// Simple emulator program
#include <stdio.h>
#include <stdint.h>
#include <stddef.h>
#include <stdlib.h>
#include <string.h>
#define SRVE_IMPLEMENTATION
#include "srve.h"
#include "../libc/elf.h"

// Some defines for virtio emulation
#define VIOE_UART0    0x10000000ULL
#define VIOE_UART_SIZE  0x1000ULL
#define VIOE_UART_HOLDING 0x0
#define VIOE_UART_LINESTATUS  0x5
#define VIOE_UART_LINESTATUS_RECEIVEABLE 1
#define VIOE_UART_LINESTATUS_TRANSMITTABLE (1<<5)

// Some defines for new BIOS functionality
#define VMRD_BASEADDRESS 0x0000000010001000UL
#define VMRD_SIZE  0x1000ULL
#define VMRD_REG_MAGIC 0
#define VMRD_REG_BLKSIZE 4
#define VMRD_REG_MEMADDR 8
#define VMRD_REG_BLKADDR 16
#define VMRD_REG_ACTION 24

// The magic number is BA5DB105, which drivers can use to distinguish
// it from virtio.
#define VMRD_MAGIC 0xBA5DB105

// This range needs to cover all I/O areas
#define IORANGE_BEGIN 0x10000000ULL
#define IORANGE_END 0x10002000ULL



typedef struct vmrd vmrd_t;

struct vmrd {
  uint64_t memoryaddress;
  uint64_t blockaddress;
  uint32_t blocksize;
  uint32_t action;
  FILE* file;
  uint64_t imagesize;
};
  
srve_core64_t core;

// Loads binary into memory at address, returning size or -1 on failure.
int64_t loadf(unsigned char* memory, unsigned long long addr, const char* fname) {
  fprintf(stderr, "loadf(%p, 0x%llx, \"%s\");\n", memory, addr, fname);
  FILE* f = fopen(fname, "r");
  if (!f) {
    fprintf(stderr, "Failed to open '%s'\n", fname);
    return -1;
  }
  
  unsigned long sz = 0;
  size_t nread;
  while ((nread = fread(memory + addr + sz, 1, 1024*1024, f)) > 0) {
    sz += (unsigned long) nread;
  }
  
  fclose(f);
}

int uart(int devnum, uint32_t offset, void* buffer, unsigned int storing, unsigned int size) {
  //fprintf(stderr, "uart(%i, 0x%x, %p, %d, %d);\n", devnum, offset, buffer, storing, size);
  
  switch (offset) {
  case VIOE_UART_HOLDING:
    if (storing) {
      fflush(stderr);
      //printf("char value is 0x%x\n", *((uint8_t*)buffer));
      //putc('X',stdout);
      putc(*((uint8_t*)buffer), stdout);
      fflush(stdout);
      //exit(0);
      return 0;
    } else {
      return -1;
    }
  case VIOE_UART_LINESTATUS:
    if (storing) {
      return -1;
    } else {
      *((char*)buffer) = VIOE_UART_LINESTATUS_TRANSMITTABLE;
      return 0;
    }
  default:
    fprintf(stderr, "uart: bad offset 0x%x\n", offset);
    return 0;
  }
}

// Only allow one disk for now, but design as though there may be more.
#define VMRD_MAX 1
vmrd_t* vmrd_array[VMRD_MAX];

uint32_t vmrd_performaction(void* memory, vmrd_t* device, uint32_t action) {
  if (memory == NULL || device == NULL || device->file == NULL || device->imagesize == 0) {
    return 'f';
  }
  
  char* membytes = memory;
  
  switch (action) {
    case 't':
      core.tracing = 1;
      return 's';
    case 'e':
      core.tracing = 0;
      return 's';
    case 'r':
      if (fseek(device->file, device->blocksize*device->blockaddress, SEEK_SET) != 0) {
        return 'f';
      }
      // TODO: Validate memory address...
      if (fread(membytes+device->memoryaddress, device->blocksize, 1, device->file) != 1) {
        return 'f';
      }
      return 's';
    default:
      return 'f';
  }
}

int vmrd(void* memory, int devnum, uint32_t offset, void* buffer, unsigned int storing, unsigned int size) {
  vmrd_t* device = &vmrd_array[devnum];
  switch (offset) {
  case VMRD_REG_MAGIC:
    if (!storing && size == 4) {
      *((uint32_t*)buffer) = VMRD_MAGIC;
      return 0;
    } else {
      goto fail;
    }
  case VMRD_REG_BLKADDR:
    if (storing && size == 8) {
      device->blockaddress = *((uint64_t*)buffer);
      return 0;
    } else if (!storing && size == 8) {
      *((uint64_t*)buffer) = device->blockaddress;
      return 0;
    } else {
      goto fail;
    }
  case VMRD_REG_MEMADDR:
    if (storing && size == 8) {
      device->memoryaddress = *((uint64_t*)buffer);
      return 0;
    } else if (!storing && size == 8) {
      *((uint64_t*)buffer) = device->memoryaddress;
      return 0;
    } else {
      goto fail;
    }
  case VMRD_REG_BLKSIZE:
    if (storing && size == 4) {
      device->blocksize = *((uint32_t*)buffer);
      return 0;
    } else if (!storing && size == 4) {
      *((uint32_t*)buffer) = device->blocksize;
      return 0;
    } else {
      goto fail;
    }
  case VMRD_REG_ACTION:
    if (storing && size == 4) {
      device->action = '*'; // Asterix action state indicates it's in use
      device->action = vmrd_performaction(memory, device,  *((uint32_t*)buffer));
      return 0;
    } else if (!storing && size == 4) {
      *((uint32_t*)buffer) = device->action;
      return 0;
    } else {
      goto fail;
    }
  default:
  fail:
    device->action = 'f';
    fprintf(stderr, "vmrd: bad access at offset 0x%x\n", offset);
    return -1;
  }
  return 0;
}

int iofunc(void* memory, uint64_t address, void* buffer, unsigned int storing, unsigned int size) {
  if (address >= VIOE_UART0 && address+size <= VIOE_UART0+VIOE_UART_SIZE) {
    return uart(0, (uint32_t) (address - VIOE_UART0), buffer, storing, size);
  }
  if (address >= VMRD_BASEADDRESS && address+size <= VMRD_BASEADDRESS+VMRD_SIZE) {
    return vmrd(memory, 0, (uint32_t) (address - VMRD_BASEADDRESS), buffer, storing, size);
  }
  fprintf(stderr, "iofunc: Bad I/O address 0x%llx\n", address);
  return -1;
}

int memfunc(void* memory, uint64_t address, void* buffer, unsigned int storing, unsigned int size) {
  if (address >= IORANGE_BEGIN && address+size <= IORANGE_END) {
    return iofunc(memory, address, buffer, storing, size);
  }
  //if (address % size) {
    //fprintf(stderr, "memfunc(%p, 0x%lx, %p, %d, %d);\n", memory, address, buffer, storing, size);
    //exit(-1);
  //}
  //address = (address << 32) >> 32;
  //fprintf(stderr, "memfunc(%p, 0x%lx, %p, %d, %d);\n", memory, address, buffer, storing, size);
  unsigned char* bmemory = memory;
  if (size == 4) {
    uint32_t* ibuffer = buffer;
    uint32_t* istorage = (void*)(bmemory + address);
    if (storing) {
      *istorage = *ibuffer;
    } else {
      *ibuffer = *istorage;
    }
    return 0;
  } else if (size == 8) {
    uint64_t* ibuffer = buffer;
    uint64_t* istorage = (void*)(bmemory + address);
    if (storing) {
      *istorage = *ibuffer;
    } else {
      *ibuffer = *istorage;
    }
    return 0;
  } else if (size == 1) {
    uint8_t* ibuffer = buffer;
    uint8_t* istorage = (void*)(bmemory + address);
    if (storing) {
      *istorage = *ibuffer;
    } else {
      *ibuffer = *istorage;
    }
    return 0;
  } else if (size == 2) {
    uint16_t* ibuffer = buffer;
    uint16_t* istorage = (void*)(bmemory + address);
    if (storing) {
      *istorage = *ibuffer;
    } else {
      *ibuffer = *istorage;
    }
    return 0;
  } else {
    return -1;
  }
}

int hexvalue(char ch) {
  switch (ch) {
    case '0': return 0;
    case '1': return 1;
    case '2': return 2;
    case '3': return 3;
    case '4': return 4;
    case '5': return 5;
    case '6': return 6;
    case '7': return 7;
    case '8': return 8;
    case '9': return 9;
    case 'a': case 'A': return 10;
    case 'b': case 'B': return 11;
    case 'c': case 'C': return 12;
    case 'd': case 'D': return 13;
    case 'e': case 'E': return 14;
    case 'f': case 'F': return 15;
    default: return -1;
  }
}

char linebuf[1000];

int insertsymbol(srve_debugsymbol_t** symvar, uint64_t addr, char* namebuffer) {
  for (int i = 0; namebuffer[i] != 0; i++) {
    if (namebuffer[i] == '.') {
      return 0; // Skip adding entries for filenames and sections
    }
  }
  srve_debugsymbol_t* sym = malloc(sizeof(srve_debugsymbol_t));
  if (!sym) {
    return -1;
  }
  sym->addr = addr;
  sym->name = strdup(namebuffer);
  sym->next = NULL;
  
  for (int i = 0; sym->name[i] != 0; i++) {
    if (sym->name[i] == '\r' || sym->name[i] == '\n') {
      sym->name[i] = 0;
      break;
    }
  }
  
  srve_debugsymbol_t* search = *symvar;
  if (search == NULL || addr < search->addr) {
    sym->next = search;
    *symvar = sym;
    return 0;
  }
  while (search->addr < addr) {
    if (search->next == NULL || search->next->addr >= addr) {
      sym->next = search->next;
      search->next = sym;
      return 0;
    }
    search = search->next;
  }
  sym->next = search->next;
  search->next = sym;
  return 0;
}

int loadsymbols(srve_debugsymbol_t** symvar, char* fname) {
  FILE* f = fopen(fname, "r");
  
  while (fgets(linebuf, 1000, f)) {
    char* s = linebuf;
    uint64_t x = 0;
    int digit;
    while ((digit = hexvalue(*s)) >= 0) {
      x *= 0x10;
      x += digit;
      s++;
    }
    while (*s == ' ') {
      s++;
    }
    if (insertsymbol(symvar, x, s) != 0) {
      return -1;
    }
  }
  
  fclose(f);
  return 0;
}

int loaddiskimage(vmrd_t* device, char* fname) {
  FILE* f = fopen(fname, "r+");
  if (f) {
    fseek(f, 0, SEEK_END);
    device->file = f;
    device->imagesize = ftell(f);
    device->action = 'i'; // Initial action state
    return 0;
  } else {
    device->file = NULL;
    device->imagesize = 0;
    device->action = 'f'; // Failed action state
    return -1;
  }
}

int main(int argc, char** argv) {
  fprintf(stderr, "SecureLang RV64/RV32 emulator, early testing version\n");
  
  char* memory = calloc(4*1024*1024*1024ULL, 1);
  if (memory == NULL) {
    fprintf(stderr, "Setup failed!\n");
    
    return -1;
  }
  uint64_t loadaddr = 0x8000000ULL; // TODO: Compiler bug prevents 0x80000000 as a constant, must be an integer conversion somewhere
  loadaddr *= 0x10;
  //printf("Loading at %dMB\n", loadaddr/(1024*1024));
  char* kfname = argv[1];
  char* sname = argv[2];
  char* fsname = argv[3];
  
  loadf(memory, loadaddr, argv[1]);
  
  srve_debugsymbol_t* syms = NULL;
  loadsymbols(&syms, sname);
  
  loaddiskimage(&vmrd_array[0], fsname);
  
  srve_debugsymbol_t* iter = syms;
  while (iter) {
    fprintf(stderr, "%lx %s\n", iter->addr, iter->name);
    iter = iter->next;
  }
  
  if (srve_core64_init(&core, &memfunc, memory, loadaddr) != 0) {
    return -1;
  }
  core.symbols = syms;
  core.tracing = 0;
  
  int64_t result;
  do {
    result = srve_core64_doinstr(&core);
  } while (result == 0);
  
  return 0;
}