import path from 'path'
import { spawn } from 'child_process'
import fs from 'fs/promises'
import { existsSync, mkdirSync } from 'fs'
import { PROJECT_ROOT, NOTEBOOK_ROOT, TEMP_ROOT } from '../../config/paths.js'
import { getUniqueFilename } from '../../utils/file.js'
import { formatTimestamp, pad2 } from '../../../shared/utils/date.js'
import { logger } from '../../utils/logger.js'

if (!existsSync(TEMP_ROOT)) {
  mkdirSync(TEMP_ROOT, { recursive: true })
}

export interface JobContext {
  jobDir: string
  now: Date
  imagesSubDir: string
  destImagesDir: string
}

export const createJobContext = async (prefix: string): Promise<JobContext> => {
  const now = new Date()
  const jobDir = path.join(TEMP_ROOT, `${prefix}_${formatTimestamp(now)}`)
  await fs.mkdir(jobDir, { recursive: true })

  const year = now.getFullYear()
  const month = pad2(now.getMonth() + 1)
  const day = pad2(now.getDate())
  const imagesSubDir = `images/${year}/${month}/${day}`
  const destImagesDir = path.join(NOTEBOOK_ROOT, imagesSubDir)
  await fs.mkdir(destImagesDir, { recursive: true })

  return { jobDir, now, imagesSubDir, destImagesDir }
}

export interface SpawnPythonOptions {
  scriptPath: string
  args: string[]
  cwd: string
  inputContent?: string
}

export const spawnPythonScript = async (options: SpawnPythonOptions): Promise<string> => {
  const { scriptPath, args, cwd, inputContent } = options

  return new Promise<string>((resolve, reject) => {
    const pythonProcess = spawn('python', ['-X', 'utf8', scriptPath, ...args], {
      cwd,
      env: { ...process.env, PYTHONIOENCODING: 'utf-8', PYTHONUTF8: '1' },
    })

    let stdout = ''
    let stderr = ''

    pythonProcess.stdout.on('data', (data) => {
      stdout += data.toString()
    })

    pythonProcess.stderr.on('data', (data) => {
      stderr += data.toString()
    })

    pythonProcess.on('close', (code) => {
      if (code !== 0) {
        logger.error('Python script error:', stderr)
        reject(new Error(`Process exited with code ${code}. Error: ${stderr}`))
      } else {
        resolve(stdout)
      }
    })

    pythonProcess.on('error', (err) => {
      reject(err)
    })

    if (inputContent !== undefined) {
      pythonProcess.stdin.write(inputContent)
      pythonProcess.stdin.end()
    }
  })
}

export interface ImageReplacement {
  start: number
  end: number
  original: string
  replacement: string
}

export const findImageDestinations = (md: string): Array<{ url: string; start: number; end: number }> => {
  const results: Array<{ url: string; start: number; end: number }> = []
  let i = 0
  while (i < md.length) {
    const bang = md.indexOf('![', i)
    if (bang === -1) break
    const closeBracket = md.indexOf(']', bang + 2)
    if (closeBracket === -1) break
    if (md[closeBracket + 1] !== '(') {
      i = closeBracket + 1
      continue
    }

    const urlStart = closeBracket + 2
    let depth = 1
    let j = urlStart
    for (; j < md.length; j++) {
      const ch = md[j]
      if (ch === '(') depth++
      else if (ch === ')') {
        depth--
        if (depth === 0) break
      }
    }
    if (depth !== 0) break
    results.push({ url: md.slice(urlStart, j), start: urlStart, end: j })
    i = j + 1
  }
  return results
}

export const applyReplacements = (md: string, replacements: ImageReplacement[]): string => {
  const sorted = [...replacements].sort((a, b) => b.start - a.start)
  let result = md
  for (const r of sorted) {
    result = `${result.slice(0, r.start)}${r.replacement}${result.slice(r.end)}`
  }
  return result
}

export const copyLocalImage = async (
  src: string,
  jobDir: string,
  htmlDir: string,
  destImagesDir: string,
  imagesSubDir: string,
  now: Date
): Promise<{ newLink: string } | null> => {
  const s0 = src.trim().replace(/^<|>$/g, '')
  if (!s0) return null

  let decoded = s0
  try {
    decoded = decodeURI(s0)
  } catch {}

  const s1 = decoded.replace(/\\/g, '/')
  const s2 = s1.startsWith('./') ? s1.slice(2) : s1
  const candidates = s2.startsWith('/')
    ? [path.join(jobDir, s2.slice(1)), path.join(htmlDir, s2.slice(1))]
    : [path.resolve(htmlDir, s2), path.resolve(jobDir, s2)]

  let foundFile: string | null = null
  for (const c of candidates) {
    if (existsSync(c)) {
      foundFile = c
      break
    }
  }

  if (!foundFile) return null

  const ext = path.extname(foundFile) || '.jpg'
  const baseName = formatTimestamp(now)
  const newFilename = await getUniqueFilename(destImagesDir, baseName, ext)
  const newPath = path.join(destImagesDir, newFilename)
  await fs.copyFile(foundFile, newPath)

  return { newLink: `/${imagesSubDir}/${newFilename}` }
}

export const cleanupJob = async (jobDir: string, additionalPaths: string[] = []): Promise<void> => {
  await fs.rm(jobDir, { recursive: true, force: true }).catch(() => {})
  for (const p of additionalPaths) {
    await fs.unlink(p).catch(() => {})
  }
}

export const getScriptPath = (toolName: string, scriptName: string): string => {
  return path.join(PROJECT_ROOT, 'tools', toolName, scriptName)
}

export const ensureScriptExists = (scriptPath: string): boolean => {
  return existsSync(scriptPath)
}