mod expression;
mod macros;

use crate::{
    ast, expect_any_keyword, expect_identifier, expect_keyword, expect_token, match_token,
    peek_keyword, peek_match,
    token::{KeywordKind, Token, TokenKind},
};

pub struct Parser {
    tokens: Vec<Token>,
    current: usize,
}

impl Parser {
    pub fn new(tokens: Vec<Token>) -> Parser {
        let tokens = tokens
            .into_iter()
            .filter(|t| !matches!(t.kind, TokenKind::NewLine))
            .collect::<Vec<_>>();

        Self { tokens, current: 0 }
    }

    pub fn module(&mut self) -> ast::Module {
        let mut statements = Vec::new();
        while !match_token!(self, TokenKind::EndOfFile) {
            let s = self.statement();
            println!("Parsed Statement {s:?}");
            statements.push(s);
        }
        ast::Module { statements }
    }

    fn statement(&mut self) -> ast::Statement {
        if peek_keyword!(self, KeywordKind::function) {
            return self.function_declaration();
        }
        self.expression_statement()
    }

    fn function_declaration(&mut self) -> ast::Statement {
        expect_keyword!(self, KeywordKind::function);
        let id = expect_identifier!(self);
        expect_token!(self, TokenKind::LeftParen, "LeftParen");

        let mut parameters = Vec::new();
        while peek_match!(self, TokenKind::Identifier(_)) {
            let name = expect_identifier!(self);
            expect_token!(self, TokenKind::Colon, "Colon");
            let typename = expect_any_keyword!(self);
            let parameter = ast::ParameterDeclaration {
                name: name.clone(),
                typename: typename.clone(),
            };
            parameters.push(parameter);
        }

        expect_token!(self, TokenKind::RightParen, "RightParen");

        expect_token!(self, TokenKind::LeftCurly, "LeftCurly");

        let mut statements = Vec::new();
        while !peek_match!(self, TokenKind::RightCurly) {
            let statement = self.statement();
            statements.push(statement);
        }

        expect_token!(self, TokenKind::RightCurly, "RightCurly");

        ast::Statement::FunctionDeclaration {
            name: id.clone(),
            parameters,
            statements,
        }
    }

    fn expression_statement(&mut self) -> ast::Statement {
        let e = self.expression();
        expect_token!(self, TokenKind::Semicolon, "Semicolon");
        ast::Statement::Expression(e)
    }
}

impl Parser {
    fn peek(&self) -> Option<&Token> {
        self.tokens.get(self.current)
    }
    fn consume(&mut self) -> Option<Token> {
        let token = self.peek().cloned();
        self.current += 1;
        token
    }
}