/**
 * claude / codex 会话文件的搬运原语。
 *
 * claude 会话 = `<projectsDir>/<sid>.jsonl` + 可选 `<projectsDir>/<sid>/`
 * （subagents、tool-results），两者必须一起搬。新版 claude 在任意目录
 * `--resume` 时会搜全部 project 目录，同一 sid 出现两份就拒绝 resume——
 * 所以「安装」总是先拷再删本机其它副本。
 */

import { promises as fsp } from 'node:fs'
import * as os from 'node:os'
import * as path from 'node:path'
import { ROLLOUT_UUID_REGEX } from './codexSessionWatcher'

export interface ClaudeSessionFiles {
  projectsDir: string
  jsonl: string
  dir?: string
}

export function claudeProjectsRoot(): string {
  return path.join(os.homedir(), '.claude', 'projects')
}

async function exists(p: string): Promise<boolean> {
  try {
    await fsp.stat(p)
    return true
  }
  catch {
    return false
  }
}

async function sessionFilesIn(projectsDir: string, sid: string): Promise<ClaudeSessionFiles | undefined> {
  const jsonl = path.join(projectsDir, `${sid}.jsonl`)
  if (!(await exists(jsonl)))
    return undefined
  const dir = path.join(projectsDir, sid)
  return (await exists(dir)) ? { projectsDir, jsonl, dir } : { projectsDir, jsonl }
}

export async function listClaudeSessionCopies(sid: string, projectsRoot: string): Promise<ClaudeSessionFiles[]> {
  let entries: string[]
  try {
    entries = await fsp.readdir(projectsRoot)
  }
  catch {
    return []
  }
  const out: ClaudeSessionFiles[] = []
  for (const name of entries) {
    const found = await sessionFilesIn(path.join(projectsRoot, name), sid)
    if (found)
      out.push(found)
  }
  return out
}

export async function findClaudeSessionFiles(sid: string, projectsRoot: string): Promise<ClaudeSessionFiles | undefined> {
  const copies = await listClaudeSessionCopies(sid, projectsRoot)
  if (copies.length === 0)
    return undefined
  const stamped = await Promise.all(copies.map(async c => ({ c, mtime: (await fsp.stat(c.jsonl)).mtimeMs })))
  stamped.sort((a, b) => b.mtime - a.mtime)
  return stamped[0].c
}

export async function copyClaudeSessionFiles(files: ClaudeSessionFiles, dstDir: string): Promise<void> {
  await fsp.mkdir(dstDir, { recursive: true })
  await fsp.copyFile(files.jsonl, path.join(dstDir, path.basename(files.jsonl)))
  if (files.dir)
    await fsp.cp(files.dir, path.join(dstDir, path.basename(files.dir)), { recursive: true, force: true })
}

async function removeClaudeSessionFiles(files: ClaudeSessionFiles): Promise<void> {
  await fsp.rm(files.jsonl, { force: true })
  if (files.dir)
    await fsp.rm(files.dir, { recursive: true, force: true })
}

export async function installClaudeSession(opts: {
  sid: string
  srcDir: string
  dstProjectsDir: string
  projectsRoot: string
}): Promise<void> {
  const src = await sessionFilesIn(path.resolve(opts.srcDir), opts.sid)
  if (!src)
    throw new Error(`源目录缺少会话文件 ${opts.sid}.jsonl：${opts.srcDir}`)
  const dst = path.resolve(opts.dstProjectsDir)
  if (src.projectsDir !== dst)
    await copyClaudeSessionFiles(src, dst)
  for (const copy of await listClaudeSessionCopies(opts.sid, opts.projectsRoot)) {
    if (path.resolve(copy.projectsDir) !== dst)
      await removeClaudeSessionFiles(copy)
  }
}

/** codex rollout 全局存放，按文件名尾部 uuid 定位；返回相对 codexRoot 的路径。 */
export async function codexRolloutRelPathFor(sid: string, codexRoot: string): Promise<string | undefined> {
  const want = sid.toLowerCase()
  let entries: string[]
  try {
    entries = await fsp.readdir(codexRoot, { recursive: true })
  }
  catch {
    return undefined
  }
  for (const entry of entries) {
    const m = path.basename(entry).match(ROLLOUT_UUID_REGEX)
    if (m && m[1].toLowerCase() === want)
      return entry
  }
  return undefined
}

export async function installCodexSession(relPath: string, srcFile: string, codexRoot: string): Promise<void> {
  const dst = path.join(codexRoot, relPath)
  await fsp.mkdir(path.dirname(dst), { recursive: true })
  await fsp.copyFile(srcFile, dst)
}

/**
 * 迁移会话里发送方的 worktree 路径重写成接收方的路径。
 * split/join 而非正则替换——路径里的 `.` `(` 等字符不用转义，出现次数就是替换次数。
 */
export async function rewritePathInFile(file: string, from: string, to: string): Promise<number> {
  const content = await fsp.readFile(file, 'utf8')
  const parts = content.split(from)
  const count = parts.length - 1
  if (count > 0)
    await fsp.writeFile(file, parts.join(to))
  return count
}

export async function rewritePathInTree(dir: string, from: string, to: string): Promise<number> {
  let entries: Array<{ name: string, isDirectory: () => boolean, isFile: () => boolean }>
  try {
    entries = await fsp.readdir(dir, { withFileTypes: true })
  }
  catch {
    return 0
  }
  let total = 0
  for (const entry of entries) {
    const full = path.join(dir, entry.name)
    if (entry.isDirectory())
      total += await rewritePathInTree(full, from, to)
    else if (entry.isFile())
      total += await rewritePathInFile(full, from, to)
  }
  return total
}