#include "version_bridge.h"
#include "version_host.h"
#include <string.h>

static uint64_t read64(const void *p) {
  uint64_t value;
  memcpy(&value, p, sizeof(value));
  return value;
}

u32 w2c_env_read_or_throw(struct w2c_env *env, u64 source, u64 destination, u64 size) {
  wasm_rt_memory_t *memory = w2c_factorio__version_memory(env->module);
  if (memory->size < 24 || source > memory->size - 24 ||
      size > memory->size || destination > memory->size - size) return 2;
  uint64_t data = read64(memory->data + source);
  uint64_t length = read64(memory->data + source + 8);
  uint64_t cursor = read64(memory->data + source + 16);
  if (data > memory->size || length > memory->size - data) return 2;
  if (cursor > length || size > length - cursor) return 1;
  memmove(memory->data + destination, memory->data + data + cursor, (size_t)size);
  cursor += size;
  memcpy(memory->data + source + 16, &cursor, sizeof(cursor));
  ++env->reads;
  return 0;
}

int factorio_version_parse(const uint8_t *bytes, size_t length, FactorioMapVersion *out) {
  if (!bytes || !out) return 2;
  if (!wasm_rt_is_initialized()) wasm_rt_init();
  w2c_factorio__version module;
  struct w2c_env env = {.module = &module};
  wasm2c_factorio__version_instantiate(&module, &env);
  uint8_t *memory = w2c_factorio__version_memory(&module)->data;
  uint64_t registers[32] = {0};
  registers[0] = 2048; /* guest output object */
  registers[1] = 512;  /* opaque stream adapter */
  registers[31] = 65280;
  uint64_t reader[3] = {4096, length < 9 ? length : 9, 0};
  memcpy(memory, registers, sizeof(registers));
  memcpy(memory + 512, reader, sizeof(reader));
  memcpy(memory + 4096, bytes, (size_t)reader[1]);
  int result = (int)w2c_factorio__version_run(&module, 0);
  if (!result) {
    uint64_t packed = read64(memory + 2048);
    *out = (FactorioMapVersion){.major = (uint16_t)(packed >> 48),
      .minor = (uint16_t)(packed >> 32), .patch = (uint16_t)(packed >> 16),
      .build = (uint16_t)packed, .flag = memory[2056]};
  }
  wasm2c_factorio__version_free(&module);
  return result;
}