use std::borrow::Borrow;

use rowan::{
    Checkpoint, GreenNode, GreenNodeBuilder, GreenNodeData, GreenTokenData, Language, NodeOrToken,
};

use crate::parser::{
    ast::lossless::{lex::SyntaxKind::*, Lang},
    Span,
};

use super::lex::{self, SyntaxKind};

mod parsers {
    use rowan::GreenNode;

    use crate::parser::ast::lossless::lex::SyntaxKind;

    use super::SyntaxError;

    struct ParseResult {
        green_node: GreenNode,
        errors: Vec<SyntaxError>,
    }

    trait Parser {
        fn parse<'src>(input: &[(SyntaxKind, &'src str)]) -> ParseResult;
    }
}

#[derive(PartialEq, Eq)]
pub struct Parse {
    pub green_node: GreenNode,
}

impl std::fmt::Debug for Parse {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        debug_print_green_node(NodeOrToken::Node(self.green_node.borrow()), f, 0)
    }
}

fn debug_print_green_node(
    node: NodeOrToken<&GreenNodeData, &GreenTokenData>,
    f: &mut std::fmt::Formatter<'_>,
    lvl: i32,
) -> std::fmt::Result {
    for _ in 0..lvl {
        f.write_str("    ")?;
    }

    match node {
        NodeOrToken::Node(n) => {
            writeln!(f, "{:?} {{", Lang::kind_from_raw(node.kind()));
            for c in n.children() {
                debug_print_green_node(c, f, lvl + 1)?;
            }
            for _ in 0..lvl {
                f.write_str("    ")?;
            }
            f.write_str("}\n")
        }
        NodeOrToken::Token(t) => {
            writeln!(f, "{:?} {:?};", Lang::kind_from_raw(t.kind()), t.text())
        }
    }
}

#[derive(Debug)]
struct Parser<'src> {
    tokens: Vec<(SyntaxKind, &'src str)>,
    builder: GreenNodeBuilder<'src>,
    errors: Vec<SyntaxError>,
}

#[derive(Debug, PartialEq, Eq)]
enum SyntaxError {
    Expected(SyntaxKind),
    AttrExpectedValue,
    /// guessed if there's a newline and attr on next line without comma
    /// should then suggest comma after attr
    ExpectedCommaBetweenAttrs,
}

pub fn parse(src: &str) -> Parse {
    let mut tokens = lex::lex(src);
    Parser {
        tokens,
        builder: GreenNodeBuilder::new(),
        errors: Vec::new(),
    }
    .parse()
}

impl Parser<'_> {
    fn parse(mut self) -> Parse {
        self.start_node(ROOT);

        match self.expr(None) {
            expr::ExprRes::Ok => (),
            expr::ExprRes::Eof => (),
            expr::ExprRes::NoExpr => todo!(),
        }

        self.builder.finish_node();
        Parse {
            green_node: self.builder.finish(),
        }
    }

    fn start_node(&mut self, kind: SyntaxKind) {
        self.builder.start_node(kind.into());
    }
    fn finish_node(&mut self) {
        self.builder.finish_node();
    }

    /// Advance one token, adding it to the current branch of the tree builder.
    fn bump(&mut self) {
        let (kind, text) = self.tokens.pop().unwrap();
        self.builder.token(kind.into(), text);
    }
    fn syntax_err(&mut self, err: SyntaxError) {
        let (_, text) = self.tokens.pop().unwrap();
        self.builder.token(PARSE_ERR.into(), text);
        self.errors.push(err);
    }
    fn syntax_err_by_checkpoint(&mut self, checkpoint: Checkpoint, err: SyntaxError) {
        self.builder.start_node_at(checkpoint, PARSE_ERR.into());
        self.finish_node();
        self.errors.push(err);
    }
    fn expected(&mut self, expected: SyntaxKind) {
        self.syntax_err(SyntaxError::Expected(expected))
    }
    /// Peek at the first unprocessed token
    fn current(&self) -> Option<SyntaxKind> {
        self.tokens.last().map(|(kind, _)| *kind)
    }
    fn next(&self) -> Option<SyntaxKind> {
        self.tokens
            .get(self.tokens.len() - 2)
            .map(|(kind, _)| *kind)
    }
    fn skip_ws(&mut self) {
        while self.current() == Some(WHITESPACE) || self.current() == Some(NEWLINE) {
            self.bump()
        }
    }
    fn skip_ws_without_newlines(&mut self) {
        while self.current() == Some(WHITESPACE) {
            self.bump()
        }
    }
}

mod expr {
    use rowan::Checkpoint;

    use super::{attrset::AttrsetRes, instr::NodeRes, Parser};
    use crate::parser::{ast::lossless::lex::SyntaxKind::*, Span};
    impl Parser<'_> {
        pub(super) fn expr(&mut self, start: Option<Checkpoint>) -> ExprRes {
            self.skip_ws();
            let start = start.unwrap_or_else(|| self.builder.checkpoint());
            match self.current() {
                Some(IDENT) => {
                    let expr_res = match self.instr() {
                        NodeRes::Ok => ExprRes::Ok,
                        NodeRes::Eof => ExprRes::Eof,
                    };
                    self.builder.start_node_at(start, EXPR.into());
                    self.finish_node();
                    expr_res
                }
                Some(_) => self.atom(Some(start)),
                None => ExprRes::Eof,
            }
        }

        pub(super) fn atom(&mut self, start: Option<Checkpoint>) -> ExprRes {
            self.skip_ws();
            let start = start.unwrap_or_else(|| self.builder.checkpoint());
            match self.current() {
                Some(INT_NUM | FLOAT_NUM | STRING) => {
                    self.bump();
                    self.builder.start_node_at(start, EXPR.into());
                    self.finish_node();
                    ExprRes::Ok
                }
                Some(L_CURLY) => match self.attrset(start) {
                    AttrsetRes::Ok => ExprRes::Ok,
                    AttrsetRes::Eof => ExprRes::Eof,
                },
                Some(L_PAREN) => {
                    self.builder.start_node_at(start, PARENTHESIZED_EXPR.into());
                    self.bump();
                    self.expr(None);
                    self.skip_ws();
                    match self.current() {
                        Some(R_PAREN) => ExprRes::Ok,
                        Some(_) => todo!(),
                        None => ExprRes::Eof,
                    }
                }
                Some(_) => ExprRes::NoExpr,
                None => ExprRes::Eof,
            }
        }
    }

    pub enum ExprRes {
        Ok,
        Eof,
        /// isnt an expression
        NoExpr,
    }
}

mod attrset {
    use chumsky::container::Container;
    use rowan::Checkpoint;

    use super::{expr::ExprRes, instr::NodeRes, Parser};
    use crate::parser::{
        ast::lossless::{lex::SyntaxKind::*, parser::SyntaxError},
        Span,
    };
    impl Parser<'_> {
        pub(super) fn attrset(&mut self, checkpoint: Checkpoint) -> AttrsetRes {
            assert_eq!(self.current(), Some(L_CURLY));
            self.bump();
            self.skip_ws();
            match self.current() {
                Some(R_CURLY) => {
                    self.builder.start_node_at(checkpoint, ATTR_SET.into());
                    self.bump();
                    self.finish_node();
                    AttrsetRes::Ok
                }
                Some(_) => {
                    self.builder.start_node_at(checkpoint, ATTR_SET.into());
                    let res = match self.attrs() {
                        AttrRes::Eof => AttrsetRes::Eof,
                        AttrRes::RCurly | AttrRes::Ok => {
                            println!("curr: {:?}", self.current());
                            AttrsetRes::Ok
                        }
                    };
                    self.finish_node();
                    res
                }
                None => AttrsetRes::Eof,
            }
            // self.start_node(ATTR);
        }

        fn attrs(&mut self) -> AttrRes {
            let mut res = AttrRes::Ok;

            while res == AttrRes::Ok {
                println!("it: {:?}", self.tokens.last());
                match self.attr() {
                    AttrRes::Ok => {
                        self.skip_ws_without_newlines();
                        println!(
                            "a: {:?}, {:?}",
                            self.tokens.last(),
                            self.tokens.get(self.tokens.len() - 2)
                        );
                        println!("errs: {:?}", self.errors);
                        res = AttrRes::Ok;
                        let checkpoint_previous_end = self.builder.checkpoint();
                        res = match self.current() {
                            Some(COMMA) => {
                                self.bump();
                                AttrRes::Ok
                            }
                            Some(R_CURLY) => {
                                self.bump();
                                res = AttrRes::Ok;
                                break;
                            }
                            Some(NEWLINE) => {
                                self.skip_ws();
                                println!(
                                    "b: {:?}, {:?}",
                                    self.tokens.last(),
                                    self.tokens.get(self.tokens.len() - 2)
                                );
                                match self.current() {
                                    Some(COMMA) => {
                                        self.bump();
                                        AttrRes::Ok
                                    }
                                    Some(R_CURLY) => {
                                        self.bump();
                                        res = AttrRes::Ok;
                                        break;
                                    }
                                    Some(IDENT) => {
                                        println!("wtf");
                                        self.syntax_err_by_checkpoint(
                                            checkpoint_previous_end,
                                            SyntaxError::ExpectedCommaBetweenAttrs,
                                        );
                                        // self.syntax_err(SyntaxError::ExpectedCommaBetweenAttrs);
                                        AttrRes::Ok
                                    }
                                    Some(_) => {
                                        self.bump();
                                        AttrRes::Ok
                                    }
                                    None => {
                                        res = AttrRes::Eof;
                                        break;
                                    }
                                }
                            }
                            Some(_) => {
                                self.bump();
                                println!(
                                    "c: {:?}, {:?}",
                                    self.tokens.last(),
                                    self.tokens.get(self.tokens.len() - 2)
                                );
                                AttrRes::Ok
                            }
                            None => {
                                res = AttrRes::Eof;
                                break;
                            }
                        }
                    }
                    AttrRes::Eof => {
                        res = AttrRes::Eof;
                        break;
                    }
                    AttrRes::RCurly => {
                        res = AttrRes::RCurly;
                        break;
                    }
                }
            }
            println!("toks_left: {:?}", self.tokens);
            res
        }

        fn attr(&mut self) -> AttrRes {
            self.skip_ws();
            self.start_node(ATTR);
            self.start_node(ATTR_NAME);
            match self.current() {
                Some(IDENT) => self.bump(),
                Some(R_CURLY) => return AttrRes::Ok,
                Some(_) => self.expected(IDENT),
                None => return AttrRes::Eof,
            }
            self.finish_node();
            self.skip_ws();
            match self.current() {
                Some(COLON) => self.bump(),
                Some(R_CURLY) => {
                    self.expected(COLON);
                    return AttrRes::RCurly;
                }
                Some(_) => self.expected(COLON),
                None => return AttrRes::Eof,
            }
            self.skip_ws();
            self.start_node(ATTR_VALUE);
            match self.expr(None) {
                ExprRes::Ok => self.bump(),
                ExprRes::Eof => return AttrRes::Eof,
                ExprRes::NoExpr => match self.current() {
                    Some(COMMA) => self.syntax_err(SyntaxError::AttrExpectedValue),
                    Some(R_CURLY) => {
                        self.syntax_err(SyntaxError::AttrExpectedValue);
                        return AttrRes::RCurly;
                    }
                    Some(_) => self.expected(EXPR),
                    None => unreachable!(),
                },
            }
            self.finish_node();
            self.finish_node();
            AttrRes::Ok
        }
    }

    #[derive(PartialEq, Eq)]
    pub enum AttrsetRes {
        Ok,
        Eof,
    }

    #[derive(PartialEq, Eq)]
    enum AttrRes {
        Ok,
        Eof,
        RCurly,
    }
}

mod instr {
    use super::Parser;
    use crate::parser::{
        ast::lossless::{lex::SyntaxKind::*, parser::expr::ExprRes},
        Span,
    };

    impl Parser<'_> {
        pub(super) fn instr(&mut self) -> NodeRes {
            assert_eq!(self.current(), Some(IDENT));
            self.skip_ws();
            self.start_node(INSTR);
            self.instr_name();

            // used to count positionals
            let mut i = 0;
            let params_checkpoint = self.builder.checkpoint();
            loop {
                match self.expr(None) {
                    ExprRes::Ok => {
                        i += 1;
                        continue;
                    }
                    ExprRes::NoExpr | ExprRes::Eof => break,
                }
            }
            if i >= 1 {
                self.builder
                    .start_node_at(params_checkpoint, INSTR_PARAMS.into());
                self.finish_node();
            }
            self.finish_node();
            NodeRes::Ok
        }

        fn instr_name(&mut self) {
            self.start_node(INSTR_NAME);
            while self.current() == Some(IDENT) {
                self.bump();
                self.skip_ws_without_newlines();
            }
            self.finish_node();
        }
    }

    pub(super) enum NodeRes {
        Ok,
        Eof,
    }
}