#include "assembler.h"
typedef enum { SYMBOL_CODE, SYMBOL_DATA, SYMBOL_PLEX } SymbolType;

typedef struct {
  char *name;
  u32 address;
  SymbolType type;
  int size;        // How much memory this symbol occupies
  int is_constant; // 1 = constant, 0 = variable
} Symbol;

typedef struct {
  Symbol *symbols;
  int count;
  int capacity;
} SymbolTable;

void symbol_table_init(SymbolTable *table) {
  table->capacity = 32;
  table->count = 0;
  table->symbols = malloc(table->capacity * sizeof(Symbol));
}

void symbol_table_add(SymbolTable *table, const char *name, u32 address,
                      SymbolType type) {
  // Check for duplicates
  for (int i = 0; i < table->count; i++) {
    if (strcmp(table->symbols[i].name, name) == 0) {
      // Allow plex redefinition for compiler evolution
      if (type == SYMBOL_PLEX && table->symbols[i].type == SYMBOL_PLEX) {
        return;
      }
      fprintf(stderr, "Error: Duplicate label '%s'\n", name);
      exit(1);
    }
  }

  if (table->count >= table->capacity) {
    table->capacity *= 2;
    table->symbols = realloc(table->symbols, table->capacity * sizeof(Symbol));
  }

  Symbol *sym = &table->symbols[table->count++];
  sym->name = strdup(name);
  sym->address = address;
  sym->type = type;
  sym->size = 4; // Default size
  sym->is_constant = 0;
}

Symbol *symbol_table_lookup(SymbolTable *table, const char *name) {
  for (int i = 0; i < table->count; i++) {
    if (strcmp(table->symbols[i].name, name) == 0) {
      return &table->symbols[i];
    }
  }
  return NULL;
}

u32 find_label_in_table(SymbolTable *table, const char *name) {
  Symbol *sym = symbol_table_lookup(table, name);
  if (!sym) {
    fprintf(stderr, "Error: Undefined label '%s'\n", name);
    exit(1);
  }
  return sym->address;
}

int get_instruction_byte_size(ExprNode *node) {
  const char *opname = node->token;

  // Simple opcodes (1 byte)
  if (strcmp(opname, "halt") == 0 || strcmp(opname, "return") == 0) {
    return 1;
  }

  // Register-based opcodes (2 bytes: opcode + register)
  if (strcmp(opname, "pop") == 0 || strcmp(opname, "jump-if-flag") == 0 ||
      strcmp(opname, "jump") == 0 || strcmp(opname, "push") == 0) {
    return 2;
  }

  if (strcmp(opname, "int-to-string") == 0 ||
      strcmp(opname, "nat-to-string") == 0 ||
      strcmp(opname, "real-to-string") == 0 ||
      strcmp(opname, "int-to-real") == 0 ||
      strcmp(opname, "nat-to-real") == 0 ||
      strcmp(opname, "real-to-int") == 0 || strcmp(opname, "load-r") == 0 ||
      strcmp(opname, "real-to-nat") == 0 || strcmp(opname, "int-to-nat") == 0 ||
      strcmp(opname, "nat-to-int") == 0 || strcmp(opname, "load-r8") == 0 ||
      strcmp(opname, "string-length") == 0 || strcmp(opname, "store") == 0 ||
      strcmp(opname, "store-8") == 0 || strcmp(opname, "store-16") == 0 ||
      strcmp(opname, "register-move") == 0 || strcmp(opname, "malloc") == 0) {
    return 3;
  }

  // Register-register-register opcodes (4 bytes: 1 + 3)
  if (strcmp(opname, "add-int") == 0 || strcmp(opname, "sub-int") == 0 ||
      strcmp(opname, "mul-int") == 0 || strcmp(opname, "div-int") == 0 ||
      strcmp(opname, "add-nat") == 0 || strcmp(opname, "sub-nat") == 0 ||
      strcmp(opname, "mul-nat") == 0 || strcmp(opname, "div-nat") == 0 ||
      strcmp(opname, "add-real") == 0 || strcmp(opname, "sub-real") == 0 ||
      strcmp(opname, "bit-shift-left") == 0 ||
      strcmp(opname, "bit-shift-right") == 0 ||
      strcmp(opname, "bit-and") == 0 || strcmp(opname, "bit-or") == 0 ||
      strcmp(opname, "bit-xor") == 0 || strcmp(opname, "mul-real") == 0 ||
      strcmp(opname, "div-real") == 0) {
    return 4;
  }

  // (5 bytes: 1 + 4)
  if (strcmp(opname, "call") == 0) {
    return 5;
  }

  // Load, Load-immediate (6 bytes: 1 + 1 + 4)
  if (strcmp(opname, "load") == 0 || strcmp(opname, "load-immediate") == 0 ||
      strcmp(opname, "load-u16") == 0 || strcmp(opname, "load-i16") == 0 ||
      strcmp(opname, "load-i8") == 0) {
    return 6;
  }

  // jump compare (7 bytes: 1 + 4 + 1 + 1)
  if (strcmp(opname, "jump-eq-int") == 0 ||
      strcmp(opname, "jump-neq-int") == 0 ||
      strcmp(opname, "jump-gt-int") == 0 ||
      strcmp(opname, "jump-lt-int") == 0 ||
      strcmp(opname, "jump-le-int") == 0 ||
      strcmp(opname, "jump-ge-int") == 0 ||
      strcmp(opname, "jump-eq-nat") == 0 ||
      strcmp(opname, "jump-neq-nat") == 0 ||
      strcmp(opname, "jump-gt-nat") == 0 ||
      strcmp(opname, "jump-lt-nat") == 0 ||
      strcmp(opname, "jump-le-nat") == 0 ||
      strcmp(opname, "jump-ge-nat") == 0 ||
      strcmp(opname, "jump-eq-real") == 0 ||
      strcmp(opname, "jump-neq-real") == 0 ||
      strcmp(opname, "jump-gt-real") == 0 ||
      strcmp(opname, "jump-lt-real") == 0 ||
      strcmp(opname, "jump-le-real") == 0 ||
      strcmp(opname, "jump-ge-real") == 0) {
    return 7;
  }

  // Syscall (1 + syscall_id (4) + args)
  if (strcmp(opname, "syscall") == 0) {
    return 1 + 4 + (node->child_count > 0 ? node->child_count - 1 : 0);
  }

  fprintf(stderr, "Unknown opcode for sizing: %s\n", opname);
  exit(-1);
}

int calculate_instruction_size(ExprNode *node) {
  if (node->child_count == 0)
    return 0;

  return get_instruction_byte_size(node);
}

void collect_symbols_in_node(SymbolTable *table, ExprNode *node,
                             u32 *current_addr, int depth) {
  char indent[32] = "";
  for (int i = 0; i < depth; i++)
    strcat(indent, "  ");

#ifdef ASM_DEBUG
  printf("%s%d %s ", indent, *current_addr, node->token);
#endif

  if (strcmp(node->token, "label") == 0) {
    if (node->child_count >= 1) {
      const char *name = node->children[0]->token;
#ifdef ASM_DEBUG
      printf(" %s -> %d\n", name, *current_addr);
#endif
      symbol_table_add(table, name, *current_addr, SYMBOL_CODE);
    }

    for (size_t i = 1; i < node->child_count; i++) {
      collect_symbols_in_node(table, node->children[i], current_addr,
                              depth + 1);
    }
  } else {
    int size = get_instruction_byte_size(node);
    *current_addr += size;
#ifdef ASM_DEBUG
    printf(" +%d bytes -> %d\n", size, *current_addr);
#endif
  }
}

void collect_symbols(SymbolTable *table, ExprNode *program) {
  // First, collect all data labels (with placeholder address)
  for (size_t i = 0; i < program->child_count; ++i) {
    ExprNode *section = program->children[i];
    if (strcmp(section->token, "data") == 0) {
      for (size_t j = 0; j < section->child_count; ++j) {
        ExprNode *item = section->children[j];
        if (strcmp(item->token, "label") == 0 && item->child_count >= 2) {
          const char *name = item->children[0]->token;
          symbol_table_add(table, name, 0, SYMBOL_DATA);
        }
      }
    }
  }

  // Second, collect all code labels with proper nesting
  u32 code_addr = 0;
  for (size_t i = 0; i < program->child_count; ++i) {
    ExprNode *section = program->children[i];
    if (strcmp(section->token, "code") == 0) {
      for (size_t j = 0; j < section->child_count; ++j) {
        collect_symbols_in_node(table, section->children[j], &code_addr, 0);
      }
    }
  }
}

u32 allocate_data(VM *vm, SymbolTable *table, const char *name, u32 size) {
  u32 addr = vm->mp;
  vm->mp += size;
  vm->frames[vm->fp].end += size;

  // Update the symbol's address
  Symbol *sym = symbol_table_lookup(table, name);
  if (sym && sym->type == SYMBOL_DATA) {
    sym->address = addr;
    sym->size = size;
  }

  return addr;
}

void emit_byte(VM *vm, u8 byte) { vm->code[vm->cp++] = byte; }

void emit_u32(VM *vm, u32 value) {
  write_u32(vm, code, vm->cp, value);
  vm->cp += 4;
}

void emit_opcode(VM *vm, Opcode op) { emit_byte(vm, op); }

int parse_register(const char *reg_str) {
  if (reg_str[0] != '$')
    return -1;
  return atoi(reg_str + 1);
}

u32 resolve_symbol(SymbolTable *table, const char *ref) {
  // Handle symbol references (e.g., &label)
  if (ref[0] == '&') {
    return find_label_in_table(table, ref + 1);
  }

  // Handle fixed-point numbers (e.g., 0.5)
  if (strchr(ref, '.')) {
    return TO_FIXED(atof(ref));
  }

  // Handle hexadecimal literals (e.g., 0x7)
  if (ref[0] == '0' && (ref[1] == 'x' || ref[1] == 'X')) {
    char *endptr;
    u32 value = (u32)strtoul(ref + 2, &endptr, 16); // Skip "0x"

    if (endptr == ref + 2 || *endptr != '\0') {
      fprintf(stderr, "Invalid hex literal: %s\n", ref);
      exit(1);
    }
    return value;
  }

  // Handle decimal literals (e.g., 7)
  char *endptr;
  u32 value = (u32)strtoul(ref, &endptr, 10);

  if (endptr == ref || *endptr != '\0') {
    fprintf(stderr, "Invalid decimal literal: %s\n", ref);
    exit(1);
  }
  return value;
}

static char *unwrap_string(const char *quoted_str) {
  if (!quoted_str)
    return NULL;

  size_t len = strlen(quoted_str);
  if (len >= 2 && quoted_str[0] == '"' && quoted_str[len - 1] == '"') {
    // Remove quotes and process escape sequences
    const char *src = quoted_str + 1;
    size_t src_len = len - 2;

    // First pass: calculate the actual length needed after escape processing
    size_t actual_len = 0;
    for (size_t i = 0; i < src_len; ++i) {
      if (src[i] == '\\' && i + 1 < src_len) {
        // Escape sequence
        actual_len++;
        i++; // Skip the next character
      } else {
        actual_len++;
      }
    }

    char *unwrapped = (char *)malloc(actual_len + 1);
    size_t dst_idx = 0;

    // Second pass: process escape sequences
    for (size_t i = 0; i < src_len; ++i) {
      if (src[i] == '\\' && i + 1 < src_len) {
        // Handle escape sequences
        switch (src[i + 1]) {
        case 'n':
          unwrapped[dst_idx++] = '\n';
          break;
        case 't':
          unwrapped[dst_idx++] = '\t';
          break;
        case 'r':
          unwrapped[dst_idx++] = '\r';
          break;
        case '\\':
          unwrapped[dst_idx++] = '\\';
          break;
        case '"':
          unwrapped[dst_idx++] = '"';
          break;
        case '\'':
          unwrapped[dst_idx++] = '\'';
          break;
        default:
          // Unknown escape, keep both characters
          unwrapped[dst_idx++] = src[i];
          unwrapped[dst_idx++] = src[i + 1];
          break;
        }
        i++; // Skip the next character
      } else {
        unwrapped[dst_idx++] = src[i];
      }
    }
    unwrapped[dst_idx] = '\0';
    return unwrapped;
  }
  // Not quoted, return copy
  return strdup(quoted_str);
}

void process_data_block(VM *vm, SymbolTable *table, ExprNode *block) {
  for (size_t i = 0; i < block->child_count; ++i) {
    ExprNode *item = block->children[i];
    if (strcmp(item->token, "label") == 0 && item->child_count >= 2) {
      const char *name = item->children[0]->token;
      ExprNode *val = item->children[1];

      if (val->child_count == 0) {
        const char *token = val->token;

        // Case 1: String literal (enclosed in quotes)
        if (token[0] == '"' && token[strlen(token) - 1] == '"') {
          char *unwrapped = unwrap_string(token);
          int len = strlen(unwrapped) + 1;
          u32 addr = allocate_data(vm, table, name, len + 4);

          write_u32(vm, memory, addr, len);
          for (int i = 0; i < len; i++) {
            write_u8(vm, memory, addr + 4 + i, unwrapped[i]);
          }
          free(unwrapped);
        }
        // Case 2: Hexadecimal integer (0x...)
        else if (token[0] == '0' && (token[1] == 'x' || token[1] == 'X')) {
          char *endptr;
          u32 value = (u32)strtoul(token + 2, &endptr, 16);

          if (endptr != token + strlen(token)) {
            fprintf(stderr, "Invalid hex in data block: %s\n", token);
            exit(1);
          }

          u32 addr = allocate_data(vm, table, name, 4);
          write_u32(vm, memory, addr, value);
        }
        // Case 3: Floating-point (has decimal point)
        else if (strchr(token, '.')) {
          float f = atof(token);
          u32 addr = allocate_data(vm, table, name, 4);
          write_u32(vm, memory, addr, TO_FIXED(f));
        }
        // Case 4: Decimal integer
        else {
          char *endptr;
          u32 value = (u32)strtoul(token, &endptr, 10);

          if (endptr != token + strlen(token)) {
            fprintf(stderr, "Invalid decimal in data block: %s\n", token);
            exit(1);
          }

          u32 addr = allocate_data(vm, table, name, 4);
          write_u32(vm, memory, addr, value);
          vm->mp += 4;
        }
      } else {
        fprintf(stderr, "Unsupported data item\n");
        exit(1);
      }
    }
  }
}

void process_code_expr(VM *vm, SymbolTable *table, ExprNode *node) {
  const char *opname = node->token;
  if (strcmp(opname, "label") == 0) {
    for (size_t i = 1; i < node->child_count; i++) {
      process_code_expr(vm, table, node->children[i]);
    }
  } else if (strcmp(opname, "halt") == 0) {
    emit_opcode(vm, OP_HALT);
  } else if (strcmp(opname, "jump") == 0) {
    emit_opcode(vm, OP_JMP);
    u32 addr = resolve_symbol(table, node->children[0]->token);
    emit_u32(vm, addr);
  } else if (strcmp(opname, "jump-if-flag") == 0) {
    emit_opcode(vm, OP_JMPF);
    u32 addr = resolve_symbol(table, node->children[0]->token);
    emit_u32(vm, addr);
  } else if (strcmp(opname, "call") == 0) {
    emit_opcode(vm, OP_CALL);
    u32 addr = resolve_symbol(table, node->children[0]->token);
    emit_u32(vm, addr);
  } else if (strcmp(opname, "return") == 0) {
    emit_opcode(vm, OP_RETURN);
  } else if (strcmp(opname, "load-immediate") == 0) {
    emit_opcode(vm, OP_LOAD_IMM);
    int reg = parse_register(node->children[0]->token);
    u32 addr = resolve_symbol(table, node->children[1]->token);
    emit_byte(vm, reg);
    emit_u32(vm, addr);
  } else if (strcmp(opname, "load") == 0) {
    emit_opcode(vm, OP_LOAD);
    int dest = parse_register(node->children[0]->token);
    u32 addr = resolve_symbol(table, node->children[1]->token);
    emit_byte(vm, dest);
    emit_u32(vm, addr);
  } else if (strcmp(opname, "load-r") == 0) {
    emit_opcode(vm, OP_LOAD_REG);
    int dest = parse_register(node->children[0]->token);
    int src1 = parse_register(node->children[1]->token);
    emit_byte(vm, dest);
    emit_byte(vm, src1);
  } else if (strcmp(opname, "load-r8") == 0) {
    emit_opcode(vm, OP_LOAD_REG8);
    int dest = parse_register(node->children[0]->token);
    int src1 = parse_register(node->children[1]->token);
    emit_byte(vm, dest);
    emit_byte(vm, src1);    
  } else if (strcmp(opname, "malloc") == 0) {
    emit_opcode(vm, OP_MALLOC);
    int dest = parse_register(node->children[0]->token);
    int src1 = parse_register(node->children[1]->token);
    emit_byte(vm, dest);
    emit_byte(vm, src1);
  } else if (strcmp(opname, "load-i8") == 0) {
    emit_opcode(vm, OP_LOADI8);
    int dest = parse_register(node->children[0]->token);
    int src1 = parse_register(node->children[1]->token);
    emit_byte(vm, dest);
    emit_byte(vm, src1);
  } else if (strcmp(opname, "load-u8") == 0) {
    emit_opcode(vm, OP_LOADU8);
    int dest = parse_register(node->children[0]->token);
    int src1 = parse_register(node->children[1]->token);
    emit_byte(vm, dest);
    emit_byte(vm, src1);
  } else if (strcmp(opname, "load-u16") == 0) {
    emit_opcode(vm, OP_LOADU16);
    int dest = parse_register(node->children[0]->token);
    int src1 = parse_register(node->children[1]->token);
    emit_byte(vm, dest);
    emit_byte(vm, src1);
  } else if (strcmp(opname, "load-i16") == 0) {
    emit_opcode(vm, OP_LOADI16);
    int dest = parse_register(node->children[0]->token);
    int src1 = parse_register(node->children[1]->token);
    emit_byte(vm, dest);
    emit_byte(vm, src1);
  } else if (strcmp(opname, "store") == 0) {
    emit_opcode(vm, OP_STORE);
    int dest = parse_register(node->children[0]->token);
    int src1 = parse_register(node->children[1]->token);
    emit_byte(vm, dest);
    emit_byte(vm, src1);
  } else if (strcmp(opname, "store-8") == 0) {
    emit_opcode(vm, OP_STORE8);
    int dest = parse_register(node->children[0]->token);
    int src1 = parse_register(node->children[1]->token);
    emit_byte(vm, dest);
    emit_byte(vm, src1);
  } else if (strcmp(opname, "store-16") == 0) {
    emit_opcode(vm, OP_STORE16);
    int dest = parse_register(node->children[0]->token);
    int src1 = parse_register(node->children[1]->token);
    emit_byte(vm, dest);
    emit_byte(vm, src1);
  } else if (strcmp(opname, "push") == 0) {
    emit_opcode(vm, OP_PUSH);
    int reg = parse_register(node->children[0]->token);
    emit_byte(vm, reg);
  } else if (strcmp(opname, "pop") == 0) {
    emit_opcode(vm, OP_POP);
    int reg = parse_register(node->children[0]->token);
    emit_byte(vm, reg);
  } else if (strcmp(opname, "register-move") == 0) {
    emit_opcode(vm, OP_REG_MOV);
    int dest = parse_register(node->children[0]->token);
    int src = parse_register(node->children[1]->token);
    emit_byte(vm, dest);
    emit_byte(vm, src);
  } else if (strcmp(opname, "syscall") == 0) {
    emit_opcode(vm, OP_SYSCALL);

    // Parse syscall ID
    u32 syscall_id = 0;
    const char *syscall_name = node->children[0]->token;
    if (strcmp(syscall_name, "EXIT") == 0)
      syscall_id = SYSCALL_EXIT;
    else if (strcmp(syscall_name, "OPEN") == 0)
      syscall_id = SYSCALL_DEVICE_OPEN;
    else if (strcmp(syscall_name, "READ") == 0)
      syscall_id = SYSCALL_DEVICE_READ;
    else if (strcmp(syscall_name, "WRITE") == 0)
      syscall_id = SYSCALL_DEVICE_WRITE;
    else if (strcmp(syscall_name, "CLOSE") == 0)
      syscall_id = SYSCALL_DEVICE_CLOSE;
    else if (strcmp(syscall_name, "IOCTL") == 0)
      syscall_id = SYSCALL_DEVICE_IOCTL;

    emit_u32(vm, syscall_id);

    // Emit register arguments
    for (size_t i = 1; i < node->child_count; ++i) {
      int reg = parse_register(node->children[i]->token);
      emit_byte(vm, reg);
    }
  } else if (strcmp(opname, "bit-shift-left") == 0) {
    emit_opcode(vm, OP_SLL);
    int dest = parse_register(node->children[0]->token);
    int src1 = parse_register(node->children[1]->token);
    int src2 = parse_register(node->children[2]->token);
    emit_byte(vm, dest);
    emit_byte(vm, src1);
    emit_byte(vm, src2);
  } else if (strcmp(opname, "bit-shift-right") == 0) {
    emit_opcode(vm, OP_SRL);
    int dest = parse_register(node->children[0]->token);
    int src1 = parse_register(node->children[1]->token);
    int src2 = parse_register(node->children[2]->token);
    emit_byte(vm, dest);
    emit_byte(vm, src1);
    emit_byte(vm, src2);
  } else if (strcmp(opname, "bit-shift-right-extend") == 0) {
    emit_opcode(vm, OP_SRE);
    int dest = parse_register(node->children[0]->token);
    int src1 = parse_register(node->children[1]->token);
    int src2 = parse_register(node->children[2]->token);
    emit_byte(vm, dest);
    emit_byte(vm, src1);
    emit_byte(vm, src2);
  } else if (strcmp(opname, "bit-and") == 0) {
    emit_opcode(vm, OP_BAND);
    int dest = parse_register(node->children[0]->token);
    int src1 = parse_register(node->children[1]->token);
    int src2 = parse_register(node->children[2]->token);
    emit_byte(vm, dest);
    emit_byte(vm, src1);
    emit_byte(vm, src2);
  } else if (strcmp(opname, "bit-or") == 0) {
    emit_opcode(vm, OP_BOR);
    int dest = parse_register(node->children[0]->token);
    int src1 = parse_register(node->children[1]->token);
    int src2 = parse_register(node->children[2]->token);
    emit_byte(vm, dest);
    emit_byte(vm, src1);
    emit_byte(vm, src2);
  } else if (strcmp(opname, "bit-xor") == 0) {
    emit_opcode(vm, OP_BXOR);
    int dest = parse_register(node->children[0]->token);
    int src1 = parse_register(node->children[1]->token);
    int src2 = parse_register(node->children[2]->token);
    emit_byte(vm, dest);
    emit_byte(vm, src1);
    emit_byte(vm, src2);
  } else if (strcmp(opname, "add-int") == 0) {
    emit_opcode(vm, OP_ADD_INT);
    int dest = parse_register(node->children[0]->token);
    int src1 = parse_register(node->children[1]->token);
    int src2 = parse_register(node->children[2]->token);
    emit_byte(vm, dest);
    emit_byte(vm, src1);
    emit_byte(vm, src2);
  } else if (strcmp(opname, "sub-int") == 0) {
    emit_opcode(vm, OP_SUB_INT);
    int dest = parse_register(node->children[0]->token);
    int src1 = parse_register(node->children[1]->token);
    int src2 = parse_register(node->children[2]->token);
    emit_byte(vm, dest);
    emit_byte(vm, src1);
    emit_byte(vm, src2);
  } else if (strcmp(opname, "mul-int") == 0) {
    emit_opcode(vm, OP_MUL_INT);
    int dest = parse_register(node->children[0]->token);
    int src1 = parse_register(node->children[1]->token);
    int src2 = parse_register(node->children[2]->token);
    emit_byte(vm, dest);
    emit_byte(vm, src1);
    emit_byte(vm, src2);
  } else if (strcmp(opname, "div-int") == 0) {
    emit_opcode(vm, OP_DIV_INT);
    int dest = parse_register(node->children[0]->token);
    int src1 = parse_register(node->children[1]->token);
    int src2 = parse_register(node->children[2]->token);
    emit_byte(vm, dest);
    emit_byte(vm, src1);
    emit_byte(vm, src2);
  } else if (strcmp(opname, "add-nat") == 0) {
    emit_opcode(vm, OP_ADD_UINT);
    int dest = parse_register(node->children[0]->token);
    int src1 = parse_register(node->children[1]->token);
    int src2 = parse_register(node->children[2]->token);
    emit_byte(vm, dest);
    emit_byte(vm, src1);
    emit_byte(vm, src2);
  } else if (strcmp(opname, "sub-nat") == 0) {
    emit_opcode(vm, OP_SUB_UINT);
    int dest = parse_register(node->children[0]->token);
    int src1 = parse_register(node->children[1]->token);
    int src2 = parse_register(node->children[2]->token);
    emit_byte(vm, dest);
    emit_byte(vm, src1);
    emit_byte(vm, src2);
  } else if (strcmp(opname, "mul-nat") == 0) {
    emit_opcode(vm, OP_MUL_UINT);
    int dest = parse_register(node->children[0]->token);
    int src1 = parse_register(node->children[1]->token);
    int src2 = parse_register(node->children[2]->token);
    emit_byte(vm, dest);
    emit_byte(vm, src1);
    emit_byte(vm, src2);
  } else if (strcmp(opname, "div-nat") == 0) {
    emit_opcode(vm, OP_DIV_UINT);
    int dest = parse_register(node->children[0]->token);
    int src1 = parse_register(node->children[1]->token);
    int src2 = parse_register(node->children[2]->token);
    emit_byte(vm, dest);
    emit_byte(vm, src1);
    emit_byte(vm, src2);
  } else if (strcmp(opname, "add-real") == 0) {
    emit_opcode(vm, OP_ADD_REAL);
    int dest = parse_register(node->children[0]->token);
    int src1 = parse_register(node->children[1]->token);
    int src2 = parse_register(node->children[2]->token);
    emit_byte(vm, dest);
    emit_byte(vm, src1);
    emit_byte(vm, src2);
  } else if (strcmp(opname, "sub-real") == 0) {
    emit_opcode(vm, OP_SUB_REAL);
    int dest = parse_register(node->children[0]->token);
    int src1 = parse_register(node->children[1]->token);
    int src2 = parse_register(node->children[2]->token);
    emit_byte(vm, dest);
    emit_byte(vm, src1);
    emit_byte(vm, src2);
  } else if (strcmp(opname, "mul-real") == 0) {
    emit_opcode(vm, OP_MUL_REAL);
    int dest = parse_register(node->children[0]->token);
    int src1 = parse_register(node->children[1]->token);
    int src2 = parse_register(node->children[2]->token);
    emit_byte(vm, dest);
    emit_byte(vm, src1);
    emit_byte(vm, src2);
  } else if (strcmp(opname, "div-real") == 0) {
    emit_opcode(vm, OP_DIV_REAL);
    int dest = parse_register(node->children[0]->token);
    int src1 = parse_register(node->children[1]->token);
    int src2 = parse_register(node->children[2]->token);
    emit_byte(vm, dest);
    emit_byte(vm, src1);
    emit_byte(vm, src2);
  } else if (strcmp(opname, "int-to-real") == 0) {
    emit_opcode(vm, OP_INT_TO_REAL);
    int dest = parse_register(node->children[0]->token);
    int src = parse_register(node->children[1]->token);
    emit_byte(vm, dest);
    emit_byte(vm, src);
  } else if (strcmp(opname, "nat-to-real") == 0) {
    emit_opcode(vm, OP_UINT_TO_REAL);
    int dest = parse_register(node->children[0]->token);
    int src = parse_register(node->children[1]->token);
    emit_byte(vm, dest);
    emit_byte(vm, src);
  } else if (strcmp(opname, "real-to-int") == 0) {
    emit_opcode(vm, OP_REAL_TO_INT);
    int dest = parse_register(node->children[0]->token);
    int src = parse_register(node->children[1]->token);
    emit_byte(vm, dest);
    emit_byte(vm, src);
  } else if (strcmp(opname, "real-to-nat") == 0) {
    emit_opcode(vm, OP_REAL_TO_UINT);
    int dest = parse_register(node->children[0]->token);
    int src = parse_register(node->children[1]->token);
    emit_byte(vm, dest);
    emit_byte(vm, src); 
  } else if (strcmp(opname, "jump-eq-int") == 0) {
    emit_opcode(vm, OP_JEQ_INT);
    u32 addr = resolve_symbol(table, node->children[0]->token);
    int src1 = parse_register(node->children[1]->token);
    int src2 = parse_register(node->children[2]->token);
    emit_u32(vm, addr);
    emit_byte(vm, src1);
    emit_byte(vm, src2);
  } else if (strcmp(opname, "jump-neq-int") == 0  ) {
    emit_opcode(vm, OP_JNEQ_INT);
    u32 addr = resolve_symbol(table, node->children[0]->token);
    int src1 = parse_register(node->children[1]->token);
    int src2 = parse_register(node->children[2]->token);
    emit_u32(vm, addr);
    emit_byte(vm, src1);
    emit_byte(vm, src2);        
  } else if (strcmp(opname, "jump-gt-int") == 0) {
    emit_opcode(vm, OP_JGT_INT);
    u32 addr = resolve_symbol(table, node->children[0]->token);
    int src1 = parse_register(node->children[1]->token);
    int src2 = parse_register(node->children[2]->token);
    emit_u32(vm, addr);
    emit_byte(vm, src1);
    emit_byte(vm, src2);
  } else if (strcmp(opname, "jump-lt-int") == 0) {
    emit_opcode(vm, OP_JLT_INT);
    u32 addr = resolve_symbol(table, node->children[0]->token);
    int src1 = parse_register(node->children[1]->token);
    int src2 = parse_register(node->children[2]->token);
    emit_u32(vm, addr);
    emit_byte(vm, src1);
    emit_byte(vm, src2);
  } else if (strcmp(opname, "jump-le-int") == 0) {
    emit_opcode(vm, OP_JLE_INT);
    u32 addr = resolve_symbol(table, node->children[0]->token);
    int src1 = parse_register(node->children[1]->token);
    int src2 = parse_register(node->children[2]->token);
    emit_u32(vm, addr);
    emit_byte(vm, src1);
    emit_byte(vm, src2);
  } else if (strcmp(opname, "jump-ge-int") == 0) {
    emit_opcode(vm, OP_JGE_INT);
    u32 addr = resolve_symbol(table, node->children[0]->token);
    int src1 = parse_register(node->children[1]->token);
    int src2 = parse_register(node->children[2]->token);
    emit_u32(vm, addr);
    emit_byte(vm, src1);
    emit_byte(vm, src2);
  } else if (strcmp(opname, "jump-eq-nat") == 0) {
    emit_opcode(vm, OP_JEQ_UINT);
    u32 addr = resolve_symbol(table, node->children[0]->token);
    int src1 = parse_register(node->children[1]->token);
    int src2 = parse_register(node->children[2]->token);
    emit_u32(vm, addr);
    emit_byte(vm, src1);
    emit_byte(vm, src2);
  } else if (strcmp(opname, "jump-neq-nat") == 0  ) {
    emit_opcode(vm, OP_JNEQ_UINT);
    u32 addr = resolve_symbol(table, node->children[0]->token);
    int src1 = parse_register(node->children[1]->token);
    int src2 = parse_register(node->children[2]->token);
    emit_u32(vm, addr);
    emit_byte(vm, src1);
    emit_byte(vm, src2);    
  } else if (strcmp(opname, "jump-gt-nat") == 0) {
    emit_opcode(vm, OP_JGT_UINT);
    u32 addr = resolve_symbol(table, node->children[0]->token);
    int src1 = parse_register(node->children[1]->token);
    int src2 = parse_register(node->children[2]->token);
    emit_u32(vm, addr);
    emit_byte(vm, src1);
    emit_byte(vm, src2);
  } else if (strcmp(opname, "jump-lt-nat") == 0) {
    emit_opcode(vm, OP_JLT_UINT);
    u32 addr = resolve_symbol(table, node->children[0]->token);
    int src1 = parse_register(node->children[1]->token);
    int src2 = parse_register(node->children[2]->token);
    emit_u32(vm, addr);
    emit_byte(vm, src1);
    emit_byte(vm, src2);
  } else if (strcmp(opname, "jump-le-nat") == 0) {
    emit_opcode(vm, OP_JLE_UINT);
    u32 addr = resolve_symbol(table, node->children[0]->token);
    int src1 = parse_register(node->children[1]->token);
    int src2 = parse_register(node->children[2]->token);
    emit_u32(vm, addr);
    emit_byte(vm, src1);
    emit_byte(vm, src2);
  } else if (strcmp(opname, "jump-ge-nat") == 0) {
    emit_opcode(vm, OP_JGE_UINT);
    u32 addr = resolve_symbol(table, node->children[0]->token);
    int src1 = parse_register(node->children[1]->token);
    int src2 = parse_register(node->children[2]->token);
    emit_u32(vm, addr);
    emit_byte(vm, src1);
    emit_byte(vm, src2);
  } else if (strcmp(opname, "jump-eq-real") == 0) {
    emit_opcode(vm, OP_JEQ_REAL);
    u32 addr = resolve_symbol(table, node->children[0]->token);
    int src1 = parse_register(node->children[1]->token);
    int src2 = parse_register(node->children[2]->token);
    emit_u32(vm, addr);
    emit_byte(vm, src1);
    emit_byte(vm, src2);
  } else if (strcmp(opname, "jump-neq-real") == 0  ) {
    emit_opcode(vm, OP_JNEQ_REAL);
    u32 addr = resolve_symbol(table, node->children[0]->token);
    int src1 = parse_register(node->children[1]->token);
    int src2 = parse_register(node->children[2]->token);
    emit_u32(vm, addr);
    emit_byte(vm, src1);
    emit_byte(vm, src2);    
  } else if (strcmp(opname, "jump-gt-real") == 0) {
    emit_opcode(vm, OP_JGT_REAL);
    u32 addr = resolve_symbol(table, node->children[0]->token);
    int src1 = parse_register(node->children[1]->token);
    int src2 = parse_register(node->children[2]->token);
    emit_u32(vm, addr);
    emit_byte(vm, src1);
    emit_byte(vm, src2);
  } else if (strcmp(opname, "jump-lt-real") == 0) {
    emit_opcode(vm, OP_JLT_REAL);
    u32 addr = resolve_symbol(table, node->children[0]->token);
    int src1 = parse_register(node->children[1]->token);
    int src2 = parse_register(node->children[2]->token);
    emit_u32(vm, addr);
    emit_byte(vm, src1);
    emit_byte(vm, src2);
  } else if (strcmp(opname, "jump-le-real") == 0) {
    emit_opcode(vm, OP_JLE_REAL);
    u32 addr = resolve_symbol(table, node->children[0]->token);
    int src1 = parse_register(node->children[1]->token);
    int src2 = parse_register(node->children[2]->token);
    emit_u32(vm, addr);
    emit_byte(vm, src1);
    emit_byte(vm, src2);
  } else if (strcmp(opname, "jump-ge-real") == 0) {
    emit_opcode(vm, OP_JGE_REAL);
    u32 addr = resolve_symbol(table, node->children[0]->token);
    int src1 = parse_register(node->children[1]->token);
    int src2 = parse_register(node->children[2]->token);
    emit_u32(vm, addr);
    emit_byte(vm, src1);
    emit_byte(vm, src2);
  } else if (strcmp(opname, "string-length") == 0) {
    emit_opcode(vm, OP_STRLEN);
    int dest = parse_register(node->children[0]->token);
    int src = parse_register(node->children[1]->token);
    emit_byte(vm, dest);
    emit_byte(vm, src);
  } else if (strcmp(opname, "string-eq") == 0) {
    emit_opcode(vm, OP_STREQ);
    int dest = parse_register(node->children[0]->token);
    int src1 = parse_register(node->children[1]->token);
    int src2 = parse_register(node->children[2]->token);
    emit_byte(vm, dest);
    emit_byte(vm, src1);
    emit_byte(vm, src2);
  } else if (strcmp(opname, "string-concat") == 0) {
    emit_opcode(vm, OP_STRCAT);
    int dest = parse_register(node->children[0]->token);
    int src1 = parse_register(node->children[1]->token);
    int src2 = parse_register(node->children[2]->token);
    emit_byte(vm, dest);
    emit_byte(vm, src1);
    emit_byte(vm, src2);
  } else if (strcmp(opname, "string-get-char") == 0) {
    emit_opcode(vm, OP_STR_GET_CHAR);
    int dest = parse_register(node->children[0]->token);
    int src1 = parse_register(node->children[1]->token);
    int src2 = parse_register(node->children[2]->token);
    emit_byte(vm, dest);
    emit_byte(vm, src1);
    emit_byte(vm, src2);
  } else if (strcmp(opname, "string-find-char") == 0) {
    emit_opcode(vm, OP_STR_FIND_CHAR);
    int dest = parse_register(node->children[0]->token);
    int src1 = parse_register(node->children[1]->token);
    int src2 = parse_register(node->children[2]->token);
    emit_byte(vm, dest);
    emit_byte(vm, src1);
    emit_byte(vm, src2);
  } else if (strcmp(opname, "string-slice") == 0) {
    emit_opcode(vm, OP_STR_SLICE);
    int dest = parse_register(node->children[0]->token);
    int src1 = parse_register(node->children[1]->token);
    int src2 = parse_register(node->children[2]->token);
    int src3 = parse_register(node->children[3]->token);
    emit_byte(vm, dest);
    emit_byte(vm, src1);
    emit_byte(vm, src2);
    emit_byte(vm, src3);
  } else if (strcmp(opname, "int-to-string") == 0) {
    emit_opcode(vm, OP_INT_TO_STRING);
    int dest = parse_register(node->children[0]->token);
    int src = parse_register(node->children[1]->token);
    emit_byte(vm, dest);
    emit_byte(vm, src);
  } else if (strcmp(opname, "nat-to-string") == 0) {
    emit_opcode(vm, OP_UINT_TO_STRING);
    int dest = parse_register(node->children[0]->token);
    int src = parse_register(node->children[1]->token);
    emit_byte(vm, dest);
    emit_byte(vm, src);
  } else if (strcmp(opname, "real-to-string") == 0) {
    emit_opcode(vm, OP_REAL_TO_STRING);
    int dest = parse_register(node->children[0]->token);
    int src = parse_register(node->children[1]->token);
    emit_byte(vm, dest);
    emit_byte(vm, src);
  } else if (strcmp(opname, "string-to-int") == 0) {
    emit_opcode(vm, OP_STRING_TO_INT);
    int dest = parse_register(node->children[0]->token);
    int src = parse_register(node->children[1]->token);
    emit_byte(vm, dest);
    emit_byte(vm, src);
  } else if (strcmp(opname, "string-to-nat") == 0) {
    emit_opcode(vm, OP_STRING_TO_UINT);
    int dest = parse_register(node->children[0]->token);
    int src = parse_register(node->children[1]->token);
    emit_byte(vm, dest);
    emit_byte(vm, src);
  } else if (strcmp(opname, "string-to-real") == 0) {
    emit_opcode(vm, OP_STRING_TO_REAL);
    int dest = parse_register(node->children[0]->token);
    int src = parse_register(node->children[1]->token);
    emit_byte(vm, dest);
    emit_byte(vm, src);
  } else {
    fprintf(stderr, "Unknown opcode: %s\n", opname);
  }
}

void assemble(VM *vm, ExprNode *program) {
  SymbolTable table;
  symbol_table_init(&table);

  // PASS 1: Collect all symbols (both code and data)
  collect_symbols(&table, program);

  // PASS 2: Process data section using symbol table
  for (size_t i = 0; i < program->child_count; ++i) {
    ExprNode *section = program->children[i];
    if (strcmp(section->token, "data") == 0) {
      process_data_block(vm, &table, section);
    }
  }

  // PASS 3: Process code section using complete symbol table
  for (size_t i = 0; i < program->child_count; ++i) {
    ExprNode *section = program->children[i];
    if (strcmp(section->token, "code") == 0) {
      for (size_t j = 0; j < section->child_count; ++j) {
        process_code_expr(vm, &table, section->children[j]);
      }
    }
  }

  // Cleanup symbol table
  for (int i = 0; i < table.count; i++) {
#ifdef ASM_DEBUG
    Symbol s = table.symbols[i];
    printf("%s[%d]\n", s.name, s.address);
#endif
    free(table.symbols[i].name);
  }
  free(table.symbols);
}