/* Copyright 2021 Nick Brassel (@tzarc)
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <quantum.h>
#include <xap.h>
#include <usb_descriptor.h>

#define QSTR2(z) #z
#define QSTR(z) QSTR2(z)

typedef enum xap_route_type_t {
    XAP_UNUSED = 0,  // "Unused" needs to be zero -- undefined routes (through preprocessor) will be skipped
    XAP_ROUTE,
    XAP_EXECUTE,
    XAP_VALUE,
    XAP_GETTER,
    XAP_CONST_MEM,
    TOTAL_XAP_ROUTE_TYPES
} xap_route_type_t;

#define XAP_ROUTE_TYPE_BIT_COUNT 3

typedef struct __attribute__((packed)) xap_route_flags_t {
    xap_route_type_t type : XAP_ROUTE_TYPE_BIT_COUNT;
    uint8_t          is_secure : 1;
} xap_route_flags_t;

_Static_assert(TOTAL_XAP_ROUTE_TYPES <= (1 << (XAP_ROUTE_TYPE_BIT_COUNT)), "Number of XAP route types is too large for XAP_ROUTE_TYPE_BITS.");
_Static_assert(sizeof(xap_route_flags_t) == 1, "xap_route_flags_t is not length of 1");

typedef struct xap_route_t xap_route_t;
struct __attribute__((packed)) xap_route_t {
    const xap_route_flags_t flags;
    union {
        // XAP_ROUTE
        struct {
            const xap_route_t *child_routes;
            const uint8_t      child_routes_len;
        };

        // XAP_EXECUTE
        bool (*handler)(xap_token_t token, const uint8_t *data, size_t data_len);

        // XAP_VALUE
        uint32_t u32value;

        // XAP_GETTER
        uint32_t (*u32getter)(void);

        // XAP_CONST_MEM
        struct {
            const void *  const_data;
            const uint8_t const_data_len;
        };
    };
};

#include <xap_generated.inl>

void xap_execute_route(xap_token_t token, const xap_route_t *routes, size_t max_routes, const uint8_t *data, size_t data_len) {
    if (data_len == 0) return;
    xap_identifier_t id = data[0];

    if (id < max_routes) {
        xap_route_t route;
        memcpy_P(&route, &routes[id], sizeof(xap_route_t));
        switch (route.flags.type) {
            case XAP_ROUTE:
                if (route.child_routes != NULL && route.child_routes_len > 0 && data_len > 0) {
                    xap_execute_route(token, route.child_routes, route.child_routes_len, &data[1], data_len - 1);
                    return;
                }
                break;

            case XAP_EXECUTE:
                if (route.handler != NULL) {
                    bool ok = (route.handler)(token, data_len == 1 ? NULL : &data[1], data_len - 1);
                    if (ok) return;
                }
                break;

            case XAP_VALUE:
                xap_respond_u32(token, route.u32value);
                return;

            case XAP_GETTER:
                xap_respond_u32(token, (route.u32getter)());
                return;

            case XAP_CONST_MEM:
                xap_respond_data_P(token, route.const_data, route.const_data_len);
                return;

            default:
                break;
        }
    }

    // Nothing got handled, so we respond with failure.
    xap_respond_failure(token, XAP_RESPONSE_FLAG_FAILED);
}

void xap_receive(xap_token_t token, const uint8_t *data, size_t length) { xap_execute_route(token, xap_route_table, sizeof(xap_route_table) / sizeof(xap_route_t), data, length); }