#include <errno.h>

#include <osmocom/core/talloc.h>
#include <osmocom/core/linuxlist.h>
#include <osmocom/gsm/tlv.h>

#include "v5x_internal.h"
#include "v5x_protocol.h"
#include "lapv5.h"
#include "layer1.h"
#include "v5x_l1_fsm.h"
#include "v5x_le_ctrl_fsm.h"
#include "v5x_le_port_fsm.h"
#include "v5x_le_pstn_fsm.h"
#include "v52_le_lcp_fsm.h"
#include "v52_le_bcc_fsm.h"
#include "v52_le_pp_fsm.h"
#include "v5x_le_management.h"
#include "logging.h"

static LLIST_HEAD(v5_instances);

struct v5x_instance *v5x_instance_alloc(void *ctx)
{
	struct v5x_instance *v5i = talloc_zero(ctx, struct v5x_instance);
	if (!v5i)
		return NULL;

	INIT_LLIST_HEAD(&v5i->interfaces);

	llist_add_tail(&v5i->list, &v5_instances);

	return v5i;
}

void v5x_instance_free(struct v5x_instance *v5i)
{
	struct v5x_interface *v5if, *v5if2;

	llist_for_each_entry_safe(v5if, v5if2, &v5i->interfaces, list)
		v5x_interface_free(v5if);

	talloc_free(v5i);
}

static void v5x_ts_init(struct v5x_timeslot *v5ts, uint8_t nr, struct v5x_link *v5l, bool b_channel)
{
	/* Never use slot 16 as B-channel, because some drivers (mISDN) will not allow this. */
	if (nr == 16)
		b_channel = false;

	v5ts->nr = nr;
	v5ts->link = v5l;
	v5ts->b_channel = b_channel;
}

static void v5x_cchan_init(struct v5x_c_channel *v5cc, struct v5x_link *v5l, struct v5x_timeslot *v5ts, bool active)
{
	v5cc->link = v5l;
	v5cc->ts = v5ts;
	v5cc->active = active;
}

struct v5x_link *v5x_link_create(struct v5x_interface *v5if, uint8_t id)
{
	int count;
	struct v5x_link *v5l;
	unsigned int i;
	int rc;

	if (v5x_link_find_id(v5if, id)) {
		LOGP(DV5, LOGL_ERROR, "Link %d already exists.\n", id);
		return NULL;
	}

	count = v5x_link_count(v5if);

	v5l = talloc_zero(v5if, struct v5x_link);
	if (!v5l)
		return NULL;

	llist_add_tail(&v5l->list, &v5if->links);
	count++;

	v5l->id = id;
	v5l->interface = v5if;
	v5l->e1_line = -1;

	/* primary and secondary link will get TS 16 */
	if (count <= 2) {
		v5x_cchan_init(&v5l->c_channel[0], v5l, &v5l->ts[16], true);
	}

	for (i = 1; i < ARRAY_SIZE(v5l->ts); i++) {
		bool b_channel = true;
		if (v5l->c_channel[0].ts && v5l->c_channel[0].ts->nr == i)
			b_channel = false;
		if (v5l->c_channel[1].ts && v5l->c_channel[1].ts->nr == i)
			b_channel = false;
		if (v5l->c_channel[2].ts && v5l->c_channel[2].ts->nr == i)
			b_channel = false;
		v5x_ts_init(&v5l->ts[i], i, v5l, b_channel);
	}

	v5l->l1 = v5x_l1_fsm_create(v5if, v5l, id);
	if (!v5l->l1)
		goto error;

	if (v5if->dialect == V5X_DIALECT_V52) {
		v5l->fi = v52_le_lcp_create(v5if, v5l, id);
		if (!v5l->fi)
			goto error;

		v5l->ctrl = v5x_le_ctrl_create(V5X_CTRL_TYPE_LINK, v5if, v5l, id);
		if (!v5l->ctrl)
			goto error;
	}

	if (count == 1) {
		v5if->primary_link = v5l;
		v5if->cc_link = v5l;
	}
	if (count == 2) {
		v5if->secondary_link = v5l;
		/* add PP */
		v5if->protection.pp = v52_le_pp_create(v5if);
		if (!v5if->protection.pp)
			goto error;
		v5if->protection.li[0] = lapv5_instance_alloc(1, &ph_data_req_dl_prot, v5if->primary_link, v5x_dl_rcv,
				v5if->primary_link, &lapd_profile_lapv5dl, "protection0");
		if (!v5if->protection.li[0])
			goto error;
		v5if->protection.li[1] = lapv5_instance_alloc(1, &ph_data_req_dl_prot, v5if->secondary_link, v5x_dl_rcv,
				v5if->secondary_link, &lapd_profile_lapv5dl, "protection1");
		if (!v5if->protection.li[1])
			goto error;
	}

	return v5l;

error:
	rc = v5x_link_destroy(v5l);
	OSMO_ASSERT(rc == 0);
	return NULL;
}

int v5x_link_destroy(struct v5x_link *v5l)
{
	struct v5x_interface *v5if = v5l->interface;
	int count;
	struct v5x_user_port *v5up;
	int i;

	count = v5x_link_count(v5l->interface);
	if (count > 1 && v5l->interface->primary_link == v5l) {
		LOGP(DV5, LOGL_ERROR, "Link %d is primary. Cannot remove it, while other links exist.\n", v5l->id);
		return -EINVAL;
	}
	if (count > 2 && v5l->interface->secondary_link == v5l) {
		LOGP(DV5, LOGL_ERROR, "Link %d is secondary (standby). Cannot remove it, while other (not primary) links exist.\n", v5l->id);
		return -EINVAL;
	}

	/* detach user ports */
	for (i = 1; i < (int)ARRAY_SIZE(v5l->ts); i++) {
		if ((v5up = v5l->ts[i].v5up)) {
			if (v5up->ts[0] == &v5l->ts[i]) {
				v5up->ts[0] = NULL;
				ph_deactivate_req(&v5l->ts[i]);
			}
			if (v5up->ts[1] == &v5l->ts[i]) {
				v5up->ts[1] = NULL;
				ph_deactivate_req(&v5l->ts[i]);
			}
		}
	}

	if (v5l->ctrl)
		v5x_le_ctrl_destroy(v5l->ctrl);

	if (v5l->fi)
		v52_le_lcp_destroy(v5l->fi);

	if (v5l->l1)
		v5x_l1_fsm_destroy(v5l->l1);

	if (v5l->interface->primary_link == v5l)
		v5l->interface->primary_link = NULL;
	if (v5l->interface->secondary_link == v5l)
		v5l->interface->secondary_link = NULL;
	if (v5l->interface->cc_link == v5l)
		v5l->interface->cc_link = NULL;

	llist_del(&v5l->list);
	count--;

	talloc_free(v5l);

	/* if we have only one link left */
	if (count == 1) {
		/* remove PP */
		if (v5if->protection.li[0]) {
			lapv5_instance_free(v5if->protection.li[0]);
			v5if->protection.li[0] = NULL;
		}
		if (v5if->protection.li[1]) {
			lapv5_instance_free(v5if->protection.li[1]);
			v5if->protection.li[1] = NULL;
		}
		if (v5if->protection.pp) {
			v52_le_pp_destroy(v5if->protection.pp);
			v5if->protection.pp = NULL;
		}
	}

	return 0;
}

struct v5x_interface *v5x_interface_alloc(struct v5x_instance *v5i, enum v5x_dialect dialect)
{
	struct v5x_interface *v5if;
	struct v5x_link *v5l;
//	struct v5x_c_channel *primary_c_chan;

	v5if = talloc_zero(v5i, struct v5x_interface);
	if (!v5if)
		return NULL;

	INIT_LLIST_HEAD(&v5if->links);
	INIT_LLIST_HEAD(&v5if->user_ports);
	INIT_LLIST_HEAD(&v5if->bcc_procs);

	llist_add_tail(&v5if->list, &v5i->interfaces);

	v5if->instance = v5i;
	v5if->dialect = dialect;

	if (v5if->dialect == V5X_DIALECT_V51) {
		v5l = v5x_link_create(v5if, 0);
		if (!v5l)
			goto error;
	}

	v5if->control.ctrl = v5x_le_ctrl_create(V5X_CTRL_TYPE_COMMON, v5if, v5if, 0);
	if (!v5if->control.ctrl)
		goto error;
	v5if->control.li = lapv5_instance_alloc(1, &ph_data_req_dl_cc, v5if, v5x_dl_rcv, v5if,
			&lapd_profile_lapv5dl, "control");
	if (!v5if->control.li)
		goto error;

	v5if->pstn.li = lapv5_instance_alloc(1, &ph_data_req_dl_cc, v5if, v5x_dl_rcv, v5if,
			&lapd_profile_lapv5dl, "pstn");
	if (!v5if->pstn.li)
		goto error;

	if (v5if->dialect == V5X_DIALECT_V52) {
		v5if->lcp.li = lapv5_instance_alloc(1, &ph_data_req_dl_cc, v5if, v5x_dl_rcv, v5if,
				&lapd_profile_lapv5dl, "lcp");
		if (!v5if->lcp.li)
			goto error;

		v5if->bcc.li = lapv5_instance_alloc(1, &ph_data_req_dl_cc, v5if, v5x_dl_rcv, v5if,
				&lapd_profile_lapv5dl, "bcc");
		if (!v5if->bcc.li)
			goto error;
	}

	return v5if;

error:
	v5x_interface_free(v5if);
	return NULL;
}

void v5x_interface_free(struct v5x_interface *v5if) {
	struct v5x_user_port *v5up, *v5up2;
	struct v52_bcc_proc *bcc, *bcc2;
	struct v5x_link *v5l;
	int rc;

	if (!v5if)
		return;

	llist_for_each_entry_safe(v5up, v5up2, &v5if->user_ports, list)
		v5x_user_port_destroy(v5up);

	llist_for_each_entry_safe(bcc, bcc2, &v5if->bcc_procs, list)
		v52_le_bcc_destroy(bcc);

	/* delete reversed safely */
	while (!llist_empty(&v5if->links)) {
		v5l = llist_last_entry(&v5if->links, struct v5x_link, list);
		rc = v5x_link_destroy(v5l);
		OSMO_ASSERT(rc == 0);
	}

	if (v5if->control.ctrl)
		v5x_le_ctrl_destroy(v5if->control.ctrl);
	if (v5if->control.li)
		lapv5_instance_free(v5if->control.li);

	if (v5if->pstn.li)
		lapv5_instance_free(v5if->pstn.li);

	if (v5if->lcp.li)
		lapv5_instance_free(v5if->lcp.li);

	if (v5if->bcc.li)
		lapv5_instance_free(v5if->bcc.li);

	llist_del(&v5if->list);

	talloc_free(v5if);
}

struct v5x_user_port *v5x_user_port_create(struct v5x_interface *v5if, uint16_t nr, enum v5x_user_type type,
	uint8_t ts1, uint8_t ts2)
{
	struct v5x_user_port *v5up;
	int i;
	int rc;

	if (v5x_user_port_find(v5if, nr, (type == V5X_USER_TYPE_ISDN))) {
		LOGP(DV5, LOGL_ERROR, "User port %d already exists.\n", nr);
		return NULL;
	}

	if (v5if->dialect == V5X_DIALECT_V51) {
		struct v5x_link *v5l;

		v5l = llist_first_entry(&v5if->links, struct v5x_link, list);
		if (!v5l->ts[ts1].b_channel) {
			LOGP(DV5, LOGL_ERROR, "Time slot %d is not a B-channel, select a different one.\n", ts1);
			return NULL;
		}
		if ((v5up = v5l->ts[ts1].v5up)) {
			LOGP(DV5, LOGL_ERROR, "Time slot %d is already assigned to another user port.\n", ts1);
			return NULL;
		}
		if (type == V5X_USER_TYPE_ISDN) {
			if (!v5l->ts[ts2].b_channel) {
				LOGP(DV5, LOGL_ERROR, "Time slot %d is not a B-channel, select a different one.\n",
					ts2);
				return NULL;
			}
			if ((v5up = v5l->ts[ts2].v5up)) {
				LOGP(DV5, LOGL_ERROR, "Time slot %d is already assigned to another user port.\n", ts2);
				return NULL;
			}
		}
	}

	v5up = talloc_zero(v5if, struct v5x_user_port);
	if (!v5up)
		return NULL;

	llist_add_tail(&v5up->list, &v5if->user_ports);

	v5up->interface = v5if;
	v5up->nr = nr;
	v5up->type = type;

	/* assign ports */
	if (v5if->dialect == V5X_DIALECT_V51) {
		struct v5x_link *v5l;

		v5l = llist_first_entry(&v5if->links, struct v5x_link, list);
		OSMO_ASSERT(ts1 >= 1 && ts1 <= 31);
		v5l->ts[ts1].v5up = v5up;
		v5up->ts[0] = &v5l->ts[ts1];
		if (type == V5X_USER_TYPE_ISDN) {
			OSMO_ASSERT(ts2 >= 1 && ts2 <= 31);
			v5l->ts[ts2].v5up = v5up;
			v5up->ts[1] = &v5l->ts[ts2];
		}
	}

	v5up->ctrl = v5x_le_ctrl_create(V5X_CTRL_TYPE_PORT, v5up, v5up, nr);
	if (!v5up->ctrl) {
		LOGP(DV5, LOGL_ERROR, "Failed to create control protocol\n");
		goto error;
	}

	switch (type) {
	case V5X_USER_TYPE_ISDN:
		LOGP(DV5, LOGL_NOTICE, "Creating V5 ISDN user port with L3 addr %d\n", nr);
		sprintf(v5up->ifname, "isdn-%d", nr);
		OSMO_ASSERT(nr <= 8175);
		v5up->port_fi = v5x_le_port_isdn_create(v5up, nr);
		if (!v5up->port_fi) {
			LOGP(DV5, LOGL_ERROR, "Failed to create port control\n");
			goto error;
		}
		break;
	case V5X_USER_TYPE_PSTN:
		LOGP(DV5, LOGL_NOTICE, "Creating V5 PSTN user port with L3 addr %d\n", nr);
		sprintf(v5up->ifname, "pstn-%d", nr);
		OSMO_ASSERT(nr <= 32767);
		v5up->port_fi = v5x_le_port_pstn_create(v5up, nr);
		if (!v5up->port_fi) {
			LOGP(DV5, LOGL_ERROR, "Failed to create port control\n");
			goto error;
		}
		v5up->pstn.proto = v5x_le_pstn_create(v5up, nr);
		if (!v5up->pstn.proto) {
			LOGP(DV5, LOGL_ERROR, "Failed to create PSTN protocol\n");
			goto error;
		}
		/* bring port into service */
		v5x_le_pstn_mdu_snd(v5up, MDU_CTRL_port_blocked);
		break;
	}

	for (i = 0; i < 2; i++) {
		v5up->ep[i].port = v5up;
		/* EC needs to adapt, NLP causes better results on quick volume changes */
		v5up->ep[i].ec = echo_can_create(EC_TAPS, ECHO_CAN_USE_ADAPTION | ECHO_CAN_USE_NLP);
		if (!v5up->ep[i].ec) {
			LOGP(DV5, LOGL_ERROR, "Failed to create line echo canceler\n");
			goto error;
		}
		rc = answertone_init(&v5up->ep[i].at, 8000);
		if (rc < 0) {
			LOGP(DV5, LOGL_ERROR, "Failed to create answer tone detector\n");
			goto error;
		}
		if (type != V5X_USER_TYPE_ISDN)
			break;
	}

	rc = ph_socket_init(&v5up->ph_socket, ph_socket_rx_cb, v5up, v5up->ifname, 1);
	if (rc < 0) {
		LOGP(DV5, LOGL_ERROR, "Failed to create PH-socket\n");
		goto error;
	}

	/* start ctrl FSM for this port */
	if (v5if->control.established)
		v5x_le_ctrl_start(v5up->ctrl);

	return v5up;

error:
	v5x_user_port_destroy(v5up);
	return NULL;
}

void v5x_user_port_destroy(struct v5x_user_port *v5up)
{
	int i;

	LOGP(DV5, LOGL_NOTICE, "Destroying V5 user port with L3 addr %d\n", v5up->nr);

	/* close first, because it sends messages */
	ph_socket_exit(&v5up->ph_socket);

	for (i = 0; i < 2; i++) {
		/* destory line echo canceler */
		if (v5up->ep[i].ec) {
			echo_can_free(v5up->ep[i].ec);
			answertone_exit(&v5up->ep[i].at);
			v5up->ep[i].ec = NULL;
		}

		/* unassign ports */
		if (v5up->ts[i]) {
			v5up->ts[i]->v5up = NULL;
			v5up->ts[i] = NULL;
		}
	}

	if (v5up->ctrl)
		v5x_le_ctrl_destroy(v5up->ctrl);

	if (v5up->port_fi)
		osmo_fsm_inst_free(v5up->port_fi);

	if (v5up->pstn.proto)
		v5x_le_pstn_destroy(v5up->pstn.proto);

	llist_del(&v5up->list);

	talloc_free(v5up);
}

void v5x_echo_reset(struct v5x_echo_proc *ep, int enable)
{
	ep->enabled = enable;
	answertone_reset(&ep->at);
	ep->tx_buffer_in = 0;
	ep->tx_buffer_out = 0;
	if (ep->ec)
		echo_can_flush(ep->ec);
}

struct v5x_user_port *v5x_user_port_find(struct v5x_interface *v5if, uint16_t nr, bool is_isdn)
{
	struct v5x_user_port *v5up;

	llist_for_each_entry(v5up, &v5if->user_ports, list) {
		if (v5up->nr == nr && is_isdn == (v5up->type == V5X_USER_TYPE_ISDN))
			return v5up;
	}
	return NULL;
}

int v5x_link_count(struct v5x_interface *v5if)
{
	struct v5x_link *v5l;
	int count = 0;

	llist_for_each_entry(v5l, &v5if->links, list)
		count++;
	return count;
}

struct v5x_link *v5x_link_find_id(struct v5x_interface *v5if, uint8_t id)
{
	struct v5x_link *v5l;

	llist_for_each_entry(v5l, &v5if->links, list) {
		if (v5l->id == id)
			return v5l;
	}
	return NULL;
}

struct v5x_link *v5x_link_find_e1_line(struct v5x_interface *v5if, uint8_t e1_line)
{
	struct v5x_link *v5l;

	llist_for_each_entry(v5l, &v5if->links, list) {
		if (v5l->e1_line == e1_line)
			return v5l;
	}
	return NULL;
}