#include <builtin.h>
#include <cache.h>
#include <fcntl.h>

#undef NORETURN
#undef PATH_SEP

#include <ruby.h>

static VALUE shellwords;

struct cmd_struct {
	const char *cmd;
	int (*fn)(int, const char **, const char *);
	int option;
};

#define RUN_SETUP (1 << 0)
#define RUN_SETUP_GENTLY (1 << 1)
#define USE_PAGER (1 << 2)
#define NEED_WORK_TREE (1 << 3)

static struct cmd_struct commands[] = {
	{ "rev-parse", cmd_rev_parse },
	{ "show", cmd_show, RUN_SETUP },
};

static VALUE git_rb_backticks(int o_argc, VALUE *o_argv, VALUE ctx)
{
	int argc, i, old;
	int pipefd[2];
	const char **argv;
	char buf[0x1000];
	VALUE command;
	int do_read;
	struct cmd_struct *cmd = NULL;
	const char *prefix = NULL;

	if (strncmp(RSTRING_PTR(o_argv[0]), "git ", 4)) {
		VALUE port, result;
		port = rb_funcall(rb_cIO, rb_intern("popen"), 1, o_argv[0]);
		result = rb_funcall(port, rb_intern("read"), 0);
		rb_funcall(result, rb_intern("chomp!"), 0);
		rb_io_close(port);
		return result;
	}

	command = rb_funcall(shellwords, rb_intern("shellsplit"), 1, o_argv[0]);
	rb_ary_shift(command);

	argc = RARRAY_LEN(command);
	argv = xcalloc(sizeof(*argv), argc);

	VALUE *rarray = RARRAY_PTR(command);
	for (i = 0; i < argc; i++)
		argv[i] = RSTRING_PTR(rarray[i]);

	old = dup(1);
	i = pipe(pipefd);
	dup2(pipefd[1], 1);
	close(pipefd[1]);

	for (i = 0; i < ARRAY_SIZE(commands); i++) {
		struct cmd_struct *p = &commands[i];
		if (strcmp(p->cmd, argv[0]))
			continue;
		cmd = p;
	}

	if (!cmd)
		rb_raise(rb_eArgError, "unknown command: %s", argv[0]);

	if (cmd->option & RUN_SETUP)
		prefix = setup_git_directory();

	i = cmd->fn(argc, argv, prefix);
	rb_last_status_set(i, getpid());

	fflush(stdout);
	dup2(old, 1);

	i = read(pipefd[0], buf, sizeof(buf));
	if (buf[i - 1] == '\n')
		i -= 1;
	buf[i] = '\0';

	return rb_str_new(buf, i);
}

void Init_git(void)
{
	rb_require("shellwords");
	shellwords = rb_define_module("Shellwords");
	rb_define_global_function("`", git_rb_backticks, -1);
}