#include <amd64/io.h>
#include <amd64/intr_defs.h>
#include <amd64/apic.h>
#include <device/device.h>
#include <device/idedrv.h>
#include <device/partitions.h>
#include <devices.h>
#include <libk/std.h>
#include <libk/list.h>
#include <libk/string.h>
#include <mm/liballoc.h>
#include <proc/proc.h>
#include <proc/reschedule.h>
#include <status.h>
#include <irq/irq.h>

#define IDE_REG_DATA     0x00
#define IDE_REG_ERROR    0x01
#define IDE_REG_SECCOUNT 0x02
#define IDE_REG_LBA0     0x03
#define IDE_REG_LBA1     0x04
#define IDE_REG_LBA2     0x05
#define IDE_REG_DRIVE    0x06
#define IDE_REG_STATUS   0x07
#define IDE_REG_CMD      0x07

#define IDE_BSY  0x80
#define IDE_DRDY 0x40
#define IDE_DF   0x20
#define IDE_ERR  0x01
#define IDE_DRQ  0x08

#define IDE_CMD_READ28   0x20
#define IDE_CMD_WRITE28  0x30
#define IDE_CMD_READ48   0x24
#define IDE_CMD_WRITE48  0x34
#define IDE_CMD_FLUSH48  0xEA
#define IDE_CMD_FLUSH28  0xE7
#define IDE_CMD_IDENTIFY 0xEC

static bool ide_wait (uint16_t io, uint32_t timeout, bool drq, bool errcheck) {
  uint32_t i = 0;
  uint8_t status;

  for (;;) {
    status = inb (io + IDE_REG_STATUS);

    if (!(status & IDE_BSY))
      break;

    if (++i >= timeout)
      return false;
  }

  if (drq) {
    i = 0;
    while (!(status & IDE_DRQ)) {
      if (status & IDE_ERR)
        return false;

      status = inb (io + IDE_REG_STATUS);

      if (status == 0xFF)
        return true;

      if (++i >= timeout)
        return false;
    }
  }

  if (errcheck && (status & (IDE_DF | IDE_ERR)))
    return false;

  return true;
}

#pragma clang optimize off
static void ide_delay (uint16_t ctrl) {
  inb (ctrl);
  inb (ctrl);
  inb (ctrl);
  inb (ctrl);
}
#pragma clang optimize on

static void ide_flush (struct idedrv* idedrv) {
  if (idedrv->lba48)
    outb (idedrv->io + IDE_REG_CMD, IDE_CMD_FLUSH48);
  else
    outb (idedrv->io + IDE_REG_CMD, IDE_CMD_FLUSH28);
}

static void ide_irq (void* arg, void* regs, struct reschedule_ctx* rctx) {
  struct idedrv* idedrv = arg;

  spin_lock (&idedrv->device->lock);

  struct list_node_link* node = idedrv->requests;

  if (node == NULL) {
    (void)inb (idedrv->io + IDE_REG_STATUS);
    spin_unlock (&idedrv->device->lock);
    return;
  }

  struct idedrv_request* req = list_entry (node, struct idedrv_request, requests_link);
  struct list_node_link* sqlist_node = req->sq.proc_list;
  struct proc_sq_entry* sq_entry = list_entry (sqlist_node, struct proc_sq_entry, sq_link);
  struct proc* resumed_proc = sq_entry->proc;
  
  uint8_t status = inb (idedrv->io + IDE_REG_STATUS);

  if ((status & (IDE_ERR | IDE_DRQ))) {
    list_remove (idedrv->requests, &req->requests_link);
    spin_unlock (&idedrv->device->lock);
    proc_sq_resume (resumed_proc, sq_entry, rctx);
    free (req);
    return;
  }

  spin_lock (&resumed_proc->lock);

  if (req->rw == 1) {
    if ((status & IDE_DRQ)) {
      uint16_t* p = req->outbuffer + (req->sector_done_count * (idedrv->sector_size / 2));
      insw (idedrv->io + IDE_REG_DATA, p, idedrv->sector_size / 2);
      req->sector_done_count++;
    }
  } else if (req->rw == 2) {
    req->sector_done_count++;
    if (req->sector_done_count < req->sector_count) {
      uint16_t* p = req->outbuffer + (req->sector_done_count * (idedrv->sector_size / 2));
      outsw (idedrv->io + IDE_REG_DATA, p, idedrv->sector_size / 2);
    }
  }

  if (req->sector_done_count >= req->sector_count) {
    if (req->rw == 2)
      ide_flush (idedrv);

    list_remove (idedrv->requests, &req->requests_link);

    spin_unlock (&resumed_proc->lock);
    spin_unlock (&idedrv->device->lock);

    free (req);
    proc_sq_resume (resumed_proc, sq_entry, rctx);
    return;
  }

  spin_unlock (&resumed_proc->lock);
  spin_unlock (&idedrv->device->lock);
}

void ide_probe (uint16_t io, uint16_t ctrl, uint8_t devno, struct ide_probe* probe) {
  probe->flags = 0;
  probe->sector_count = 0;
  probe->sector_size = 0;

  uint16_t identify_buffer[256];

  uint8_t status = inb (io + IDE_REG_STATUS);

  if (status == 0xFF)
    return;

  outb (io + IDE_REG_DRIVE, 0xA0 | (devno << 4));
  ide_delay (ctrl);

  outb (io + IDE_REG_SECCOUNT, 0);
  outb (io + IDE_REG_LBA0, 0);
  outb (io + IDE_REG_LBA1, 0);
  outb (io + IDE_REG_LBA2, 0);

  outb (io + IDE_REG_CMD, IDE_CMD_IDENTIFY);

  status = inb (io + IDE_REG_STATUS);

  if (status == 0)
    return;

  if (!ide_wait (io, 100000, true, true)) {
    return;
  }

  insw (io + IDE_REG_DATA, identify_buffer, 256);

  probe->flags |= IDE_PROBE_AVAIL;

  if ((identify_buffer[106] & 0xC000) == 0x4000) {
    if (identify_buffer[106] & (1 << 12)) {
      uint32_t words_per_sector =
          (uint32_t)identify_buffer[117] | ((uint32_t)identify_buffer[118] << 16);
      probe->sector_size = (size_t)words_per_sector * 2;
    }
  }

  if ((identify_buffer[83] & (1 << 10)) != 0)
    probe->flags |= IDE_PROBE_LBA48;

  if ((probe->flags & IDE_PROBE_LBA48)) {
    probe->sector_count =
        (size_t)((uint64_t)identify_buffer[100] | ((uint64_t)identify_buffer[101] << 16) |
                 ((uint64_t)identify_buffer[102] << 32) | ((uint64_t)identify_buffer[103] << 48));
  } else {
    probe->sector_count =
        (size_t)((uint64_t)identify_buffer[60] | ((uint64_t)identify_buffer[61] << 16));
  }

  probe->io = io;
  probe->ctrl = ctrl;
  probe->devno = devno;

  if (probe->sector_size == 0)
    probe->sector_size = 512;
}

static void ide_prepare (struct idedrv* idedrv, size_t sector, uint16_t sector_count, bool clear) {
  if (clear)
    outb (idedrv->ctrl, 0x00);

  if (idedrv->lba48) {
    outb (idedrv->io + IDE_REG_DRIVE, 0x40 | (idedrv->devno << 4));
    ide_delay (idedrv->ctrl);

    outb (idedrv->io + IDE_REG_SECCOUNT, (sector_count >> 8) & 0xFF);
    outb (idedrv->io + IDE_REG_LBA0, (sector >> 24) & 0xFF);
    outb (idedrv->io + IDE_REG_LBA1, (sector >> 32) & 0xFF);
    outb (idedrv->io + IDE_REG_LBA2, (sector >> 40) & 0xFF);

    outb (idedrv->io + IDE_REG_SECCOUNT, sector_count & 0xFF);
    outb (idedrv->io + IDE_REG_LBA0, sector & 0xFF);
    outb (idedrv->io + IDE_REG_LBA1, (sector >> 8) & 0xFF);
    outb (idedrv->io + IDE_REG_LBA2, (sector >> 16) & 0xFF);
  } else {
    outb (idedrv->io + IDE_REG_DRIVE, 0xE0 | (idedrv->devno << 4) | ((sector >> 24) & 0xFF));
    ide_delay (idedrv->ctrl);

    uint8_t count = (sector_count == 256) ? 0 : (uint8_t)sector_count;
    outb (idedrv->io + IDE_REG_SECCOUNT, count);
    outb (idedrv->io + IDE_REG_LBA0, sector & 0xFF);
    outb (idedrv->io + IDE_REG_LBA1, (sector >> 8) & 0xFF);
    outb (idedrv->io + IDE_REG_LBA2, (sector >> 16) & 0xFF);
  }
}

bool idedrv_init (struct device* device, void* arg, struct proc* proc, struct reschedule_ctx* rctx) {
  (void)proc, (void)rctx;

  struct idedrv_init* init = arg;

  struct idedrv* idedrv = malloc (sizeof (*idedrv));

  if (idedrv == NULL)
    return false;

  idedrv->device = device;
  idedrv->lba48 = init->lba48;
  idedrv->sector_count = init->sector_count;
  idedrv->sector_size = init->sector_size;
  idedrv->io = init->io;
  idedrv->ctrl = init->ctrl;
  idedrv->devno = init->devno;
  idedrv->primscnd = init->primscnd;

  device->udata = idedrv;

  if (idedrv->primscnd == 1) {
    ioapic_route_irq (IDE_DRIVE_PRIM, 14, 0, thiscpu->lapic_id);
    irq_attach (&ide_irq, idedrv, IDE_DRIVE_PRIM);
  } else if (idedrv->primscnd == 2) {
    ioapic_route_irq (IDE_DRIVE_SCND, 15, 0, thiscpu->lapic_id);
    irq_attach (&ide_irq, idedrv, IDE_DRIVE_SCND);
  }

  return true;
}

void idedrv_fini (struct device* device, struct proc* proc, struct reschedule_ctx* rctx) {
  struct idedrv* idedrv = device->udata;

  struct list_node_link* req_link, *tmp_req_link;
  list_foreach (idedrv->requests, req_link, tmp_req_link) {
    struct idedrv_request* req = list_entry (req_link, struct idedrv_request, requests_link);
    list_remove (idedrv->requests, &req->requests_link);
    struct proc_sq_entry* sq_entry = list_entry (req->sq.proc_list, struct proc_sq_entry, sq_link);
    proc_sq_resume (proc, sq_entry, rctx);
    free (req);
  }

  irq_detach (idedrv->primscnd == 1 ? IDE_DRIVE_PRIM : IDE_DRIVE_SCND);
  free (idedrv);
}

int idedrv_read (struct device* device, struct proc* proc, struct reschedule_ctx* rctx, void* a1,
                 void* a2, void* a3, void* a4) {
  (void)proc, (void)rctx, (void)a4;

  if (a1 == NULL || a2 == NULL || a3 == NULL)
    return -ST_BAD_ADDRESS_SPACE;

  size_t sector = *(size_t*)a1;
  size_t sector_count = *(size_t*)a2;
  uint16_t* buffer = a3;

  struct idedrv* idedrv = device->udata;

  if (sector + sector_count > idedrv->sector_count)
    return -ST_OOB_ERROR;

  spin_lock (&proc->lock);
  bool is_kproc = (proc->flags & PROC_KPROC) != 0;
  spin_unlock (&proc->lock);

  /* /1* polling *1/ */
  /* if (is_kproc) { */
    ide_prepare (idedrv, sector, sector_count, false);

    uint8_t cmd = idedrv->lba48 ? IDE_CMD_READ48 : IDE_CMD_READ28;
    outb (idedrv->io + IDE_REG_CMD, cmd);

    for (uint16_t s = 0; s < sector_count; s++) {
      if (!ide_wait (idedrv->io, 100000, true, true))
        return -ST_XDRV_READ_ERROR;

      insw (idedrv->io + IDE_REG_DATA, buffer + (s * (idedrv->sector_size / 2)), (idedrv->sector_size / 2));
    }
    
    return ST_OK;
  /* } else { /1* IRQ *1/ */
  /*   struct idedrv_request* req = malloc (sizeof (*req)); */

  /*   if (req == NULL) */
  /*     return -ST_OOM_ERROR; */

  /*   memset (req, 0, sizeof (*req)); */
  /*   req->outbuffer = buffer; */
  /*   req->sector_count = sector_count; */
  /*   req->sector_done_count = 0; */
  /*   req->rw = 1; */

  /*   list_append (idedrv->requests, &req->requests_link); */
  /*   proc_sq_suspend (proc, &req->sq, NULL, rctx); */

  /*   ide_prepare (idedrv, sector, sector_count, true); */

  /*   uint8_t cmd = idedrv->lba48 ? IDE_CMD_READ48 : IDE_CMD_READ28; */
  /*   outb (idedrv->io + IDE_REG_CMD, cmd); */

  /*   return ST_OK; */
  /* } */
}

int idedrv_write (struct device* device, struct proc* proc, struct reschedule_ctx* rctx, void* a1,
                  void* a2, void* a3, void* a4) {
  (void)proc, (void)rctx, (void)a4;

  if (a1 == NULL || a2 == NULL || a3 == NULL)
    return -ST_BAD_ADDRESS_SPACE;

  size_t sector = *(size_t*)a1;
  size_t sector_count = *(size_t*)a2;
  uint16_t* buffer = a3;

  struct idedrv* idedrv = device->udata;

  if (sector + sector_count > idedrv->sector_count)
    return -ST_OOB_ERROR;
  
  spin_lock (&proc->lock);
  bool is_kproc = (proc->flags & PROC_KPROC) != 0;
  spin_unlock (&proc->lock);

  /* /1* polling *1/ */
  /* if (is_kproc) { */
    ide_prepare (idedrv, sector, sector_count, false);

    uint8_t cmd = idedrv->lba48 ? IDE_CMD_WRITE48 : IDE_CMD_WRITE28;
    outb (idedrv->io + IDE_REG_CMD, cmd);

    for (uint16_t s = 0; s < sector_count; s++) {
      if (!ide_wait (idedrv->io, 100000, true, true))
        return -ST_XDRV_WRITE_ERROR;

      outsw (idedrv->io + IDE_REG_DATA, buffer + (s * (idedrv->sector_size / 2)), (idedrv->sector_size / 2));
    }

    return ST_OK;
  /* } else { /1* IRQ *1/ */
  /*   struct idedrv_request* req = malloc (sizeof (*req)); */

  /*   if (req == NULL) */
  /*     return -ST_OOM_ERROR; */

  /*   memset (req, 0, sizeof (*req)); */
  /*   req->outbuffer = buffer; */
  /*   req->sector_count = sector_count; */
  /*   req->sector_done_count = 0; */
  /*   req->rw = 2; */

  /*   list_append (idedrv->requests, &req->requests_link); */
  /*   proc_sq_suspend (proc, &req->sq, NULL, rctx); */

  /*   ide_prepare (idedrv, sector, sector_count, true); */

  /*   uint8_t cmd = idedrv->lba48 ? IDE_CMD_WRITE48 : IDE_CMD_WRITE28; */
  /*   outb (idedrv->io + IDE_REG_CMD, cmd); */

  /*   if (!ide_wait (idedrv->io, 100000, true, true)) { */
  /*     list_remove (idedrv->requests, &req->requests_link); */
  /*     struct proc_sq_entry* sq_entry = list_entry (req->sq.proc_list, struct proc_sq_entry, sq_link); */
  /*     proc_sq_resume (proc, sq_entry, rctx); */
  /*     free (req); */
  /*     return -ST_XDRV_WRITE_ERROR; */
  /*   } */

  /*   outsw (idedrv->io + IDE_REG_DATA, buffer, idedrv->sector_size / 2); */

  /*   return ST_OK; */
  /* } */
}

int idedrv_get_device_type (struct device* device, struct proc* proc, struct reschedule_ctx* rctx,
                            void* a1, void* a2, void* a3, void* a4) {
  (void)proc, (void)rctx, (void)device, (void)a2, (void)a3, (void)a4;

  if (a1 == NULL)
    return -ST_BAD_ADDRESS_SPACE;

  int* device_type = (int*)a1;

  *device_type = XDRV_TYPE_IDEDRV;

  return ST_OK;
}

int idedrv_get_sector_size (struct device* device, struct proc* proc, struct reschedule_ctx* rctx,
                            void* a1, void* a2, void* a3, void* a4) {
  (void)proc, (void)rctx, (void)a2, (void)a3, (void)a4;

  if (a1 == NULL)
    return -ST_BAD_ADDRESS_SPACE;

  size_t* secsize = (size_t*)a1;

  struct idedrv* idedrv = device->udata;

  *secsize = idedrv->sector_size;

  return ST_OK;
}

int idedrv_get_size (struct device* device, struct proc* proc, struct reschedule_ctx* rctx,
                     void* a1, void* a2, void* a3, void* a4) {
  (void)proc, (void)rctx, (void)a2, (void)a3, (void)a4;

  if (a1 == NULL)
    return -ST_BAD_ADDRESS_SPACE;

  size_t* size = (size_t*)a1;

  struct idedrv* idedrv = device->udata;

  *size = idedrv->sector_size * idedrv->sector_count;

  return ST_OK;
}