// firmware/src/config.h
#pragma once
#include <Arduino.h>

struct DeviceConfig {
    String device_id;      // e.g. "dc-0042"
    String location_id;    // e.g. "retailer-123"
    String hmac_secret;    // 32-byte hex string
    String wifi_ssid;
    String wifi_pass;
    uint8_t line_offset;   // 0-100, percent of frame height for virtual line
};

// Load all config from NVS. Returns false if device_id/location_id/hmac_secret missing.
bool config_load(DeviceConfig& cfg);

// Save WiFi credentials to NVS (called by provisioning after captive portal).
bool config_save_wifi(const String& ssid, const String& pass);

// Returns true if wifi_ssid is set in NVS.
bool config_has_wifi();

// Erase WiFi credentials only (factory reset — preserves device_id etc).
void config_clear_wifi();