#define _GNU_SOURCE
#include <assert.h>
#include <glob.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "cbs.h"

#define TARGET "oryx"

enum {
	SIMD_AVX2 = 1 << 0,
	SIMD_NEON = 1 << 1,
	SIMD_SSE4_1 = 1 << 2,
};

static char *cflags_all[] = {
	"-pipe",
	"-std=c11",
	"-Wall",
	"-Wextra",
	"-Wno-attributes",
	"-Wno-parentheses",
	"-Wno-pointer-sign",
	"-Wpedantic",
	"-Wvla",
#if __GLIBC__
	"-D_GNU_SOURCE",
#endif
#if __GNUC__
	"-Dlikely(x)=__builtin_expect(!!(x), 1)",
	"-Dunlikely(x)=__builtin_expect(!!(x), 0)",
#else
	"-D__attribute__(x)=",
	"-Dlikely(x)=(x)",
	"-Dunlikely(x)=(x)",
#endif
};

static char *cflags_dbg[] = {
	"-DDEBUG=1", "-fsanitize=address,undefined", "-g3", "-ggdb3", "-O0",
};

static char *cflags_rls[] = {
	"-DNDEBUG=1", "-flto", "-march=native", "-mtune=native", "-O3",
};

static char *argv0;
static bool fflag, rflag;
static int simd_flags;

static void cc(void *);
static void ld(void);
static bool tagvalid(const char *);
static void ckd_cpu_flags(void);
static int globerr(const char *, int);

static void
usage(void)
{
	fprintf(stderr,
	        "Usage: %s [-fr]\n"
	        "       %s clean\n",
	        argv0, argv0);
	exit(EXIT_FAILURE);
}

int
main(int argc, char **argv)
{
	cbsinit(argc, argv);
	rebuild();

	argv0 = argv[0];

	int opt;
	while ((opt = getopt(argc, argv, "fr")) != -1) {
		switch (opt) {
		case 'f':
			fflag = true;
			break;
		case 'r':
			rflag = true;
			break;
		default:
			usage();
		}
	}

	argc -= optind;
	argv += optind;

	struct strs cmd = {0};

	if (argc > 0) {
		if (strcmp("clean", *argv) == 0) {
			strspushl(&cmd, "find", ".", "-name", TARGET, "-or", "-name", "*.o",
			          "-delete");
			cmdput(cmd);
			cmdexec(cmd);
		} else {
			fprintf(stderr, "%s: invalid subcommand — ‘%s’\n", argv0, *argv);
			usage();
		}

		return EXIT_SUCCESS;
	}

	ckd_cpu_flags();

	glob_t g;
	assert(glob("src/*.c", 0, globerr, &g) == 0);

	int procs = nproc();
	if (procs == -1)
		procs = 8;

	tpool tp;
	tpinit(&tp, procs);
	for (size_t i = 0; i < g.gl_pathc; i++)
		tpenq(&tp, cc, g.gl_pathv[i], NULL);
	tpwait(&tp);
	tpfree(&tp);

	ld();

	globfree(&g);
	strsfree(&cmd);
	return EXIT_SUCCESS;
}

void
cc(void *arg)
{
	if (!tagvalid(arg))
		return;

	struct strs cmd = {0};
	char *dst = swpext(arg, "o"), *src = arg;

	if (!fflag && !foutdatedl(dst, src))
		goto out;

	strspushenvl(&cmd, "CC", "cc");
	strspush(&cmd, cflags_all, lengthof(cflags_all));
	if (rflag)
		strspushenv(&cmd, "CFLAGS", cflags_rls, lengthof(cflags_rls));
	else
		strspushenv(&cmd, "CFLAGS", cflags_dbg, lengthof(cflags_dbg));
	if (simd_flags != 0)
		strspushl(&cmd, "-DORYX_SIMD=1");
	strspushl(&cmd, "-o", dst, "-c", src);

	cmdput(cmd);
	cmdexec(cmd);
	strsfree(&cmd);
out:
	free(dst);
}

void
ld(void)
{
	glob_t g;
	bool dobuild = fflag;
	struct strs cmd = {0};

	strspushenvl(&cmd, "CC", "cc");
	strspush(&cmd, cflags_all, lengthof(cflags_all));
	if (rflag)
		strspushenv(&cmd, "CFLAGS", cflags_rls, lengthof(cflags_rls));
	else
		strspushenv(&cmd, "CFLAGS", cflags_dbg, lengthof(cflags_dbg));
	strspushl(&cmd, "-o", TARGET);

	assert(glob("src/*.o", 0, globerr, &g) == 0);
	for (size_t i = 0; i < g.gl_pathc; i++) {
		if (!tagvalid(g.gl_pathv[i]))
			continue;
		if (foutdatedl(TARGET, g.gl_pathv[i]))
			dobuild = true;
		strspushl(&cmd, g.gl_pathv[i]);
	}

	if (dobuild) {
		cmdput(cmd);
		cmdexec(cmd);
	}

	globfree(&g);
	strsfree(&cmd);
}

bool
tagvalid(const char *file)
{
	if (strstr(file, "-avx2.") != NULL && (simd_flags & SIMD_AVX2) == 0)
		return false;
	if (strstr(file, "-neon.") != NULL && (simd_flags & SIMD_NEON) == 0)
		return false;
	if (strstr(file, "-sse4_1.") != NULL && (simd_flags & SIMD_SSE4_1) == 0)
		return false;
	return true;
}

void
ckd_cpu_flags(void)
{
	if (!rflag)
		return;
#if __GNUC__ && __x86_64__
	uint32_t exx;

	asm volatile("cpuid" : "=b"(exx) : "a"(7), "c"(0));
	if (exx & (1 << 5)) {
		simd_flags |= SIMD_AVX2;
		return;
	}

	asm volatile("cpuid" : "=c"(exx) : "a"(1), "c"(0));
	if (exx & (1 << 19))
		simd_flags |= SIMD_SSE4_1;
#elif __ARM_NEON
	simd_flags |= SIMD_NEON;
#endif
}

int
globerr(const char *s, int e)
{
	fprintf(stderr, "glob: %s: %s\n", s, strerror(e));
	exit(EXIT_FAILURE);
}