import { createHash } from 'node:crypto'
import * as os from 'node:os'
import * as path from 'node:path'

export const DEFAULT_WORKTREE_TEMPLATE = '~/Sources/worktree/$project_name/$feature_name'

/**
 * 设计文档 / 计划按 ECC 布局存放：`.claude/specs/<stem>.md`、`.claude/plans/<stem>.md`，
 * 文件名的 stem 就是 slug，两者共用同一个 stem。少数布局把文件名固定成
 * `plan.md` / `spec.md`，这时 slug 退回父目录名；再兜底路径 hash，保证不为空。
 */
export function deriveSlug(planFile: string): string {
  const stem = path.basename(planFile).replace(/\.md$/, '')
  if (stem && stem !== 'plan' && stem !== 'spec')
    return stem
  const parent = path.basename(path.dirname(planFile))
  if (parent && parent !== '.' && parent !== '/')
    return parent
  return createHash('sha256').update(planFile).digest('hex').slice(0, 8)
}

/** 实施分支固定形如 `feature/<slug>`；接管方只有分支名，从这里反推 worktree 目录名。 */
export function slugFromBranch(branch: string): string {
  return branch.startsWith('feature/') ? branch.slice('feature/'.length) : branch
}

/**
 * 把 worktreeDirectory 模板展开成绝对路径。`~` 在这里展开：git/execFile 不经 shell，
 * 不会自己做 tilde 展开。
 */
export function resolveWorktreeDir(template: string, workspaceRoot: string, slug: string): string {
  let p = template
    .split('$project_name')
    .join(path.basename(workspaceRoot))
    .split('$project_root')
    .join(workspaceRoot)
    .split('$feature_name')
    .join(slug)
  if (p.startsWith('~'))
    p = path.join(os.homedir(), p.slice(1))
  return path.resolve(p)
}