use std::{cell::RefCell, collections::HashMap, rc::Rc};

use talc_lang::{
	exception::{exception, Result},
	lformat,
	parser::{parse_float, parse_int},
	symbol::{symbol, Symbol, SYM_TYPE_ERROR, SYM_VALUE_ERROR},
	throw,
	value::{ops::RatioExt, HashValue, Rational64, Value},
	Vm,
};
use talc_macros::native_func;

use crate::unpack_args;

pub fn load(vm: &mut Vm) {
	vm.set_global_name("type", type_().into());
	vm.set_global_name("is", is().into());
	vm.set_global_name("as", as_().into());
	vm.set_global_name("copy", copy().into());

	vm.set_global_name("str", str_().into());
	vm.set_global_name("repr", repr().into());

	vm.set_global_name("symbol_name", symbol_name().into());
	vm.set_global_name("symbol_of", symbol_of().into());
	vm.set_global_name("symbol_exists", symbol_exists().into());

	vm.set_global_name("cell", cell().into());
	vm.set_global_name("uncell", uncell().into());
	vm.set_global_name("cell_replace", cell_replace().into());
	vm.set_global_name("cell_take", cell_take().into());

	vm.set_global_name("func_state", func_state().into());
	vm.set_global_name("func_arity", func_arity().into());
	vm.set_global_name("func_name", func_name().into());
	vm.set_global_name("apply", apply().into());
	vm.set_global_name("compile", compile().into());
}

//
//  types
//

#[native_func(1, "type")]
pub fn type_(_: &mut Vm, args: Vec<Value>) -> Result<Value> {
	let [_, val] = unpack_args!(args);
	Ok(val.get_type().into())
}

#[native_func(2)]
pub fn is(_: &mut Vm, args: Vec<Value>) -> Result<Value> {
	let [_, val, ty] = unpack_args!(args);
	let Value::Symbol(ty) = ty else {
		throw!(*SYM_TYPE_ERROR, "type expected symbol, got {ty:#}")
	};
	Ok((val.get_type() == ty).into())
}

#[native_func(2, "as")]
pub fn as_(_: &mut Vm, args: Vec<Value>) -> Result<Value> {
	let [_, val, ty] = unpack_args!(args);
	let Value::Symbol(ty) = ty else {
		throw!(*SYM_TYPE_ERROR, "type expected symbol, got {ty:#}")
	};
	if val.get_type() == ty {
		return Ok(val)
	}
	match (val, ty.name().as_bytes()) {
		(_, b"nil") => Ok(Value::Nil),
		(v, b"string") => Ok(Value::String(lformat!("{v}").into())),
		(v, b"bool") => Ok(Value::Bool(v.truthy())),

		(Value::Symbol(s), b"int") => Ok(Value::Int(s.id() as i64)),

		(Value::Int(x), b"ratio") => Ok(Value::Ratio(x.into())),
		(Value::Int(x), b"float") => Ok(Value::Float(x as f64)),
		(Value::Int(x), b"complex") => Ok(Value::Complex((x as f64).into())),
		(Value::Ratio(x), b"int") => Ok(Value::Int(x.to_integer())),
		(Value::Ratio(x), b"float") => Ok(Value::Float(x.to_f64())),
		(Value::Ratio(x), b"complex") => Ok(Value::Complex(x.to_f64().into())),
		(Value::Float(x), b"int") => Ok(Value::Int(x as i64)),
		(Value::Float(x), b"ratio") => {
			let r = Rational64::approximate_float(x).ok_or_else(|| {
				exception!(
					*SYM_VALUE_ERROR,
					"float {x:?} could not be converted to ratio"
				)
			})?;
			Ok(Value::Ratio(r))
		}
		(Value::Float(x), b"complex") => Ok(Value::Complex(x.into())),

		(Value::String(s), b"int") => parse_int(s.as_ref(), 10)
			.map(i64::into)
			.map_err(|_| exception!(*SYM_VALUE_ERROR, "could not parse {s:#} as integer")),

		(Value::String(s), b"float") => parse_float(s.as_ref())
			.map(f64::into)
			.map_err(|_| exception!(*SYM_VALUE_ERROR, "could not parse {s:#} as float")),

		(v, _) => throw!(
			*SYM_TYPE_ERROR,
			"cannot convert value of type {} to type {}",
			v.get_type().name(),
			ty.name()
		),
	}
}

pub fn copy_inner(value: Value) -> Result<Value> {
	match value {
		Value::Nil
		| Value::Bool(_)
		| Value::Symbol(_)
		| Value::Int(_)
		| Value::Ratio(_)
		| Value::Float(_)
		| Value::Complex(_)
		| Value::Range(_)
		| Value::String(_) => Ok(value),
		Value::Cell(c) => {
			let c = Rc::unwrap_or_clone(c).take();
			let c = copy_inner(c)?;
			Ok(RefCell::new(c).into())
		}
		Value::List(l) => {
			let l = Rc::unwrap_or_clone(l).take();
			let v: Result<Vec<Value>> = l.into_iter().map(copy_inner).collect();
			Ok(v?.into())
		}
		Value::Table(t) => {
			let t = Rc::unwrap_or_clone(t).take();
			let v: Result<HashMap<HashValue, Value>> = t
				.into_iter()
				.map(|(k, v)| copy_inner(v).map(|v| (k, v)))
				.collect();
			Ok(v?.into())
		}
		Value::Native(ref n) => match n.copy_value()? {
			Some(x) => Ok(x),
			None => throw!(
				*SYM_TYPE_ERROR,
				"cannot copy value of type {}",
				value.get_type().name()
			),
		},
		_ => throw!(
			*SYM_TYPE_ERROR,
			"cannot copy value of type {}",
			value.get_type().name()
		),
	}
}

#[native_func(1)]
pub fn copy(_: &mut Vm, args: Vec<Value>) -> Result<Value> {
	let [_, val] = unpack_args!(args);
	copy_inner(val)
}

//
//  strings
//

#[native_func(1, "str")]
pub fn str_(_: &mut Vm, args: Vec<Value>) -> Result<Value> {
	let [_, val] = unpack_args!(args);
	Ok(lformat!("{val}").into())
}

#[native_func(1)]
pub fn repr(_: &mut Vm, args: Vec<Value>) -> Result<Value> {
	let [_, val] = unpack_args!(args);
	Ok(lformat!("{val:#}").into())
}

//
//  symbols
//

#[native_func(1)]
pub fn symbol_name(_: &mut Vm, args: Vec<Value>) -> Result<Value> {
	let [_, val] = unpack_args!(args);
	let Value::Symbol(s) = val else {
		throw!(*SYM_TYPE_ERROR, "symbol_name: expected symbol")
	};
	Ok(s.name().into())
}

#[native_func(1)]
pub fn symbol_of(_: &mut Vm, args: Vec<Value>) -> Result<Value> {
	let [_, val] = unpack_args!(args);
	let Value::String(s) = val else {
		throw!(*SYM_TYPE_ERROR, "symbol_of: expected string")
	};
	Ok(Symbol::get(s.as_ref()).into())
}

#[native_func(1)]
pub fn symbol_exists(_: &mut Vm, args: Vec<Value>) -> Result<Value> {
	let [_, val] = unpack_args!(args);
	let Value::String(s) = val else {
		throw!(*SYM_TYPE_ERROR, "symbol_of: expected string")
	};
	match Symbol::try_get(s.as_ref()) {
		Some(s) => Ok(s.into()),
		None => Ok(Value::Nil),
	}
}

//
//  cells
//

#[native_func(1)]
pub fn cell(_: &mut Vm, args: Vec<Value>) -> Result<Value> {
	let [_, value] = unpack_args!(args);
	Ok(RefCell::new(value).into())
}

#[native_func(1)]
pub fn uncell(_: &mut Vm, args: Vec<Value>) -> Result<Value> {
	let [_, cell] = unpack_args!(args);
	let Value::Cell(cell) = cell else {
		throw!(*SYM_TYPE_ERROR, "uncell: value is not a cell")
	};
	Ok(Rc::unwrap_or_clone(cell).into_inner())
}

#[native_func(2)]
pub fn cell_replace(_: &mut Vm, args: Vec<Value>) -> Result<Value> {
	let [_, cell, value] = unpack_args!(args);
	let Value::Cell(cell) = cell else {
		throw!(*SYM_TYPE_ERROR, "cell_replace: value is not a cell")
	};
	Ok(cell.replace(value))
}

#[native_func(1)]
pub fn cell_take(_: &mut Vm, args: Vec<Value>) -> Result<Value> {
	let [_, cell] = unpack_args!(args);
	let Value::Cell(cell) = cell else {
		throw!(*SYM_TYPE_ERROR, "cell_take: value is not a cell")
	};
	Ok(cell.replace(Value::Nil))
}

//
//  functions
//

#[native_func(1)]
pub fn func_state(_: &mut Vm, args: Vec<Value>) -> Result<Value> {
	let [_, func] = unpack_args!(args);
	match func {
		Value::NativeFunc(_) => Ok(Value::Nil),
		Value::Function(f) => {
			let l: Vec<Value> = f.state.iter().map(|v| Value::Cell(v.clone())).collect();
			Ok(l.into())
		}
		_ => throw!(
			*SYM_TYPE_ERROR,
			"closure_state: {func:#} is not a talc function"
		),
	}
}

#[native_func(1)]
pub fn func_arity(_: &mut Vm, args: Vec<Value>) -> Result<Value> {
	let [_, func] = unpack_args!(args);
	let Some(attrs) = func.func_attrs() else {
		throw!(*SYM_TYPE_ERROR, "closure_state: {func:#} is not a function")
	};
	Ok((attrs.arity as i64).into())
}

#[native_func(1)]
pub fn func_name(_: &mut Vm, args: Vec<Value>) -> Result<Value> {
	let [_, func] = unpack_args!(args);
	let Some(attrs) = func.func_attrs() else {
		throw!(*SYM_TYPE_ERROR, "closure_state: {func:#} is not a function")
	};
	if let Some(name) = attrs.name {
		Ok(name.into())
	} else {
		Ok(Value::Nil)
	}
}

#[native_func(2)]
pub fn apply(vm: &mut Vm, args: Vec<Value>) -> Result<Value> {
	let [_, func, lst] = unpack_args!(args);
	if func.func_attrs().is_none() {
		throw!(
			*SYM_TYPE_ERROR,
			"apply: first argument must be a function, found {func:#}"
		)
	}
	let Value::List(l) = lst else {
		throw!(
			*SYM_TYPE_ERROR,
			"apply: second argument must be a list, found {lst:#}"
		)
	};
	let mut args = l.borrow().clone();
	args.insert(0, func.clone());
	vm.call_value(func, args)
}

#[native_func(1)]
pub fn compile(_: &mut Vm, args: Vec<Value>) -> Result<Value> {
	let [_, src] = unpack_args!(args);
	let Value::String(src) = src else {
		throw!(
			*SYM_TYPE_ERROR,
			"compile: argument must be a string, found {src:#}"
		)
	};
	let src = src.to_str().map_err(|e| {
		exception!(
			*SYM_VALUE_ERROR,
			"compile: argument must be valid unicode ({e})"
		)
	})?;
	let ast =
		talc_lang::parser::parse(src).map_err(|e| exception!(symbol!("parse_error"), "{e}"))?;
	let func = talc_lang::compiler::compile(&ast, None);
	Ok(func.into())
}