// cp.c, version 0.0.2
// OMKOV coreutils implementation of POSIX cp
// Copyright (C) 2021, Jakob Wakeling
// MIT Licence

#include "util/error.h"
#include "util/optget.h"

#include <sys/stat.h>

#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>

#define VERSION "0.0.2"

static struct lop lops[] = {
	{ "help",    ARG_NUL, 256 },
	{ "version", ARG_NUL, 257 },
	{ NULL, 0, 0 }
};

static bool fflag, Hflag, iflag, Lflag, Pflag, pflag, Rflag;

static inline void cp(const char *dst, char *const *src, size_t n);
static inline void fcopy(const char *dst, const char *src);
static inline bool fsame(FILE *f1, FILE *f2);

static void hlp(void);
static void ver(void);

int main(int ac, char *av[]) { A0 = av[0];
	struct opt opt = OPTGET_INIT; opt.str = "fHiLPpR"; opt.lops = lops;
	for (int o; (o = optget(&opt, av, 1)) != -1;) switch (o) {
	case 'f': { fflag = true; break; }
	case 'H': { Hflag = true; break; }
	case 'i': { iflag = true; break; }
	case 'L': { Lflag = true; break; }
	case 'P': { Pflag = true; break; }
	case 'p': { pflag = true; break; }
	case 'R': { Rflag = true; break; }
	case 256: { hlp(); return 0; }
	case 257: { ver(); return 0; }
	default: { return 1; }
	}
	
	if (opt.ind == ac) { error(1, "missing source operand"); }
	else if (opt.ind == ac - 1) { error(1, "missing destination operand"); }
	else { cp(av[ac - 1], &av[opt.ind], ac - opt.ind - 1); }
	
	return warned;
}

/* Copy one or more files to a specified destination */
static inline void cp(const char *dst, char *const *src, size_t n) {
	return fcopy(dst, *src);
}

/* Copy a file to a specified destination */
static inline void fcopy(const char *dst, const char *src) {
	uint8_t b[BUFSIZ * 16]; FILE *fi = NULL, *fo = NULL; struct stat st;
	
	if (!(fi = fopen(src, "rb"))) { warn("%s: %s", src, serr()); goto end; }
	if (!(fo = fopen(dst, "wb"))) { warn("%s: %s", dst, serr()); goto end; }
	
	if (fsame(fi, fo)) { warn("%s, %s: same file", src, dst); goto end; }
	
	for (register size_t c; (c = fread(b, 1, sizeof (b), fi));) {
		if (fwrite(b, 1, c, fo) != c) { warn("%s: %s", dst, serr()); goto end; }
	}
	
	// Copy permissions from src to destination
	if (stat(src, &st)) { warn("%s: %s", src, serr()); goto end; }
	if (chmod(dst, st.st_mode)) { warn("%s: %s", dst, serr()); goto end; }
	
end:;
	if (fi && fclose(fi)) { warn("%s: %s", src, serr()); }
	if (fo && fclose(fo)) { warn("%s: %s", dst, serr()); }
	return;
}

/* Check if two FILEs point to the same file */
static inline bool fsame(FILE *f1, FILE *f2) {
	struct stat s1, s2; fstat(fileno(f1), &s1); fstat(fileno(f2), &s2);
	return (s1.st_dev == s2.st_dev) && (s1.st_ino == s2.st_ino);
}

/* Print help information */
static void hlp(void) {
	puts("cp - Copy files");
	puts("\nUsage:");
	puts("  cp [-Pfip] source destination");
	puts("  cp [-Pfip] source... destination");
	puts("  cp -R [-H|-L|-P] [-fip] source... destination");
	puts("\nOptions:");
	puts("  -f         UNIMPLEMENTED");
	puts("  -H         UNIMPLEMENTED");
	puts("  -i         UNIMPLEMENTED");
	puts("  -L         UNIMPLEMENTED");
	puts("  -P         UNIMPLEMENTED");
	puts("  -p         UNIMPLEMENTED");
	puts("  -R         UNIMPLEMENTED");
	puts("  --help     Display help information");
	puts("  --version  Display version information");
}

/* Print version information */
static void ver(void) {
	puts("OMKOV coreutils cp, version " VERSION);
	puts("Copyright (C) 2021, Jakob Wakeling");
	puts("MIT Licence (https://opensource.org/licenses/MIT)");
}