// selfhost/cmd/w6a/main.ww — port of cmd/w6a/main.c.
//
// w6a = amd64 assembler. Read .s, parse, encode, emit ELF .o.
//
//   w6a_ww -o file.o file.s

use os;
use mem;
use types;
use lex;
use parse;
use asm;
use obj;

fn cstreq(a: *u8, lit: str) bool = {
	let n: u64 = lit.len: u64;
	let i: u64 = 0u64;
	for (i < n) {
		let li: i32 = i: i32;
		if (a[i] != lit[li]) { return false; };
		i += 1u64;
	};
	if (a[i] != 0u8) { return false; };
	return true;
};

fn cstrlen(p: *u8) u64 = {
	let n: u64 = 0u64;
	for (p[n] != 0u8) { n += 1u64; };
	return n;
};

// Slurp the whole file into a fresh buffer.
fn slurp(path: *u8) (*u8, u64) = {
	let fd: i32 = os.open(path, os.O_RDONLY, 0i32);
	if (fd < 0) { return nil, 0u64; };
	let n: i64 = os.filesize(fd);
	if (n < 0i64) { os.close(fd); return nil, 0u64; };
	let nz: u64 = n: u64;
	let buf: *u8 = os.alloc(nz + 1u64): *u8;
	let got: i64 = os.readfull(fd, buf, nz);
	os.close(fd);
	if (got != n) { return nil, 0u64; };
	buf[nz] = 0u8;
	return buf, nz;
};

export fn main(argc: i32, argv: **u8) i32 = {
	let src: *u8 = nil;
	let out: *u8 = nil;

	let i: i32 = 1;
	for (i < argc) {
		let a: *u8 = argv[i];
		if (cstreq(a, "-o")) {
			i += 1;
			if (i >= argc) {
				os.write(2, "w6a: -o requires arg\n".ptr, 20u64);
				return 2;
			};
			out = argv[i];
		} else { if (a[0u64] == 45u8) {
			os.write(2, "w6a: unknown flag\n".ptr, 17u64);
			return 2;
		} else {
			if (src != nil) {
				os.write(2, "w6a: only one input\n".ptr, 19u64);
				return 2;
			};
			src = a;
		}; };
		i += 1;
	};

	if (src == nil) {
		os.write(2, "usage: w6a_ww -o file.o file.s\n".ptr, 30u64);
		return 2;
	};
	if (out == nil) {
		os.write(2, "w6a: missing -o\n".ptr, 15u64);
		return 2;
	};

	let buf: *u8;
	let blen: u64;
	buf, blen = slurp(src);
	if (buf == nil) {
		os.write(2, "w6a: cannot read input\n".ptr, 22u64);
		return 1;
	};

	let ar: *arena = newarena();
	let asm: asm_;
	let nlen: u64 = cstrlen(src);
	let fname: str = astrndup(ar, src, nlen);
	a_init(&asm, ar, fname, buf, blen);

	if (a_parse(&asm) != 0) { return 1; };
	if (a_encode(&asm) != 0) { return 1; };

	// Open output for write.
	let fd: i32 = os.open(out, os.O_WRONLY | os.O_CREAT | os.O_TRUNC, 420i32);	// 0o644
	if (fd < 0) {
		os.write(2, "w6a: cannot open output\n".ptr, 23u64);
		return 1;
	};
	let rc: i32 = a_emit_elf(&asm, fd);
	os.close(fd);
	return rc;
};