#include <string.h>
#include <stdio.h>
#include <sys/uio.h>
#include "try.h"
#include "util.h"
#include "wire.h"
#include "log.h"

// SPEC: https://dbus.freedesktop.org/doc/dbus-specification.html#id-1.4.6
_WIRE_DEF_BYTE_TYPE(i8, int8_t)
_WIRE_DEF_BYTE_TYPE(u8, uint8_t)
_WIRE_DEF_TYPE(i16, int16_t, 2)
_WIRE_DEF_TYPE(u16, uint16_t, 2)
_WIRE_DEF_TYPE(i32, int32_t, 4)
_WIRE_DEF_TYPE(u32, uint32_t, 4)
_WIRE_DEF_TYPE(boolean, uint32_t, 4)

bool wire_write_align(WireCtx *c, uint32_t alignment)
{
    // Thanks: https://github.com/c-util/c-stdaux/blob/ed5fee49a3ec13fe79f30324b23c73cd41805514/src/c-stdaux-gnuc.h#L431
    uint32_t new_cursor = ((c->byte_cursor) + (alignment) - 1) & ~((alignment) - 1);

    if (unlikely(new_cursor >= c->data_len || new_cursor < c->byte_cursor)) {
        return false;
    }
    while (c->byte_cursor < new_cursor) {
        c->data[c->byte_cursor++] = '\0';
    }
    return true;
}

bool wire_align(WireCtx *c, uint32_t alignment)
{
    // Thanks: https://github.com/c-util/c-stdaux/blob/ed5fee49a3ec13fe79f30324b23c73cd41805514/src/c-stdaux-gnuc.h#L431
    uint32_t new_cursor = ((c->byte_cursor) + (alignment) - 1) & ~((alignment) - 1);

    if (unlikely(new_cursor >= c->data_len || new_cursor < c->byte_cursor)) {
        return false;
    }
    c->byte_cursor = new_cursor;
    return true;
}

char *wire_set_signature_single_char(WireCtx *c, const char s)
{
    TRYPTR_NIL(wire_set_u8(c, 1));

    uint32_t new_cursor = c->byte_cursor + 2; /* + 2 because of the extra null termination that strings have */
    if (unlikely(new_cursor >= c->data_len)) {
        return NULL;
    }

    // TODO?
    char *dest = (char*)&c->data[c->byte_cursor];
    dest[0] = s;
    dest[1] = '\0';

    c->byte_cursor = new_cursor; 

    return dest;
}

char *wire_get_string_impl(WireCtx *c, bool as_signature)
{
    uint32_t len = 0;
    if (as_signature) {
        len = *(uint8_t*)TRYPTR_NIL(wire_get_u8(c));
    } else {
        len = *(uint32_t*)TRYPTR_NIL(wire_get_u32(c));
    }

    uint32_t new_cursor = c->byte_cursor + len + 1; /* + 1 because of the extra null termination that strings have */
    if (unlikely(new_cursor >= c->data_len)) {
        return NULL;
    }

    // strings always end with a null byte
    if (unlikely(c->data[c->byte_cursor + len] != '\0')) {
        return NULL;
    }

    char *str = (char *)&c->data[c->byte_cursor];

    c->byte_cursor = new_cursor; 

    return str;
}

char *wire_set_string_fixed(WireCtx *c, const char *str, uint32_t len)
{
    // len includes the null byte

    TRYPTR_NIL(wire_set_u32(c, len - 1));

    uint32_t new_cursor = c->byte_cursor + len;
    if (unlikely(new_cursor >= c->data_len)) {
        return NULL;
    }

    // TODO?
    char *dest = (char*)&c->data[c->byte_cursor];
    memcpy(dest, str, len);

    c->byte_cursor = new_cursor; 

    return dest;
}

char *wire_set_string_impl(WireCtx *c, const char *str, bool as_signature)
{
    uint32_t len = strlen(str);
    if (as_signature) {
        TRYPTR_NIL(wire_set_u8(c, len));
    } else {
        TRYPTR_NIL(wire_set_u32(c, len));
    }

    uint32_t new_cursor = c->byte_cursor + len + 1; /* + 1 because of the extra null termination that strings have */
    if (unlikely(new_cursor >= c->data_len)) {
        return NULL;
    }

    // TODO?
    char *dest = (char*)&c->data[c->byte_cursor];
    memcpy(dest, str, len + 1);

    c->byte_cursor = new_cursor; 

    return dest;
}

char *wire_get_string_check(WireCtx *c, int min_length, int max_length) {
    char *str = TRYPTR_NIL(wire_get_string_impl(c, false));
    int length = strlen(str);
    if (unlikely(length < min_length || length > max_length)) return NULL;
    return str;
}

int wire_parse_message(WireCtx *c, WireMsg *msg)
{
    // SPEC: https://dbus.freedesktop.org/doc/dbus-specification.html#message-protocol-messages
    msg->endianness = *(uint8_t*)TRYPTR(wire_get_u8(c));
    if (msg->endianness == 'B') {
        // we only support little endian
        return -1;
    }

    msg->type = *(uint8_t*)TRYPTR(wire_get_u8(c));
    msg->flags = *(uint8_t*)TRYPTR(wire_get_u8(c));
    msg->protocol_version = *(uint8_t*)TRYPTR(wire_get_u8(c));
    msg->body_length = *(uint32_t*)TRYPTR(wire_get_u32(c));
    msg->serial = *(uint32_t*)TRYPTR(wire_get_u32(c));
    msg->header_fields_length = *(uint32_t*)TRYPTR(wire_get_u32(c));

    TRYPTR(wire_write_align(c, 8));

    msg->header_length = c->byte_cursor;
    size_t header_fields_end = c->byte_cursor + msg->header_fields_length;
    if (unlikely(header_fields_end >= c->data_len)) {
        return -1;
    }

    VERBOSE("start parse message: type=%d, no_reply_expected=%d\n", msg->type, msg->flags & DBUS_FLAG_NO_REPLY_EXPECTED);

    while (c->byte_cursor < header_fields_end) {
        uint8_t field_code = *(uint8_t*)TRYPTR(wire_get_u8(c));
        TRYPTR(wire_get_signature(c));

        switch (field_code) {
            case DBUS_HEADER_FIELD_PATH: /* through */
            case DBUS_HEADER_FIELD_INTERFACE: /* through */
            case DBUS_HEADER_FIELD_MEMBER: /* through */
            case DBUS_HEADER_FIELD_ERROR_NAME: /* through */
            case DBUS_HEADER_FIELD_DESTINATION: {
                char *str = TRYPTR(wire_get_string(c));
                VERBOSE("field: %s\n", str);
                msg->fields[field_code].t.str = str;
            } break;
            case DBUS_HEADER_FIELD_SIGNATURE: {
                char *str = TRYPTR(wire_get_signature(c));
                VERBOSE("field: %s\n", str);
                msg->fields[field_code].t.str = str;
            } break;
            case DBUS_HEADER_FIELD_REPLY_SERIAL: {
                uint32_t u = *(uint32_t*)TRYPTR(wire_get_u32(c));
                VERBOSE("field: %d\n", u);
                msg->fields[field_code].t.u32 = u;
            } break;
            default: {
                WARN("header: unknown field: %d\n", field_code);
                return -1;
            } break;
        }
        msg->fields[field_code].present = true;

        // Structs are always aligned to `8`.
        // SPEC: https://dbus.freedesktop.org/doc/dbus-specification.html#id-1.4.6
        TRYPTR(wire_align(c, 8));

        if (msg->header_fields_count++ > WIRE_MESSAGE_MAX_HEADER_FIELDS) {
            return -1;
        }
    }

    VERBOSE("end parse message\n");

    /* header ends at 8 byte boundry */
    TRYPTR(wire_align(c, 8));

    return 0;
}

int wire_compose_signal(WireCtx *c, WireMsg *out_msg, const char *signature, const char *member, uint32_t **out_body_length)
{
    out_msg->endianness = 'l';
    TRYPTR(wire_set_u8(c, 'l')); /* endianness */
    out_msg->type = DBUS_MESSAGE_SIGNAL;
    TRYPTR(wire_set_u8(c, DBUS_MESSAGE_SIGNAL)); /* type */
    out_msg->flags = 0 | DBUS_FLAG_NO_REPLY_EXPECTED;
    TRYPTR(wire_set_u8(c, out_msg->flags)); /* flags */
    out_msg->protocol_version = DBUS_PROTOCOL_VERSION;
    TRYPTR(wire_set_u8(c, DBUS_PROTOCOL_VERSION)); /* protocol_version */
    uint32_t *body_length = TRYPTR(wire_set_u32(c, 0)); /* body length */
    TRYPTR(wire_set_u32(c, 1)); /* serial */
    uint32_t *header_fields_length = TRYPTR(wire_set_u32(c, 0)); /* header_fields_length */

    uint32_t header_fields_start = c->byte_cursor;

    /* header fields */
    {
        /* SENDER */
        {
            out_msg->fields[DBUS_HEADER_FIELD_SENDER].t.str = "org.freedesktop.DBus";
            out_msg->fields[DBUS_HEADER_FIELD_SENDER].present = true;

            /* byte (field code) */
            TRYPTR(wire_set_u8(c, DBUS_HEADER_FIELD_SENDER));
            /* variant */
            /* signature */
            TRYPTR(wire_set_signature(c, "s"));
            /* string */
            TRYPTR(wire_set_string(c, "org.freedesktop.DBus"));

            // need to align to 8 byte boundry after each array element?
            TRYPTR(wire_write_align(c, 8));
        }

        /* INTERFACE */
        {
            out_msg->fields[DBUS_HEADER_FIELD_INTERFACE].t.str = "org.freedesktop.DBus";
            out_msg->fields[DBUS_HEADER_FIELD_INTERFACE].present = true;

            /* byte (field code) */
            TRYPTR(wire_set_u8(c, DBUS_HEADER_FIELD_INTERFACE));
            /* variant */
            /* signature */
            TRYPTR(wire_set_signature(c, "s"));
            /* string */
            TRYPTR(wire_set_string(c, "org.freedesktop.DBus"));

            // need to align to 8 byte boundry after each array element?
            TRYPTR(wire_write_align(c, 8));
        }

        /* PATH */
        {
            out_msg->fields[DBUS_HEADER_FIELD_PATH].t.str = "/org/freedesktop/DBus";
            out_msg->fields[DBUS_HEADER_FIELD_PATH].present = true;

            /* byte (field code) */
            TRYPTR(wire_set_u8(c, DBUS_HEADER_FIELD_PATH));
            /* variant */
            /* signature */
            TRYPTR(wire_set_signature(c, "o"));
            /* string */
            TRYPTR(wire_set_string(c, "/org/freedesktop/DBus"));

            // need to align to 8 byte boundry after each array element?
            TRYPTR(wire_write_align(c, 8));
        }

        /* MEMBER */
        {
            out_msg->fields[DBUS_HEADER_FIELD_MEMBER].t.str = (char*)member;
            out_msg->fields[DBUS_HEADER_FIELD_MEMBER].present = true;

            /* byte (field code) */
            TRYPTR(wire_set_u8(c, DBUS_HEADER_FIELD_MEMBER));
            /* variant */
            /* signature */
            TRYPTR(wire_set_signature(c, "s"));
            /* string */
            TRYPTR(wire_set_string(c, member));

            // need to align to 8 byte boundry after each array element?
            TRYPTR(wire_write_align(c, 8));
        }

        /* SIGNATURE */
        {
            out_msg->fields[DBUS_HEADER_FIELD_SIGNATURE].t.str = (char*)signature;
            out_msg->fields[DBUS_HEADER_FIELD_SIGNATURE].present = true;

            /* byte (field code) */
            TRYPTR(wire_set_u8(c, DBUS_HEADER_FIELD_SIGNATURE));
            /* variant */
            /* signature */
            TRYPTR(wire_set_signature(c, "g"));
            /* signature */
            TRYPTR(wire_set_signature(c, signature));
        }
    }

    *header_fields_length = c->byte_cursor - header_fields_start;

    // header ends on an 8 byte alignment
    TRYPTR(wire_write_align(c, 8));

    if (out_body_length) {
        *out_body_length = body_length;
    }

    return 0;
}

int wire_compose_reply(WireCtx *c, WireMsg *msg, const char *signature, uint32_t **out_body_length)
{
    
    TRYPTR(wire_set_u8(c, msg->endianness)); /* endianness */
    TRYPTR(wire_set_u8(c, DBUS_MESSAGE_METHOD_RETURN)); /* type */
    TRYPTR(wire_set_u8(c, 0 | DBUS_FLAG_NO_REPLY_EXPECTED)); /* flags */
    TRYPTR(wire_set_u8(c, DBUS_PROTOCOL_VERSION)); /* protocol_version */
    uint32_t *body_length = TRYPTR(wire_set_u32(c, 0)); /* body length */
    TRYPTR(wire_set_u32(c, msg->serial+1)); /* serial */
    uint32_t *header_fields_length = TRYPTR(wire_set_u32(c, 0)); /* header_fields_length */

    uint32_t header_fields_start = c->byte_cursor;

    /* header fields */
    {
        /* SENDER */
        {
            /* byte (field code) */
            TRYPTR(wire_set_u8(c, DBUS_HEADER_FIELD_SENDER));
            /* variant */
            /* signature */
            TRYPTR(wire_set_signature(c, "s"));
            /* string */
            TRYPTR(wire_set_string(c, "org.freedesktop.DBus"));

            // need to align to 8 byte boundry after each array element?
            TRYPTR(wire_write_align(c, 8));
        }

        /* SIGNATURE */
        {
            /* byte (field code) */
            TRYPTR(wire_set_u8(c, DBUS_HEADER_FIELD_SIGNATURE));
            /* variant */
            /* signature */
            TRYPTR(wire_set_signature(c, "g"));
            /* signature */
            TRYPTR(wire_set_signature(c, signature));

            // need to align to 8 byte boundry after each array element?
            TRYPTR(wire_write_align(c, 8));
        }

        /* REPLY_SERIAL */
        {
            /* byte (field code) */
            TRYPTR(wire_set_u8(c, DBUS_HEADER_FIELD_REPLY_SERIAL));
            /* variant */
            /* signature */
            TRYPTR(wire_set_signature(c, "u"));
            /* reply serial */
            TRYPTR(wire_set_u32(c, msg->serial));
        }
    }

    *header_fields_length = c->byte_cursor - header_fields_start;

    // header ends on an 8 byte alignment
    TRYPTR(wire_write_align(c, 8));

    if (out_body_length) {
        *out_body_length = body_length;
    }

    return 0;
}

int wire_compose_error(WireCtx *c, WireMsg *msg, const char *error_name)
{
    
    TRYPTR(wire_set_u8(c, msg->endianness)); /* endianness */
    TRYPTR(wire_set_u8(c, DBUS_MESSAGE_ERROR)); /* type */
    TRYPTR(wire_set_u8(c, 0)); /* flags */
    TRYPTR(wire_set_u8(c, DBUS_PROTOCOL_VERSION)); /* protocol_version */
    TRYPTR(wire_set_u32(c, 0)); /* body length */
    TRYPTR(wire_set_u32(c, msg->serial+1)); /* serial */
    uint32_t *header_fields_length = TRYPTR(wire_set_u32(c, 0)); /* header_fields_length */

    uint32_t header_fields_start = c->byte_cursor;

    /* header fields */
    {
        /* ERROR_NAME */
        {
            /* byte (field code) */
            TRYPTR(wire_set_u8(c, DBUS_HEADER_FIELD_ERROR_NAME));
            /* variant */
            /* signature */
            TRYPTR(wire_set_signature(c, "s"));
            /* string */
            TRYPTR(wire_set_string(c, error_name));

            // need to align to 8 byte boundry after each array element?
            TRYPTR(wire_write_align(c, 8));
        }

        /* REPLY_SERIAL */
        {
            /* byte (field code) */
            TRYPTR(wire_set_u8(c, DBUS_HEADER_FIELD_REPLY_SERIAL));
            /* variant */
            /* signature */
            TRYPTR(wire_set_signature(c, "u"));
            /* reply serial */
            TRYPTR(wire_set_u32(c, msg->serial));
        }
    }

    *header_fields_length = c->byte_cursor - header_fields_start;

    // header ends on an 8 byte alignment
    TRYPTR(wire_write_align(c, 8));

    return 0;
}

int wire_compose_unicast_reply(WireCtx *msg_c, WireMsg *msg, char *sender_unique_name, struct iovec bufs[2], WireCtx *header_ctx)
{
    TRYPTR(wire_set_u8(header_ctx, msg->endianness)); /* endianness */
    TRYPTR(wire_set_u8(header_ctx, msg->type)); /* type */
    TRYPTR(wire_set_u8(header_ctx, msg->flags)); /* flags */
    TRYPTR(wire_set_u8(header_ctx, DBUS_PROTOCOL_VERSION)); /* protocol_version */
    TRYPTR(wire_set_u32(header_ctx, msg->body_length)); /* body length */
    TRYPTR(wire_set_u32(header_ctx, msg->serial)); /* serial */
    uint32_t *header_fields_length = TRYPTR(wire_set_u32(header_ctx, 0)); /* header_fields_length */

    // We don't need to do this because at this point we will always end up on an 8 byte alignment.
    //TRYPTR(wire_write_align(header_ctx, 8));

    uint32_t header_fields_start = header_ctx->byte_cursor;

    TRYPTR(wire_set_u8(header_ctx, DBUS_HEADER_FIELD_SENDER));
    TRYPTR(wire_set_signature_single_char(header_ctx, 's'));
    TRYPTR(wire_set_string_fixed(header_ctx, sender_unique_name, UNIQUE_NAME_LENGTH));

    // We don't need to do this because the unique names are fixed-size, such that we always end up on an 8 byte alignment here.
    //TRYPTR(wire_write_align(header_ctx, 8));

    *header_fields_length = header_ctx->byte_cursor - header_fields_start + msg->header_fields_length;

    // TODO: is this right?
    if (unlikely(msg_c->byte_cursor + msg->body_length >= msg_c->data_len)) {
        return -1;
    }

    bufs[0] = (struct iovec){ header_ctx->data, header_ctx->byte_cursor };
    bufs[1] = (struct iovec){ msg_c->data + msg->header_length, msg_c->byte_cursor + msg->body_length - msg->header_length };

    msg_c->byte_cursor += msg->body_length;

    return 0;
}

int wire_collect_strings(WireCtx *c, WireMsg *msg, WireMsgBodyString *strings, int strings_count)
{
    if (!msg->fields[DBUS_HEADER_FIELD_SIGNATURE].present) {
        return -1;
    }

    char *sig = msg->fields[DBUS_HEADER_FIELD_SIGNATURE].t.str;
    int stri = 0;
    int sigi = 0;
    uint32_t body_cursor = c->byte_cursor;

    while (*sig) {
        switch (*sig) {
            case 'y': {
                TRYPTR(wire_get_u8(c));
            } break;
            case 'b': {
                TRYPTR(wire_get_u32(c));
            } break;
            case 'n': {
                TRYPTR(wire_get_i16(c));
            } break;
            case 'q': {
                TRYPTR(wire_get_u16(c));
            } break;
            case 'i': {
                TRYPTR(wire_get_i32(c));
            } break;
            case 'u': {
                TRYPTR(wire_get_u32(c));
            } break;
            case 'o': /* through */
            case 's': {
                char *s = TRYPTR(wire_get_string(c));
                if (sigi >= strings_count) {
                    return -1;
                }
                strings[sigi].index = sigi;
                strings[sigi].str = s;
            } break;
            case 'g': {
                char *s = TRYPTR(wire_get_signature(c));
                if (sigi >= strings_count) {
                    return -1;
                }
                strings[sigi].index = sigi;
                strings[sigi].str = s;
            } break;
            case 'a': {
                uint32_t array_size = *(uint32_t*)TRYPTR(wire_get_u32(c));
                uint32_t new_cursor = c->byte_cursor + array_size;
                if (new_cursor >= c->data_len) {
                    return -1;
                }
                c->byte_cursor = new_cursor;
            } break;

            default: {
                goto end_nonfatal;
            }
        }

        sigi++;
        sig++;
    }

end_nonfatal:

    c->byte_cursor = body_cursor;

    return stri;
}