#ifndef LIGHTNING_LIGHTNINGD_SUBD_H
#define LIGHTNING_LIGHTNINGD_SUBD_H
#include "config.h"
#include <ccan/endian/endian.h>
#include <ccan/list/list.h>
#include <ccan/short_types/short_types.h>
#include <ccan/tal/tal.h>
#include <lightningd/msg_queue.h>

struct io_conn;

enum subd_msg_ret {
	SUBD_NEED_FD,
	SUBD_COMPLETE
};

/* By convention, replies are requests + 100 */
#define SUBD_REPLY_OFFSET 100

/* One of our subds. */
struct subd {
	/* Name, like John, or "lightningd_hsm" */
	const char *name;
	/* The Big Cheese. */
	struct lightningd *ld;
	/* pid, for waiting for status when it dies. */
	int pid;
	/* Connection. */
	struct io_conn *conn;

	/* If we are associated with a single peer, this points to it. */
	struct peer *peer;

	/* For logging */
	struct log *log;

	/* Callback when non-reply message comes in. */
	enum subd_msg_ret (*msgcb)(struct subd *, const u8 *, int);
	const char *(*msgname)(int msgtype);
	void (*finished)(struct subd *sd, int status);

	/* Buffer for input. */
	u8 *msg_in;
	/* While we're reading an fd in. */
	int fd_in;

	/* Messages queue up here. */
	struct msg_queue outq;

	/* Callbacks for replies. */
	struct list_head reqs;
};

/**
 * new_subd - create a new subdaemon.
 * @ctx: context to allocate from
 * @ld: global state
 * @name: basename of daemon
 * @peer: peer to take ownership of if non-NULL
 * @msgname: function to get name from messages
 * @msgcb: function to call when non-fatal message received (or NULL)
 * @finished: function to call when it's finished (with exit status).
 * @...: the fds to hand as fd 3, 4... terminated with -1.
 *
 * @msgcb is called with fd == -1 when a message is received; if it
 * returns SUBD_NEED_FD, we read an fd from the daemon and call it
 * again with that as the third arg.
 *
 * If this succeeds subd owns @peer.
 */
struct subd *new_subd(const tal_t *ctx,
		      struct lightningd *ld,
		      const char *name,
		      struct peer *peer,
		      const char *(*msgname)(int msgtype),
		      enum subd_msg_ret (*msgcb)
		      (struct subd *, const u8 *, int fd),
		      void (*finished)(struct subd *, int), ...);

/**
 * subd_send_msg - queue a message to the subdaemon.
 * @sd: subdaemon to request
 * @msg_out: message (can be take)
 */
void subd_send_msg(struct subd *sd, const u8 *msg_out);

/**
 * subd_send_msg - queue a file descriptor to pass to the subdaemon.
 * @sd: subdaemon to request
 * @fd: the file descriptor (closed after passing).
 */
void subd_send_fd(struct subd *sd, int fd);

/**
 * subd_req - queue a request to the subdaemon.
 * @sd: subdaemon to request
 * @msg_out: request message (can be take)
 * @fd_out: if >=0 fd to pass at the end of the message (closed after)
 * @fd_in: if not NULL, where to put fd read in at end of reply.
 * @replycb: callback when reply comes in, returns false to shutdown daemon.
 * @replycb_data: final arg to hand to @replycb
 *
 * @replycb cannot free @sd, so it returns false to remove it.
 */
#define subd_req(sd, msg_out, fd_out, fd_in, replycb, replycb_data)	\
	subd_req_((sd), (msg_out), (fd_out), (fd_in),			\
		       typesafe_cb_preargs(bool, void *,		\
					   (replycb), (replycb_data),	\
					   struct subd *,		\
					   const u8 *),			\
		       (replycb_data))
void subd_req_(struct subd *sd,
		    const u8 *msg_out,
		    int fd_out, int *fd_in,
		    bool (*replycb)(struct subd *, const u8 *, void *),
		    void *replycb_data);

char *opt_subd_debug(const char *optarg, struct lightningd *ld);

#endif /* LIGHTNING_LIGHTNINGD_SUBD_H */