// selfhost/cmd/wcc/type.ww — port of cmd/wcc/type.c.
//
// Status: full structural port. The C version uses module-globals for
// the primitive types (tyvoid, tyi32, …); ww doesn't have writable
// global storage yet, so we bundle the primitives into a `tctx` that
// the checker passes around explicitly. typesinit fills the tctx
// once per arena.

use os;
use mem;

// ---- TypeKind ---------------------------------------------------------
// Numeric values must stay aligned with cmd/wcc/ww.h TypeKind so the
// next diff signal (typed-AST printer / cgen) can compare across the
// two implementations.

def TY_NONE:     i32 = 0;
def TY_VOID:     i32 = 1;
def TY_BOOL:     i32 = 2;
def TY_RUNE:     i32 = 3;
def TY_I8:       i32 = 4;
def TY_I16:      i32 = 5;
def TY_I32:      i32 = 6;
def TY_I64:      i32 = 7;
def TY_U8:       i32 = 8;
def TY_U16:      i32 = 9;
def TY_U32:      i32 = 10;
def TY_U64:      i32 = 11;
def TY_UINT:     i32 = 12;
def TY_INT:      i32 = 13;
def TY_UINTPTR:  i32 = 14;
def TY_F32:      i32 = 15;
def TY_F64:      i32 = 16;
def TY_STR:      i32 = 17;
def TY_PTR:      i32 = 18;
def TY_SLICE:    i32 = 19;
def TY_ARRAY:    i32 = 20;
def TY_STRUCT:   i32 = 21;
def TY_FN:       i32 = 22;
def TY_CHAN:     i32 = 23;
def TY_NAMED:    i32 = 24;
def TY_TUPLE:    i32 = 25;
def TY_TAGGED:   i32 = 26;
def TY_ERR:      i32 = 27;
def TY_UNTYPED_INT:   i32 = 28;
def TY_UNTYPED_FLOAT: i32 = 29;
def TY_UNTYPED_STR:   i32 = 30;
def TY_UNTYPED_RUNE:  i32 = 31;
def TY_UNTYPED_BOOL:  i32 = 32;
def TY_UNTYPED_NIL:   i32 = 33;

// ---- tinfo / tfield / tparam -----------------------------------------

type tfield = struct {
	name:   str,
	type_:  *tinfo,
	offset: u64,
	tnext:  *tfield,
};

type tparam = struct {
	name:   str,
	type_:  *tinfo,
	tnext:  *tparam,
};

type tinfo = struct {
	kind:     i32,
	size:     u64,
	align:    u64,
	sub:      *tinfo,	// ptr/slice/array/chan element
	alen:     u64,
	fields:   *tfield,
	params:   *tparam,
	ret:      *tinfo,
	variadic: i32,
	name:     str,
	under:    *tinfo,
};

// ---- tctx — the box of primitive types -------------------------------

type tctx = struct {
	a:        *arena,
	tyvoid:  *tinfo,
	tybool:  *tinfo,
	tyrune:  *tinfo,
	tyi8:    *tinfo,
	tyi16:   *tinfo,
	tyi32:   *tinfo,
	tyi64:   *tinfo,
	tyu8:    *tinfo,
	tyu16:   *tinfo,
	tyu32:   *tinfo,
	tyu64:   *tinfo,
	tyint:   *tinfo,
	tyuint:  *tinfo,
	tyuintptr: *tinfo,
	tyf32:   *tinfo,
	tyf64:   *tinfo,
	tystr:   *tinfo,
	tyerr:   *tinfo,
	tyuntypedint:   *tinfo,
	tyuntypedfloat: *tinfo,
	tyuntypedstr:   *tinfo,
	tyuntypedrune:  *tinfo,
	tyuntypedbool:  *tinfo,
	tyuntypednil:   *tinfo,
};

// ---- constructors -----------------------------------------------------

export fn newtype(a: *arena, k: i32) *tinfo = {
	let t: *tinfo = amalloc(a, 96u64): *tinfo;
	t.kind = k;
	return t;
};

fn prim(a: *arena, k: i32, nm: str, sz: u64, al: u64) *tinfo = {
	let t: *tinfo = newtype(a, k);
	t.name = nm;
	t.size = sz;
	if (al > 0u64) { t.align = al; } else { t.align = sz; };
	return t;
};

export fn typesinit(c: *tctx, a: *arena) void = {
	c.a = a;
	c.tyvoid   = prim(a, TY_VOID, "void",  0u64, 1u64);
	c.tybool   = prim(a, TY_BOOL, "bool",  1u64, 1u64);
	c.tyrune   = prim(a, TY_RUNE, "rune",  4u64, 4u64);
	c.tyi8     = prim(a, TY_I8,   "i8",    1u64, 1u64);
	c.tyi16    = prim(a, TY_I16,  "i16",   2u64, 2u64);
	c.tyi32    = prim(a, TY_I32,  "i32",   4u64, 4u64);
	c.tyi64    = prim(a, TY_I64,  "i64",   8u64, 8u64);
	c.tyu8     = prim(a, TY_U8,   "u8",    1u64, 1u64);
	c.tyu16    = prim(a, TY_U16,  "u16",   2u64, 2u64);
	c.tyu32    = prim(a, TY_U32,  "u32",   4u64, 4u64);
	c.tyu64    = prim(a, TY_U64,  "u64",   8u64, 8u64);
	c.tyint    = prim(a, TY_INT,  "int",   8u64, 8u64);
	c.tyuint   = prim(a, TY_UINT, "uint",  8u64, 8u64);
	c.tyuintptr= prim(a, TY_UINTPTR, "uintptr", 8u64, 8u64);
	c.tyf32    = prim(a, TY_F32,  "f32",   4u64, 4u64);
	c.tyf64    = prim(a, TY_F64,  "f64",   8u64, 8u64);
	c.tystr    = prim(a, TY_STR,  "str",  16u64, 8u64);
	c.tyerr    = prim(a, TY_ERR,  "<err>", 0u64, 1u64);

	c.tyuntypedint   = prim(a, TY_UNTYPED_INT,   "untyped_int",   0u64, 1u64);
	c.tyuntypedfloat = prim(a, TY_UNTYPED_FLOAT, "untyped_float", 0u64, 1u64);
	c.tyuntypedstr   = prim(a, TY_UNTYPED_STR,   "untyped_str",   0u64, 1u64);
	c.tyuntypedrune  = prim(a, TY_UNTYPED_RUNE,  "untyped_rune",  0u64, 1u64);
	c.tyuntypedbool  = prim(a, TY_UNTYPED_BOOL,  "untyped_bool",  0u64, 1u64);
	c.tyuntypednil   = prim(a, TY_UNTYPED_NIL,   "untyped_nil",   0u64, 1u64);
};

export fn typeptr(a: *arena, sub: *tinfo) *tinfo = {
	let t: *tinfo = newtype(a, TY_PTR);
	t.sub = sub;
	t.size = 8u64;
	t.align = 8u64;
	return t;
};

export fn typeslice(a: *arena, sub: *tinfo) *tinfo = {
	let t: *tinfo = newtype(a, TY_SLICE);
	t.sub = sub;
	t.size = 24u64;
	t.align = 8u64;
	return t;
};

export fn typearray(a: *arena, sub: *tinfo, n: u64) *tinfo = {
	let t: *tinfo = newtype(a, TY_ARRAY);
	t.sub = sub;
	t.alen = n;
	if (sub != nil) {
		t.size = sub.size * n;
		t.align = sub.align;
	} else {
		t.align = 1u64;
	};
	return t;
};

export fn typechan(a: *arena, sub: *tinfo) *tinfo = {
	let t: *tinfo = newtype(a, TY_CHAN);
	t.sub = sub;
	t.size = 8u64;
	t.align = 8u64;
	return t;
};

export fn typenamed(a: *arena, name: str, under: *tinfo) *tinfo = {
	let t: *tinfo = newtype(a, TY_NAMED);
	t.name = name;
	t.under = under;
	if (under != nil) {
		t.size = under.size;
		t.align = under.align;
	};
	return t;
};

// ---- predicates -------------------------------------------------------

export fn typeisint(t: *tinfo) bool = {
	if (t == nil) { return false; };
	let k: i32 = t.kind;
	if (k == TY_I8)  { return true; };
	if (k == TY_I16) { return true; };
	if (k == TY_I32) { return true; };
	if (k == TY_I64) { return true; };
	if (k == TY_U8)  { return true; };
	if (k == TY_U16) { return true; };
	if (k == TY_U32) { return true; };
	if (k == TY_U64) { return true; };
	if (k == TY_INT) { return true; };
	if (k == TY_UINT){ return true; };
	if (k == TY_UINTPTR) { return true; };
	if (k == TY_RUNE){ return true; };
	if (k == TY_UNTYPED_INT)  { return true; };
	if (k == TY_UNTYPED_RUNE) { return true; };
	if (k == TY_NAMED) { return typeisint(t.under); };
	return false;
};

export fn typeisfloat(t: *tinfo) bool = {
	if (t == nil) { return false; };
	let k: i32 = t.kind;
	if (k == TY_F32) { return true; };
	if (k == TY_F64) { return true; };
	if (k == TY_UNTYPED_FLOAT) { return true; };
	if (k == TY_NAMED) { return typeisfloat(t.under); };
	return false;
};

export fn typeisnum(t: *tinfo) bool = {
	if (typeisint(t)) { return true; };
	return typeisfloat(t);
};

export fn typeisunsigned(t: *tinfo) bool = {
	if (t == nil) { return false; };
	let k: i32 = t.kind;
	if (k == TY_U8)  { return true; };
	if (k == TY_U16) { return true; };
	if (k == TY_U32) { return true; };
	if (k == TY_U64) { return true; };
	if (k == TY_UINT){ return true; };
	if (k == TY_UINTPTR) { return true; };
	if (k == TY_NAMED) { return typeisunsigned(t.under); };
	return false;
};

export fn typeisuntyped(t: *tinfo) bool = {
	if (t == nil) { return false; };
	let k: i32 = t.kind;
	if (k == TY_UNTYPED_INT)   { return true; };
	if (k == TY_UNTYPED_FLOAT) { return true; };
	if (k == TY_UNTYPED_STR)   { return true; };
	if (k == TY_UNTYPED_RUNE)  { return true; };
	if (k == TY_UNTYPED_BOOL)  { return true; };
	if (k == TY_UNTYPED_NIL)   { return true; };
	return false;
};

// typeeq — structural equality. Named types compare nominally.
export fn typeeq(a: *tinfo, b: *tinfo) bool = {
	if (a == b) { return true; };
	if (a == nil) { return false; };
	if (b == nil) { return false; };
	if (a.kind != b.kind) { return false; };
	let k: i32 = a.kind;
	if (k == TY_PTR)   { return typeeq(a.sub, b.sub); };
	if (k == TY_SLICE) { return typeeq(a.sub, b.sub); };
	if (k == TY_CHAN)  { return typeeq(a.sub, b.sub); };
	if (k == TY_ARRAY) {
		if (a.alen != b.alen) { return false; };
		return typeeq(a.sub, b.sub);
	};
	if (k == TY_FN) {
		if (a.variadic != b.variadic) { return false; };
		if (!typeeq(a.ret, b.ret))   { return false; };
		let pa: *tparam = a.params;
		let pb: *tparam = b.params;
		for (true) {
			if (pa == nil) { if (pb == nil) { return true; }; return false; };
			if (pb == nil) { return false; };
			if (!typeeq(pa.type_, pb.type_)) { return false; };
			pa = pa.tnext;
			pb = pb.tnext;
		};
		return true;
	};
	if (k == TY_STRUCT) {
		let fa: *tfield = a.fields;
		let fb: *tfield = b.fields;
		for (true) {
			if (fa == nil) { if (fb == nil) { return true; }; return false; };
			if (fb == nil) { return false; };
			let na: str = fa.name;
			let nb: str = fb.name;
			if (na.len != nb.len) { return false; };
			let i: i32 = 0;
			for (i < na.len) {
				if (na[i] != nb[i]) { return false; };
				i += 1;
			};
			if (!typeeq(fa.type_, fb.type_)) { return false; };
			fa = fa.tnext;
			fb = fb.tnext;
		};
		return true;
	};
	if (k == TY_NAMED) { return false; };	// nominal: only same ptr
	if (k == TY_TUPLE) {
		let pa: *tparam = a.params;
		let pb: *tparam = b.params;
		for (true) {
			if (pa == nil) { if (pb == nil) { return true; }; return false; };
			if (pb == nil) { return false; };
			if (!typeeq(pa.type_, pb.type_)) { return false; };
			pa = pa.tnext;
			pb = pb.tnext;
		};
		return true;
	};
	return true;	// primitives match by kind alone
};