// 工具四（待辦事項）的純邏輯：解析、渲染、到點判斷。讀寫與指令在 register.tsx。

export const TODO_COMMAND = 'anima-todo'
export const TODO_KEY = 'todos'
export const TYPES_KEY = 'todoTypes'
export const DEFAULT_TYPES = ['提醒', '開發', '研究', '維護']

export type Status = 'pending' | 'reminded' | 'done'
export type Todo = { id: number; type: string; at: number; task: string; project: string; status: Status; result?: string }

export const USAGE =
  '用法：\n' +
  '/jsc-anima:anima-todo add <類型> <YYYY-MM-DD> <HH:MM> <任務>　建立\n' +
  '/jsc-anima:anima-todo update <編號> <類型> <YYYY-MM-DD> <HH:MM> <任務>　更新\n' +
  '/jsc-anima:anima-todo list　列出全部\n' +
  '/jsc-anima:anima-todo type <名稱>　新增自訂類型\n' +
  '/jsc-anima:anima-todo run <編號>　確認後執行\n' +
  '/jsc-anima:anima-todo done <編號>　標記完成（不執行）'

const pad = (n: number) => String(n).padStart(2, '0')

export const fmtTime = (ms: number): string => {
  const d = new Date(ms)
  return `${d.getFullYear()}-${pad(d.getMonth() + 1)}-${pad(d.getDate())} ${pad(d.getHours())}:${pad(d.getMinutes())}`
}

// 排程時間以本機時區解讀。
export const parseTime = (date: string | undefined, time: string | undefined): number | undefined => {
  const d = /^(\d{4})-(\d{2})-(\d{2})$/.exec(date ?? '')
  const t = /^(\d{1,2}):(\d{2})$/.exec(time ?? '')
  if (!d || !t) return undefined
  const [y, mo, da, h, mi] = [d[1], d[2], d[3], t[1], t[2]].map(Number) as [number, number, number, number, number]
  const out = new Date(y, mo - 1, da, h, mi)
  if (out.getMonth() !== mo - 1 || out.getDate() !== da || h > 23 || mi > 59) return undefined
  return out.getTime()
}

export type Parsed =
  | { op: 'add'; type: string; at: number; task: string }
  | { op: 'update'; id: number; type: string; at: number; task: string }
  | { op: 'list' }
  | { op: 'type'; name: string }
  | { op: 'run' | 'done'; id: number }

const spec = (w: string[]): { type: string; at: number; task: string } | undefined => {
  const [type, date, time, ...rest] = w
  const at = parseTime(date, time)
  const task = rest.join(' ').trim()
  return type && at !== undefined && task ? { type, at, task } : undefined
}

export const parseArgs = (args: string): Parsed | undefined => {
  const w = args.trim().split(/\s+/).filter(Boolean)
  const [op, ...rest] = w
  const id = Number(rest[0])
  if (op === 'list' && rest.length === 0) return { op }
  if (op === 'type' && rest.length === 1) return { op, name: rest[0]! }
  if ((op === 'run' || op === 'done') && rest.length === 1 && Number.isInteger(id) && id > 0) return { op, id }
  if (op === 'add') {
    const s = spec(rest)
    return s ? { op, ...s } : undefined
  }
  if (op === 'update' && Number.isInteger(id) && id > 0) {
    const s = spec(rest.slice(1))
    return s ? { op, id, ...s } : undefined
  }
  return undefined
}

export const dueNow = (todos: Todo[], now: number): Todo[] => todos.filter(t => t.status === 'pending' && t.at <= now)

export const nextId = (todos: Todo[]): number => todos.reduce((m, t) => Math.max(m, t.id), 0) + 1

const STATUS_TEXT: Record<Status, string> = { pending: '待辦', reminded: '已提醒', done: '完成' }

export const renderList = (todos: Todo[]): string =>
  todos.length === 0
    ? '目前沒有待辦。'
    : todos
        .slice()
        .sort((a, b) => a.at - b.at)
        .map(t => `#${t.id} [${t.type}] ${fmtTime(t.at)} ${t.task}（${STATUS_TEXT[t.status]}，專案：${t.project || '無'}）`)
        .join('\n')

export const reminderText = (t: Todo): string =>
  `到點了：[${t.type}] ${t.task}（#${t.id}，專案：${t.project || '無'}）。要我執行的話請輸入 /jsc-anima:${TODO_COMMAND} run ${t.id}，確認前我不會動手。`

export const RUN_SYSTEM = '你要執行使用者確認過的待辦，簡短回報你做了什麼與結果；沒做到的事如實說明。'