export type DocsGroup = 'Overview' | 'Manual' | 'Earth' | 'Frontend' | 'Backend' | 'Agents' | 'Ops' | 'Other'
export type DocsLang = 'zh' | 'en'

export interface DocsEntry {
  slug: string
  filename: string
  title: string
  group: DocsGroup
  order: number
  access: DocsAccess
}

export type DocsAccess = 'public' | 'docs_user' | 'docs_developer' | 'docs_admin'

export interface DocsCatalogItem {
  slug: string
  filename: string
  lang: DocsLang
  title: string
  group: DocsGroup
  order: number
  access: DocsAccess
}

export interface DocsHeading {
  id: string
  level: number
  text: string
}

export interface DocsMetadataEntry {
  zh: { title: string; group: DocsGroup; order: number }
  en: { title: string; group: DocsGroup; order: number }
}

const DOCS_GROUP_LABELS: Record<DocsLang, Record<DocsGroup, string>> = {
  zh: {
    Overview: '概览',
    Manual: '使用手册',
    Earth: '地球可视化',
    Frontend: '前端',
    Backend: '后端',
    Agents: '智能体',
    Ops: '运维',
    Other: '其他',
  },
  en: {
    Overview: 'Overview',
    Manual: 'Manual',
    Earth: 'Earth',
    Frontend: 'Frontend',
    Backend: 'Backend',
    Agents: 'Agents',
    Ops: 'Ops',
    Other: 'Other',
  },
}

const DOCS_README_FILENAME = 'README.md'
const MAX_HEADING_ID_LENGTH = 80
export const defaultDocsSlug = 'overview'

export const DOCS_METADATA: Record<string, DocsMetadataEntry> = {
  [DOCS_README_FILENAME]: {
    zh: { title: '技术文档', group: 'Overview', order: 0 },
    en: { title: 'Technical Docs', group: 'Overview', order: 0 },
  },
  'quickstart.md': {
    zh: { title: '快速开始', group: 'Manual', order: 1 },
    en: { title: 'Quickstart', group: 'Manual', order: 1 },
  },
  'manual.md': {
    zh: { title: 'Planet 使用手册', group: 'Manual', order: 2 },
    en: { title: 'Planet Manual', group: 'Manual', order: 2 },
  },
  'location-pipeline-user.md': {
    zh: { title: 'Earth 位置候选采集使用手册', group: 'Manual', order: 3 },
    en: { title: 'Earth Location Candidate Collection User Guide', group: 'Manual', order: 3 },
  },
  'earth-frontend-context.md': {
    zh: { title: 'Earth 前端结构', group: 'Earth', order: 10 },
    en: { title: 'Earth Frontend Context', group: 'Earth', order: 10 },
  },
  'earth-layer-style-reference.md': {
    zh: { title: 'Earth 图层样式属性索引', group: 'Earth', order: 11 },
    en: { title: 'Earth Layer Style Reference', group: 'Earth', order: 11 },
  },
  'earth-render-layer-order.md': {
    zh: { title: 'Earth 渲染图层顺序', group: 'Earth', order: 12 },
    en: { title: 'Earth Render Layer Order', group: 'Earth', order: 12 },
  },
  'earth-satellite-footprint-policy.md': {
    zh: { title: 'Earth 卫星覆盖策略', group: 'Earth', order: 13 },
    en: { title: 'Earth Satellite Footprint Policy', group: 'Earth', order: 13 },
  },
  'earth-bgp-context.md': {
    zh: { title: 'BGP 态势上下文', group: 'Earth', order: 14 },
    en: { title: 'BGP Context', group: 'Earth', order: 14 },
  },
  'earth-news-live-streams-collector-format.md': {
    zh: { title: '新闻直播采集格式', group: 'Earth', order: 15 },
    en: { title: 'News Live Streams Collector Format', group: 'Earth', order: 15 },
  },
  'earth-interactable-usage.md': {
    zh: { title: 'Earth 可交互图标接入', group: 'Earth', order: 16 },
    en: { title: 'Earth Interactable Usage', group: 'Earth', order: 16 },
  },
  'earth-toolbar-overlay-coordination.md': {
    zh: { title: 'Earth 工具栏与浮层协同', group: 'Earth', order: 17 },
    en: { title: 'Earth Toolbar and Overlay Coordination', group: 'Earth', order: 17 },
  },
  'frontend-admin-frontend-context.md': {
    zh: { title: '控制台前端结构', group: 'Frontend', order: 20 },
    en: { title: 'Admin Frontend Context', group: 'Frontend', order: 20 },
  },
  'frontend-layout-guidelines.md': {
    zh: { title: '前端布局指南', group: 'Frontend', order: 21 },
    en: { title: 'Frontend Layout Guidelines', group: 'Frontend', order: 21 },
  },
  'docs-gatekeeper-development.md': {
    zh: { title: 'Docs Gatekeeper 开发说明', group: 'Frontend', order: 22 },
    en: { title: 'Docs Gatekeeper Development Guide', group: 'Frontend', order: 22 },
  },
  'backend-collectors.md': {
    zh: { title: '数据采集系统', group: 'Backend', order: 30 },
    en: { title: 'Data Collectors', group: 'Backend', order: 30 },
  },
  'backend-system-service-control.md': {
    zh: { title: '系统服务控制', group: 'Backend', order: 31 },
    en: { title: 'System Service Control', group: 'Backend', order: 31 },
  },
  'datasource-collector-settings-connectivity.md': {
    zh: { title: '数据源、采集器设置与连接验证', group: 'Backend', order: 32 },
    en: { title: 'Datasource Collector Settings and Connectivity', group: 'Backend', order: 32 },
  },
  'backend-datasources-api-performance.md': {
    zh: { title: '数据源 API 性能', group: 'Backend', order: 33 },
    en: { title: 'Datasource API Performance', group: 'Backend', order: 33 },
  },
  'location-pipeline-development.md': {
    zh: { title: '通用位置估算管线开发说明', group: 'Backend', order: 34 },
    en: { title: 'Shared Location Resolution Pipeline Development Guide', group: 'Backend', order: 34 },
  },
  'agents-aiprovider.md': {
    zh: { title: 'AI Provider 指南', group: 'Agents', order: 40 },
    en: { title: 'AI Provider Guide', group: 'Agents', order: 40 },
  },
  'ops-docker-compose-buildx-upgrade.md': {
    zh: { title: 'Docker + Compose + Buildx 升级', group: 'Ops', order: 50 },
    en: { title: 'Docker + Compose + Buildx Upgrade', group: 'Ops', order: 50 },
  },
  'ops-planet-sh-startup.md': {
    zh: { title: 'planet.sh 启动机制', group: 'Ops', order: 51 },
    en: { title: 'planet.sh Startup', group: 'Ops', order: 51 },
  },
}

const GROUP_ORDER: DocsGroup[] = ['Overview', 'Manual', 'Earth', 'Frontend', 'Backend', 'Agents', 'Ops', 'Other']

export function slugFromFilename(filename: string): string {
  return filename === DOCS_README_FILENAME ? defaultDocsSlug : filename.replace(/\.md$/, '')
}

export function getDocsEntries(lang: DocsLang, catalogItems: DocsCatalogItem[]): DocsEntry[] {
  return catalogItems
    .filter((item) => item.lang === lang)
    .map((item) => ({
      slug: item.slug,
      filename: item.filename,
      title: item.title,
      group: item.group,
      order: item.order,
      access: item.access,
    }))
    .sort((a, b) => a.order - b.order || a.title.localeCompare(b.title))
}

export function getDocsEntry(slug: string | undefined, entries: DocsEntry[]): DocsEntry | undefined {
  const normalizedSlug = slug || defaultDocsSlug
  return entries.find((entry) => entry.slug === normalizedSlug)
}

export function groupDocsEntries(entries: DocsEntry[]): Array<{ group: DocsGroup; entries: DocsEntry[] }> {
  return GROUP_ORDER.map((group) => ({
    group,
    entries: entries.filter((entry) => entry.group === group),
  })).filter((group) => group.entries.length > 0)
}

export function getDocsGroupLabel(group: DocsGroup, lang: DocsLang): string {
  return DOCS_GROUP_LABELS[lang][group]
}

export function createHeadingId(text: string, usedIds: Map<string, number>): string {
  const base = text
    .toLowerCase()
    .replace(/`([^`]+)`/g, '$1')
    .replace(/[^\p{L}\p{N}\s-]/gu, '')
    .trim()
    .replace(/\s+/g, '-')
    .slice(0, MAX_HEADING_ID_LENGTH) || 'section'
  const count = usedIds.get(base) || 0
  usedIds.set(base, count + 1)
  return count === 0 ? base : `${base}-${count + 1}`
}

export function extractHeadings(markdown: string): DocsHeading[] {
  const usedIds = new Map<string, number>()
  return markdown
    .split(/\r?\n/)
    .map((line) => line.trim().match(/^(#{1,3})\s+(.+)$/))
    .filter((match): match is RegExpMatchArray => Boolean(match))
    .map((match) => {
      const text = match[2].trim()
      return {
        id: createHeadingId(text, usedIds),
        level: match[1].length,
        text,
      }
    })
}

// Returns a factory — call factory() inside MarkdownRenderer to get a fresh resolver
// per render. This is necessary because StrictMode double-invokes renders, which
// would exhaust a shared stateful closure and cause heading IDs to become undefined.
export function createHeadingIdResolver(markdown: string): () => (text: string, level: number) => string | undefined {
  const headings = extractHeadings(markdown)

  return () => {
    const indexByKey = new Map<string, number>()
    return (text: string, level: number) => {
      const key = `${level}:${text}`
      const currentIndex = indexByKey.get(key) || 0
      indexByKey.set(key, currentIndex + 1)
      const matchingHeadings = headings.filter((heading) => heading.level === level && heading.text === text)
      return matchingHeadings[currentIndex]?.id
    }
  }
}

export function slugFromDocsHref(href: string): string | null {
  const normalized = decodeURIComponent(href).split('#')[0].replace(/\\/g, '/')
  const filename = normalized.split('/').pop()

  if (!filename?.endsWith('.md')) {
    return null
  }

  return slugFromFilename(filename)
}