// The list of themes the user can pick from, applying one, and remembering the choice.

// ---------------------------------------------------------------- paths

// Cached on `app` because platform_get_path_program_data loads shell32 on Windows and is slow.
app_program_data_dir :: () -> string {
  if app.program_data_dir.count  return app.program_data_dir;

  push_allocator(context.default_allocator);

  program_data_path := platform_get_path_program_data(,,temp);
  dir := sprint("%/%", program_data_path, APP_FOLDER_NAME);
  this_allocation_is_not_a_leak(dir.data);

  if !make_directory_if_it_does_not_exist(dir, recursive=true) {
    log_error("[theme] Failed to create directory %.", dir);
  }

  app.program_data_dir = dir;
  return dir;
}

app_themes_dir :: () -> string {
  return tprint("%/themes", app_program_data_dir());
}

// Read-only themes copied out of assets/ by first.jai. Absent in a tree that was never built.
app_shipped_themes_dir :: () -> string {
  working_directory := app_install_directory();
  return tprint("%1data/themes", working_directory);
}

app_user_settings_path :: () -> string {
  return tprint("%/%", app_program_data_dir(), APP_USER_SETTINGS_FILE_NAME);
}

// ---------------------------------------------------------------- registry

app_theme_startup :: () {
  app_theme_refresh_registry();

  // main loads settings.config before creating the window.
  name := app_user_settings.theme;
  if !name.count  name = APP_DEFAULT_THEME_NAME;

  if !app_theme_apply_name(name) {
    log("[theme] Falling back to the built-in % theme.", APP_DEFAULT_THEME_NAME);
    app_theme_apply_name(APP_DEFAULT_THEME_NAME);
  }
}

APP_DEFAULT_THEME_NAME :: "Default";

app_theme_refresh_registry :: () {
  push_allocator(context.default_allocator);

  // Remember the selection by name; indices move as files appear and disappear.
  selected: string;
  if app_theme.current_index >= 0 && app_theme.current_index < cast(s32) app_theme.entries.count {
    selected = copy_string(app_theme.entries[app_theme.current_index].name,, temp);
  }

  for * app_theme.entries {
    free(it.name);
    if it.path.count  free(it.path);
  }
  array_reset_keeping_memory(*app_theme.entries);

  array_add(*app_theme.entries, .{copy_string(APP_DEFAULT_THEME_NAME), "", .Builtin, .Default});
  array_add(*app_theme.entries, .{copy_string("Dark"),                 "", .Builtin, .Dark});
  array_add(*app_theme.entries, .{copy_string("Light"),                "", .Builtin, .Light});
  array_add(*app_theme.entries, .{copy_string("Classic"),              "", .Builtin, .Classic});

  builtin_count := app_theme.entries.count;

  // A user theme of the same name shadows the shipped one, so scan shipped first.
  theme_scan_directory(app_shipped_themes_dir(), create_if_missing = false);
  theme_scan_directory(app_themes_dir(),         create_if_missing = true);

  files := array_view(app_theme.entries, builtin_count, app_theme.entries.count - builtin_count);
  quick_sort(files, (a: Theme_Entry, b: Theme_Entry) -> int { return compare(a.name, b.name); });

  app_theme.current_index = -1;
  if selected.count {
    for app_theme.entries  if it.name == selected { app_theme.current_index = xx it_index; break; }
  }
}

theme_scan_directory :: (dir: string, create_if_missing: bool) {
  // visit_files returns false rather than creating anything, so make the directory first.
  if create_if_missing && !make_directory_if_it_does_not_exist(dir, recursive=true) {
    log_error("[theme] Failed to create %.", dir);
    return;
  }
  if !file_exists(dir)  return;

  visit_files(dir, false, dir, theme_visit_file, visit_files=true, visit_directories=false);
}

theme_visit_file :: (info: *File_Visit_Info, dir: string) {
  if !ends_with(info.short_name, APP_THEME_FILE_EXT)  return;

  stem := slice(info.short_name, 0, info.short_name.count - APP_THEME_FILE_EXT.count);
  if !stem.count  return;

  for * app_theme.entries {
    if it.name != stem  continue;
    if it.source == .Builtin {
      log("[theme] Ignoring %: it shadows the built-in % theme.", info.full_name, stem);
      return;
    }
    free(it.path);
    it.path = copy_string(info.full_name);   // a user theme replaces the shipped one
    return;
  }

  array_add(*app_theme.entries, .{copy_string(stem), copy_string(info.full_name), .File, .Default});
}

app_theme_find_index :: (name: string) -> s32 {
  for app_theme.entries  if it.name == name  return xx it_index;
  return -1;
}

// ---------------------------------------------------------------- applying

app_theme_apply_index :: (index: s32) -> bool {
  if index < 0 || index >= cast(s32) app_theme.entries.count {
    log_error("[theme] Theme index % is out of range.", index);
    return false;
  }

  entry := app_theme.entries[index];

  if entry.source == .Builtin {
    app_theme_build_builtin(entry.base, *app_theme.master);
    app_theme.palette = app_theme_default_palette();
    // The default accent is too light to stand out on the Light theme's background.
    if entry.base == .Light  app_theme.palette.active_window_border = .{0.10, 0.30, 0.75, 1.0};
  } else {
    // Load into scratch so a bad file cannot leave a half-applied theme on screen.
    style: ImGui.Style;
    palette: App_Palette;
    name: string;
    if !app_theme_load_file(entry.path, *style, *palette, *name)  return false;

    app_theme.master  = style;
    app_theme.palette = palette;
  }

  app_theme.ref   = app_theme.master;
  app_theme.dirty = false;
  app_theme.current_index = index;
  app_theme_bake(app.win_scale);

  log("[theme] Applied theme %.", entry.name);
  return true;
}

app_theme_apply_name :: (name: string) -> bool {
  index := app_theme_find_index(name);
  if index < 0 {
    log_error("[theme] No theme named %.", name);
    return false;
  }
  return app_theme_apply_index(index);
}

app_theme_current :: () -> *Theme_Entry {
  if app_theme.current_index < 0 || app_theme.current_index >= cast(s32) app_theme.entries.count  return null;
  return *app_theme.entries[app_theme.current_index];
}

// ---------------------------------------------------------------- saving

app_theme_save_as :: (name: string) -> bool {
  // Copied because callers pass entries[].name, and refreshing the registry below frees those.
  trimmed := copy_string(trim(name),, temp);
  if !trimmed.count {
    app_theme_set_status("Theme name cannot be empty.", is_error = true);
    return false;
  }
  if app_theme_name_is_builtin(trimmed) {
    app_theme_set_status(tprint("% is a built-in theme name.", trimmed), is_error = true);
    return false;
  }
  if !theme_name_is_valid_file_name(trimmed) {
    app_theme_set_status("A theme name cannot contain / \\ : * ? \" < > | or control characters, end in a dot, or be a reserved name such as CON or NUL.", is_error = true);
    return false;
  }

  path := tprint("%1/%2%3", app_themes_dir(), trimmed, APP_THEME_FILE_EXT);
  if !app_theme_save_file(path, *app_theme.master, *app_theme.palette, trimmed, .Default) {
    app_theme_set_status(tprint("Could not save %.", path), is_error = true);
    return false;
  }

  app_theme_refresh_registry();

  // Re-read what we just wrote: hex quantizes colors to 8 bits per channel, and master must
  // agree with the file or every later comparison against it is off by a fraction.
  if !app_theme_apply_name(trimmed)  return false;

  app_save_user_settings_file();
  app_theme_set_status(tprint("Saved %.", path), is_error = false);
  return true;
}

// The name becomes a file name in the themes folder, so it must be one on every platform.
theme_name_is_valid_file_name :: (name: string) -> bool {
  if name == "." || name == ".." || name[name.count - 1] == #char "."  return false;
  for 0..name.count - 1 {
    c := name[it];
    if c < 32 || find_index_from_left("/\\:*?\"<>|", c) >= 0  return false;
  }

  // Windows reserves these device names, with or without an extension.
  RESERVED :: string.["CON", "PRN", "AUX", "NUL",
    "COM1", "COM2", "COM3", "COM4", "COM5", "COM6", "COM7", "COM8", "COM9",
    "LPT1", "LPT2", "LPT3", "LPT4", "LPT5", "LPT6", "LPT7", "LPT8", "LPT9"];
  stem := name;
  dot := find_index_from_left(name, #char ".");
  if dot >= 0  stem = slice(name, 0, dot);
  for RESERVED  if equal_nocase(stem, it)  return false;
  return true;
}

app_theme_save_current :: () -> bool {
  entry := app_theme_current();
  if !entry {
    app_theme_set_status("No theme is selected.", is_error = true);
    return false;
  }
  if entry.source == .Builtin {
    app_theme_set_status("Built-in themes cannot be overwritten. Use Save As.", is_error = true);
    return false;
  }
  return app_theme_save_as(entry.name);
}

app_theme_reload_current :: () -> bool {
  entry := app_theme_current();
  if !entry  return false;
  name := copy_string(entry.name,, temp);
  if !app_theme_apply_index(app_theme.current_index) {
    toast_show(.Error, "Could not reload theme %; see the Event Log", name);
    return false;
  }
  toast_show(.Success, "Reloaded theme %", name);
  return true;
}

app_theme_open_folder :: () {
  dir := app_themes_dir();
  if !make_directory_if_it_does_not_exist(dir, recursive=true) {
    app_theme_set_status(tprint("Could not create %.", dir), is_error = true);
    return;
  }
  #if USING_WINDOWS {
    dir = copy_string(dir,, temp);
    path_overwrite_separators(dir, #char "\\");
  }
  if !platform_open_directory(dir)  app_theme_set_status(tprint("Could not open %.", dir), is_error = true);
}

app_theme_open_current_file :: () {
  entry := app_theme_current();
  if !entry || entry.source == .Builtin || !entry.path.count {
    app_theme_set_status("Built-in themes have no file. Use Save As to make one.", is_error = true);
    return;
  }
  app_open_config_file(entry.path);
}

app_theme_name_is_builtin :: (name: string) -> bool {
  for app_theme.entries  if it.source == .Builtin && it.name == name  return true;
  return false;
}

app_theme_set_status :: (message: string, is_error: bool) {
  push_allocator(context.default_allocator);
  if app_theme.status.count  free(app_theme.status);
  app_theme.status = copy_string(message);
  app_theme.status_is_error = is_error;
  if is_error  log_error("[theme] %", message);
  else         log("[theme] %", message);
  toast_show(ifx is_error then Toast_Kind.Error else .Success, "%", message);
}

// ---------------------------------------------------------------- user settings

app_user_settings: App_User_Settings;
App_User_Settings :: struct {
  theme: string;   // "" means the default theme; heap-allocated
  ocr_model: string;   // [ocr] model: the OCR model's name in models.config; "" means the default; heap-allocated
  // [export] folder, one line each: the folders Export offers for a capture's original, the first
  // the default. None means the Downloads folder. Heap-allocated.
  export_folders: [..] string;
  // [library] folder: the library, set by hand and read at startup; "" means LIBRARY_FOLDER_DEFAULT.
  // Heap-allocated.
  library_folder: string;

  // Of the monitor the window first opens on.
  window_width_fraction:  float = 0.80;
  window_height_fraction: float = 0.75;

  // ImGui's style.FontSizeBase and style.FontScaleMain. 0 until read from the file or taken from
  // the live style, and while 0 the startup values ImGui and app_imgui_init set are kept.
  font_size_base:  float;
  font_scale_main: float;

  // Entries the Event Log keeps in memory; the oldest are dropped past it. The log file keeps every line.
  event_log_capacity: s64 = EVENT_LOG_CAPACITY_DEFAULT;

  // [video]: screen recording (app/screen_record.jai), set by hand. video_capture is "auto", "dxgi"
  // or "wgc"; heap-allocated, "" meaning auto.
  video_fps: s64 = VIDEO_FPS_DEFAULT;
  video_cursor := true;
  video_capture: string;
  video_system_audio := true;   // what the computer plays
  video_microphone: bool;       // off unless asked for

  // The [hotkeys] lines. Only meaningful when the section was seen; see hotkeys_install.
  hotkey_bindings: [..] Hotkey_Binding;
  // The [global_hotkeys] lines, likewise; see global_hotkeys_install.
  global_hotkey_bindings: [..] Hotkey_Binding;
}

settings_free :: (s: *App_User_Settings) {
  free(s.theme,, context.default_allocator);
  free(s.ocr_model,, context.default_allocator);
  for s.export_folders  free(it,, context.default_allocator);
  array_free(s.export_folders);
  free(s.library_folder,, context.default_allocator);
  free(s.video_capture,, context.default_allocator);
  array_free(s.hotkey_bindings);
  array_free(s.global_hotkey_bindings);
}

WINDOW_FRACTION_MIN :: 0.1;
WINDOW_FRACTION_MAX :: 1.0;
FONT_SIZE_BASE_MIN  :: 8.0;   // the Debug Panel slider's range
FONT_SIZE_BASE_MAX  :: 64.0;
EVENT_LOG_CAPACITY_DEFAULT :: 4096;
EVENT_LOG_CAPACITY_MIN     :: 64;
EVENT_LOG_CAPACITY_MAX     :: 1_000_000;
VIDEO_FPS_DEFAULT          :: 30;
VIDEO_FPS_MIN              :: 1;
VIDEO_FPS_MAX              :: 120;

// Fills app_user_settings. Returns true when the file should be written back: it is missing, or
// is the current version but lacks a key, so every setting ends up listed there to edit by hand.
// A file of another version is left alone.
app_load_user_settings_file :: () -> write_back: bool {
  defer settings_note_synced();
  path := app_user_settings_path();
  if !file_exists(path) {
    hotkeys_install(hotkey_defaults());
    global_hotkeys_install(global_hotkey_defaults());
    return true;
  }

  file_data, read_ok := read_entire_file(path,, temp);
  ok := false;
  seen: Settings_Seen;
  version: s64;
  if read_ok {
    settings_file_hash = Hash.fnv1a_hash(file_data.data, file_data.count);
    ok, seen, version = settings_parse(path, file_data, *app_user_settings);
  }
  if !ok {
    log_error("[settings] Could not read %; using defaults for this session. Fix or remove it, then restart.", path);
    toast_show(.Error, "Could not read %; see the Event Log", APP_USER_SETTINGS_FILE_NAME);
  }

  bindings: [] Hotkey_Binding = hotkey_defaults();
  if ok && seen.hotkeys  bindings = app_user_settings.hotkey_bindings;
  hotkeys_install(hotkeys_with_missing_defaults(hotkey_actions, bindings, hotkey_defaults(), version));

  global_bindings: [] Hotkey_Binding = global_hotkey_defaults();
  if ok && seen.global_hotkeys  global_bindings = app_user_settings.global_hotkey_bindings;
  global_hotkeys_install(hotkeys_with_missing_defaults(global_hotkey_actions, global_bindings, global_hotkey_defaults(), version));

  if !ok  return false;

  // A new action unmentioned in either section needs writing back (a "none" marker if this file
  // predates the per-action convention, the shipped default otherwise) so it actually reaches the
  // user rather than waiting for them to trigger some unrelated save.
  hotkeys_missing, _ := hotkeys_missing_lines(hotkey_actions, bindings, hotkey_defaults(), version);
  global_missing,  _ := hotkeys_missing_lines(global_hotkey_actions, global_bindings, global_hotkey_defaults(), version);
  if hotkeys_missing.count || global_missing.count  return true;

  #if OS == .LINUX  seen.global_hotkeys = true;   // not written there: Linux has no global hotkeys yet
  return !(seen.theme && seen.width && seen.height && seen.font_size && seen.font_scale && seen.event_log && seen.hotkeys && seen.global_hotkeys && seen.ocr_model && seen.export_folder && seen.library_folder && seen.video_fps && seen.video_cursor && seen.video_capture && seen.video_system_audio && seen.video_microphone);
}

Settings_Seen :: struct {
  theme, width, height, font_size, font_scale, event_log, hotkeys, global_hotkeys, ocr_model, export_folder, library_folder: bool;
  video_fps, video_cursor, video_capture, video_system_audio, video_microphone: bool;
}

// Of the file's bytes as last loaded or written, so a watcher event for our own save, or for an
// edit that changed nothing, is not applied again.
settings_file_hash: u64;

// The settings the app itself changes, as it holds them now.
Settings_App_Values :: struct {
  theme: string;
  ocr_model: string;
  export_folders: string;   // the list, a line each
  font_size_base:  float;
  font_scale_main: float;
}

// The app values as of the last load or save. A save keeps what the file says for a setting that
// has not changed in the app since, so an edit made by hand while the app runs is not overwritten.
settings_synced: Settings_App_Values;   // its strings heap-allocated

settings_app_values :: () -> Settings_App_Values {
  values: Settings_App_Values;
  entry := app_theme_current();
  values.theme = ifx entry then entry.name else app_user_settings.theme;
  if !values.theme.count  values.theme = APP_DEFAULT_THEME_NAME;
  values.ocr_model = ifx app_user_settings.ocr_model.count then app_user_settings.ocr_model else OCR_DEFAULT_MODEL;
  values.export_folders = join(..app_user_settings.export_folders, "\n",, temp);

  values.font_size_base  = app_user_settings.font_size_base;
  values.font_scale_main = app_user_settings.font_scale_main;
  if app.imgui_context {
    style := ImGui.GetStyle();
    if style.FontSizeBase > 0  values.font_size_base = style.FontSizeBase;
    values.font_scale_main = style.FontScaleMain;
  }
  if values.font_size_base  <= 0  values.font_size_base  = default_global_font_size;
  if values.font_scale_main <= 0  values.font_scale_main = 1.0;
  return values;
}

settings_note_synced :: () {
  free(settings_synced.theme,, context.default_allocator);
  free(settings_synced.ocr_model,, context.default_allocator);
  free(settings_synced.export_folders,, context.default_allocator);
  settings_synced = settings_app_values();
  settings_synced.theme = copy_string(settings_synced.theme,, context.default_allocator);
  settings_synced.ocr_model = copy_string(settings_synced.ocr_model,, context.default_allocator);
  settings_synced.export_folders = copy_string(settings_synced.export_folders,, context.default_allocator);
}

// Parses the file's contents into out, replacing its theme and hotkey bindings. ok is false when
// the file's version is outside the readable range. version is the file's own @version,
// meaningful only when ok is true; see APP_USER_SETTINGS_OLDEST_READABLE_VERSION.
settings_parse :: (path: string, file_data: string, out: *App_User_Settings) -> ok: bool, seen: Settings_Seen, version: s64 {
  seen: Settings_Seen;
  hotkey_actions_init();
  global_hotkey_actions_init();

  out.hotkey_bindings.allocator = context.default_allocator;
  array_reset(*out.hotkey_bindings);
  out.global_hotkey_bindings.allocator = context.default_allocator;
  array_reset(*out.global_hotkey_bindings);
  for out.export_folders  free(it,, context.default_allocator);
  out.export_folders.allocator = context.default_allocator;
  array_reset(*out.export_folders);

  seen_version := false;
  version: s64;
  line_number  := 0;
  offset: s64  = 0;
  section: string;

  line: string;
  while theme_next_line(file_data, *offset, *line) {
    line_number += 1;

    valid, stripped := strip_comment(line);
    if !valid  continue;

    body := trim(stripped);
    if !body.count  continue;

    if body[0] == #char "@" {
      key, value, split_ok := theme_split_directive(body);
      if split_ok && key == "version" {
        rest := value;
        parsed_version, parsed := parse_int(*rest, s64);
        if !parsed || parsed_version < APP_USER_SETTINGS_OLDEST_READABLE_VERSION || parsed_version > APP_USER_SETTINGS_VERSION {
          log_error("[settings] % is version %, expected % to %. Ignoring it.",
            path, value, APP_USER_SETTINGS_OLDEST_READABLE_VERSION, APP_USER_SETTINGS_VERSION);
          return false, seen, version;
        }
        version = parsed_version;
        seen_version = true;
      }
      continue;
    }

    if settings_is_section_header(body) {
      section = body;
      if section == HOTKEYS_SECTION  seen.hotkeys = true;
      if section == GLOBAL_HOTKEYS_SECTION  seen.global_hotkeys = true;
      continue;
    }
    if !seen_version  continue;

    if section == HOTKEYS_SECTION {
      binding, binding_ok, error := hotkey_parse_line(body, hotkey_actions);
      if binding_ok  array_add(*out.hotkey_bindings, binding);
      else           log_error("[settings] %:%: %", path, line_number, error);
      continue;
    }
    if section == GLOBAL_HOTKEYS_SECTION {
      binding, binding_ok, error := hotkey_parse_line(body, global_hotkey_actions);
      if binding_ok  array_add(*out.global_hotkey_bindings, binding);
      else           log_error("[settings] %:%: %", path, line_number, error);
      continue;
    }

    key, value, split_ok := theme_split_key(body);
    if !split_ok  continue;

    if section == "[ocr]" && key == "model" {
      free(out.ocr_model,, context.default_allocator);
      out.ocr_model = copy_string(settings_unquote(value),, context.default_allocator);
      seen.ocr_model = true;
    } else if section == "[export]" && key == "folder" {
      folder := settings_unquote(value);   // an empty line says the list is empty
      if folder.count  array_add(*out.export_folders, copy_string(folder,, context.default_allocator));
      seen.export_folder = true;
    } else if section == "[library]" && key == "folder" {
      free(out.library_folder,, context.default_allocator);
      out.library_folder = copy_string(settings_unquote(value),, context.default_allocator);
      seen.library_folder = true;
    } else if section == "[ui]" && key == "theme" {
      free(out.theme,, context.default_allocator);
      out.theme = copy_string(settings_unquote(value),, context.default_allocator);
      seen.theme = true;
    } else if section == "[window]" && key == "width_fraction" {
      seen.width = settings_read_float(*out.window_width_fraction, path, line_number, key, value, WINDOW_FRACTION_MIN, WINDOW_FRACTION_MAX);
    } else if section == "[window]" && key == "height_fraction" {
      seen.height = settings_read_float(*out.window_height_fraction, path, line_number, key, value, WINDOW_FRACTION_MIN, WINDOW_FRACTION_MAX);
    } else if section == "[font]" && key == "size_base" {
      seen.font_size = settings_read_float(*out.font_size_base, path, line_number, key, value, FONT_SIZE_BASE_MIN, FONT_SIZE_BASE_MAX);
    } else if section == "[font]" && key == "scale_main" {
      seen.font_scale = settings_read_float(*out.font_scale_main, path, line_number, key, value, FONT_SCALE_MIN, FONT_SCALE_MAX);
    } else if section == "[video]" && key == "fps" {
      seen.video_fps = settings_read_int(*out.video_fps, path, line_number, key, value, VIDEO_FPS_MIN, VIDEO_FPS_MAX);
    } else if section == "[video]" && key == "cursor" {
      seen.video_cursor = settings_read_bool(*out.video_cursor, path, line_number, key, value);
    } else if section == "[video]" && key == "system_audio" {
      seen.video_system_audio = settings_read_bool(*out.video_system_audio, path, line_number, key, value);
    } else if section == "[video]" && key == "microphone" {
      seen.video_microphone = settings_read_bool(*out.video_microphone, path, line_number, key, value);
    } else if section == "[video]" && key == "capture" {
      capture := to_lower_copy(settings_unquote(value),, temp);
      if capture == "auto" || capture == "dxgi" || capture == "wgc" {
        free(out.video_capture,, context.default_allocator);
        out.video_capture = copy_string(capture,, context.default_allocator);
        seen.video_capture = true;
      } else {
        log_error("[settings] %:%: capture is %; it takes auto, dxgi or wgc. Using auto.", path, line_number, value);
      }
    } else if section == "[logging]" && key == "event_log_capacity" {
      seen.event_log = settings_read_int(*out.event_log_capacity, path, line_number, key, value, EVENT_LOG_CAPACITY_MIN, EVENT_LOG_CAPACITY_MAX);
    } else {
      log("[settings] %:%: unknown key % in %. Ignored.", path, line_number, key, section);
    }
  }

  return seen_version, seen, version;
}

// Exactly [name]: a hotkey line binding the [ key also starts with '['.
settings_is_section_header :: (body: string) -> bool {
  if body.count < 3 || body[0] != #char "[" || body[body.count - 1] != #char "]"  return false;
  for 1..body.count - 2 {
    c := body[it];
    if !((c >= #char "a" && c <= #char "z") || (c >= #char "A" && c <= #char "Z") || (c >= #char "0" && c <= #char "9") || c == #char "_")  return false;
  }
  return true;
}

// "..." with "" for a literal quote. Anything else is returned as is. The result may point into value.
settings_unquote :: (value: string) -> string {
  if value.count < 2 || value[0] != #char "\"" || value[value.count - 1] != #char "\""  return value;

  inner := slice(value, 1, value.count - 2);
  if !contains(inner, "\"\"")  return inner;
  return replace(inner, "\"\"", "\"",, temp);
}

// Quoted when the value would not survive a reload bare: a " #" or a leading # reads as a comment,
// the outer spaces are trimmed, and any quote would open quoting.
settings_quote_if_needed :: (value: string) -> string {
  needs_quotes := contains(value, " #") || contains(value, "\t#") || contains(value, "\"") ||
      (value.count > 0 && (value[0] == #char "#" || is_space2(value[0]) || is_space2(value[value.count - 1])));
  if !needs_quotes  return value;
  return tprint("\"%\"", replace(value, "\"", "\"\"",, temp));
}

settings_read_bool :: (out: *bool, path: string, line_number: int, key: string, value: string) -> bool {
  if equal_nocase(value, "true")   { out.* = true;  return true; }
  if equal_nocase(value, "false")  { out.* = false; return true; }
  log_error("[settings] %:%: % is not true or false. Using the default.", path, line_number, key);
  return false;
}

settings_read_int :: (out: *s64, path: string, line_number: int, key: string, value: string, lo: s64, hi: s64) -> bool {
  v, ok, rest := string_to_int(trim(value));
  if !ok || trim(rest).count {
    log_error("[settings] %:%: % is not a whole number. Using the default.", path, line_number, key);
    return false;
  }
  out.* = clamp(v, lo, hi);
  if out.* != v  log("[settings] %:%: % % is outside % to %; using %.", path, line_number, key, v, lo, hi, out.*);
  return true;
}

settings_read_float :: (out: *float, path: string, line_number: int, key: string, value: string, lo: float, hi: float) -> bool {
  v: [1] float;
  if !theme_parse_floats(value, v) {
    log_error("[settings] %:%: % is not a number. Using the default.", path, line_number, key);
    return false;
  }
  out.* = clamp(v[0], lo, hi);
  if out.* != v[0]  log("[settings] %:%: % % is outside % to %; using %.", path, line_number, key, v[0], lo, hi, out.*);
  return true;
}

app_apply_font_settings :: () {
  style := ImGui.GetStyle();
  if app_user_settings.font_size_base > 0 {
    style.FontSizeBase = app_user_settings.font_size_base;
    style._NextFrameFontSizeBase = app_user_settings.font_size_base; // #hack as of ImGui v1.92.7, as in the Debug Panel
  }
  if app_user_settings.font_scale_main > 0  style.FontScaleMain = app_user_settings.font_scale_main;
}

// For saves the user asked for. The startup write-back saves quietly.
app_save_user_settings_file_and_toast :: (what: string) {
  if app_save_user_settings_file()  toast_show(.Success, "Saved % to %", what, APP_USER_SETTINGS_FILE_NAME);
  else                              toast_show(.Error, "Could not save %; see the Event Log", APP_USER_SETTINGS_FILE_NAME);
}

app_save_user_settings_file :: () -> bool {
  // The theme is taken from the registry once it is up; before that, whatever was loaded stands.
  entry := app_theme_current();
  if entry && entry.name != app_user_settings.theme {
    free(app_user_settings.theme,, context.default_allocator);
    app_user_settings.theme = copy_string(entry.name,, context.default_allocator);
  }
  if app.imgui_context {
    style := ImGui.GetStyle();
    if style.FontSizeBase > 0  app_user_settings.font_size_base = style.FontSizeBase;
    app_user_settings.font_scale_main = style.FontScaleMain;
  }

  values := settings_app_values();
  theme           := values.theme;
  ocr_model       := values.ocr_model;
  export_folders: [] string = app_user_settings.export_folders;
  font_size_base  := values.font_size_base;
  font_scale_main := values.font_scale_main;

  // The file may have been edited by hand since it was read: the window size is only ever set
  // there, and the other settings keep the file's value unless changed in the app.
  path := app_user_settings_path();
  on_disk: App_User_Settings;
  defer settings_free(*on_disk);
  disk_ok: bool;
  seen: Settings_Seen;
  disk_version: s64;
  disk_data: string;
  edit_pending: bool;   // a hand edit the watcher has not delivered yet
  if file_exists(path) {
    read_ok: bool;
    disk_data, read_ok = read_entire_file(path,, temp);
    if read_ok {
      disk_ok, seen, disk_version = settings_parse(path, disk_data, *on_disk);
      edit_pending = Hash.fnv1a_hash(disk_data.data, disk_data.count) != settings_file_hash;
    }
    if !disk_ok {
      // Refuse rather than fall through to the defaults below: we can't tell what the user wants
      // to keep in a file we can't read or that isn't a version we understand.
      log_error("[settings] % did not parse; refusing to overwrite it. Fix or remove it, then try again.", path);
      return false;
    }
  }
  if disk_ok {
    if seen.theme      && values.theme           == settings_synced.theme && on_disk.theme.count  theme = on_disk.theme;
    if seen.ocr_model  && values.ocr_model       == settings_synced.ocr_model && on_disk.ocr_model.count  ocr_model = on_disk.ocr_model;
    if seen.export_folder && values.export_folders == settings_synced.export_folders  export_folders = on_disk.export_folders;
    if seen.font_size  && values.font_size_base  == settings_synced.font_size_base   font_size_base  = on_disk.font_size_base;
    if seen.font_scale && values.font_scale_main == settings_synced.font_scale_main  font_scale_main = on_disk.font_scale_main;
    if seen.width      app_user_settings.window_width_fraction  = on_disk.window_width_fraction;
    if seen.height     app_user_settings.window_height_fraction = on_disk.window_height_fraction;
    if seen.event_log  app_user_settings.event_log_capacity     = on_disk.event_log_capacity;
    if seen.library_folder {
      free(app_user_settings.library_folder,, context.default_allocator);
      app_user_settings.library_folder = copy_string(on_disk.library_folder,, context.default_allocator);
    }
    if seen.video_fps     app_user_settings.video_fps    = on_disk.video_fps;
    if seen.video_cursor  app_user_settings.video_cursor = on_disk.video_cursor;
    // video_system_audio and video_microphone are the app's: the recording toolbar's buttons set them.
    if seen.video_capture {
      free(app_user_settings.video_capture,, context.default_allocator);
      app_user_settings.video_capture = copy_string(on_disk.video_capture,, context.default_allocator);
    }
  }

  builder: String_Builder;
  builder.allocator = temp;

  print_to_builder(*builder, "# % user settings.\n", APP_NAME);
  print_to_builder(*builder, "@version %\n\n", APP_USER_SETTINGS_VERSION);
  append(*builder, "[ui]\n");
  print_to_builder(*builder, "theme: %\n\n", settings_quote_if_needed(theme));
  append(*builder, "[window]\n");
  append(*builder, "# Initial size, as a fraction of the monitor it opens on.\n");
  print_to_builder(*builder, "width_fraction: %\n",  FF(app_user_settings.window_width_fraction,  2));
  print_to_builder(*builder, "height_fraction: %\n\n", FF(app_user_settings.window_height_fraction, 2));
  append(*builder, "[font]\n");
  append(*builder, "# Text size is size_base * scale_main * the monitor's DPI scale. The font size hotkeys change scale_main.\n");
  print_to_builder(*builder, "size_base: %\n",  FF(font_size_base,  1));
  print_to_builder(*builder, "scale_main: %\n\n", FF(font_scale_main, 2));
  append(*builder, "[ocr]\n");
  append(*builder, "# The OCR model, by its name in ocr-models/models.config: ppocr-v5-mobile (light) or ppocr-v5-server (heavy).\n");
  print_to_builder(*builder, "model: %\n\n", settings_quote_if_needed(ocr_model));
  append(*builder, "[export]\n");
  append(*builder, "# The folders Export (in the Capture window) offers to write a capture to as it was imported, a\n");
  append(*builder, "# folder: line each; the first is the default. None: the Downloads folder.\n");
  for export_folders  print_to_builder(*builder, "folder: %\n", settings_quote_if_needed(it));
  if !export_folders  append(*builder, "folder:\n");
  append(*builder, "\n");
  append(*builder, "[library]\n");
  append(*builder, "# The folder of .mcap files mcap shows and imports into; ~/ is the home folder. Read when mcap\n");
  append(*builder, "# starts; -library FOLDER on the command line overrides it.\n");
  print_to_builder(*builder, "folder: %\n\n", settings_quote_if_needed(ifx app_user_settings.library_folder.count then app_user_settings.library_folder else LIBRARY_FOLDER_DEFAULT));
  append(*builder, "[video]\n");
  append(*builder, "# Screen recording (Ctrl+PrintScreen; Opt+Cmd+Shift+2 on macOS). fps: frames a second at most, written only when the\n");
  append(*builder, "# screen changes. cursor: true or false. capture (Windows): auto (Desktop Duplication, else\n");
  append(*builder, "# Windows.Graphics.Capture), dxgi or wgc. system_audio: what the computer plays; microphone: the\n");
  append(*builder, "# default input device. Each true or false.\n");
  print_to_builder(*builder, "fps: %\n", app_user_settings.video_fps);
  print_to_builder(*builder, "cursor: %\n", ifx app_user_settings.video_cursor then "true" else "false");
  print_to_builder(*builder, "capture: %\n", ifx app_user_settings.video_capture.count then app_user_settings.video_capture else "auto");
  print_to_builder(*builder, "system_audio: %\n", ifx app_user_settings.video_system_audio then "true" else "false");
  print_to_builder(*builder, "microphone: %\n\n", ifx app_user_settings.video_microphone then "true" else "false");
  append(*builder, "[logging]\n");
  append(*builder, "# Entries the Event Log keeps in memory. Past it the oldest are dropped; the log file keeps every line.\n");
  print_to_builder(*builder, "event_log_capacity: %\n", app_user_settings.event_log_capacity);

  // Hotkeys are only ever set by hand, so the sections are kept as written, comments and all; only
  // actions neither bound nor explicitly "none" in the file are appended, so new ones reach
  // existing users. Linux registers none, so its default is no section; one written by hand is
  // still kept.
  new_hotkey_count := 0;

  global_hotkeys_text := ifx OS == .LINUX then "" else DEFAULT_GLOBAL_HOTKEYS_DATA;
  if disk_ok && seen.global_hotkeys {
    global_hotkeys_text = settings_section_text(disk_data, GLOBAL_HOTKEYS_SECTION);
    if global_hotkeys_text.count && global_hotkeys_text[global_hotkeys_text.count - 1] != #char "\n"
      global_hotkeys_text = tprint("%\n", global_hotkeys_text);
    missing, active := hotkeys_missing_lines(global_hotkey_actions, on_disk.global_hotkey_bindings, global_hotkey_defaults(), disk_version);
    global_hotkeys_text = tprint("%1%2", global_hotkeys_text, missing);
    new_hotkey_count += active;
  }
  if global_hotkeys_text.count {
    append(*builder, "\n");
    append(*builder, global_hotkeys_text);
    if global_hotkeys_text[global_hotkeys_text.count - 1] != #char "\n"  append(*builder, "\n");
  }

  hotkeys_text := DEFAULT_HOTKEYS_DATA;
  if disk_ok && seen.hotkeys {
    hotkeys_text = settings_section_text(disk_data, HOTKEYS_SECTION);
    if hotkeys_text.count && hotkeys_text[hotkeys_text.count - 1] != #char "\n"
      hotkeys_text = tprint("%\n", hotkeys_text);
    missing, active := hotkeys_missing_lines(hotkey_actions, on_disk.hotkey_bindings, hotkey_defaults(), disk_version);
    hotkeys_text = tprint("%1%2", hotkeys_text, missing);
    new_hotkey_count += active;
  }
  append(*builder, "\n");
  append(*builder, hotkeys_text);
  if hotkeys_text.count && hotkeys_text[hotkeys_text.count - 1] != #char "\n"  append(*builder, "\n");

  file_text := builder_to_string(*builder,, temp);

  temp_path := tprint("%.tmp", path);
  if !write_entire_file(temp_path, file_text) {
    log_error("[settings] Could not write %.", temp_path);
    return false;
  }
  if !atomic_file_replace_or_just_rename_if_destination_file_does_not_exist(temp_path, path) {
    log_error("[settings] Could not move % to %.", temp_path, path);
    return false;
  }

  // With an edit pending the old hash is kept, so the event for this write reloads the file,
  // which now holds the edit merged with the app's changes, and applies it, hotkeys included.
  if !edit_pending  settings_file_hash = Hash.fnv1a_hash(file_text.data, file_text.count);
  settings_note_synced();

  if new_hotkey_count {
    plural := ifx new_hotkey_count == 1 then "" else "s";
    log("[settings] Added % new hotkey% with their default bindings to %.", new_hotkey_count, plural, path);
    toast_show(.Success, "Added % new hotkey% to %; open it to see or change %",
      new_hotkey_count, plural, APP_USER_SETTINGS_FILE_NAME, APP_USER_SETTINGS_FILE_NAME);
  }
  return true;
}

// From the header line up to the next section or the end of the file. "" when there is none.
settings_section_text :: (file_data: string, header: string) -> string {
  start := -1;
  offset: s64 = 0;
  line: string;
  while true {
    line_start := offset;
    if !theme_next_line(file_data, *offset, *line)  break;

    valid, stripped := strip_comment(line);
    if !valid  continue;
    body := trim(stripped);
    if !settings_is_section_header(body)  continue;

    if start >= 0  return slice(file_data, start, line_start - start);
    if body == header  start = line_start;
  }
  if start < 0  return "";
  return slice(file_data, start, file_data.count - start);
}

// ---------------------------------------------------------------- live reload

// Applies settings.config when it differs from what was last loaded or written. Window size is
// taken in but only acts at the next start.
app_reload_user_settings_if_changed :: () {
  path := app_user_settings_path();
  file_data, read_ok := read_entire_file(path,, temp);
  if !read_ok  return;   // being replaced, or deleted; the next event tries again

  hash := Hash.fnv1a_hash(file_data.data, file_data.count);
  if hash == settings_file_hash  return;
  settings_file_hash = hash;

  fresh: App_User_Settings;
  ok, seen, version := settings_parse(path, file_data, *fresh);
  if !ok {
    settings_free(*fresh);
    log_error("[settings] Could not apply the changes to %; keeping the current settings.", path);
    toast_show(.Error, "Could not apply the changes to %; see the Event Log", APP_USER_SETTINGS_FILE_NAME);
    return;
  }

  old := app_user_settings;
  app_user_settings = fresh;
  defer settings_free(*old);

  theme := ifx fresh.theme.count then fresh.theme else APP_DEFAULT_THEME_NAME;
  current := app_theme_current();
  if !current || current.name != theme {
    if app_theme_find_index(theme) < 0  app_theme_refresh_registry();   // a theme file added since
    app_theme_apply_name(theme);
  }

  if fresh.font_size_base != old.font_size_base || fresh.font_scale_main != old.font_scale_main {
    app_apply_font_settings();
  }

  if fresh.event_log_capacity != old.event_log_capacity  logger_set_event_log_capacity(fresh.event_log_capacity);
  if fresh.ocr_model != old.ocr_model  ocr_ui_settings_changed();   // app/ocr_ui.jai
  if fresh.library_folder != old.library_folder {
    log("[settings] The library folder is now %; mcap shows it from its next start.", ifx fresh.library_folder.count then fresh.library_folder else LIBRARY_FOLDER_DEFAULT);
    toast_show(.Success, "The new library folder is shown when mcap starts again");
  }

  bindings: [] Hotkey_Binding = hotkey_defaults();
  if seen.hotkeys  bindings = app_user_settings.hotkey_bindings;
  hotkeys_install(hotkeys_with_missing_defaults(hotkey_actions, bindings, hotkey_defaults(), version));

  global_bindings: [] Hotkey_Binding = global_hotkey_defaults();
  if seen.global_hotkeys  global_bindings = app_user_settings.global_hotkey_bindings;
  global_hotkeys_install(hotkeys_with_missing_defaults(global_hotkey_actions, global_bindings, global_hotkey_defaults(), version));
  global_hotkeys_reapply();

  settings_note_synced();
  log("[settings] Applied the changes to %.", path);
  toast_show(.Success, "Applied the changes to %", APP_USER_SETTINGS_FILE_NAME);
}

// Opens a settings or theme file with the system's default editor for it.
app_open_config_file :: (path: string) {
  platform_open_file_in_default_program(path, path_strip_filename(path));
}

settings_watch: struct {
  watcher: Watcher.File_Watcher(void);
  started: bool;
  changed: bool;
}

app_settings_watch_start :: () {
  dir := app_program_data_dir();
  // macOS's FSEvents always watches recursively, and the module logs an error when asked not to.
  if !Watcher.init(*settings_watch.watcher, settings_watch_callback, watch_recursively = OS == .MACOS) {
    log_error("[settings] Could not watch %. Changes to % apply at the next start.", dir, APP_USER_SETTINGS_FILE_NAME);
    return;
  }
  if !Watcher.add_directories(*settings_watch.watcher, dir) {
    log_error("[settings] Could not watch %. Changes to % apply at the next start.", dir, APP_USER_SETTINGS_FILE_NAME);
    Watcher.deinit(settings_watch.watcher);
    return;
  }
  settings_watch.started = true;
}

app_settings_watch_frame :: () {
  if !settings_watch.started  return;

  Watcher.process_changes(*settings_watch.watcher);
  if !settings_watch.changed  return;

  settings_watch.changed = false;
  app_reload_user_settings_if_changed();
}

app_settings_watch_stop :: () {
  if !settings_watch.started  return;
  Watcher.deinit(settings_watch.watcher);
  settings_watch.started = false;
}

// The whole directory is watched (on macOS recursively), so everything but the settings file is
// dropped. Editors save by rename as often as in place, so every event kind counts.
settings_watch_callback :: (watcher: *Watcher.File_Watcher(void), change: *Watcher.File_Change, user_data: *void) {
  // A lost buffer on Windows arrives as SCAN_CHILDREN on the folder, not as an event for the file.
  if change.events & (Watcher.File_Change_Event.OVERFLOW | .SCAN_CHILDREN) { settings_watch.changed = true; return; }

  name := path_filename(change.full_path);
  matches := ifx OS == .WINDOWS then equal_nocase(name, APP_USER_SETTINGS_FILE_NAME) else name == APP_USER_SETTINGS_FILE_NAME;
  if matches  settings_watch.changed = true;
}

#scope_file

Hash    :: #import "Hash";
Watcher :: #import "File_Watcher";