use std::rc::Rc;
use std::str::FromStr;

use crate::tokenizing::TokenKind;
use crate::builtin::Builtin;

#[derive(Debug, PartialEq, Clone)]
pub struct PrefixOp {
  sigil: Rc<String>,
  pub builtin: Option<Builtin>,
}

impl PrefixOp {
  #[allow(dead_code)]
  pub fn sigil(&self) -> &Rc<String> {
    &self.sigil
  }
  pub fn is_prefix(op: &str) -> bool {
    match op {
      "+" => true,
      "-" => true,
      "!" => true,
      _ => false
    }
  }
}

impl FromStr for PrefixOp {
  type Err = ();

  fn from_str(s: &str) -> Result<Self, Self::Err> {
    use Builtin::*;

    let builtin = match s {
      "+" => Ok(Increment),
      "-" => Ok(Negate),
      "!" => Ok(BooleanNot),
      _ => Err(())
    };

    builtin.map(|builtin| PrefixOp { sigil: Rc::new(s.to_string()), builtin: Some(builtin) })
  }
}

#[derive(Debug, PartialEq, Clone)]
pub struct BinOp {
  sigil: Rc<String>,
  pub builtin: Option<Builtin>,
}

impl BinOp {
  pub fn from_sigil(sigil: &str) -> BinOp {
    let builtin = Builtin::from_str(sigil).ok();
    BinOp { sigil: Rc::new(sigil.to_string()), builtin }
  }
  pub fn sigil(&self) -> &Rc<String> {
    &self.sigil
  }
  pub fn from_sigil_token(tok: &TokenKind) -> Option<BinOp> {
    let s = token_kind_to_sigil(tok)?;
    Some(BinOp::from_sigil(s))
  }

  pub fn min_precedence() -> i32 {
    i32::min_value()
  }
  pub fn get_precedence_from_token(op_tok: &TokenKind) -> Option<i32> {
    let s = token_kind_to_sigil(op_tok)?;
    Some(binop_precedences(s))
  }
}

fn token_kind_to_sigil<'a>(tok: &'a TokenKind) -> Option<&'a str> {
  use self::TokenKind::*;
  Some(match tok {
    Operator(op) => op.as_str(),
    Period => ".",
    Pipe => "|",
    Slash => "/",
    LAngleBracket => "<",
    RAngleBracket => ">",
    Equals => "=",
    _ => return None
  })
}

fn binop_precedences(s: &str) -> i32 {
  let default = 10_000_000;
  match s {
    "+" => 10,
    "-" => 10,
    "*" =>  20,
    "/" =>  20,
    "%" =>  20,
    "++" => 30,
    "^" =>  30,
    "&" =>  20,
    "|" => 20,
    ">" => 20,
    ">=" => 20,
    "<" =>  20,
    "<=" => 20,
    "==" => 40,
    "=" =>  10,
    "<=>" => 30,
    _ => default,
  }
}