use std::{
	hash::Hash,
	rc::Rc,
};

use crate::{
	instruction::Instruction as Inst,
	loader::{
		self,
		DecodeInstruction,
	},
	state::{
		Block,
		Chunk,
		State,
	},
	string_interner::Interner,
	value::Value,
};

fn calculate_hash<T: Hash>(t: &T) -> u64 {
	use std::hash::Hasher;
	
	let mut s = std::collections::hash_map::DefaultHasher::new ();
	t.hash(&mut s);
	s.finish()
}

/// Takes arguments and a parsed Lua chunk, runs its,
/// and returns the output

fn run_chunk (vm: &mut State, args: &[&str], chunk: Chunk) -> Vec <Value> {
	vm.upvalues = vm.upvalues_from_args(args.into_iter ().map (|s| s.to_string ()));
	vm.set_chunk (chunk);
	vm.execute ().unwrap ()
}

/// Takes arguments and Lua bytecode, loads it, runs it,
/// and return the output

fn run_bytecode (vm: &mut State, args: &[&str], bc: &[u8]) -> Vec <Value> {
	let chunk = loader::parse_chunk (&bc, &mut vm.si).unwrap ();
	run_chunk (vm, args, chunk)
}

/// Takes arguments and Lua source code, 
/// invokes `luac` to compile it to bytecode,
/// runs it, and returns the output

fn run_source (vm: &mut State, args: &[&str], s: &str) -> Vec <Value> {
	let bc = loader::compile_bytecode (s.as_bytes ().to_vec ()).unwrap ();
	run_bytecode (vm, args, &bc)
}

#[test]
fn bools () {
	/*
	local function bool_to_x (b)
		if b then
			return 99
		else
			return 98
		end
	end

	local x = bool_to_x (not not arg [1])
	print (x)
	return x
	*/
	
	let mut si = Interner::default ();
	/*
	let chunk = Chunk {
		blocks: vec! [
			Block {
				instructions: vec! [
					Inst::VarArgPrep (0),
					Inst::Closure (0, 0),
					Inst::Move (1, 0),
					
					Inst::LoadFalse (2),
					Inst::Call (1, 2, 1),
					
					Inst::Move (1, 0),
					Inst::LoadTrue (2),
					Inst::Call (1, 2, 1),
					
					Inst::Move (1, 0),
					Inst::GetTabUp (2, 0, 0),
					Inst::GetI (2, 2, 1),
					Inst::Not (2, 2),
					Inst::Not (2, 2),
					Inst::Call (1, 2, 2),
					Inst::GetTabUp (2, 0, 1),
					Inst::Move (3, 1),
					Inst::Call (2, 2, 1),
					Inst::Return (1, 2, 1, false),
					Inst::Return (2, 1, 1, false),
				],
				constants: vec! [
					si.to_value ("arg"),
					si.to_value ("print"),
				],
				upvalues: vec! [],
			}.into (),
			Block {
				instructions: vec! [
					Inst::Test (0, false),
					Inst::Jmp (3),
					Inst::LoadI (1, 99),
					Inst::Return1 (1),
					Inst::Jmp (2),
					Inst::LoadI (1, 98),
					Inst::Return1 (1),
					Inst::Return0,
				],
				constants: vec! [],
				upvalues: vec! [],
			}.into (),
		],
	};
	
	let mut vm = crate::State::new_with_args (Chunk::default (), si, vec! [].into_iter());
	
	for (arg, expected) in [
		(vec! ["_exe_name"], vec! [98.into ()]),
		(vec! ["_exe_name", "asdf"], vec! [99.into ()]),
	] {
		let expected: Vec <Value> = expected;
		
		let actual = run_chunk (&mut vm, &arg, chunk.clone ());
		assert_eq! (actual, expected);
	}
	*/
}

#[test]
fn closure () {
	let source = include_bytes! ("../test_vectors/closure.lua");
	let bytecode = &crate::loader::compile_bytecode (source.to_vec ()).unwrap ();
	let mut si = Interner::default ();
	let chunk = crate::loader::parse_chunk (bytecode, &mut si).unwrap ();
	
	let mut vm = crate::State::new_with_args (Chunk::default (), si, vec! [].into_iter());
	assert_eq! (run_chunk (&mut vm, &["_exe_name"], chunk), vec! [Value::from (23i64)]);
}

#[test]
fn floats () {
	/*
	local a = 0.5
	local b = 3

	local x = a + b

	print (x)
	return x
	*/
	
	let mut si = Interner::default ();
	/*
	let block = Block {
		instructions: vec! [
			Inst::VarArgPrep (0),
			Inst::LoadK (0, 0),
			Inst::LoadI (1, 3),
			Inst::Add (2, 0, 1),
			Inst::MmBin (0, 1, 6),
			Inst::GetTabUp (3, 0, 1),
			Inst::Move (4, 2),
			Inst::Call (3, 2, 1),
			Inst::Return (2, 2, 1, false),
			Inst::Return (3, 1, 1, false),
		],
		constants: vec! [
			0.5.into (),
			si.to_value ("print"),
		],
		upvalues: vec! [],
	};
	let chunk = Chunk {
		blocks: vec! [block.into ()],
	};
	
	let mut vm = crate::State::new_with_args (Chunk::default (), si, vec! [].into_iter());
	
	for (arg, expected) in [
		(vec! ["_exe_name"], vec! [3.5.into ()]),
		(vec! ["_exe_name", " "], vec! [3.5.into ()]),
	] {
		let expected: Vec <Value> = expected;
		let actual = run_chunk (&mut vm, &arg, chunk.clone ());
		
		assert_eq! (actual, expected);
	}
	*/
}

#[test]
fn fma () {
	let source = include_bytes! ("../test_vectors/fma.lua");
	let mut si = Interner::default ();
	let bytecode = &crate::loader::compile_bytecode (source.to_vec ()).unwrap ();
	let chunk = crate::loader::parse_chunk (bytecode, &mut si).unwrap ();
	
	assert_eq! (chunk.blocks.len (), 5);
	assert_eq! (chunk.blocks [3].upvalues.len (), 2);
	
	let i = chunk.blocks [1].instructions [0];
	assert_eq! (i.opcode (), 0x22);
	assert_eq! (i.a (), 2);
	assert_eq! (i.b (), 0);
	assert_eq! (i.c (), 1);
	
	let i = chunk.blocks [1].instructions [1];
	assert_eq! (i.opcode (), 0x2e);
	assert_eq! (i.a (), 0);
	assert_eq! (i.b (), 1);
	assert_eq! (i.c (), 6);
	
	let i = chunk.blocks [2].instructions [0];
	assert_eq! (i.opcode (), 0x24);
	assert_eq! (i.a (), 2);
	assert_eq! (i.b (), 0);
	assert_eq! (i.c (), 1);
	
	let i = chunk.blocks [2].instructions [1];
	assert_eq! (i.opcode (), 0x2e);
	assert_eq! (i.a (), 0);
	assert_eq! (i.b (), 1);
	assert_eq! (i.c (), 8);
	
	let i = chunk.blocks [3].instructions [2];
	assert_eq! (i.opcode (), 0x00);
	assert_eq! (i.a (), 5);
	assert_eq! (i.b (), 0);
	
	let i = chunk.blocks [3].instructions [4];
	assert_eq! (i.opcode (), 0x44);
	assert_eq! (i.a (), 4);
	assert_eq! (i.b (), 3);
	assert_eq! (i.c (), 2);
	
	let i = chunk.blocks [4].instructions [1];
	assert_eq! (i.opcode (), 0x01);
	assert_eq! (i.a (), 1);
	assert_eq! (i.sbx (), 10);
	
	let mut vm = crate::State::new_with_args (chunk, si, vec! ["_exe_name".to_string ()].into_iter ());
	let actual = vm.execute ().unwrap ();
	let expected = vec! [Value::from (122)];
	
	assert_eq! (actual, expected);
}

#[test]
fn function_calls () {
	let si = Interner::default ();
	let mut vm = crate::State::new_with_args (crate::Chunk::default (), si, vec! ["_exe_name".to_string ()].into_iter ());
	
	vm.eval ("print (x ())").ok ();
	vm.eval ("x = function () return 5 end").ok ();
	
	// Currently failing because I don't have a way to jump into a Lua
	// function that's no longer in the currently-executing chunk
	vm.eval ("print (x ())").ok ();
}

#[test]
fn function_returns () {
	let si = Interner::default ();
	let mut vm = crate::State::new_with_args (crate::Chunk::default (), si, vec! ["_exe_name".to_string ()].into_iter ());
	
	assert_eq! (
		vm.eval ("return ((function () return 5 end)())").unwrap (), 
		vec! [Value::from (5)]
	);	
	assert_eq! (
		vm.eval ("return (math.sqrt (25))").unwrap (), 
		vec! [Value::from (5.0)]
	);
	
	
}

#[test]
fn heap () {
	use std::{
		cell::RefCell,
		collections::HashMap,
		rc::Rc,
	};
	use crate::value::Table;
	
	let mut si = Interner::default ();
	
	{
		let mut allocations = HashMap::new ();
		let mut ctr = 0;
		
		let c = ctr;
		allocations.insert (ctr, Table::default ());
		ctr += 1;
		
		let a = ctr;
		allocations.insert (ctr, Table::default ());
		ctr += 1;
		
		allocations.get_mut (&a).unwrap ().insert (1, c);
		
		allocations.get_mut (&c).unwrap ().insert (2, si.to_value ("eee"));
	}
	
	if true {
		#[derive (Clone, Debug, PartialEq)]
		enum Value {
			S (Rc <String>),
			T (Rc <RefCell <HashMap <i64, Value>>>),
		}
		
		let c = Value::T (Default::default ());
		
		let a = Value::T (Default::default ());
		match &a {
			Value::T (t) => t.borrow_mut ().insert (1, c.clone ()),
			_ => panic! ("impossible"),
		};
		
		match &c {
			Value::T (t) => t.borrow_mut ().insert (2, Value::S (Rc::new (String::from ("eee")))),
			_ =>panic! ("impossible"),
		};
		
		let actual = match &a {
			Value::T (t) => match t.borrow ().get (&1) {
				Some (Value::T (t)) => t.borrow ().get (&2).unwrap ().clone (),
				_ => panic! ("impossible"),
			},
			_ => panic! ("impossible"),
		};
		
		assert_eq! (actual, Value::S (Rc::new ("eee".into ())));
	}
}

#[test]
fn is_93 () {
	let mut si = Interner::default ();
	
	assert_eq! (si.to_value ("93"), si.to_value ("93"));
	assert_ne! (si.to_value ("94"), si.to_value ("93"));
	assert_ne! (calculate_hash (&si.to_value ("94")), calculate_hash (&si.to_value ("93")));
	assert_ne! (Value::Nil, si.to_value ("93"));
	
	let src = br#"
	if arg [1] == "93" then
		print "it's 93"
		return 0
	else
		print "it's not 93"
		return 1
	end
	"#;
	
	let bc = loader::compile_bytecode (src.to_vec ()).unwrap ();
	let chunk = loader::parse_chunk (&bc, &mut si).unwrap ();
	
	let i = chunk.blocks [0].instructions [3];
	assert_eq! (i.opcode (), 0x3c);
	assert_eq! (i.a (), 0);
	assert_eq! (i.b (), 1);
	assert_eq! (i.k (), false);
	
	let i = chunk.blocks [0].instructions [4];
	assert_eq! (i.opcode (), 0x38);
	assert_eq! (i.sj (), 6);
	
	let mut vm = crate::State::new_with_args (Chunk::default (), si, vec! [].into_iter());
	
	let run = run_chunk;
	
	assert_eq! (run (&mut vm, &[""], chunk.clone ()), vec! [Value::from (1)]);
	assert_eq! (run (&mut vm, &["", "93"], chunk.clone ()), vec! [Value::from (0)]);
	assert_eq! (run (&mut vm, &["", "94"], chunk.clone ()), vec! [Value::from (1)]);
}

#[test]
fn native_functions () {
	fn add (_: &mut State) -> i32 {
		0
	}
	
	fn multiply (_: &mut State) -> i32 {
		0
	}
	
	fn greet (_: &mut State) -> i32 {
		0
	}
	
	let _funcs = [
		add,
		multiply,
		greet,
	];
}

#[test]
fn tables_1 () {
	// I don't capture stdout yet, but I can at least make sure basic table
	// operations don't crash
	
	let src = r#"
	print " 1"
	
	print (nil)
	print (false)
	print (true)
	print (1993)
	print (1993.00)
	print "Hello."
	
	print " 2"
	
	local t = {}
	print (t)
	print (t [1])
	t [1] = "asdf"
	print (t [1])
	t.x = 1993
	print (t.x)
	
	t.t = { 3.14159 }
	print (t ["t"][1])
	"#;
	
	let si = Interner::default ();
	let mut vm = crate::State::new_with_args (Chunk::default (), si, vec! [].into_iter());
	run_source (&mut vm, &[], src);
}

#[test]
fn tables_2 () {
	let src = r#"
	print " 3"
	
	local c = {}
	local a = { c }
	print (a [1])
	c [2] = "eee"
	print (a [2])
	"#;
	
	let si = Interner::default ();
	let mut vm = crate::State::new_with_args (Chunk::default (), si, vec! [].into_iter());
	run_source (&mut vm, &[], src);
}

#[test]
fn tailcall () {
	let mut si = Interner::default ();
	
	let src = br#"
	return tonumber ("5")
	"#;
	
	let bc = loader::compile_bytecode (src.to_vec ()).unwrap ();
	let chunk = loader::parse_chunk (&bc, &mut si).unwrap ();
	
	// assert_eq! (chunk.blocks [0].instructions [3].opcode (), Instruction::TailCall (0, 2, 1, false));
	assert_eq! (chunk.blocks [0].instructions [3].opcode (), 0x45);
	
	let mut vm = crate::State::new_with_args (Chunk::default (), si, vec! [].into_iter());
	
	let actual = run_chunk (&mut vm, &[], chunk);
	let expected = vec! [Value::from (5)];
	
	assert_eq! (actual, expected);
}

#[test]
fn rust_stuff () {
	// Per https://www.lua.org/doc/jucs05.pdf,
	// "The Implementation of Lua 5.0",
	// 
	// Lua's tagged union values are 12-16 bytes on a 32-bit system
	// with 64-bit floats
	// 
	// It would be nice if LunarWaveVM is the same or better.
	// I'm also just checking a bunch of my assumptions about how
	// Rust organizes and sizes different types
	
	use std::mem::size_of;
	
	{
		// Make sure that Rx / Box are both pointers that hide the size
		// of big types
		
		assert! (size_of::<Box <()>> () <= 8);
		assert! (size_of::<std::rc::Rc <()>> () <= 8);
	}
	
	{
		// Make sure LWVM's Values are 16 bytes or smaller.
		// Because types are usually aligned to their size, f64s
		// are supposed to be aligned to 8 bytes. So even an `Option <f64>`
		// uses 8 bytes to say "Some" or "None".
		// I could _maybe_ fudge this somehow but it's fine to start with.
		
		let sz = size_of::<crate::value::Value> ();
		let expected = 16;
		assert! (sz <= expected, "{sz} > {expected}");
	}
	
	{
		// All these are 8 bytes for the same reason Value is 16 bytes.
		// Luckily Rust doesn't seem to stack the 4-byte overhead
		// of Result and Option.
		
		let sz = size_of::<(i32, i32)> ();
		let expected = 8;
		assert! (sz == expected, "{sz} != {expected}");
		
		let sz = size_of::<Option <i32>> ();
		let expected = 8;
		assert! (sz == expected, "{sz} != {expected}");
		
		let sz = size_of::<Result <i32, i32>> ();
		let expected = 8;
		assert! (sz == expected, "{sz} != {expected}");
		
		let sz = size_of::<Result <Option <i32>, i32>> ();
		let expected = 8;
		assert! (sz == expected, "{sz} != {expected}");
	}
	
	assert_eq! (size_of::<crate::instruction::Instruction> (), 8);
	
	let x = vec! [100, 101, 102, 103];
	let x: Rc <[u32]> = Rc::from (x);
}