import { commands as defaultCommands, type ShellCommand } from "../commands.ts";
import type { Unsubscribe, Workbench } from "../workbench.ts";

/** The command tables bound on this page, so a view that reads every key can leave theirs alone. */
const bound = new Set<readonly ShellCommand[]>();

const isMac = () => /Mac|iPhone|iPad/.test(navigator.platform);

/** Runs shell commands from their keybindings. */
export function bindKeys(target: Window, workbench: Workbench, commands: readonly ShellCommand[] = defaultCommands): Unsubscribe {
  const mac = isMac();
  const onKey = (event: KeyboardEvent) => {
    const match = commands.find((c) => c.keys && matches(c.keys, event, mac));
    if (!match) return;
    event.preventDefault();
    match.run(workbench);
  };
  target.addEventListener("keydown", onKey);
  bound.add(commands);
  return () => {
    target.removeEventListener("keydown", onKey);
    bound.delete(commands);
  };
}

/** Whether `event` is a bound command's keybinding. */
export function isBound(event: KeyboardEvent): boolean {
  const mac = isMac();
  for (const commands of bound) if (commands.some((c) => c.keys && matches(c.keys, event, mac))) return true;
  return false;
}

/** Matches `Mod+Shift+E` against a key event by physical key, so Alt and Shift don't change the letter. */
export function matches(keys: string, event: Pick<KeyboardEvent, "code" | "metaKey" | "ctrlKey" | "altKey" | "shiftKey">, mac: boolean): boolean {
  const parts = keys.split("+");
  const key = parts.pop()!;
  const mods = new Set(parts.map((m) => (m === "Mod" ? (mac ? "Meta" : "Ctrl") : m)));
  if (mods.has("Meta") !== event.metaKey || mods.has("Ctrl") !== event.ctrlKey) return false;
  if (mods.has("Alt") !== event.altKey || mods.has("Shift") !== event.shiftKey) return false;
  return event.code === codeOf(key);
}

function codeOf(key: string): string {
  if (/^[A-Z]$/i.test(key)) return `Key${key.toUpperCase()}`;
  if (/^\d$/.test(key)) return `Digit${key}`;
  return { "\\": "Backslash", "`": "Backquote", "/": "Slash", ",": "Comma", ".": "Period" }[key] ?? key;
}