use anyhow::{bail, Result};
use indexmap::IndexSet;
use itertools::Itertools;
use lazy_static::lazy_static;
use std::collections::HashMap;

use crate::parser;

mod instruction;
pub use crate::compiler::instruction::Instruction;

pub trait Compilable<T, U> {
    fn compile(&self, data: &T) -> Result<U>;
}

#[derive(Debug)]
pub struct Word {
    pub id: usize,
    pub instructions: Vec<Instruction>,
    pub times_used: usize,
}

#[derive(Debug, PartialEq, Eq, Hash)]
pub struct Condition {
    pub if_instructions: Vec<Instruction>,
    pub else_instructions: Vec<Instruction>,
}

#[derive(Debug)]
pub struct Data {
    pub words: HashMap<String, Word>,
    // pub word_graph:
    pub conditions: IndexSet<Condition>,
    pub strings: IndexSet<String>,
}

pub const TEMPLATE_ASM: &str = include_str!("compiler/template.asm");

lazy_static! {
    #[derive(Debug)]
    pub static ref TEMPLATE: hence::parser::ast::Body = hence::parser::parse(
        hence::lexer::lex(TEMPLATE_ASM).unwrap()
    )
    .unwrap()
    .body;
}

impl Data {
    pub fn default() -> Self {
        Self {
            words: HashMap::new(),
            conditions: IndexSet::new(),
            strings: IndexSet::new(),
        }
    }

    pub fn generate_instructions(
        &mut self,
        body: parser::ast::Body,
        optimize: bool,
    ) -> Result<Vec<Instruction>> {
        let mut instructions: Vec<Instruction> = vec![];
        let mut iter = body.into_iter().peekable();
        while let Some(node) = iter.next() {
            match node {
                _ if optimize && iter.next_if_eq(&node).is_some() => {
                    let count = iter.by_ref().peeking_take_while(|n| *n == node).count() + 2;
                    instructions.push(Instruction::Multiple {
                        instruction: Box::new(
                            self.generate_instructions(vec![node], optimize)?
                                .into_iter()
                                .next()
                                .unwrap(),
                        ),
                        count,
                    });
                }
                parser::ast::Node::Comment(_) => {}
                parser::ast::Node::String { mode, string } => {
                    instructions.push(match mode.as_str() {
                        "." => {
                            let id = self.strings.insert_full(string).0;
                            Instruction::StringPrint(id)
                        }
                        "r" => {
                            let id = self.strings.insert_full(string).0;
                            Instruction::StringReference(id)
                        }
                        "asm" => Instruction::AsmQuote(string),
                        _ => bail!("Unknown string mode: {}", mode),
                    });
                }
                parser::ast::Node::Number(x) => {
                    instructions.push(instruction::Instruction::Push(x as u16));
                }
                parser::ast::Node::WordDefinition {
                    name,
                    stack: _,
                    body,
                } => {
                    if Instruction::from_word(&name).is_some() {
                        bail!("Word already exists as compiler instruction: {}", name);
                    } else if self.words.contains_key(&name) {
                        bail!("Word already exists as user word definition: {}", name);
                    }

                    let ins = self.generate_instructions(body, optimize)?;

                    self.words.insert(
                        name,
                        Word {
                            id: self.words.len(),
                            instructions: ins,
                            times_used: 0,
                        },
                    );
                }
                parser::ast::Node::Condition { if_body, else_body } => {
                    let if_instructions = self.generate_instructions(if_body, optimize)?;
                    let else_instructions = self.generate_instructions(else_body, optimize)?;
                    let id = self
                        .conditions
                        .insert_full(Condition {
                            if_instructions,
                            else_instructions,
                        })
                        .0;
                    instructions.push(Instruction::Condition(id));
                }
                parser::ast::Node::Word(x) => {
                    if let Some(ins) = Instruction::from_word(&x) {
                        instructions.push(ins);
                    } else if let Some(w) = self.words.get_mut(&x) {
                        instructions.push(Instruction::Call(x));
                        w.times_used += 1;
                    } else {
                        bail!("Word does not exist: {}", x);
                    }
                }
            }
        }

        Ok(instructions)
    }

    pub fn embed(&self, body: hence::parser::ast::Body) -> Result<hence::parser::ast::Body> {
        let mut x = TEMPLATE.to_vec();

        // strings
        for (id, s) in self.strings.iter().enumerate() {
            x.extend([
                hence::parser::ast::Node::Label(format!("data_strings_{}", id)),
                hence::parser::ast::Node::MacroCall {
                    name: "bytes".to_string(),
                    args: vec![hence::arg::Arg::String(s.to_string())],
                },
                hence::parser::ast::Node::Label(format!("data_strings_end_{}", id)),
            ]);
        }

        // conditions
        for (id, c) in self.conditions.iter().enumerate() {
            x.push(hence::parser::ast::Node::Label(format!("conditions_{}", id)));
            x.extend(
                
                );
        }

        // words
        for (name, word) in &self
            .words
            .iter()
            .filter(|(_, w)| w.times_used > 1)
            .sorted_by(|a, b| Ord::cmp(&a.1.id, &b.1.id))
            .collect::<Vec<_>>()
        {
            x.extend(vec![
                hence::parser::ast::Node::Label(format!("words_{}", word.id)),
                hence::parser::ast::Node::Comment(format!("word: \"{}\"", name)),
            ]);
            x.extend(
                word.instructions
                    .iter()
                    .map(|ins| ins.compile(self))
                    .collect::<Result<Vec<hence::parser::ast::Body>>>()
                    .unwrap()
                    .into_iter()
                    .flatten(),
            );
            x.push(hence::parser::ast::Node::MacroCall {
                name: "return_call_stack_jump".to_string(),
                args: vec![],
            });
        }

        x.extend([
            hence::parser::ast::Node::Label("main".to_string()),
            hence::parser::ast::Node::MacroCall {
                name: "main".to_string(),
                args: vec![hence::arg::Arg::Variable("main".to_string())],
            },
        ]);
        x.extend(body);
        x.push(hence::parser::ast::Node::MacroCall {
            name: "std_stop".to_string(),
            args: vec![],
        });

        Ok(x)
    }
}

pub fn compile(ast: parser::ast::AST, optimize: bool) -> Result<hence::parser::ast::AST> {
    let mut data = Data::default();
    let instructions = data.generate_instructions(ast.body, optimize)?;

    Ok(hence::parser::ast::AST {
        body: data.embed(
            instructions
                .iter()
                .map(|ins| ins.compile(&data))
                .collect::<Result<Vec<hence::parser::ast::Body>>>()
                .unwrap()
                .into_iter()
                .flatten()
                .collect(),
        )?,
    })
}