// React port of main.ts's `requestFastForward` (#67): one keystroke, every
// spawn default resolved — most recent project (or the one the operator is
// on), its last command, a fresh generated branch handle, worktree on with a
// new branch. A failed POST, or any missing default, falls back to the same
// pre-filled form `onFallback` opens, rather than a dead keystroke.

import { useCallback } from "react";

import { createSession, fetchNames, getDaemonInfo, projects as fetchProjects } from "../../api.js";
import { buildFastForwardRequest, fastForwardSeed, resolveFastForward } from "../../fastForward.js";
import { FALLBACK_PRESETS, type SpawnFormSeed } from "../../spawnForm.js";
import type { Project, Session, SpawnPreset } from "../../types.js";

export interface UseFastForwardOptions {
  /** The project of the session the operator is currently on, if any — its
   * base repo for a worktree session, else its cwd. Same rule the plain
   * spawn modal's seed uses, so `N` lands where the operator currently is. */
  focusedCwd?: string;
  onSpawned(session: Session): void;
  onFallback(seed: SpawnFormSeed): void;
}

async function resolvePresets(): Promise<SpawnPreset[]> {
  try {
    const info = await getDaemonInfo();
    if (info.presets?.length) return info.presets;
  } catch {
    // keep fallbacks
  }
  return FALLBACK_PRESETS;
}

/** Returns a function to call on the fast-forward keystroke. */
export function useFastForward(opts: UseFastForwardOptions): () => Promise<void> {
  const { focusedCwd, onSpawned, onFallback } = opts;

  return useCallback(async () => {
    const [discovered, handle] = await Promise.all([
      fetchProjects().catch(() => [] as Project[]),
      fetchNames(1)
        .then((batch) => batch.names[0])
        .catch(() => undefined),
    ]);
    const presets = await resolvePresets();
    const resolved = resolveFastForward(discovered, presets, handle, focusedCwd);
    const req = buildFastForwardRequest(resolved);
    if (req) {
      try {
        onSpawned(await createSession(req));
        return;
      } catch {
        // degrades to the pre-filled form below, never a silent dead key
      }
    }
    onFallback(fastForwardSeed(resolved));
  }, [focusedCwd, onSpawned, onFallback]);
}