#include "php_snuffleupagus.h"

#if (HAVE_PHP_SESSION && !defined(COMPILE_DL_SESSION))

#ifdef ZTS
static ts_rsrc_id session_globals_id = 0;
#define SESSION_G(v) ZEND_TSRMG(session_globals_id, php_ps_globals *, v)
#ifdef COMPILE_DL_SESSION
ZEND_TSRMLS_CACHE_EXTERN();
#endif
#else
static php_ps_globals *session_globals = NULL;
#define SESSION_G(v) (ps_globals.v)
#endif

static ps_module *s_module;
#if PHP_VERSION_ID < 70300
static ps_module *s_original_mod;
#else
static const ps_module *s_original_mod;
#endif
static int (*old_s_read)(PS_READ_ARGS);
static int (*old_s_write)(PS_WRITE_ARGS);
static int (*previous_sessionRINIT)(INIT_FUNC_ARGS) = NULL;
static ZEND_INI_MH((*old_OnUpdateSaveHandler)) = NULL;

static void check_sid_length(zend_string *sid) {
  const sp_config_session *cfg = &(SPCFG(session));

  if (sid) {
    if (cfg->sid_min_length && ZSTR_LEN(sid) < cfg->sid_min_length) {
      sp_log_auto("session", cfg->simulation, "Session ID is too short");
    }
    if (cfg->sid_max_length && ZSTR_LEN(sid) > cfg->sid_max_length) {
      sp_log_auto("session", cfg->simulation, "Session ID is too long");
    }
  }
}

static int sp_hook_s_read(PS_READ_ARGS) {
  const sp_config_session *cfg = &(SPCFG(session));
  check_sid_length(key);

  int r = old_s_read(mod_data, key, val, maxlifetime);

  if ((NULL == val) || (NULL == *val) || (0 == ZSTR_LEN(*val))) {
    return r;
  }

  if (r == SUCCESS && cfg->encrypt) {
    zend_string *orig_val = *val;
    zval val_zval;
    ZVAL_PSTRINGL(&val_zval, ZSTR_VAL(*val), ZSTR_LEN(*val));

    int ret = decrypt_zval(&val_zval, cfg->simulation, NULL);
    if (ZEND_HASH_APPLY_KEEP != ret) {
      zend_bailout();
    }

    *val = zend_string_dup(val_zval.value.str, 0);
    zend_string_release(orig_val);
  }

  return r;
}

static int sp_hook_s_write(PS_WRITE_ARGS) {
  const sp_config_session *cfg = &(SPCFG(session));
  check_sid_length(key);

  if (ZSTR_LEN(val) > 0 && cfg->encrypt) {
    zend_string *new_val = encrypt_zval(val);
    return old_s_write(mod_data, key, new_val, maxlifetime);
  }
  return old_s_write(mod_data, key, val, maxlifetime);
}

static void sp_hook_session_module() {
#if PHP_VERSION_ID < 70300
  ps_module *old_mod = SESSION_G(mod);
#else
  const ps_module *old_mod = SESSION_G(mod);
#endif
  ps_module *mod;

  if (old_mod == NULL || s_module == old_mod) {
    return;  // LCOV_EXCL_LINE
  }

  if (s_module == NULL) {
    s_module = mod = malloc(sizeof(ps_module));
    if (mod == NULL) {
      return;  // LCOV_EXCL_LINE
    }
  }

  s_original_mod = old_mod;

  mod = s_module;
  memcpy(mod, old_mod, sizeof(ps_module));

  old_s_read = mod->s_read;
  mod->s_read = sp_hook_s_read;

  old_s_write = mod->s_write;
  mod->s_write = sp_hook_s_write;

  SESSION_G(mod) = mod;
}

static PHP_INI_MH(sp_OnUpdateSaveHandler) {
#if PHP_VERSION_ID < 70100
  /* PHP7.0 doesn't handle well recusively set session handlers */
  if (stage == PHP_INI_STAGE_RUNTIME &&
      SESSION_G(session_status) == php_session_none && s_original_mod &&
      zend_string_equals_literal(new_value, "user") == 0 &&
      strcmp(((ps_module *)s_original_mod)->s_name, "user") == 0) {
    return SUCCESS;
  }
#endif

  SESSION_G(mod) = s_original_mod;

  int r = old_OnUpdateSaveHandler(entry, new_value, mh_arg1, mh_arg2, mh_arg3, stage);

  sp_hook_session_module();

  return r;
}

static int sp_hook_session_RINIT(INIT_FUNC_ARGS) {
  int ret = previous_sessionRINIT(INIT_FUNC_ARGS_PASSTHRU);
  sp_hook_session_module();
  return ret;
}

void hook_session() {
  zend_module_entry *module;

  if ((module = zend_hash_str_find_ptr(&module_registry, ZEND_STRL("session"))) == NULL) {
    return;  // LCOV_EXCL_LINE
  }

#ifdef ZTS
  if (session_globals_id == 0) {
    session_globals_id = *module->globals_id_ptr;
  }
#else
  if (session_globals == NULL) {
    session_globals = module->globals_ptr;
  }
#endif
  if (old_OnUpdateSaveHandler != NULL) {
    return;  // LCOV_EXCL_LINE
  }

  previous_sessionRINIT = module->request_startup_func;
  module->request_startup_func = sp_hook_session_RINIT;

  zend_ini_entry *ini_entry;
  if ((ini_entry = zend_hash_str_find_ptr(EG(ini_directives), ZEND_STRL("session.save_handler"))) != NULL) {
    old_OnUpdateSaveHandler = ini_entry->on_modify;
    ini_entry->on_modify = sp_OnUpdateSaveHandler;
  }
  s_module = NULL;

  sp_hook_session_module();
}

#else

void hook_session() {}

#endif  // HAVE_PHP_SESSION && !defined(COMPILE_DL_SESSION)