use crate::value::*;
use imbl::*;
use ran::ran_f64;
use std::rc::Rc;

#[derive(Clone, Debug)]
pub enum BaseFn {
    Nullary(fn() -> Value),
    Unary(fn(&Value) -> Value),
    Binary(fn(&Value, &Value) -> Value),
    Ternary(fn(&Value, &Value, &Value) -> Value),
}

pub fn eq(x: &Value, y: &Value) -> Value {
    if x == y {
        Value::True
    } else {
        Value::False
    }
}

pub fn add(x: &Value, y: &Value) -> Value {
    match (x, y) {
        (Value::Number(x), Value::Number(y)) => Value::Number(x + y),
        _ => unreachable!("internal Ludus error"),
    }
}

pub fn sub(x: &Value, y: &Value) -> Value {
    match (x, y) {
        (Value::Number(x), Value::Number(y)) => Value::Number(x - y),
        _ => unreachable!("internal Ludus error"),
    }
}

pub fn unbox(x: &Value) -> Value {
    match x {
        Value::Box(cell) => cell.as_ref().borrow().clone(),
        _ => unreachable!("internal Ludus error"),
    }
}

pub fn store(b: &Value, val: &Value) -> Value {
    if let Value::Box(cell) = b {
        cell.replace(val.clone());
        val.clone()
    } else {
        unreachable!("internal Ludus error")
    }
}

// TODO: do better than returning just the docstr
// name, patterns, AND docstring
pub fn doc(f: &Value) -> Value {
    match f {
        Value::Fn(f) => f.as_ref().doc(),
        _ => Value::Interned("no documentation found"),
    }
}

pub fn assoc(dict: &Value, key: &Value, value: &Value) -> Value {
    match (dict, key) {
        (Value::Dict(d), Value::Keyword(k)) => Value::Dict(Box::new(d.update(k, value.clone()))),
        _ => unreachable!("internal Ludus error"),
    }
}

pub fn r#bool(x: &Value) -> Value {
    match x {
        Value::Nil | Value::False => Value::False,
        _ => Value::True,
    }
}

pub fn chars(x: &Value) -> Value {
    match x {
        Value::Interned(s) => {
            let chars = s.chars();

            let mut charlist = vector![];
            for char in chars {
                if char.is_ascii() {
                    charlist.push_back(Value::String(Rc::new(char.to_string())))
                } else {
                    return Value::Tuple(Rc::new(vec![
                        Value::Keyword("err"),
                        Value::String(Rc::new(format!("{char} is not an ascii character"))),
                    ]));
                }
            }
            Value::Tuple(Rc::new(vec![
                Value::Keyword("ok"),
                Value::List(Box::new(charlist)),
            ]))
        }
        Value::String(s) => {
            let chars = s.chars();

            let mut charlist = vector![];
            for char in chars {
                if char.is_ascii() {
                    charlist.push_back(Value::String(Rc::new(char.to_string())))
                } else {
                    return Value::Tuple(Rc::new(vec![
                        Value::Keyword("err"),
                        Value::String(Rc::new(format!("{char} is not an ascii character"))),
                    ]));
                }
            }
            Value::Tuple(Rc::new(vec![
                Value::Keyword("ok"),
                Value::List(Box::new(charlist)),
            ]))
        }
        _ => unreachable!("internal Ludus error"),
    }
}

// TODO: figure out how to get to opportunistic mutation here
pub fn concat(x: &Value, y: &Value) -> Value {
    match (x, y) {
        (Value::Interned(x), Value::Interned(y)) => Value::String(Rc::new(format!("{x}{y}"))),
        (Value::String(x), Value::String(y)) => Value::String(Rc::new(format!("{x}{y}"))),
        (Value::String(x), Value::Interned(y)) => Value::String(Rc::new(format!("{x}{y}"))),
        (Value::Interned(x), Value::String(y)) => Value::String(Rc::new(format!("{x}{y}"))),
        (Value::List(x), Value::List(y)) => {
            let mut newlist = *x.clone();
            newlist.append(*y.clone());
            Value::List(Box::new(newlist))
        }
        _ => unreachable!("internal Ludus error"),
    }
}

pub fn append(x: &Value, y: &Value) -> Value {
    match x {
        Value::List(list) => {
            let mut newlist = list.clone();
            newlist.push_back(y.clone());
            Value::List(newlist)
        }
        _ => unreachable!("internal Ludus error"),
    }
}

pub fn dec(x: &Value) -> Value {
    match x {
        Value::Number(n) => Value::Number(n - 1.0),
        _ => unreachable!("internal Ludus error"),
    }
}

pub fn inc(x: &Value) -> Value {
    match x {
        Value::Number(n) => Value::Number(n + 1.0),
        _ => unreachable!("internal Ludus error"),
    }
}

pub fn div(x: &Value, y: &Value) -> Value {
    match (x, y) {
        (Value::Number(x), Value::Number(y)) => Value::Number(x / y),
        _ => unreachable!("internal Ludus error"),
    }
}

pub fn mult(x: &Value, y: &Value) -> Value {
    match (x, y) {
        (Value::Number(x), Value::Number(y)) => Value::Number(x * y),
        _ => unreachable!("internal Ludus error"),
    }
}

pub fn dissoc(dict: &Value, key: &Value) -> Value {
    match (dict, key) {
        (Value::Dict(dict), Value::Keyword(key)) => {
            let mut new = dict.clone();
            new.remove(key);
            Value::Dict(new)
        }
        _ => unreachable!("internal Ludus error"),
    }
}

pub fn first(ordered: &Value) -> Value {
    match ordered {
        Value::List(list) => match list.front() {
            Some(n) => n.clone(),
            None => Value::Nil,
        },
        Value::Tuple(tuple) => match tuple.first() {
            Some(n) => n.clone(),
            None => Value::Nil,
        },
        _ => unreachable!("internal Ludus error"),
    }
}

// TODO: figure out how to handle negative numbers
// the cast from f64 to usize discards sign info
pub fn at(ordered: &Value, i: &Value) -> Value {
    match (ordered, i) {
        (Value::List(list), Value::Number(n)) => {
            let i = *n as usize;
            match list.get(i) {
                Some(n) => n.clone(),
                None => Value::Nil,
            }
        }
        (Value::Tuple(tuple), Value::Number(n)) => {
            let i = *n as usize;
            match tuple.get(i) {
                Some(n) => n.clone(),
                None => Value::Nil,
            }
        }
        _ => unreachable!("internal Ludus error"),
    }
}

pub fn get(dict: &Value, key: &Value) -> Value {
    match (dict, key) {
        (Value::Dict(dict), Value::Keyword(key)) => match dict.get(key) {
            Some(x) => x.clone(),
            None => Value::Nil,
        },
        _ => unreachable!("internal Ludus error"),
    }
}

pub fn last(ordered: &Value) -> Value {
    match ordered {
        Value::List(list) => match list.last() {
            Some(x) => x.clone(),
            None => Value::Nil,
        },
        Value::Tuple(tuple) => match tuple.last() {
            Some(x) => x.clone(),
            None => Value::Nil,
        },
        _ => unreachable!("internal Ludus error"),
    }
}

// TODO: fix this: x is a list of all the args passed to Ludus's print!
pub fn print(x: &Value) -> Value {
    let Value::List(args) = x else {
        unreachable!("internal Ludus error")
    };
    let out = args
        .iter()
        .map(|val| format!("{val}"))
        .collect::<Vec<_>>()
        .join("");
    println!("{out}");
    Value::Keyword("ok")
}

pub fn show(x: &Value) -> Value {
    Value::String(Rc::new(format!("{x}")))
}

pub fn rest(ordered: &Value) -> Value {
    match ordered {
        Value::List(list) => Value::List(Box::new(list.clone().split_at(1).1)),
        Value::Tuple(tuple) => {
            Value::List(Box::new(Vector::from_iter(tuple.iter().next().cloned())))
        }
        _ => unreachable!("internal Ludus error"),
    }
}

pub fn count(coll: &Value) -> Value {
    match coll {
        Value::Dict(d) => Value::Number(d.len() as f64),
        Value::List(l) => Value::Number(l.len() as f64),
        Value::Tuple(t) => Value::Number(t.len() as f64),
        Value::String(s) => Value::Number(s.len() as f64),
        Value::Interned(s) => Value::Number(s.len() as f64),
        _ => unreachable!("internal Ludus error"),
    }
}

pub fn range(start: &Value, end: &Value) -> Value {
    match (start, end) {
        (Value::Number(start), Value::Number(end)) => {
            let start = *start as isize;
            let end = *end as isize;
            let mut range = Vector::new();
            for n in start..end {
                range.push_back(Value::Number(n as f64))
            }
            Value::List(Box::new(range))
        }
        _ => unreachable!("internal Ludus error"),
    }
}

pub fn slice(ordered: &Value, start: &Value, end: &Value) -> Value {
    match (ordered, start, end) {
        (Value::List(list), Value::Number(start), Value::Number(end)) => {
            let mut newlist = list.clone();
            let start = std::cmp::max(*start as usize, 0);
            let end = std::cmp::min(*end as usize, list.len());
            Value::List(Box::new(newlist.slice(start..end)))
        }
        // TODO: figure out something better to do than return an empty string on a bad slice
        (Value::String(string), Value::Number(start), Value::Number(end)) => {
            let start = std::cmp::max(*start as usize, 0);
            let end = std::cmp::min(*end as usize, string.len());
            Value::String(Rc::new(
                string
                    .clone()
                    .as_str()
                    .get(start..end)
                    .unwrap_or("")
                    .to_string(),
            ))
        }
        (Value::Interned(string), Value::Number(start), Value::Number(end)) => {
            let start = std::cmp::max(*start as usize, 0);
            let end = std::cmp::min(*end as usize, string.len());
            Value::String(Rc::new(string.get(start..end).unwrap_or("").to_string()))
        }
        _ => unreachable!("internal Ludus error"),
    }
}

pub fn list(x: &Value) -> Value {
    match x {
        Value::List(_) => x.clone(),
        Value::Tuple(t) => Value::List(Box::new(Vector::from_iter(t.iter().cloned()))),
        Value::Dict(d) => {
            let kvs = d.iter();
            let mut list = vector![];
            for (key, value) in kvs {
                let kv = Value::Tuple(Rc::new(vec![Value::Keyword(key), value.clone()]));
                list.push_back(kv);
            }
            Value::List(Box::new(list))
        }
        _ => Value::List(Box::new(vector![x.clone()])),
    }
}

pub fn number(x: &Value) -> Value {
    match x {
        Value::Interned(string) => match string.parse::<f64>() {
            Ok(n) => Value::Tuple(Rc::new(vec![Value::Keyword("ok"), Value::Number(n)])),
            Err(_) => Value::Tuple(Rc::new(vec![
                Value::Keyword("err"),
                Value::String(Rc::new(format!("could not parse `{string}` as a number"))),
            ])),
        },
        Value::String(string) => match string.parse::<f64>() {
            Ok(n) => Value::Tuple(Rc::new(vec![Value::Keyword("ok"), Value::Number(n)])),
            Err(_) => Value::Tuple(Rc::new(vec![
                Value::Keyword("err"),
                Value::String(Rc::new(format!("could not parse `{string}` as a number"))),
            ])),
        },
        _ => unreachable!("internal Ludus error"),
    }
}

pub fn r#type(x: &Value) -> Value {
    match x {
        Value::Nil => Value::Keyword("nil"),
        Value::Number(_) => Value::Keyword("number"),
        Value::True | Value::False => Value::Keyword("bool"),
        Value::Keyword(_) => Value::Keyword("keyword"),
        Value::Tuple(_) => Value::Keyword("tuple"),
        Value::Interned(_) => Value::Keyword("string"),
        Value::String(_) => Value::Keyword("string"),
        Value::List(_) => Value::Keyword("list"),
        Value::Dict(_) => Value::Keyword("dict"),
        Value::Fn(_) => Value::Keyword("fn"),
        Value::Box(_) => Value::Keyword("box"),
        Value::BaseFn(_) => Value::Keyword("fn"),
        Value::Partial(_) => Value::Keyword("fn"),
        Value::Nothing => unreachable!(),
    }
}

pub fn split(source: &Value, splitter: &Value) -> Value {
    match (source, splitter) {
        (Value::String(source), Value::String(splitter)) => {
            let parts = source.split_terminator(splitter.as_str());
            let mut list = vector![];
            for part in parts {
                list.push_back(Value::String(Rc::new(part.to_string())));
            }
            Value::List(Box::new(list))
        }
        (Value::String(source), Value::Interned(splitter)) => {
            let parts = source.split_terminator(splitter);
            let mut list = vector![];
            for part in parts {
                list.push_back(Value::String(Rc::new(part.to_string())));
            }
            Value::List(Box::new(list))
        }
        (Value::Interned(source), Value::String(splitter)) => {
            let parts = source.split_terminator(splitter.as_str());
            let mut list = vector![];
            for part in parts {
                list.push_back(Value::String(Rc::new(part.to_string())));
            }
            Value::List(Box::new(list))
        }
        (Value::Interned(source), Value::Interned(splitter)) => {
            let parts = source.split_terminator(splitter);
            let mut list = vector![];
            for part in parts {
                list.push_back(Value::String(Rc::new(part.to_string())));
            }
            Value::List(Box::new(list))
        }
        _ => unreachable!("internal Ludus error"),
    }
}

pub fn upcase(string: &Value) -> Value {
    match string {
        Value::String(string) => Value::String(Rc::new(string.to_uppercase())),
        Value::Interned(string) => Value::String(Rc::new(string.to_uppercase())),
        _ => unreachable!("internal Ludus error"),
    }
}

pub fn downcase(string: &Value) -> Value {
    match string {
        Value::String(string) => Value::String(Rc::new(string.to_lowercase())),
        Value::Interned(string) => Value::String(Rc::new(string.to_lowercase())),
        _ => unreachable!("internal Ludus error"),
    }
}

pub fn trim(string: &Value) -> Value {
    match string {
        Value::String(string) => Value::String(Rc::new(string.trim().to_string())),
        Value::Interned(string) => Value::String(Rc::new(string.trim().to_string())),
        _ => unreachable!("internal Ludus error"),
    }
}

pub fn triml(string: &Value) -> Value {
    match string {
        Value::String(string) => Value::String(Rc::new(string.trim_start().to_string())),
        Value::Interned(string) => Value::String(Rc::new(string.trim_start().to_string())),
        _ => unreachable!("internal Ludus error"),
    }
}

pub fn trimr(string: &Value) -> Value {
    match string {
        Value::String(string) => Value::String(Rc::new(string.trim_end().to_string())),
        Value::Interned(string) => Value::String(Rc::new(string.trim_end().to_string())),
        _ => unreachable!("internal Ludus error"),
    }
}

pub fn atan_2(x: &Value, y: &Value) -> Value {
    match (x, y) {
        (Value::Number(x), Value::Number(y)) => Value::Number(x.atan2(*y)),
        _ => unreachable!("internal Ludus error"),
    }
}

pub fn ceil(x: &Value) -> Value {
    match x {
        Value::Number(x) => Value::Number(x.ceil()),
        _ => unreachable!("internal Ludus error"),
    }
}

pub fn cos(x: &Value) -> Value {
    match x {
        Value::Number(x) => Value::Number(x.cos()),
        _ => unreachable!("internal Ludus error"),
    }
}

pub fn floor(x: &Value) -> Value {
    match x {
        Value::Number(x) => Value::Number(x.floor()),
        _ => unreachable!("internal Ludus error"),
    }
}

pub fn random() -> Value {
    Value::Number(ran_f64())
}

pub fn round(x: &Value) -> Value {
    match x {
        Value::Number(x) => Value::Number(x.round()),
        _ => unreachable!("internal Ludus error"),
    }
}

pub fn sin(x: &Value) -> Value {
    match x {
        Value::Number(x) => Value::Number(x.sin()),
        _ => unreachable!("internal Ludus error"),
    }
}

pub fn sqrt(x: &Value) -> Value {
    match x {
        Value::Number(x) => Value::Number(x.sqrt()),
        _ => unreachable!("internal Ludus error"),
    }
}

pub fn tan(x: &Value) -> Value {
    match x {
        Value::Number(x) => Value::Number(x.tan()),
        _ => unreachable!("internal Ludus error"),
    }
}

pub fn gt(x: &Value, y: &Value) -> Value {
    match (x, y) {
        (Value::Number(x), Value::Number(y)) => {
            if x > y {
                Value::True
            } else {
                Value::False
            }
        }
        _ => unreachable!("internal Ludus error"),
    }
}

pub fn gte(x: &Value, y: &Value) -> Value {
    match (x, y) {
        (Value::Number(x), Value::Number(y)) => {
            if x >= y {
                Value::True
            } else {
                Value::False
            }
        }
        _ => unreachable!("internal Ludus error"),
    }
}

pub fn lt(x: &Value, y: &Value) -> Value {
    match (x, y) {
        (Value::Number(x), Value::Number(y)) => {
            if x < y {
                Value::True
            } else {
                Value::False
            }
        }
        _ => unreachable!("internal Ludus error"),
    }
}

pub fn lte(x: &Value, y: &Value) -> Value {
    match (x, y) {
        (Value::Number(x), Value::Number(y)) => {
            if x <= y {
                Value::True
            } else {
                Value::False
            }
        }
        _ => unreachable!("internal Ludus error"),
    }
}

pub fn r#mod(x: &Value, y: &Value) -> Value {
    match (x, y) {
        (Value::Number(x), Value::Number(y)) => Value::Number(x % y),
        _ => unreachable!("internal Ludus error"),
    }
}

pub fn base() -> Value {
    let members = vec![
        ("add", Value::BaseFn(BaseFn::Binary(add))),
        ("append", Value::BaseFn(BaseFn::Binary(append))),
        ("assoc", Value::BaseFn(BaseFn::Ternary(assoc))),
        ("at", Value::BaseFn(BaseFn::Binary(at))),
        ("atan_2", Value::BaseFn(BaseFn::Binary(atan_2))),
        ("bool", Value::BaseFn(BaseFn::Unary(r#bool))),
        ("ceil", Value::BaseFn(BaseFn::Unary(ceil))),
        ("chars", Value::BaseFn(BaseFn::Unary(chars))),
        ("concat", Value::BaseFn(BaseFn::Binary(concat))),
        ("cos", Value::BaseFn(BaseFn::Unary(cos))),
        ("count", Value::BaseFn(BaseFn::Unary(count))),
        ("dec", Value::BaseFn(BaseFn::Unary(dec))),
        ("dissoc", Value::BaseFn(BaseFn::Binary(dissoc))),
        ("div", Value::BaseFn(BaseFn::Binary(div))),
        ("doc!", Value::BaseFn(BaseFn::Unary(doc))),
        ("downcase", Value::BaseFn(BaseFn::Unary(downcase))),
        ("eq?", Value::BaseFn(BaseFn::Binary(eq))),
        ("first", Value::BaseFn(BaseFn::Unary(first))),
        ("floor", Value::BaseFn(BaseFn::Unary(floor))),
        ("get", Value::BaseFn(BaseFn::Binary(get))),
        ("gt?", Value::BaseFn(BaseFn::Binary(gt))),
        ("gte?", Value::BaseFn(BaseFn::Binary(gte))),
        ("inc", Value::BaseFn(BaseFn::Unary(inc))),
        ("last", Value::BaseFn(BaseFn::Unary(last))),
        ("list", Value::BaseFn(BaseFn::Unary(list))),
        ("lt?", Value::BaseFn(BaseFn::Binary(lt))),
        ("lte?", Value::BaseFn(BaseFn::Binary(lte))),
        ("mod", Value::BaseFn(BaseFn::Binary(r#mod))),
        ("mult", Value::BaseFn(BaseFn::Binary(mult))),
        ("number", Value::BaseFn(BaseFn::Unary(number))),
        ("pi", Value::Number(std::f64::consts::PI)),
        ("print!", Value::BaseFn(BaseFn::Unary(print))),
        ("random", Value::BaseFn(BaseFn::Nullary(random))),
        ("range", Value::BaseFn(BaseFn::Binary(range))),
        ("rest", Value::BaseFn(BaseFn::Unary(rest))),
        ("round", Value::BaseFn(BaseFn::Unary(round))),
        ("show", Value::BaseFn(BaseFn::Unary(show))),
        ("sin", Value::BaseFn(BaseFn::Unary(sin))),
        ("slice", Value::BaseFn(BaseFn::Ternary(slice))),
        ("split", Value::BaseFn(BaseFn::Binary(split))),
        ("sqrt", Value::BaseFn(BaseFn::Unary(sqrt))),
        ("sqrt_2", Value::Number(std::f64::consts::SQRT_2)),
        ("store!", Value::BaseFn(BaseFn::Binary(store))),
        ("sub", Value::BaseFn(BaseFn::Binary(sub))),
        ("tan", Value::BaseFn(BaseFn::Unary(tan))),
        ("trim", Value::BaseFn(BaseFn::Unary(trim))),
        ("triml", Value::BaseFn(BaseFn::Unary(triml))),
        ("trimr", Value::BaseFn(BaseFn::Unary(trimr))),
        ("type", Value::BaseFn(BaseFn::Unary(r#type))),
        ("unbox", Value::BaseFn(BaseFn::Unary(unbox))),
        ("upcase", Value::BaseFn(BaseFn::Unary(upcase))),
    ];
    Value::Dict(Box::new(HashMap::from(members)))
}