import { THINKING_COT_MAX } from '../config/limits.js'
import type { ThinkingMode } from '../types.js'

const ESC = String.fromCharCode(27)
const ANSI_RE = new RegExp(`${ESC}\\[[0-9;]*m`, 'g')
const WS_RE = /\s+/g

export const stripAnsi = (s: string) => s.replace(ANSI_RE, '')

export const hasAnsi = (s: string) => s.includes(`${ESC}[`) || s.includes(`${ESC}]`)

const renderEstimateLine = (line: string) => {
  const trimmed = line.trim()

  if (trimmed.startsWith('|')) {
    return trimmed
      .split('|')
      .filter(Boolean)
      .map(cell => cell.trim())
      .join('  ')
  }

  return line
    .replace(/!\[(.*?)\]\(([^)\s]+)\)/g, '[image: $1]')
    .replace(/\[(.+?)\]\((https?:\/\/[^\s)]+)\)/g, '$1')
    .replace(/`([^`]+)`/g, '$1')
    .replace(/\*\*(.+?)\*\*/g, '$1')
    .replace(/(?<!\w)__(.+?)__(?!\w)/g, '$1')
    .replace(/\*(.+?)\*/g, '$1')
    .replace(/(?<!\w)_(.+?)_(?!\w)/g, '$1')
    .replace(/~~(.+?)~~/g, '$1')
    .replace(/==(.+?)==/g, '$1')
    .replace(/\[\^([^\]]+)\]/g, '[$1]')
    .replace(/^#{1,6}\s+/, '')
    .replace(/^\s*[-*+]\s+\[( |x|X)\]\s+/, (_m, checked: string) => `• [${checked.toLowerCase() === 'x' ? 'x' : ' '}] `)
    .replace(/^\s*[-*+]\s+/, '• ')
    .replace(/^\s*(\d+)\.\s+/, '$1. ')
    .replace(/^\s*(?:>\s*)+/, '│ ')
}

export const compactPreview = (s: string, max: number) => {
  const one = s.replace(WS_RE, ' ').trim()

  return !one ? '' : one.length > max ? one.slice(0, max - 1) + '…' : one
}

export const estimateTokensRough = (text: string) => (!text ? 0 : (text.length + 3) >> 2)

export const edgePreview = (s: string, head = 16, tail = 28) => {
  const one = s.replace(WS_RE, ' ').trim().replace(/\]\]/g, '] ]')

  return !one
    ? ''
    : one.length <= head + tail + 4
      ? one
      : `${one.slice(0, head).trimEnd()}.. ${one.slice(-tail).trimStart()}`
}

export const pasteTokenLabel = (text: string, lineCount: number) => {
  const preview = edgePreview(text)

  if (!preview) {
    return `[[ [${fmtK(lineCount)} lines] ]]`
  }

  const [head = preview, tail = ''] = preview.split('.. ', 2)

  return tail
    ? `[[ ${head.trimEnd()}.. [${fmtK(lineCount)} lines] .. ${tail.trimStart()} ]]`
    : `[[ ${preview} [${fmtK(lineCount)} lines] ]]`
}

export const thinkingPreview = (reasoning: string, mode: ThinkingMode, max: number = THINKING_COT_MAX) => {
  const raw = reasoning.trim()

  return !raw || mode === 'collapsed' ? '' : mode === 'full' ? raw : compactPreview(raw.replace(WS_RE, ' '), max)
}

export const stripTrailingPasteNewlines = (text: string) => (/[^\n]/.test(text) ? text.replace(/\n+$/, '') : text)

export const toolTrailLabel = (name: string) =>
  name
    .split('_')
    .filter(Boolean)
    .map(p => p[0]!.toUpperCase() + p.slice(1))
    .join(' ') || name

export const formatToolCall = (name: string, context = '') => {
  const label = toolTrailLabel(name)
  const preview = compactPreview(context, 64)

  return preview ? `${label}("${preview}")` : label
}

export const buildToolTrailLine = (name: string, context: string, error?: boolean, note?: string) => {
  const detail = compactPreview(note ?? '', 72)

  return `${formatToolCall(name, context)}${detail ? ` :: ${detail}` : ''} ${error ? ' ✗' : ' ✓'}`
}

export const isToolTrailResultLine = (line: string) => line.endsWith(' ✓') || line.endsWith(' ✗')

export const parseToolTrailResultLine = (line: string) => {
  if (!isToolTrailResultLine(line)) {
    return null
  }

  const mark = line.endsWith(' ✗') ? '✗' : '✓'
  const body = line.slice(0, -2)
  const [call, detail] = body.split(' :: ', 2)

  if (detail != null) {
    return { call, detail, mark }
  }

  const legacy = body.indexOf(': ')

  if (legacy > 0) {
    return { call: body.slice(0, legacy), detail: body.slice(legacy + 2), mark }
  }

  return { call: body, detail: '', mark }
}

export const isTransientTrailLine = (line: string) => line.startsWith('drafting ') || line === 'analyzing tool output…'

export const sameToolTrailGroup = (label: string, entry: string) =>
  entry === `${label} ✓` ||
  entry === `${label} ✗` ||
  entry.startsWith(`${label}(`) ||
  entry.startsWith(`${label} ::`) ||
  entry.startsWith(`${label}:`)

export const lastCotTrailIndex = (trail: readonly string[]) => {
  for (let i = trail.length - 1; i >= 0; i--) {
    if (!isToolTrailResultLine(trail[i]!)) {
      return i
    }
  }

  return -1
}

export const estimateRows = (text: string, w: number, compact = false) => {
  let fence: { char: '`' | '~'; len: number } | null = null
  let rows = 0

  for (const raw of text.split('\n')) {
    const line = stripAnsi(raw)
    const maybeFence = line.match(/^\s*(`{3,}|~{3,})(.*)$/)

    if (maybeFence) {
      const marker = maybeFence[1]!
      const lang = maybeFence[2]!.trim()

      if (!fence) {
        fence = { char: marker[0] as '`' | '~', len: marker.length }

        if (lang) {
          rows += Math.ceil((`─ ${lang}`.length || 1) / w)
        }
      } else if (marker[0] === fence.char && marker.length >= fence.len) {
        fence = null
      }

      continue
    }

    const inCode = Boolean(fence)
    const trimmed = line.trim()

    if (!inCode && trimmed.startsWith('|') && /^[|\s:-]+$/.test(trimmed)) {
      continue
    }

    const rendered = inCode ? line : renderEstimateLine(line)

    if (compact && !rendered.trim()) {
      continue
    }

    rows += Math.ceil((rendered.length || 1) / w)
  }

  return Math.max(1, rows)
}

export const flat = (r: Record<string, string[]>) => Object.values(r).flat()

const COMPACT_NUMBER = new Intl.NumberFormat('en-US', { maximumFractionDigits: 1, notation: 'compact' })

export const fmtK = (n: number) => COMPACT_NUMBER.format(n).replace(/[KMBT]$/, s => s.toLowerCase())

export const pick = <T>(a: T[]) => a[Math.floor(Math.random() * a.length)]!

export const isPasteBackedText = (text: string) =>
  /\[\[paste:\d+(?:[^\n]*?)\]\]|\[paste #\d+ (?:attached|excerpt)(?:[^\n]*?)\]/.test(text)