// Sauna user settings — M3 step 5 (settings + persistence).
//
// One JSON file at %APPDATA%\sauna\config.json holds every user-facing
// knob. spatial_light loads it at startup (CLI flags override for the
// run), live-applies edits via a file watcher (the gate: change a
// setting -> see it in-headset -> restart -> it stuck), and writes it
// back on the 's' console key (persisting live-tuned values).
//
// Missing file = defaults (first run); missing keys = per-key defaults
// (forward compatibility). Saves are atomic (tmp + rename) so a
// half-written file never gets live-applied.

#pragma once

#include <cstdint>
#include <string>
#include <vector>

namespace sauna {

struct Settings {
  // Virtual screen placement. Distance moves the plane (angular size
  // changes); scale multiplies physical size at any distance. scale=1 =>
  // primary monitor width = kSceneQuadW (the M2 anchor, 2.1333 m).
  double screen_distance_m = 2.0;
  double screen_scale = 1.0;
  // Curved arrangement (M4 ergonomics): screens sit on a cylinder of
  // radius screen_distance_m around the head, each rotated so its normal
  // points at the user, adjacent edges touching in OS left-to-right
  // order. Every screen is equidistant — a side monitor no longer sits
  // farther (and smaller) than the primary the way the flat plane put
  // it. false = M3 flat plane, OS-faithful gaps. Live-applies ('c' key).
  bool screen_curved = true;

  // Render. supersample applies at startup only (eye render targets are
  // allocated once) and only affects the TWO-PASS path — warp-direct (the
  // default since the M4 step-2 gate) samples the desktop directly and
  // needs none, so the default dropped 1.5 -> 1.0. predict_ms live-applies.
  double supersample = 1.0;
  // Prediction (M4 step 3): predict_auto ON spans the gyro extrapolation
  // to the measured sample->photon time of each frame (vsync-derived;
  // ~latch margin + half a scanout). predict_ms is the manual span, used
  // when auto is off or no vsync reference exists (free-run); both
  // live-apply. Old configs lack the key and default to auto.
  bool predict_auto = true;
  double predict_ms = 20.0;

  // Neck model (eye midpoint relative to neck pivot, head frame).
  bool neck_enabled = true;
  double neck_forward_mm = 80.0;
  double neck_up_mm = 75.0;

  // 0 = use the headset flash config default.
  double ipd_mm = 0.0;

  // Global recenter binding, e.g. "ctrl+alt+home". See ParseHotkey.
  std::string recenter_hotkey = "ctrl+alt+home";

  // DXGI output indices to skip in capture mode. Startup only.
  std::vector<int> monitor_exclude;

  // Cursor overlay in captured screens: -1 auto (= on), 0 never (set on
  // a machine whose duplicated image already contains a software cursor
  // — accessibility pointer size/color, some HDR states — where the
  // overlay would double it), 1 always. Live-applies.
  int cursor_overlay = -1;

  // Display policy (M3 step 4). brightness 0–1023, or -1 = hands-off: the
  // firmware re-applies its own stored startup brightness (config tag
  // 0x0A, set by the Beyond Utility) every time the displays come on, so
  // sauna only sends a value when the user explicitly sets one — and then
  // must re-send it after every panel power cycle (idle wake, don).
  // Live-applies. idle_timeout_min: no head motion this long -> panels
  // off, motion/don wakes, worn vetoes (0 disables); live-applies.
  // refresh_hz 75 (native 5088x2544) or 90 (3840x1920) — startup only.
  int brightness = -1;
  double idle_timeout_min = 10.0;
  double refresh_hz = 75.0;

  // Wake a parked headset on head motion (legacy behavior). Default OFF:
  // every supported unit has a prox sensor, and the don is the
  // deliberate wake signal — motion wake fires from desk bumps and
  // cable tugs. Forced on internally when no prox hardware is present
  // (motion is then the only wake). Live-applies.
  bool wake_on_motion = false;
};

// %APPDATA%\sauna\config.json ("" if APPDATA unset — caller treats as
// no persistence).
std::string SettingsPath();

// Loads SettingsPath() into *out. Missing file: *out = defaults, returns
// true. Malformed JSON / unreadable: returns false with *err set and *out
// = defaults (callers run on defaults rather than dying).
bool LoadSettings(Settings* out, std::string* err);

// Atomic save (tmp + MoveFileEx replace). Creates %APPDATA%\sauna.
bool SaveSettings(const Settings& s, std::string* err);

// Last-write time of the settings file (FILETIME ticks; 0 = missing).
// The live-apply watcher polls this.
uint64_t SettingsFileTime();

// Per-serial calibration store (M4 step 1 — instant-start gyro bias):
// %APPDATA%\sauna\calib\<serial>.json ("" if APPDATA unset or serial
// empty). Seeded into the AHRS at startup so tracking starts from the
// first sample; background still-window refreshes keep the file current.
std::string GyroBiasPath(const std::string& serial);

// False if no stored bias (first run), unreadable, or malformed.
bool LoadGyroBias(const std::string& serial, double biasLsb[3]);

// Atomic save (tmp + rename), creates the calib dir. False with *err set
// on failure.
bool SaveGyroBias(const std::string& serial, const double biasLsb[3],
                  std::string* err);

// "ctrl+alt+home" -> RegisterHotKey (mods, vk). Tokens separated by '+':
// modifiers ctrl/alt/shift/win, then one key: a-z 0-9, f1-f24, home, end,
// insert, delete, pageup, pagedown, space, pause. False on parse failure
// (caller keeps the previous binding). Caller adds MOD_NOREPEAT.
bool ParseHotkey(const std::string& spec, uint32_t* mods, uint32_t* vk);

}  // namespace sauna