import { MODIFIER_KEYS, type KeyboardShortcut, type Platform } from "@/lib/keyboard/constants";
import { detectPlatform, matchesShortcut } from "@/lib/keyboard/utils";

type HoldModifier = (typeof MODIFIER_KEYS)[keyof typeof MODIFIER_KEYS];

function resolvePlatform(platform?: Platform): Platform {
  return platform ?? detectPlatform();
}

function getCtrlOrCmdModifier(platform?: Platform): HoldModifier {
  return resolvePlatform(platform) === "mac" ? MODIFIER_KEYS.CMD : MODIFIER_KEYS.CTRL;
}

export function getHoldModifier(
  shortcut: KeyboardShortcut,
  platform?: Platform,
): HoldModifier | null {
  const modifiers = shortcut.modifiers;
  if (!modifiers) return null;

  if (modifiers.ctrlOrCmd) return getCtrlOrCmdModifier(platform);
  if (modifiers.cmd) return MODIFIER_KEYS.CMD;
  if (modifiers.ctrl) return MODIFIER_KEYS.CTRL;
  if (modifiers.alt) return MODIFIER_KEYS.ALT;
  if (modifiers.shift) return MODIFIER_KEYS.SHIFT;
  return null;
}

export function hasHoldModifier(shortcut: KeyboardShortcut): boolean {
  return getHoldModifier(shortcut) !== null;
}

export function isCycleShortcutEvent(event: KeyboardEvent, shortcut: KeyboardShortcut): boolean {
  if (event.repeat) return false;
  return matchesShortcut(event, shortcut);
}

/**
 * Make ctrlOrCmd's hold modifier match the key that opened this interaction.
 * Browsers accept either Control or Meta for ctrlOrCmd, including off-platform
 * variants such as Control on macOS.
 */
export function snapshotHeldShortcut(
  event: KeyboardEvent,
  shortcut: KeyboardShortcut,
): KeyboardShortcut {
  if (!shortcut.modifiers?.ctrlOrCmd || event.ctrlKey === event.metaKey) return shortcut;
  const { ctrlOrCmd: _ctrlOrCmd, ...modifiers } = shortcut.modifiers;
  return {
    ...shortcut,
    modifiers: { ...modifiers, ...(event.ctrlKey ? { ctrl: true } : { cmd: true }) },
  };
}

function isHoldModifierPressed(event: KeyboardEvent, modifier: HoldModifier): boolean {
  if (modifier === MODIFIER_KEYS.CMD) return event.metaKey;
  if (modifier === MODIFIER_KEYS.CTRL) return event.ctrlKey;
  if (modifier === MODIFIER_KEYS.ALT) return event.altKey;
  return event.shiftKey;
}

/**
 * Match a deliberate switcher continuation key press. Once a picker is open,
 * its primary hold modifier is sufficient; secondary modifiers may be released.
 */
export function isHeldCycleKeyEvent(
  event: KeyboardEvent,
  shortcut: KeyboardShortcut,
  platform?: Platform,
): boolean {
  if (event.repeat || event.key.toLowerCase() !== shortcut.key.toLowerCase()) return false;
  const holdModifier = getHoldModifier(shortcut, platform);
  return holdModifier
    ? isHoldModifierPressed(event, holdModifier)
    : matchesShortcut(event, shortcut);
}

export function isCommitReleaseEvent(
  event: KeyboardEvent,
  shortcut: KeyboardShortcut,
  platform?: Platform,
): boolean {
  return event.key === getHoldModifier(shortcut, platform);
}