use std::{fmt::Debug, path::PathBuf};

use thiserror::Error;

use crate::{
    ast::Block,
    token_stream::{
        TokenStream, TokenStreamError,
        lexer::{Error as TokenizerError, Token, tokenize},
    },
    vm::{ClosureRunner, VirtualMachine},
};

mod ast;
mod compile;
mod token_stream;
pub mod vm;

#[derive(Error, Debug)]
pub enum CompilationError {
    #[error(transparent)]
    TokenStreamError(#[from] TokenStreamError),
    #[error(transparent)]
    TokenizationError(#[from] TokenizerError),
}

#[derive(Clone)]
pub struct CompilationUnit {
    pub instructions: Vec<vm::Instruction>,
    pub state: compile::State,
    pub constants: Vec<vm::Constant>,
}

impl Debug for CompilationUnit {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.debug_struct("CompilationUnit")
            .field("instructions", &self.instructions)
            .field("state", &self.state)
            .field("constants", &self.constants)
            .finish()
    }
}

impl CompilationUnit {
    pub fn with_virtual_machine<'a>(&self, vm: &'a mut VirtualMachine) -> ExecutionUnit<'a> {
        let chunk_id = vm.new_prototype(self.instructions.clone());
        for prototype in &self.state.prototypes {
            vm.new_prototype(prototype.clone());
        }

        vm.constants = self.constants.clone();

        ExecutionUnit { chunk_id, vm }
    }
}

pub struct ExecutionUnit<'a> {
    chunk_id: u32,
    vm: &'a mut VirtualMachine,
}

impl<'a> ExecutionUnit<'a> {
    pub fn execute(self) -> ClosureRunner {
        let closure = self.vm.create_closure(self.chunk_id);
        closure.run(Vec::new())
    }
}

pub fn compile(
    text: &str,
    unit: Option<&CompilationUnit>,
) -> Result<CompilationUnit, CompilationError> {
    let file_path = PathBuf::from("../examples/test.lua");
    let tokens = tokenize(text)?;
    let mut stream = TokenStream::from(&file_path, &tokens);

    // dbg!(&tokens);

    let chunk = stream.parse::<Block>()?;
    stream.expect(Token::Eof)?;

    // dbg!(&chunk);

    let constants = chunk
        .find_constants(
            &mut Default::default(),
            if let Some(unit) = unit {
                unit.constants.clone()
            } else {
                Vec::new()
            },
        )
        .into_iter()
        .collect::<Vec<_>>();

    let mut state = compile::State {
        constants: constants.clone(),
        prototypes: if let Some(unit) = unit {
            unit.state.prototypes.clone()
        } else {
            Vec::new()
        },
    };
    let mut scope = Default::default();
    let instructions = chunk.compile(&mut state, &mut scope);

    // dbg!(&instructions);

    // dbg!(&constants);

    Ok(CompilationUnit {
        instructions,
        state,
        constants,
    })
}