// Fast-forward spawn (#67): one keystroke, every default resolved, no form.
// Pure resolution only — the caller (main.ts) owns the fetches and the POST,
// and falls back to a seeded spawn form when anything is missing.

import type { CreateSessionRequest, Project, SpawnPreset } from "./types.js";
import { sortProjects } from "./projectList.js";

/** What one fast-forward keystroke resolved. Anything absent means "open a
 *  form pre-filled with the rest instead of spawning". */
export interface FastForwardResolution {
  project?: Project;
  command?: string;
  /** A generated handle for the worktree branch (#131). Not a session name:
   *  the fast path names no session. */
  handle?: string;
}

/** The defaults: the currently focused session's project when it's still a
 *  known project, else the most recent one (fresh-first, same ordering the
 *  picker shows) — so `N` lands where the operator currently is, matching
 *  what plain `n` seeds from `spawnSimilarProjectSeed`. Its last command
 *  falls back to the first non-custom preset, and the branch handle is
 *  freshly generated when the daemon supplied one. */
export function resolveFastForward(
  projects: Project[],
  presets: SpawnPreset[],
  handle?: string,
  focusedCwd?: string,
): FastForwardResolution {
  const project =
    projects.find((p) => p.path === focusedCwd) ?? sortProjects(projects, new Date())[0];
  const lastCommand = project?.last_command?.trim();
  const command =
    lastCommand || presets.find((p) => p.command !== "")?.command || undefined;
  return { project, command, handle: handle || undefined };
}

/** The immediate spawn request — worktree on, new branch named after the
 *  generated handle — or `null` when any default is missing.
 *
 *  The request carries no name (#131): the daemon assigns a provisional one
 *  and replaces it once the session sees its first prompt. A name here would
 *  also collide with the branch handle's own session. */
export function buildFastForwardRequest(
  res: FastForwardResolution,
): CreateSessionRequest | null {
  const { project, command, handle } = res;
  if (!project || !command?.trim() || !handle) return null;
  return {
    cwd: project.path,
    command,
    worktree: {
      base_repo: project.base_repo ?? project.path,
      branch: handle,
      create_branch: true,
    },
  };
}

/** Seed for the fallback spawn form: whatever did resolve goes into the
 *  form; the rest stays with its own defaults. The name field stays empty
 *  (#131) — the handle seeds the branch, not the session name. */
export function fastForwardSeed(res: FastForwardResolution) {
  return {
    cwd: res.project?.path ?? "",
    command: res.command ?? "",
    name: "",
    // Left undefined rather than false when nothing resolved: the form
    // defaults the toggle on, and `false` would stick, so the fallback form
    // would disagree with both a normally-opened form and the TUI's fast path
    // (#67 review).
    worktreeEnabled: res.project ? true : undefined,
    worktreeBranch:
      res.project && res.handle ? res.handle : undefined,
  };
}