import type { Key } from 'ink';
import type { AuditTuiAction, PaneId } from './audit-state';
import { PANE_BY_NUMBER } from './audit-state';

export interface KeymapResult {
  actions: AuditTuiAction[];
  /** App-level signals the reducer can't express. */
  signal?: 'quit' | 'help' | 'remediate' | 'reaudit' | 'copy' | 'toggle-theme';
}

/**
 * Translate one keypress (input string + ink Key flags) into reducer
 * actions and/or app-level signals. Pure function — no side effects,
 * no React.
 *
 * Ink's `useInput(handler)` calls `handler(input, key)` for every
 * keypress; this function is what `handler` delegates to.
 */
export function handleKey(input: string, key: Key, focused: PaneId): KeymapResult {
  // Quit
  if (key.ctrl && input === 'c') return { actions: [], signal: 'quit' };
  if (input === 'q' && !key.ctrl && !key.meta) return { actions: [], signal: 'quit' };

  // Help overlay
  if (input === '?') return { actions: [{ type: 'toggle-help' }] };

  // Pane jump (1-5)
  if (input === '1' || input === '2' || input === '3' || input === '4' || input === '5') {
    return { actions: [{ type: 'focus', pane: PANE_BY_NUMBER[input] }] };
  }

  // Tab / Shift-Tab: cycle focus
  if (key.tab) {
    return { actions: [{ type: 'cycle', direction: key.shift ? -1 : 1 }] };
  }

  // Movement: arrows + j/k
  if (key.upArrow || (input === 'k' && !key.ctrl)) {
    return { actions: [{ type: 'move', direction: -1 }] };
  }
  if (key.downArrow || (input === 'j' && !key.ctrl)) {
    return { actions: [{ type: 'move', direction: 1 }] };
  }

  // Enter: drill in
  if (key.return) {
    return { actions: [{ type: 'enter' }] };
  }

  // Escape: step back; on top-of-chain panes, signal quit
  if (key.escape) {
    if (focused === 'summary' || focused === 'categories') {
      return { actions: [], signal: 'quit' };
    }
    return { actions: [{ type: 'escape' }] };
  }

  // Action hotkeys
  if (input === 'r' && !key.shift) return { actions: [], signal: 'remediate' };
  if (input === 'R' || (input === 'r' && key.shift)) return { actions: [], signal: 'reaudit' };
  // Yank — clipboard copy. Parent decides what to copy based on the
  // focused pane (detail content, command log, etc.).
  if (input === 'y' && !key.shift) return { actions: [], signal: 'copy' };
  // Theme toggle. Routed as a signal so the parent can also flash a
  // confirmation in the keybar — the user otherwise has no visual cue
  // that anything happened (theme currently only drives modal colors).
  if (input === 't' && !key.shift) return { actions: [], signal: 'toggle-theme' };

  return { actions: [] };
}