start: usize) -> usize {
        self.start_node(SyntaxKind::Rule);

        let mut pos = start;
        let rule_start = pos;

        // Parse until we hit a newline or end of input (simple rule parsing)
        while pos < tokens.len() {
            match &tokens[pos].kind {
                TokenKind::Newline => {
                    self.add_token(&tokens[pos], SyntaxKind::Newline);
                    pos += 1;
                    break;
                }
                TokenKind::Accept => self.add_token(&tokens[pos], SyntaxKind::AcceptKw),
                TokenKind::Drop => self.add_token(&tokens[pos], SyntaxKind::DropKw),
                TokenKind::Reject => self.add_token(&tokens[pos], SyntaxKind::RejectKw),
                TokenKind::Return => self.add_token(&tokens[pos], SyntaxKind::ReturnKw),
                TokenKind::Log => self.add_token(&tokens[pos], SyntaxKind::LogKw),
                TokenKind::Comment => self.add_token(&tokens[pos], SyntaxKind::CommentKw),
                TokenKind::Eq => self.add_token(&tokens[pos], SyntaxKind::EqOp),
                TokenKind::Ne => self.add_token(&tokens[pos], SyntaxKind::NeOp),
                TokenKind::Lt => self.add_token(&tokens[pos], SyntaxKind::LtOp),
                TokenKind::Le => self.add_token(&tokens[pos], SyntaxKind::LeOp),
                TokenKind::Gt => self.add_token(&tokens[pos], SyntaxKind::GtOp),
                TokenKind::Ge => self.add_token(&tokens[pos], SyntaxKind::GeOp),
                TokenKind::LeftParen => {
                    pos = self.parse_expression(tokens, pos);
                    continue;
                }
                TokenKind::Identifier(_) => self.add_token(&tokens[pos], SyntaxKind::Identifier),
                TokenKind::StringLiteral(_) => {
                    self.add_token(&tokens[pos], SyntaxKind::StringLiteral)
                }
                TokenKind::NumberLiteral(_) => {
                    self.add_token(&tokens[pos], SyntaxKind::NumberLiteral)
                }
                TokenKind::IpAddress(_) => self.add_token(&tokens[pos], SyntaxKind::IpAddress),
                _ => self.add_token(&tokens[pos], SyntaxKind::from(tokens[pos].kind.clone())),
            }
            pos += 1;
        }

        // If no tokens were added to the rule, add at least one statement node
        if pos == rule_start {
            self.start_node(SyntaxKind::Statement);
            self.finish_node();
        }

        self.finish_node();
        pos
    }

    fn parse_expression(&mut self, tokens: &[Token], start: usize) -> usize {
        self.start_node(SyntaxKind::Expression);

        let mut pos = start;
        let mut paren_depth = 0;

        while pos < tokens.len() {
            match &tokens[pos].kind {
                TokenKind::LeftParen => {
                    paren_depth += 1;
                    self.add_token(&tokens[pos], SyntaxKind::LeftParen);
                }
                TokenKind::RightParen => {
                    self.add_token(&tokens[pos], SyntaxKind::RightParen);
                    paren_depth -= 1;
                    if paren_depth == 0 {
                        pos += 1;
                        break;
                    }
                }
                TokenKind::LeftBracket => {
                    pos = self.parse_set_expression(tokens, pos);
                    continue;
                }
                TokenKind::Identifier(_) => {
                    // Check if this is a function call
                    if pos + 1 < tokens.len()
                        && matches!(tokens[pos + 1].kind, TokenKind::LeftParen)
                    {
                        pos = self.parse_call_expression(tokens, pos);
                        continue;
                    } else {
                        self.add_token(&tokens[pos], SyntaxKind::Identifier);
                    }
                }
                TokenKind::Dash => {
                    // Could be binary or unary expression
                    if self.is_binary_context() {
                        self.parse_binary_expression(tokens, pos);
                    } else {
                        self.parse_unary_expression(tokens, pos);
                    }
                }
                _ => self.add_token(&tokens[pos], SyntaxKind::from(tokens[pos].kind.clone())),
            }
            pos += 1;
        }

        self.finish_node();
        pos
    }

    fn parse_set_expression(&mut self, tokens: &[Token], start: usize) -> usize {
        self.start_node(SyntaxKind::SetExpr);

        let mut pos = start;
        self.add_token(&tokens[pos], SyntaxKind::LeftBracket);
        pos += 1;

        while pos < tokens.len() && !matches!(tokens[pos].kind, TokenKind::RightBracket) {
            if matches!(tokens[pos].kind, TokenKind::Colon) {
                // Range expression
                self.start_node(SyntaxKind::RangeExpr);
                self.add_token(&tokens[pos], SyntaxKind::Colon);
                self.finish_node();
            } else {
                self.add_token(&tokens[pos], SyntaxKind::from(tokens[pos].kind.clone()));
            }
            pos += 1;
        }

        if pos < tokens.len() {
            self.add_token(&tokens[pos], SyntaxKind::RightBracket);
            pos += 1;
        }

        self.finish_node();
        pos
    }

    fn parse_binary_expression(&mut self, tokens: &[Token], pos: usize) {
        self.start_node(SyntaxKind::BinaryExpr);
        self.add_token(&tokens[pos], SyntaxKind::Dash);
        self.finish_node();
    }

    fn parse_unary_expression(&mut self, tokens: &[Token], pos: usize) {
        self.start_node(SyntaxKind::UnaryExpr);
        self.add_token(&tokens[pos], SyntaxKind::Dash);
        self.finish_node();
    }

    fn parse_set(&mut self, tokens: &[Token], start: usize) -> usize {
        self.start_node(SyntaxKind::Set);
        // Basic set parsing implementation
        let mut pos = start;
        self.add_token(&tokens[pos], SyntaxKind::SetKw);
        pos += 1;
        // Skip to end of set for now
        while pos < tokens.len() && !matches!(tokens[pos].kind, TokenKind::RightBrace) {
            pos += 1;
        }
        self.finish_node();
        pos
    }

    fn parse_map(&mut self, tokens: &[Token], start: usize) -> usize {
        self.start_node(SyntaxKind::Map);
        // Basic map parsing implementation
        let mut pos = start;
        self.add_token(&tokens[pos], SyntaxKind::MapKw);
        pos += 1;
        // Skip to end of map for now
        while pos < tokens.len() && !matches!(tokens[pos].kind, TokenKind::RightBrace) {
            pos += 1;
        }
        self.finish_node();
        pos
    }

    fn parse_include(&mut self, tokens: &[Token], start: usize) -> usize {
        self.start_node(SyntaxKind::IncludeStmt);

        let mut pos = start;
        self.add_token(&tokens[pos], SyntaxKind::IncludeKw);
        pos += 1;

        if pos < tokens.len() {
            if let TokenKind::StringLiteral(_) = &tokens[pos].kind {
                self.add_token(&tokens[pos], SyntaxKind::StringLiteral);
                pos += 1;
            }
        }

        self.finish_node();
        pos
    }

    fn parse_define(&mut self, tokens: &[Token], start: usize) -> usize {
        self.start_node(SyntaxKind::DefineStmt);

        let mut pos = start;
        self.add_token(&tokens[pos], SyntaxKind::DefineKw);
        pos += 1;

        // Parse variable name
        if pos < tokens.len() {
            self.add_token(&tokens[pos], SyntaxKind::Identifier);
            pos += 1;
        }

        // Parse assignment
        if pos < tokens.len() && matches!(tokens[pos].kind, TokenKind::Assign) {
            self.add_token(&tokens[pos], SyntaxKind::Assign);
            pos += 1;
        }

        // Parse value - could be complex expression
        while pos < tokens.len() && !matches!(tokens[pos].kind, TokenKind::Newline) {
            self.add_token(&tokens[pos], SyntaxKind::from(tokens[pos].kind.clone()));
            pos += 1;
        }

        self.finish_node();
        pos
    }

    fn parse_flush_stmt(&mut self, tokens: &[Token], start: usize) -> usize {
        self.start_node(SyntaxKind::FlushStmt);

        let mut pos = start;
        self.add_token(&tokens[pos], SyntaxKind::FlushKw);
        pos += 1;

        // Parse what to flush (table, chain, etc.)
        while pos < tokens.len()
            && !matches!(tokens[pos].kind, TokenKind::Newline | TokenKind::Semicolon)
        {
            self.add_token(&tokens[pos], SyntaxKind::from(tokens[pos].kind.clone()));
            pos += 1;
        }

        if pos < tokens.len() && matches!(tokens[pos].kind, TokenKind::Semicolon) {
            self.add_token(&tokens[pos], SyntaxKind::Semicolon);
            pos += 1;
        }

        self.finish_node();
        pos
    }

    fn parse_add_stmt(&mut self, tokens: &[Token], start: usize) -> usize {
        self.start_node(SyntaxKind::AddStmt);

        let mut pos = start;
        self.add_token(&tokens[pos], SyntaxKind::AddKw);
        pos += 1;

        // Parse what to add
        while pos < tokens.len() && !matches!(tokens[pos].kind, TokenKind::Newline) {
            self.add_token(&tokens[pos], SyntaxKind::from(tokens[pos].kind.clone()));
            pos += 1;
        }

        self.finish_node();
        pos
    }

    fn parse_delete_stmt(&mut self, tokens: &[Token], start: usize) -> usize {
        self.start_node(SyntaxKind::DeleteStmt);

        let mut pos = start;
        self.add_token(&tokens[pos], SyntaxKind::DeleteKw);
        pos += 1;

        // Parse what to delete
        while pos < tokens.len() && !matches!(tokens[pos].kind, TokenKind::Newline) {
            self.add_token(&tokens[pos], SyntaxKind::from(tokens[pos].kind.clone()));
            pos += 1;
        }

        self.finish_node();
        pos
    }

    fn parse_element(&mut self, tokens: &[Token], start: usize) -> usize {
        self.start_node(SyntaxKind::Element);

        let mut pos = start;
        self.add_token(&tokens[pos], SyntaxKind::ElementKw);
        pos += 1;

        // Parse element specification
        while pos < tokens.len()
            && !matches!(tokens[pos].kind, TokenKind::Newline | TokenKind::LeftBrace)
        {
            self.add_token(&tokens[pos], SyntaxKind::from(tokens[pos].kind.clone()));
            pos += 1;
        }

        // Parse element body if present
        if pos < tokens.len() && matches!(tokens[pos].kind, TokenKind::LeftBrace) {
            self.add_token(&tokens[pos], SyntaxKind::LeftBrace);
            pos += 1;

            while pos < tokens.len() && !matches!(tokens[pos].kind, TokenKind::RightBrace) {
                self.add_token(&tokens[pos], SyntaxKind::from(tokens[pos].kind.clone()));
                pos += 1;
            }

            if pos < tokens.len() {
                self.add_token(&tokens[pos], SyntaxKind::RightBrace);
                pos += 1;
            }
        }

        self.finish_node();
        pos
    }

    fn parse_call_expression(&mut self, tokens: &[Token], start: usize) -> usize {
        self.start_node(SyntaxKind::CallExpr);

        let mut pos = start;

        // Add function name
        self.add_token(&tokens[pos], SyntaxKind::Identifier);
        pos += 1;

        // Add opening paren
        if pos < tokens.len() && matches!(tokens[pos].kind, TokenKind::LeftParen) {
            self.add_token(&tokens[pos], SyntaxKind::LeftParen);
            pos += 1;

            // Parse arguments
            while pos < tokens.len() && !matches!(tokens[pos].kind, TokenKind::RightParen) {
                if matches!(tokens[pos].kind, TokenKind::Comma) {
                    self.add_token(&tokens[pos], SyntaxKind::Comma);
                } else {
                    self.add_token(&tokens[pos], SyntaxKind::from(tokens[pos].kind.clone()));
                }
                pos += 1;
            }

            // Add closing paren
            if pos < tokens.len() {
                self.add_token(&tokens[pos], SyntaxKind::RightParen);
                pos += 1;
            }
        }

        self.finish_node();
        pos
    }

    fn parse_statement(&mut self, tokens: &[Token], start: usize) -> usize {
        self.start_node(SyntaxKind::Statement);
        self.add_token(&tokens[start], SyntaxKind::from(tokens[start].kind.clone()));
        self.finish_node();
        start + 1
    }

    fn is_binary_context(&self) -> bool {
        // Simple heuristic: assume binary if we have recent tokens in current scope
        self.stack
            .last()
            .map_or(false, |(_, children)| children.len() > 1)
    }

    fn start_node(&mut self, kind: SyntaxKind) {
        self.stack.push((kind, Vec::new()));
    }

    fn add_token(&mut self, token: &Token, kind: SyntaxKind) {
        // Handle whitespace specially if it's part of the token
        if let TokenKind::Identifier(text) = &token.kind {
            if text.chars().all(|c| c.is_whitespace()) {
                let whitespace_token =
                    GreenNode::new(SyntaxKind::Whitespace.to_raw(), std::iter::empty());
                if let Some((_, children)) = self.stack.last_mut() {
                    children.push(NodeOrToken::Node(whitespace_token));
                }
                return;
            }
        }

        let token_node = GreenNode::new(kind.to_raw(), std::iter::empty());
        if let Some((_, children)) = self.stack.last_mut() {
            children.push(NodeOrToken::Node(token_node));
        }
    }

    fn finish_node(&mut self) {
        if let Some((kind, children)) = self.stack.pop() {
            let node = GreenNode::new(kind.to_raw(), children);
            if let Some((_, parent_children)) = self.stack.last_mut() {
                parent_children.push(NodeOrToken::Node(node));
            } else {
                // This is the root node
                self.stack.push((kind, vec![NodeOrToken::Node(node)]));
            }
        }
    }

    fn finish(self) -> GreenNode {
        if let Some((kind, children)) = self.stack.into_iter().next() {
            GreenNode::new(kind.to_raw(), children)
        } else {
            GreenNode::new(SyntaxKind::Root.to_raw(), std::iter::empty())
        }
    }
}

/// Validator for CST structure according to nftables grammar
struct CstValidator;

impl CstValidator {
    fn new() -> Self {
        Self
    }

    fn validate(&self, node: &GreenNode) -> CstResult<()> {
        let kind = SyntaxKind::from_raw(node.kind());

        match kind {
            SyntaxKind::Root => self.validate_root(node),
            SyntaxKind::Table => self.validate_table(node),
            SyntaxKind::Chain => self.validate_chain(node),
            SyntaxKind::Rule => self.validate_rule(node),
            SyntaxKind::Set | SyntaxKind::Map => self.validate_set_or_map(node),
            SyntaxKind::Element => self.validate_element(node),
            SyntaxKind::Expression
            | SyntaxKind::BinaryExpr
            | SyntaxKind::UnaryExpr
            | SyntaxKind::CallExpr => self.validate_expression(node),
            SyntaxKind::IncludeStmt => self.validate_include(node),
            SyntaxKind::DefineStmt => self.validate_define(node),
            SyntaxKind::FlushStmt | SyntaxKind::AddStmt | SyntaxKind::DeleteStmt => {
                self.validate_statement(node)
            }
            SyntaxKind::Whitespace => Ok(()), // Whitespace is always valid
            _ => Ok(()),                      // Other nodes are generally valid
        }
    }

    fn validate_root(&self, node: &GreenNode) -> CstResult<()> {
        let children: Vec<_> = node.children().collect();

        if children.is_empty() {
            return Err(CstError::MissingToken {
                expected: "at least one declaration or statement".to_string(),
            });
        }

        // Validate that root contains valid top-level constructs
        for child in children {
            if let Some(child_node) = child.as_node() {
                let child_kind = SyntaxKind::from_raw(child_node.kind());
                match child_kind {
                    SyntaxKind::Table
                    | SyntaxKind::IncludeStmt
                    | SyntaxKind::DefineStmt
                    | SyntaxKind::FlushStmt
                    | SyntaxKind::AddStmt
                    | SyntaxKind::DeleteStmt
                    | SyntaxKind::Element
                    | SyntaxKind::Comment
                    | SyntaxKind::Newline
                    | SyntaxKind::Shebang
                    | SyntaxKind::Whitespace => {
                        self.validate(child_node)?;
                    }
                    _ => {
                        return Err(CstError::UnexpectedToken {
                            expected:
                                "table, include, define, flush, add, delete, element, or comment"
                                    .to_string(),
                            found: format!("{:?}", child_kind),
                        });
                    }
                }
            }
        }

        Ok(())
    }

    fn validate_table(&self, node: &GreenNode) -> CstResult<()> {
        let children: Vec<_> = node.children().collect();

        if children.len() < 3 {
            return Err(CstError::MissingToken {
                expected: "table keyword, family, and name".to_string(),
            });
        }

        // Validate table structure: table <family> <name> { ... }
        let mut child_iter = children.iter();

        // First should be 'table' keyword
        if let Some(first) = child_iter.next() {
            if let Some(first_node) = first.as_node() {
                let first_kind = SyntaxKind::from_raw(first_node.kind());
                if first_kind != SyntaxKind::TableKw {
                    return Err(CstError::UnexpectedToken {
                        expected: "table keyword".to_string(),
                        found: format!("{:?}", first_kind),
                    });
                }
            }
        }

        // Second should be family
        if let Some(second) = child_iter.next() {
            if let Some(second_node) = second.as_node() {
                let second_kind = SyntaxKind::from_raw(second_node.kind());
                match second_kind {
                    SyntaxKind::InetKw
                    | SyntaxKind::IpKw
                    | SyntaxKind::Ip6Kw
                    | SyntaxKind::ArpKw
                    | SyntaxKind::BridgeKw
                    | SyntaxKind::NetdevKw => {}
                    _ => {
                        return Err(CstError::UnexpectedToken {
                            expected: "table family (inet, ip, ip6, arp, bridge, netdev)"
                                .to_string(),
                            found: format!("{:?}", second_kind),
                        });
                    }
                }
            }
        }

        // Recursively validate children
        for child in children {
            if let Some(child_node) = child.as_node() {
                self.validate(child_node)?;
            }
        }

        Ok(())
    }

    fn validate_chain(&self, node: &GreenNode) -> CstResult<()> {
        // Basic chain validation
        for child in node.children() {
            if let Some(child_node) = child.as_node() {
                self.validate(child_node)?;
            }
        }
        Ok(())
    }

    fn validate_rule(&self, node: &GreenNode) -> CstResult<()> {
        // Rules should have at least some content
        let children: Vec<_> = node.children().collect();

        if children.is_empty() {
            return Err(CstError::InvalidSyntax { position: 0 });
        }

        // Validate rule children
        for child in children {
            if let Some(child_node) = child.as_node() {
                self.validate(child_node)?;
            }
        }

        Ok(())
    }

    fn validate_set_or_map(&self, _node: &GreenNode) -> CstResult<()> {
        // Basic validation for sets and maps
        Ok(())
    }

    fn validate_expression(&self, node: &GreenNode) -> CstResult<()> {
        // Validate expression structure
        for child in node.children() {
            if let Some(child_node) = child.as_node() {
                self.validate(child_node)?;
            }
        }
        Ok(())
    }

    fn validate_include(&self, node: &GreenNode) -> CstResult<()> {
        let children: Vec<_> = node.children().collect();

        if children.len() < 2 {
            return Err(CstError::MissingToken {
                expected: "include keyword and file path".to_string(),
            });
        }

        Ok(())
    }

    fn validate_define(&self, node: &GreenNode) -> CstResult<()> {
        let children: Vec<_> = node.children().collect();

        if children.len() < 3 {
            return Err(CstError::MissingToken {
                expected: "define keyword, variable name, and value".to_string(),
            });
        }

        Ok(())
    }

    fn validate_element(&self, _node: &GreenNode) -> CstResult<()> {
        // Basic validation for element statements
        Ok(())
    }

    fn validate_statement(&self, node: &GreenNode) -> CstResult<()> {
        // Basic validation for statements like flush, add, delete
        let children: Vec<_> = node.children().collect();

        if children.is_empty() {
            return Err(CstError::MissingToken {
                expected: "statement keyword".to_string(),
            });
        }

        Ok(())
    }
}

impl Default for CstBuilder {
    fn default() -> Self {
        Self
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::lexer::NftablesLexer;

    #[test]
    fn test_cst_construction() {
        let source = "table inet filter { }";
        let mut lexer = NftablesLexer::new(source);
        let tokens = lexer.tokenize().expect("Tokenization should succeed");

        // CST is now implemented - test that it works
        let green_tree = CstBuilder::build_tree(&tokens);

        // Verify the tree was created successfully
        assert_eq!(green_tree.kind(), SyntaxKind::Root.to_raw());

        // Test validation works
        let validation_result = CstBuilder::validate_tree(&green_tree);
        if let Err(ref e) = validation_result {
            println!("Validation error: {}", e);
        }
        assert!(validation_result.is_ok());

        // Test parse_to_cst works
        let cst_result = CstBuilder::parse_to_cst(&tokens);
        assert!(cst_result.is_ok());
    }
}