use std::io::{Read, Write};
use std::sync::{Arc, Mutex};

use binread::{BinRead, BinReadable};
use block::Block;
use frame::Frame;
use ijvmreader::IJVMReader;
use ops::{num_to_op, Args, Operation};
use pool::Pool;
use stack::Stack;
use Result;

#[cfg(feature = "bonus:heap")]
use heap::Heaps;
#[cfg(feature = "bonus:network")]
use netstack::NetStack;
use std::convert::TryInto;

pub const MAGIC_HEADER: u32 = 0x1DEA_DFAD;

pub struct Machine {
    pub wide: bool,
    pub halted: bool,
    pub pool: Pool,
    pub block: Block,
    pub frame: Vec<Frame>,

    #[cfg(feature = "bonus:network")]
    pub net: NetStack,
    #[cfg(feature = "bonus:heap")]
    pub heap: Heaps,

    pub stream_in: Box<dyn Read + Send + Sync>,
    pub stream_out: Arc<Mutex<dyn Write + Send + Sync>>,
}

impl Machine {
    pub fn new(pool: Pool, block: Block) -> Machine {
        Machine {
            wide: false,
            halted: false,
            pool,
            block,
            frame: vec![Frame::new_extendable(0)],
            stream_in: Box::new(::std::io::stdin()),
            stream_out: Arc::new(Mutex::new(::std::io::stdout())),

            #[cfg(feature = "bonus:network")]
            net: NetStack::new(),

            #[cfg(feature = "bonus:heap")]
            heap: Heaps::new(),
        }
    }

    pub fn new_from_reader(mut reader: IJVMReader) -> Result<Machine> {
        let magic = reader.read_u32()?;
        if magic != MAGIC_HEADER {
            return Err("Invalid magic header");
        }
        let constants = match reader.read_block() {
            Ok(a) => a,
            Err(_) => return Err("Failed to read constants block"),
        };
        let text = match reader.read_block() {
            Ok(block) => block,
            Err(_) => return Err("Failed to read text block"),
        };

        let pool = Pool::new(constants)?;

        Ok(Machine::new(pool, text))
    }

    pub fn new_from_file(file: &str) -> Result<Machine> {
        let reader = IJVMReader::new(file).unwrap();
        Machine::new_from_reader(reader)
    }

    pub fn new_from_slice(source: &[u8]) -> Result<Machine> {
        let reader = IJVMReader::new_from_slice(source);
        Machine::new_from_reader(reader)
    }

    pub fn step(&mut self) -> Result<()> {
        match self.block.read_op() {
            Ok(Operation::Op(a, func, _)) => {
                if cfg!(feature = "debug:instr") {
                    println!("{}", a);
                    println!("Stack: {:?}", self.cur_frame().stack.data);
                    let x = func(self);
                    println!("Stack: {:?}", self.cur_frame().stack.data);
                    x
                } else {
                    func(self)
                }
            }
            Ok(Operation::Invalid) => {
                println!("Reached invalid operation");
                Err("Invalid op")
            }
            Err(str) => Err(str),
        }
    }

    pub fn run(&mut self) -> Result<()> {
        while self.has_step() {
            self.step()?;
        }
        Ok(())
    }

    pub fn has_step(&self) -> bool {
        !self.halted && self.block.has_i8()
    }

    pub fn get_program_counter(&self) -> usize {
        self.block.cur()
    }

    pub fn get_tos(&mut self) -> Result<i32> {
        self.cur_stack().top()?.try_into()
    }

    pub fn cur_frame(&mut self) -> &mut Frame {
        self.frame.last_mut().unwrap()
    }

    pub fn cur_stack(&mut self) -> &mut Stack {
        &mut self.cur_frame().stack
    }

    pub fn cur_instruction(&mut self) -> u8 {
        self.block[self.get_program_counter()]
    }

    pub fn next_instruction(&mut self) -> Result<(String, Vec<i32>)> {
        let checkpoint = self.block.cur();

        let mut opcode = self.block.read_u8()?;
        let mut params = Vec::new();
        let mut wide = false;

        // WIDE
        if opcode == 0xC4 {
            wide = true;
            opcode = self.block.read_u8()?;
        }

        let (name, args) = match num_to_op(opcode) {
            Operation::Invalid => return Err("Invalid operation"),
            Operation::Op(name, _, args) => (name, args),
        };

        for arg in args {
            let v = match arg {
                Args::Byte => i32::from(self.block.read_i8()?),
                Args::Short => i32::from(self.block.read_i16()?),
                Args::Var => {
                    if wide {
                        i32::from(self.block.read_u16()?)
                    } else {
                        i32::from(self.block.read_u8()?)
                    }
                }
                Args::Label => i32::from(self.block.read_i16()?),
                Args::Constant => i32::from(self.block.read_u16()?),
            };
            params.push(v);
        }

        self.block.seek(checkpoint).unwrap();
        Ok(((*name).to_string(), params))
    }

    //    pub fn get_stack_pointer(&self) -> usize {
    //        return self.frame.last().unwrap().stack.len();
    //    }

    pub fn read_index(&mut self) -> Result<usize> {
        if self.wide {
            self.wide = false;
            return Ok(self.block.read_u16()? as usize);
        }
        Ok(self.block.read_u8()? as usize)
    }

    pub fn set_input(&mut self, instream: Box<dyn Read + Send + Sync>) {
        self.stream_in = instream;
    }

    pub fn set_output(&mut self, outstream: Arc<Mutex<dyn Write + Send + Sync>>) {
        self.stream_out = outstream;
    }
}