#![allow(dead_code)]

use num_bigint::BigUint;
use std::collections::HashMap;
pub mod opcodes;
pub mod u256;

#[derive(Default)]
pub struct Stack {
    pub pc: usize,
    pub calldata_i: usize,
    pub calldata_size: usize,
    pub stack: Vec<[u8; 32]>,
    pub storage: HashMap<[u8; 32], Vec<u8>>,
    pub mem: Vec<u8>,
    pub gas: u64,
    pub opcodes: HashMap<u8, opcodes::Opcode>,
}

impl Stack {
    pub fn new() -> Stack {
        let mut s = Stack {
            pc: 0,
            calldata_i: 0,
            calldata_size: 32,
            stack: Vec::new(),
            storage: HashMap::new(),
            mem: Vec::new(),
            gas: 10000000000,
            opcodes: HashMap::new(),
        };
        s.opcodes = opcodes::new_opcodes();
        s
    }
    pub fn print_stack(&self) {
        println!("stack ({}):", self.stack.len());
        for i in (0..self.stack.len()).rev() {
            // println!("{:x}", &self.stack[i][28..]);
            println!("{:?}", vec_u8_to_hex(self.stack[i].to_vec()));
        }
    }
    pub fn print_memory(&self) {
        if self.mem.len() > 0 {
            println!("memory ({}):", self.mem.len());
            println!("{:?}", vec_u8_to_hex(self.mem.to_vec()));
        }
    }
    pub fn print_storage(&self) {
        if self.storage.len() > 0 {
            println!("storage ({}):", self.storage.len());
            for (key, value) in self.storage.iter() {
                println!(
                    "{:?}: {:?}",
                    vec_u8_to_hex(key.to_vec()),
                    vec_u8_to_hex(value.to_vec())
                );
            }
        }
    }
    pub fn push(&mut self, b: [u8; 32]) {
        self.stack.push(b);
    }
    // push_arbitrary performs a push, but first converting the arbitrary-length
    // input into a 32 byte array
    pub fn push_arbitrary(&mut self, b: &[u8]) {
        // TODO if b.len()>32 return error
        let mut d: [u8; 32] = [0; 32];
        d[32 - b.len()..].copy_from_slice(b);
        self.stack.push(d);
    }
    // put_arbitrary puts in the last element of the stack the value
    pub fn put_arbitrary(&mut self, b: &[u8]) {
        // TODO if b.len()>32 return error
        let mut d: [u8; 32] = [0; 32];
        d[0..b.len()].copy_from_slice(b); // put without left padding
        let l = self.stack.len();
        self.stack[l - 1] = d;
    }
    pub fn pop(&mut self) -> Result<[u8; 32], String> {
        match self.stack.pop() {
            Some(x) => Ok(x),
            None => Err(format!("pop err")), // WIP
        }
    }

    pub fn execute(
        &mut self,
        code: &[u8],
        calldata: &[u8],
        debug: bool,
    ) -> Result<Vec<u8>, String> {
        self.pc = 0;
        self.calldata_i = 0;
        let l = code.len();

        while self.pc < l {
            let opcode = code[self.pc];
            if !self.opcodes.contains_key(&opcode) {
                return Err(format!("invalid opcode {:x}", opcode));
            }

            if debug {
                println!(
                    "{} (0x{:x}): pc={:?} gas={:?}",
                    self.opcodes.get(&opcode).unwrap().name,
                    opcode,
                    self.pc,
                    self.gas,
                );
                self.print_stack();
                self.print_memory();
                self.print_storage();
                println!();
            }
            match opcode & 0xf0 {
                0x00 => {
                    // arithmetic
                    match opcode {
                        0x00 => {
                            println!("0x00: STOP");
                            return Ok(Vec::new());
                        }
                        0x01 => self.add()?,
                        0x02 => self.mul()?,
                        0x03 => self.sub()?,
                        0x04 => self.div()?,
                        0x05 => self.sdiv()?,
                        0x06 => self.modulus()?,
                        0x07 => self.smod()?,
                        0x08 => self.add_mod()?,
                        0x09 => self.mul_mod()?,
                        0x0a => self.exp()?,
                        // 0x0b => self.sign_extend(),
                        _ => return Err(format!("unimplemented {:x}", opcode)),
                    }
                    self.pc += 1;
                }
                0x30 => {
                    match opcode {
                        0x35 => self.calldata_load(&calldata),
                        0x36 => self.calldata_size(&calldata),
                        0x39 => self.code_copy(&code)?,
                        _ => return Err(format!("unimplemented {:x}", opcode)),
                    }
                    self.pc += 1;
                }
                0x50 => {
                    self.pc += 1;
                    match opcode {
                        0x51 => self.mload()?,
                        0x52 => self.mstore()?,
                        0x55 => self.sstore()?,
                        0x56 => self.jump()?,
                        0x57 => self.jump_i()?,
                        0x5b => self.jump_dest()?,
                        _ => return Err(format!("unimplemented {:x}", opcode)),
                    }
                }
                0x60 | 0x70 => {
                    // push
                    let n = (opcode - 0x5f) as usize;
                    self.push_arbitrary(&code[self.pc + 1..self.pc + 1 + n]);
                    self.pc += 1 + n;
                }
                0x80 => {
                    // 0x8x dup
                    let l = self.stack.len();
                    if opcode > 0x7f {
                        self.stack.push(self.stack[l - (opcode - 0x7f) as usize]);
                    } else {
                        self.stack.push(self.stack[(0x7f - opcode) as usize]);
                    }
                    self.pc += 1;
                }
                0x90 => {
                    // 0x9x swap
                    let l = self.stack.len();
                    let pos;
                    if opcode > 0x8e {
                        pos = l - (opcode - 0x8e) as usize;
                    } else {
                        pos = (0x8e - opcode) as usize;
                    }
                    self.stack.swap(pos, l - 1);
                    self.pc += 1;
                }
                0xf0 => {
                    if opcode == 0xf3 {
                        let pos_to_return = u256::u256_to_u64(self.pop()?) as usize;
                        let len_to_return = u256::u256_to_u64(self.pop()?) as usize;
                        return Ok(self.mem[pos_to_return..pos_to_return + len_to_return].to_vec());
                    }
                }
                _ => {
                    return Err(format!("unimplemented {:x}", opcode));
                }
            }
            self.gas -= self.opcodes.get(&opcode).unwrap().gas;
        }
        Ok(Vec::new())
    }
}
pub fn vec_u8_to_hex(bytes: Vec<u8>) -> String {
    let strs: Vec<String> = bytes.iter().map(|b| format!("{:02X}", b)).collect();
    strs.join("")
}