/*
DingusPPC - The Experimental PowerPC Macintosh emulator
Copyright (C) 2018-23 divingkatae and maximum
                      (theweirdo)     spatium

(Contact divingkatae#1017 or powermax#2286 on Discord for more info)

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 3 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 <https://www.gnu.org/licenses/>.
*/

#include <core/timermanager.h>
#include <devices/common/scsi/scsi.h>
#include <loguru.hpp>

#include <cinttypes>
#include <cstring>

void ScsiDevice::notify(ScsiMsg msg_type, int param)
{
    if (msg_type == ScsiMsg::BUS_PHASE_CHANGE) {
        switch (param) {
        case ScsiPhase::RESET:
            LOG_F(9, "ScsiDevice %d: bus reset aknowledged", this->scsi_id);
            break;
        case ScsiPhase::SELECTION:
            // check if something tries to select us
            if (this->bus_obj->get_data_lines() & (1 << scsi_id)) {
                LOG_F(9, "ScsiDevice %d selected", this->scsi_id);
                TimerManager::get_instance()->add_oneshot_timer(
                    BUS_SETTLE_DELAY,
                    [this]() {
                        // don't confirm selection if BSY or I/O are asserted
                        if (this->bus_obj->test_ctrl_lines(SCSI_CTRL_BSY | SCSI_CTRL_IO))
                            return;
                        this->bus_obj->assert_ctrl_line(this->scsi_id, SCSI_CTRL_BSY);
                        this->bus_obj->confirm_selection(this->scsi_id);
                        this->initiator_id = this->bus_obj->get_initiator_id();
                        if (this->bus_obj->test_ctrl_lines(SCSI_CTRL_ATN)) {
                            this->switch_phase(ScsiPhase::MESSAGE_OUT);
                        } else {
                            this->switch_phase(ScsiPhase::COMMAND);
                        }
                });
            }
            break;
        }
    }
}

void ScsiDevice::switch_phase(const int new_phase)
{
    this->cur_phase = new_phase;
    this->bus_obj->switch_phase(this->scsi_id, this->cur_phase);
}

void ScsiDevice::next_step()
{
    switch (this->cur_phase) {
    case ScsiPhase::DATA_OUT:
        if (this->data_size >= this->incoming_size) {
            if (this->post_xfer_action != nullptr) {
                this->post_xfer_action();
            }
            this->switch_phase(ScsiPhase::STATUS);
        }
        break;
    case ScsiPhase::DATA_IN:
        if (!this->has_data()) {
            this->switch_phase(ScsiPhase::STATUS);
        }
        break;
    case ScsiPhase::COMMAND:
        this->process_command();
        if (this->cur_phase != ScsiPhase::COMMAND) {
            if (this->prepare_data()) {
                this->bus_obj->assert_ctrl_line(this->scsi_id, SCSI_CTRL_REQ);
            } else {
                ABORT_F("ScsiDevice: prepare_data() failed");
            }
        }
        break;
    case ScsiPhase::STATUS:
        this->switch_phase(ScsiPhase::MESSAGE_IN);
        break;
    case ScsiPhase::MESSAGE_OUT:
        this->switch_phase(ScsiPhase::COMMAND);
        break;
    case ScsiPhase::MESSAGE_IN:
    case ScsiPhase::BUS_FREE:
        this->bus_obj->release_ctrl_lines(this->scsi_id);
        this->switch_phase(ScsiPhase::BUS_FREE);
        break;
    default:
        LOG_F(WARNING, "ScsiDevice: nothing to do for phase %d", this->cur_phase);
    }
}

void ScsiDevice::prepare_xfer(ScsiBus* bus_obj, int& bytes_in, int& bytes_out)
{
    this->cur_phase = bus_obj->current_phase();

    switch (this->cur_phase) {
    case ScsiPhase::COMMAND:
        this->data_ptr = this->cmd_buf;
        this->data_size = 0;
        bytes_out = 0;
        break;
    case ScsiPhase::STATUS:
        this->data_ptr = &this->status;
        this->data_size = 1;
        bytes_out = 1;
        break;
    case ScsiPhase::DATA_IN:
        bytes_out = this->data_size;
        break;
    case ScsiPhase::DATA_OUT:
        break;
    case ScsiPhase::MESSAGE_OUT:
        this->data_ptr = this->msg_buf;
        this->data_size = bytes_in;
        bytes_out = 0;
        break;
    case ScsiPhase::MESSAGE_IN:
        this->data_ptr = this->msg_buf;
        this->data_size = 1;
        bytes_out = 1;
        break;
    default:
        ABORT_F("ScsiDevice: unhandled phase %d in prepare_xfer()", this->cur_phase);
    }
}

static const int CmdGroupLen[8] = {6, 10, 10, -1, -1, 12, -1, -1};

int ScsiDevice::xfer_data() {
    this->cur_phase = bus_obj->current_phase();

    switch (this->cur_phase) {
    case ScsiPhase::MESSAGE_OUT:
        if (this->bus_obj->pull_data(this->initiator_id, this->msg_buf, 1)) {
            if (this->msg_buf[0] & 0x80) {
                LOG_F(9, "%s: IDENTIFY MESSAGE received, code = 0x%X",
                      this->name.c_str(), this->msg_buf[0]);
                this->next_step();
            } else {
                ABORT_F("%s: unsupported message received, code = 0x%X",
                        this->name.c_str(), this->msg_buf[0]);
            }
        }
        break;
    case ScsiPhase::COMMAND:
        if (this->bus_obj->pull_data(this->initiator_id, this->cmd_buf, 1)) {
            int cmd_len = CmdGroupLen[this->cmd_buf[0] >> 5];
            if (cmd_len < 0) {
                ABORT_F("%s: unsupported command received, code = 0x%X",
                        this->name.c_str(), this->msg_buf[0]);
            }
            if (this->bus_obj->pull_data(this->initiator_id, &this->cmd_buf[1], cmd_len - 1))
                this->next_step();
        }
        break;
    default:
        ABORT_F("ScsiDevice: unhandled phase %d in xfer_data()", this->cur_phase);
    }

    return 0;
}

int ScsiDevice::send_data(uint8_t* dst_ptr, const int count)
{
    if (dst_ptr == nullptr || !count) {
        return 0;
    }

    int actual_count = std::min(this->data_size, count);

    std::memcpy(dst_ptr, this->data_ptr, actual_count);
    this->data_ptr  += actual_count;
    this->data_size -= actual_count;

    // attempt to return the requested amount of data
    // when data_size drops down to zero
    if (!this->data_size) {
        if (this->get_more_data() && count > actual_count) {
            dst_ptr += actual_count;
            actual_count = std::min(this->data_size, count - actual_count);
            std::memcpy(dst_ptr, this->data_ptr, actual_count);
            this->data_ptr  += actual_count;
            this->data_size -= actual_count;
        }
    }

    return actual_count;
}

int ScsiDevice::rcv_data(const uint8_t* src_ptr, const int count)
{
    // accumulating incoming data in the pre-configured buffer
    std::memcpy(this->data_ptr, src_ptr, count);
    this->data_ptr  += count;
    this->data_size += count;

    if (this->cur_phase == ScsiPhase::COMMAND)
        this->next_step();

    return count;
}