export const PLUGIN = 'jsc-anima'
export const SKILL_PREFIX = 'anima-'
export const SKILL_DIR = 'skills'
export const GUIDE_SKILL = 'jsc-anima'
export const LIST_START = '<!-- skills:start -->'
export const LIST_END = '<!-- skills:end -->'

export type Parsed = { name: string; description: string; body: string }

export const slugify = (s: string): string =>
  s.toLowerCase().replace(/[^a-z0-9]+/g, '-').replace(/^-+|-+$/g, '')

export const commandOf = (skill: string): string => `/${PLUGIN}:${SKILL_PREFIX}${skill}`

// 指令第一個字是技能名稱，其餘是描述。
export const parseArgs = (args: string): { skill: string; description: string } | undefined => {
  const m = args.trim().match(/^(\S+)\s+([\s\S]+)$/)
  if (!m) return undefined
  const skill = slugify(m[1]!)
  return skill ? { skill, description: m[2]!.trim() } : undefined
}

export const parseSkillMd = (md: string): Parsed | undefined => {
  const m = md.trim().match(/^---\n([\s\S]*?)\n---\n([\s\S]*)$/)
  if (!m) return undefined
  const field = (k: string) => m[1]!.match(new RegExp(`^${k}:\\s*(.+)$`, 'm'))?.[1]?.trim().replace(/^["']|["']$/g, '')
  return { name: field('name') ?? '', description: field('description') ?? '', body: m[2]!.trim() }
}

// 回傳錯誤訊息清單，空陣列代表通過。
export const validateSkill = (md: string, skill: string): string[] => {
  const p = parseSkillMd(md)
  if (!p) return ['缺少 frontmatter（--- 包住的 name 與 description）']
  const errs: string[] = []
  if (p.name !== `${SKILL_PREFIX}${skill}`) errs.push(`name 必須是 ${SKILL_PREFIX}${skill}，實際為「${p.name}」`)
  if (!p.description) errs.push('description 不可為空')
  if (p.body.length < 20) errs.push('內文過短')
  return errs
}

export const bumpVersion = (v: string, kind: 'minor' | 'patch'): string => {
  const [a = 0, b = 0, c = 0] = v.split('.').map(n => Number(n) || 0)
  return kind === 'minor' ? `${a}.${b + 1}.0` : `${a}.${b}.${c + 1}`
}

export type SkillEntry = { skill: string; description: string }

export const parseEntries = (readme: string): SkillEntry[] => {
  const block = readme.split(LIST_START)[1]?.split(LIST_END)[0] ?? ''
  const out: SkillEntry[] = []
  for (const line of block.split('\n')) {
    const m = line.match(/^- `\/jsc-anima:anima-([^`\s]+)[^`]*` — (.*)$/)
    if (m) out.push({ skill: m[1]!, description: m[2]! })
  }
  return out
}

export const upsertEntry = (list: SkillEntry[], e: SkillEntry): SkillEntry[] =>
  [...list.filter(x => x.skill !== e.skill), e].sort((a, b) => a.skill.localeCompare(b.skill))

// 技能 README：名稱 /jsc-anima:jsc-anima、技能列表（完整可複製指令）與範例。
export const renderGuide = (list: SkillEntry[], example?: { skill: string; input: string }): string => {
  const ex = example ?? { skill: list[0]?.skill ?? 'example', input: '' }
  return [
    `# /${PLUGIN}:${GUIDE_SKILL}`,
    '',
    '動漫助理的使用說明。先用 `/jsc-anima:{作品代號}-{角色代號}` 啟動角色，再使用下列技能。',
    '',
    '## 技能列表',
    '',
    LIST_START,
    ...list.map(e => `- \`${commandOf(e.skill)}\` — ${e.description}`),
    LIST_END,
    '',
    '## 範例',
    '',
    '```',
    `${commandOf(ex.skill)}${ex.input ? ' ' + ex.input : ''}`,
    '```',
    '',
    '產生新技能：`/jsc-anima:anima-skill <技能名稱> <描述>`，通過驗證與實跑後自動對預設分支建立 PR。',
    '',
  ].join('\n')
}

export const guideSkillMd = (): string =>
  `---\nname: ${GUIDE_SKILL}\ndescription: jsc-anima 動漫助理的使用說明與技能列表\n---\n\n請讀取同目錄的 README.md 並依內容回答使用者。\n`

export const setReadmeVersion = (readme: string, version: string): string => {
  const line = `目前版本：${version}`
  return /^目前版本：.*$/m.test(readme)
    ? readme.replace(/^目前版本：.*$/m, line)
    : readme.replace(/^(# jsc-anima\n)/m, `$1\n${line}\n`)
}

export const setPluginVersion = (json: string, version: string): string =>
  json.replace(/("version":\s*")[^"]*(")/, `$1${version}$2`)

export const generatePrompt = (skill: string, description: string): string =>
  [
    `請撰寫一個 Claude 技能，技能名稱 ${SKILL_PREFIX}${skill}，用途：${description}`,
    '只輸出 JSON（不要程式碼圍欄），格式：{"skill":"<SKILL.md 全文，含 frontmatter name 與 description，內文用繁體中文>","example":"<一筆範例輸入>"}',
    `frontmatter 的 name 必須是 ${SKILL_PREFIX}${skill}。`,
  ].join('\n')

export const parseGenerated = (text: string): { skill: string; example: string } | undefined => {
  try {
    const j = JSON.parse(text.trim().replace(/^```(?:json)?\n?|\n?```$/g, ''))
    if (typeof j.skill === 'string' && typeof j.example === 'string') return { skill: j.skill, example: j.example }
  } catch {}
  return undefined
}