/**
 * fun 结点：根据描述词（prompt）用 python/imagedl 搜索并下载一张图片到 savePath
 * 入参：prompt（描述词）, savePath（相对路径时基于 folderPath）
 */
const path = require('path')
const fs = require('fs')
const { spawnSync } = require('child_process')
const { getPythonExeFromConfig } = require('../../../python-exe-from-config.js')

const configPath = process.env.STATIC_ROOT
  ? path.join(path.dirname(path.resolve(process.env.STATIC_ROOT)), 'config.js')
  : path.join(__dirname, '..', '..', '..', '..', 'config.js')
const config = fs.existsSync(configPath) ? require(configPath) : {}
const projectRoot = (config.projectRoot && fs.existsSync(config.projectRoot))
  ? config.projectRoot
  : path.dirname(path.resolve(configPath))
const scriptPath = path.join(projectRoot, 'python', 'scripts', 'download-img-by-prompt.py')
const imagedlParent = path.join(projectRoot, 'python')
const imagedlRequirements = path.join(projectRoot, 'python', 'imagedl', 'requirements.txt')

function buildSavePath(savePath, folderPath) {
  if (!savePath || typeof savePath !== 'string') return null
  const trimmed = savePath.trim()
  if (path.isAbsolute(trimmed) || trimmed.match(/^[A-Za-z]:/)) return trimmed
  return folderPath ? path.join(folderPath, trimmed) : path.resolve(projectRoot, trimmed)
}

/** spawnSync 非 0 退出时拼详细日志（含启动失败、信号、截断后的 stdout/stderr） */
function formatSpawnFailure (r, pythonPath, scriptPath) {
  const maxLen = 1500
  const trunc = (s) => {
    const t = String(s || '').trim()
    if (!t) return ''
    return t.length > maxLen ? `${t.slice(0, maxLen)}…(truncated)` : t
  }
  const parts = []
  if (pythonPath) {
    const abs = path.isAbsolute(pythonPath) || /^[A-Za-z]:/.test(pythonPath)
    const missing = abs && !fs.existsSync(pythonPath)
    parts.push(`python=${pythonPath}${missing ? ' (file missing)' : ''}`)
  }
  if (scriptPath) parts.push(`script=${scriptPath}`)
  if (r.error) {
    const e = r.error
    const code = e.code != null ? String(e.code) : ''
    parts.push(`spawnError${code ? `[${code}]` : ''}: ${e.message || e}`)
  }
  if (r.signal) parts.push(`signal=${r.signal}`)
  if (r.status !== null && r.status !== undefined) parts.push(`exitCode=${r.status}`)
  else parts.push('exitCode=(null)')
  const stderr = trunc(r.stderr)
  const stdout = trunc(r.stdout)
  if (stderr) parts.push(`stderr: ${stderr}`)
  if (stdout) parts.push(`stdout: ${stdout}`)
  return parts.length ? parts.join(' | ') : 'download-img 执行失败（无子进程输出）'
}

async function executeDownloadImg({ prompt, savePath, folderPath }) {
  if (!prompt || typeof prompt !== 'string' || !prompt.trim()) return { success: false, error: 'download-img 缺少 prompt 参数' }
  if (savePath == null) return { success: false, error: 'download-img 缺少 savePath 参数' }
  const absolutePath = buildSavePath(String(savePath).trim(), folderPath)
  if (!absolutePath) return { success: false, error: 'download-img savePath 无效' }
  if (!fs.existsSync(scriptPath)) return { success: false, error: `脚本不存在: ${scriptPath}` }

  const pythonPath = getPythonExeFromConfig(config)
  const args = [scriptPath, '--prompt', prompt.trim(), '--save-path', absolutePath.replace(/\\/g, '/')]
  const runScript = () => spawnSync(pythonPath, args, {
    encoding: 'utf-8',
    timeout: 120000,
    env: { ...process.env, PYTHONIOENCODING: 'utf-8', IMAGEDL_PARENT: imagedlParent },
    cwd: projectRoot
  })

  let r = runScript()
  let out = (r.stdout || '').trim()
  const err = (r.stderr || '').trim()
  const fullOut = out + (err ? '\n' + err : '')

  if (r.status !== 0 && fs.existsSync(imagedlRequirements) && (fullOut.includes('No module named') || fullOut.includes('ModuleNotFoundError'))) {
    spawnSync(pythonPath, ['-m', 'pip', 'install', '-r', imagedlRequirements, '-q'], {
      encoding: 'utf-8',
      timeout: 180000,
      cwd: projectRoot
    })
    r = runScript()
    out = (r.stdout || '').trim()
  }

  if (r.status !== 0) {
    return { success: false, error: formatSpawnFailure(r, pythonPath, scriptPath) }
  }
  // stdout 可能包含进度条等，取最后一行以 { 开头的行作为 JSON
  const lines = out.split(/\r?\n/).map(s => s.trim()).filter(Boolean)
  let jsonStr = lines[lines.length - 1]
  if (!jsonStr || !jsonStr.startsWith('{')) {
    const lastJson = lines.filter(l => l.startsWith('{')).pop()
    jsonStr = lastJson || out
  }
  let result
  try {
    result = JSON.parse(jsonStr)
  } catch (_) {
    const raw = String(out || '').trim()
    const tail = raw.length > 800 ? raw.slice(-800) : raw
    return { success: false, error: `无法解析 JSON 输出 | stdout(tail): ${tail || '(empty)'}` }
  }
  if (!result.success) return { success: false, error: result.error || '未下载到图片' }
  return { success: true, path: result.path }
}

module.exports = { executeDownloadImg }