#ifndef SUBMISSION_BACKEND_H
#define SUBMISSION_BACKEND_H

struct submission_recipient;
struct submission_backend;
union submission_backend_module_context;

struct submission_backend_vfuncs {
	void (*destroy)(struct submission_backend *backend);

	void (*start)(struct submission_backend *backend);
	void (*ready)(struct submission_backend *backend,
		      enum smtp_capability caps);

	void (*fail)(struct submission_backend *backend, const char *enh_code,
		     const char *reason);

	void (*client_input_pre)(struct submission_backend *backend);
	void (*client_input_post)(struct submission_backend *backend);

	uoff_t (*get_max_mail_size)(struct submission_backend *backend);

	void (*trans_start)(struct submission_backend *backend,
			    struct smtp_server_transaction *trans,
			    const struct smtp_address *path,
			    const struct smtp_params_mail *params);
	void (*trans_free)(struct submission_backend *backend,
			   struct smtp_server_transaction *trans);

	/* Command handlers:

	   These implement the behavior of the various core SMTP commands.
	   SMTP commands are handled asynchronously, which means that the
	   command is not necessarily finished when these handlers end. A
	   command is finished either when 1 is returned or a reply is submitted
	   for it. When a handler returns 0, the command implementation is
	   waiting for an external event and when it returns -1 an error
	   occurred. When 1 is returned, a default success reply is submitted
	   implicitly. Not submitting an error reply when -1 is returned causes
	   an assert fail. See src/lib-smtp/smtp-server.h for details.

	   When overriding these handler vfuncs, the base implementation should
	   usually be called at some point. When it is called immediately, its
	   result can be returned as normal. When the override returns 0, the
	   base implementation would be called at a later time when some
	   external state is achieved. Note that the overriding function then
	   assumes the responsibility to submit the default reply when none is
	   submitted and the base implementation returns 1.

	   Also note that only the default backend actually triggers all of
	   these command callbacks. Secondary backends only get called for
	   transaction commands and only when that backend is tied to the
	   transaction somehow; e.g., as the primary transaction backend or when
	   it is tied to one of the approved recipients.
	  */
	int (*cmd_helo)(struct submission_backend *backend,
			struct smtp_server_cmd_ctx *cmd,
			struct smtp_server_cmd_helo *data);

	int (*cmd_mail)(struct submission_backend *backend,
			struct smtp_server_cmd_ctx *cmd,
			struct smtp_server_cmd_mail *data);
	int (*cmd_rcpt)(struct submission_backend *backend,
			struct smtp_server_cmd_ctx *cmd,
			struct submission_recipient *srcpt);
	int (*cmd_rset)(struct submission_backend *backend,
			struct smtp_server_cmd_ctx *cmd);
	int (*cmd_data)(struct submission_backend *backend,
			struct smtp_server_cmd_ctx *cmd,
			struct smtp_server_transaction *trans,
			struct istream *data_input, uoff_t data_size);

	int (*cmd_vrfy)(struct submission_backend *backend,
			struct smtp_server_cmd_ctx *cmd,
			const char *param);
	int (*cmd_noop)(struct submission_backend *backend,
			struct smtp_server_cmd_ctx *cmd);

	int (*cmd_quit)(struct submission_backend *backend,
			struct smtp_server_cmd_ctx *cmd);
};

struct submission_backend {
	pool_t pool;
	struct client *client;

	struct submission_backend *prev, *next;

	struct submission_backend_vfuncs v;

	struct istream *data_input;
	uoff_t data_size;

	char *fail_enh_code;
	char *fail_reason;

	/* Module-specific contexts. */
	ARRAY(union submission_backend_module_context *) module_contexts;

	bool started:1;
	bool ready:1;
	bool trans_started:1;
};

struct submission_backend_module_register {
	unsigned int id;
};

union submission_backend_module_context {
	struct submission_backend_module_register *reg;
};
extern struct submission_backend_module_register
submission_backend_module_register;

void submission_backend_init(struct submission_backend *backend,
			     pool_t pool, struct client *client,
			     const struct submission_backend_vfuncs *vfunc);
void submission_backends_destroy_all(struct client *client);

void submission_backend_start(struct submission_backend *backend);
void submission_backend_started(struct submission_backend *backend,
				enum smtp_capability caps);

void submission_backend_fail(struct submission_backend *backend,
			     struct smtp_server_cmd_ctx *cmd,
			     const char *enh_code, const char *reason)
	ATTR_NULL(2);

void submission_backends_client_input_pre(struct client *client);
void submission_backends_client_input_post(struct client *client);

uoff_t submission_backend_get_max_mail_size(struct submission_backend *backend);

void submission_backend_trans_start(struct submission_backend *backend,
				    struct smtp_server_transaction *trans);
void submission_backends_trans_start(struct client *client,
				     struct smtp_server_transaction *trans);
void submission_backends_trans_free(struct client *client,
				     struct smtp_server_transaction *trans);

void submission_backend_helo_reply_submit(struct submission_backend *backend,
					  struct smtp_server_cmd_ctx *cmd,
					  struct smtp_server_cmd_helo *data);
int submission_backend_cmd_helo(struct submission_backend *backend,
				struct smtp_server_cmd_ctx *cmd,
				struct smtp_server_cmd_helo *data);

int submission_backend_cmd_mail(struct submission_backend *backend,
				struct smtp_server_cmd_ctx *cmd,
				struct smtp_server_cmd_mail *data);
int submission_backend_cmd_rcpt(struct submission_backend *backend,
				struct smtp_server_cmd_ctx *cmd,
				struct submission_recipient *srcpt);
int submission_backend_cmd_rset(struct submission_backend *backend,
				struct smtp_server_cmd_ctx *cmd);
int submission_backends_cmd_data(struct client *client,
				 struct smtp_server_cmd_ctx *cmd,
				 struct smtp_server_transaction *trans,
				 struct istream *data_input, uoff_t data_size);

int submission_backend_cmd_vrfy(struct submission_backend *backend,
				struct smtp_server_cmd_ctx *cmd,
				const char *param);
int submission_backend_cmd_noop(struct submission_backend *backend,
				struct smtp_server_cmd_ctx *cmd);

int submission_backend_cmd_quit(struct submission_backend *backend,
				struct smtp_server_cmd_ctx *cmd);

#endif