/*  RetroArch - A frontend for libretro.
 *  Copyright (C) 2025 The RetroArch team
 *
 *  RetroArch 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 Found-
 *  ation, either version 3 of the License, or (at your option) any later version.
 *
 *  RetroArch 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 RetroArch.
 *  If not, see <http://www.gnu.org/licenses/>.
 */

#include <CoreMIDI/CoreMIDI.h>
#include <libretro.h>
#include <lists/string_list.h>
#include <string/stdstring.h>

#include "../midi_driver.h"
#include "../../verbosity.h"

#define CORE_MIDI_QUEUE_SIZE 1024

typedef struct
{
    midi_event_t events[CORE_MIDI_QUEUE_SIZE]; /* Event buffer */
    int read_index;         /* Current read position */
    int write_index;        /* Current write position */
} coremidi_queue_t;

typedef struct
{
    MIDIClientRef client;            /* CoreMIDI client */
    MIDIPortRef input_port;          /* Input port for receiving MIDI data */
    MIDIPortRef output_port;         /* Output port for sending MIDI data */
    MIDIEndpointRef input_endpoint;  /* Selected input endpoint */
    MIDIEndpointRef output_endpoint; /* Selected output endpoint */
    coremidi_queue_t input_queue;    /* Queue for incoming MIDI events */
} coremidi_t;

/* Write to the queue */
static bool coremidi_queue_write(coremidi_queue_t *q, const midi_event_t *ev)
{
    int next_write = (q->write_index + 1) % CORE_MIDI_QUEUE_SIZE;
    if (next_write == q->read_index) /* Queue full */
        return false;

    memcpy(&q->events[q->write_index], ev, sizeof(*ev));
    q->write_index = next_write;
    return true;
}

/* MIDIReadProc callback function */
static void midi_read_callback(const MIDIPacketList *pktlist,
   void *readProcRefCon, void *srcConnRefCon) 
{
    uint32_t i;
    midi_event_t event;
    coremidi_t *d = (coremidi_t *)readProcRefCon;
    const MIDIPacket *packet = &pktlist->packet[0];

    for (i = 0; i < pktlist->numPackets; i++)
    {
        const uint8_t *data = packet->data;
        size_t length       = packet->length;
        const MIDITimeStamp timestamp = packet->timeStamp;

        while (length > 0)
        {
            size_t msg_size = midi_driver_get_event_size(data[0]);
            if (msg_size == 0 || msg_size > length)
                break;

            event.data       = (uint8_t*)data;
            event.data_size  = msg_size;
            event.delta_time = (uint32_t)timestamp;

            /* Add to queue */
            coremidi_queue_write(&d->input_queue, &event);

            data   += msg_size;
            length -= msg_size;
        }

        packet = MIDIPacketNext(packet);
    }
}

/* Initialize the CoreMIDI client and ports */
static void *coremidi_init(const char *input, const char *output)
{
    OSStatus err;
    coremidi_t *d = (coremidi_t *)calloc(1, sizeof(coremidi_t));
    if (!d)
    {
        RARCH_ERR("[MIDI] Out of memory.\n");
        return NULL;
    }

    err = MIDIClientCreate(CFSTR("RetroArch MIDI Client"),
                   NULL, NULL, &d->client);
    if (err != noErr)
    {
        RARCH_ERR("[MIDI] MIDIClientCreate failed: %d.\n", err);
        free(d);
        return NULL;
    }

    RARCH_LOG("[MIDI] CoreMIDI client created successfully.\n");

    /* Create input port if specified */
    if (input)
    {
        err = MIDIInputPortCreate(d->client, CFSTR("Input Port"),
              midi_read_callback, d, &d->input_port);
        if (err != noErr)
        {
            RARCH_ERR("[MIDI] MIDIInputPortCreate failed: %d.\n", err);
            MIDIClientDispose(d->client);
            free(d);
            return NULL;
        }
    }
    else
    {
        RARCH_LOG("[MIDI] CoreMIDI input port created successfully.\n");
    }

    /* Create output port if specified */
    if (output)
    {
        err = MIDIOutputPortCreate(d->client,
              CFSTR("Output Port"), &d->output_port);
        if (err != noErr)
        {
            RARCH_ERR("[MIDI] MIDIOutputPortCreate failed: %d.\n", err);
            if (d->input_port)
                MIDIPortDispose(d->input_port);
            MIDIClientDispose(d->client);
            free(d);
            return NULL;
        }
    }
    else
    {
        RARCH_LOG("[MIDI] CoreMIDI output port created successfully.\n");
    }

    return d;
}

/* Get available input devices */
static bool coremidi_get_avail_inputs(struct string_list *inputs)
{
    ItemCount count = MIDIGetNumberOfSources();
    union string_list_elem_attr attr = {0};

    for (ItemCount i = 0; i < count; i++)
    {
        MIDIEndpointRef endpoint = MIDIGetSource(i);
        CFStringRef name;
        char buf[256];

        OSStatus err = MIDIObjectGetStringProperty(endpoint, kMIDIPropertyDisplayName, &name);
        if (err == noErr)
        {
            if (CFStringGetCString(name, buf, sizeof(buf), kCFStringEncodingUTF8))
            {
                if (!string_list_append(inputs, buf, attr))
                {
                    RARCH_ERR("[MIDI] Failed to append input device to list: %s.\n", buf);
                    CFRelease(name);
                    return false;
                }
                RARCH_LOG("[MIDI] Input device added to list: %s.\n", buf);
            }
            CFRelease(name);
        }
        else
        {
            RARCH_WARN("[MIDI] Failed to get display name for input device %d: %d.\n", i, err);
        }
    }

    return true;
}

/* Get available output devices */
static bool coremidi_get_avail_outputs(struct string_list *outputs)
{
    ItemCount count = MIDIGetNumberOfDestinations();
    union string_list_elem_attr attr = {0};

    for (ItemCount i = 0; i < count; i++)
    {
        char buf[256];
        MIDIEndpointRef endpoint = MIDIGetDestination(i);
        CFStringRef name;
        OSStatus err = MIDIObjectGetStringProperty(endpoint, kMIDIPropertyDisplayName, &name);
        if (err == noErr)
        {
            if (CFStringGetCString(name, buf, sizeof(buf), kCFStringEncodingUTF8))
            {
                if (!string_list_append(outputs, buf, attr))
                {
                    RARCH_ERR("[MIDI] Failed to append output device to list: %s.\n", buf);
                    CFRelease(name);
                    return false;
                }
                RARCH_LOG("[MIDI] Output device added to list: %s.\n", buf);
            }
            CFRelease(name);
        }
        else
        {
            RARCH_WARN("[MIDI] Failed to get display name for output device %d: %d.\n", i, err);
        }
    }

    return true;
}

/* Set the input device */
static bool coremidi_set_input(void *p, const char *input)
{
    ItemCount count;
    coremidi_t *d = (coremidi_t *)p;
    if (!d || !d->input_port)
    {
        RARCH_WARN("[MIDI] Input port not initialized.\n");
        return false;
    }

    /* Disconnect current input endpoint */
    if (d->input_endpoint)
    {
        RARCH_LOG("[MIDI] Disconnecting current input endpoint.\n");
        MIDIPortDisconnectSource(d->input_port, d->input_endpoint);
        d->input_endpoint = 0;
    }

    /* If input is NULL or "Off", just return success */
    if (!input || string_is_equal(input, "Off"))
    {
        RARCH_LOG("[MIDI] Input set to Off.\n");
        return true;
    }

    /* Find the input endpoint by name */
    count = MIDIGetNumberOfSources();
    for (ItemCount i = 0; i < count; i++)
    {
        char buf[256];
        MIDIEndpointRef endpoint = MIDIGetSource(i);
        CFStringRef name;
        OSStatus err = MIDIObjectGetStringProperty(endpoint, kMIDIPropertyDisplayName, &name);
        if (err == noErr)
        {
            if (CFStringGetCString(name, buf, sizeof(buf), kCFStringEncodingUTF8)
                && string_is_equal(input, buf))
            {
                err = MIDIPortConnectSource(d->input_port, endpoint, NULL);
                CFRelease(name);
                if (err == noErr)
                {
                    d->input_endpoint = endpoint;
                    RARCH_LOG("[MIDI] Input endpoint set to %s.\n", buf);
                    return true;
                }
                RARCH_WARN("[MIDI] Failed to connect input endpoint: %d.\n", err);
                return false;
            }
            CFRelease(name);
        }
    }

    RARCH_WARN("[MIDI] Input device not found: %s.\n", input);
    return false;
}

/* Set the output device */
static bool coremidi_set_output(void *p, const char *output)
{
    ItemCount i, count;
    coremidi_t *d = (coremidi_t *)p;
    if (!d || !d->output_port)
    {
        RARCH_WARN("[MIDI] Output port not initialized.\n");
        return false;
    }

    /* If output is NULL or "Off", just return success */
    if (!output || string_is_equal(output, "Off"))
    {
        RARCH_LOG("[MIDI] Output set to Off.\n");
        d->output_endpoint = 0;
        return true;
    }

    /* Find the output endpoint by name */
    count = MIDIGetNumberOfDestinations();
    for (i = 0; i < count; i++)
    {
        char buf[256];
        MIDIEndpointRef endpoint = MIDIGetDestination(i);
        CFStringRef name;
        OSStatus err = MIDIObjectGetStringProperty(endpoint, kMIDIPropertyDisplayName, &name);
        if (err == noErr)
        {
            if (CFStringGetCString(name, buf, sizeof(buf), kCFStringEncodingUTF8)
                && string_is_equal(output, buf))
            {
                d->output_endpoint = endpoint;
                RARCH_LOG("[MIDI] Output endpoint set to %s.\n", buf);
                CFRelease(name);
                return true;
            }
            CFRelease(name);
        }
    }

    RARCH_WARN("[MIDI] Output device not found: %s.\n", output);
    return false;
}

/* Read from the queue */
static bool coremidi_queue_read(coremidi_queue_t *q, midi_event_t *ev)
{
    if (q->read_index == q->write_index) /* Queue empty */
        return false;

    memcpy(ev, &q->events[q->read_index], sizeof(*ev));
    q->read_index = (q->read_index + 1) % CORE_MIDI_QUEUE_SIZE;
    return true;
}

/* Read a MIDI event */
static bool coremidi_read(void *p, midi_event_t *event)
{
    int result;
    coremidi_t *d = (coremidi_t *)p;

    if (!d || !event)
    {
        RARCH_WARN("[MIDI] Invalid parameters in coremidi_read.\n");
        return false;
    }

    if (!d->input_port || !d->input_endpoint)
    {
        RARCH_WARN("[MIDI] Input not configured.\n");
        return false;
    }

    result = coremidi_queue_read(&d->input_queue, event);
#if DEBUG
    RARCH_LOG("[MIDI] Input queue read result: %d.\n", result);
#endif
    return result;
}

/* Write a MIDI event */
static bool coremidi_write(void *p, const midi_event_t *event)
{
    coremidi_t *d = (coremidi_t *)p;

    if (!d || !event)
    {
        RARCH_WARN("[MIDI] Invalid parameters in coremidi_write.\n");
        return false;
    }

    if (!d->output_port || !d->output_endpoint)
    {
        RARCH_WARN("[MIDI] Output not configured.\n");
        return false;
    }

    /* Validate event data */
    if (!event->data || event->data_size == 0 || event->data_size > 65535)
    {
        RARCH_WARN("[MIDI] Invalid event data in coremidi_write.\n");
        return false;
    }

    /* Create a MIDIPacketList with sufficient buffer size */
    char packetListBuffer[sizeof(MIDIPacketList) + sizeof(MIDIPacket) + event->data_size];
    MIDIPacketList *packetList = (MIDIPacketList *)packetListBuffer;
    MIDIPacket *packet = MIDIPacketListInit(packetList);

    /* Add the event to the packet list */
    if (!(packet = MIDIPacketListAdd(packetList, sizeof(packetListBuffer),
             packet, 0, event->data_size, event->data)))
    {
        RARCH_WARN("[MIDI] Failed to create MIDIPacketList.\n");
        return false;
    }

    /* Send the packet */
    OSStatus err = MIDISend(d->output_port, d->output_endpoint, packetList);
    if (err != noErr)
    {
        RARCH_WARN("[MIDI] MIDISend failed: %d.\n", err);
        return false;
    }

    return true;
}

/* Flush the output buffer */
static bool coremidi_flush(void *p)
{
    coremidi_t *d = (coremidi_t *)p;

    if (!d)
    {
        RARCH_WARN("[MIDI] Invalid parameters in coremidi_flush.\n");
        return false;
    }

    if (!d->output_port || !d->output_endpoint)
    {
        RARCH_WARN("[MIDI] Output not configured.\n");
        return false;
    }

    return true;
}

/* Free resources and cleanup */
static void coremidi_free(void *p)
{
    coremidi_t *d = (coremidi_t *)p;

    if (!d)
    {
        RARCH_WARN("[MIDI] Invalid parameters in coremidi_free.\n");
        return;
    }

    /* Clean up MIDI resources */
    if (d->input_port)
    {
        RARCH_LOG("[MIDI] Disconnecting input port...\n");
        MIDIPortDisconnectSource(d->input_port, d->input_endpoint);
        MIDIPortDispose(d->input_port);
    }

    if (d->output_port)
    {
        RARCH_LOG("[MIDI] Disconnecting output port...\n");
        MIDIPortDisconnectSource(d->output_port, d->output_endpoint);
        MIDIPortDispose(d->output_port);
    }

    if (d->client)
    {
        RARCH_LOG("[MIDI] Disposing of CoreMIDI client...\n");
        MIDIClientDispose(d->client);
    }

    /* Free the driver instance */
    free(d);
}

/* CoreMIDI driver API */
midi_driver_t midi_coremidi = {
    .ident = "coremidi",
    .init = coremidi_init,
    .free = coremidi_free,
    .set_input = coremidi_set_input,
    .set_output = coremidi_set_output,
    .read = coremidi_read,
    .write = coremidi_write,
    .flush = coremidi_flush,
    .get_avail_inputs = coremidi_get_avail_inputs,
    .get_avail_outputs = coremidi_get_avail_outputs,
};