import { useEffect, useState } from 'react'
import { createMemo, deleteMemo, getMemos, type Org, type WorkMemo } from '../api/client'

const CUSTOM_CONTACT_VALUE = '__custom__'

const dateFormatter = new Intl.DateTimeFormat('ko-KR', {
  year: 'numeric',
  month: '2-digit',
  day: '2-digit',
  hour: '2-digit',
  minute: '2-digit',
})

function formatDateTime(createdAt: number): string {
  return dateFormatter.format(new Date(createdAt))
}

function applicantOptionLabel(org: Org): string | null {
  if (!org.applicant) {
    return null
  }
  return org.applicant.title ? `${org.applicant.name} ${org.applicant.title}` : org.applicant.name
}

/** 신청기관 담당자, 문정원 담당자, 아이티앤 담당자, 담당 변호사 중 배정되어 있는 사람만 후보로 낸다.
 * 이름이 같은 사람이 중복 등록돼 있어도 셀렉트 옵션은 한 번만 보이도록 중복을 없앤다. */
function contactOptions(org: Org): string[] {
  const candidates = [
    applicantOptionLabel(org),
    org.mj?.name ?? null,
    org.itn?.name ?? null,
    org.lawyer?.name ?? null,
  ]
  const seen = new Set<string>()
  // 요구사항: 선택박스 최상단은 항상 '시스템'이다 (자동/시스템성 메모 구분용)
  const options: string[] = ['시스템']
  for (const candidate of candidates) {
    if (!candidate || candidate.trim() === '' || seen.has(candidate)) {
      continue
    }
    seen.add(candidate)
    options.push(candidate)
  }
  return options
}

/** 기관관리 상세의 업무메모 탭. 통화 등 담당자와의 연락 내용을 기록/조회/삭제한다. */
export default function WorkMemos({ org }: { org: Org }) {
  const options = contactOptions(org)

  const [memos, setMemos] = useState<WorkMemo[]>([])
  const [loading, setLoading] = useState(false)
  const [contactChoice, setContactChoice] = useState(options[0] ?? CUSTOM_CONTACT_VALUE)
  const [customContactName, setCustomContactName] = useState('')
  const [body, setBody] = useState('')
  const [busy, setBusy] = useState(false)
  const [error, setError] = useState<string | null>(null)

  useEffect(() => {
    let cancelled = false
    setLoading(true)

    getMemos(org.id)
      .then((data) => {
        if (!cancelled) {
          setMemos(data)
        }
      })
      .finally(() => {
        if (!cancelled) {
          setLoading(false)
        }
      })

    return () => {
      cancelled = true
    }
  }, [org.id])

  const isCustom = contactChoice === CUSTOM_CONTACT_VALUE
  const effectiveContactName = (isCustom ? customContactName : contactChoice).trim()
  const canSubmit = effectiveContactName !== '' && body.trim() !== '' && !busy

  async function handleSubmit() {
    if (!canSubmit) {
      return
    }
    setBusy(true)
    setError(null)
    try {
      const created = await createMemo(org.id, { contactName: effectiveContactName, body })
      setMemos((prev) => [created, ...prev])
      setBody('')
    } catch (e) {
      setError(e instanceof Error ? e.message : '메모 등록에 실패했습니다.')
    } finally {
      setBusy(false)
    }
  }

  async function handleDelete(memo: WorkMemo) {
    if (!window.confirm('이 메모를 삭제할까요?')) {
      return
    }
    try {
      await deleteMemo(org.id, memo.id)
      setMemos((prev) => prev.filter((m) => m.id !== memo.id))
    } catch (e) {
      setError(e instanceof Error ? e.message : '메모 삭제에 실패했습니다.')
    }
  }

  return (
    <div className="p-4">
      <section className="rounded-lg border border-gray-200 p-4">
        <div className="grid grid-cols-1 gap-3 sm:grid-cols-2">
          <div className="flex flex-col gap-1 text-sm">
            <label htmlFor="memo-contact-choice" className="text-xs text-gray-500">
              담당자
            </label>
            <select
              id="memo-contact-choice"
              value={contactChoice}
              onChange={(e) => setContactChoice(e.target.value)}
              className="rounded-md border border-gray-300 px-2 py-1.5 text-sm"
            >
              {options.map((option) => (
                <option key={option} value={option}>
                  {option}
                </option>
              ))}
              <option value={CUSTOM_CONTACT_VALUE}>직접 입력</option>
            </select>
          </div>

          {isCustom && (
            <div className="flex flex-col gap-1 text-sm">
              <label htmlFor="memo-contact-name" className="text-xs text-gray-500">
                담당자 이름
              </label>
              <input
                id="memo-contact-name"
                type="text"
                value={customContactName}
                onChange={(e) => setCustomContactName(e.target.value)}
                className="rounded-md border border-gray-300 px-2 py-1.5 text-sm"
              />
            </div>
          )}
        </div>

        <div className="mt-3 flex flex-col gap-1 text-sm">
          <label htmlFor="memo-body" className="text-xs text-gray-500">
            메모 내용
          </label>
          <textarea
            id="memo-body"
            rows={3}
            value={body}
            onChange={(e) => setBody(e.target.value)}
            className="rounded-md border border-gray-300 px-2 py-1.5 text-sm"
          />
        </div>

        {error && <p className="mt-2 text-xs text-red-600">{error}</p>}

        <div className="mt-3 flex justify-end">
          <button
            type="button"
            disabled={!canSubmit}
            onClick={() => void handleSubmit()}
            className="rounded-md bg-blue-600 px-4 py-1.5 text-sm font-semibold text-white hover:bg-blue-700 disabled:cursor-not-allowed disabled:bg-gray-300"
          >
            등록
          </button>
        </div>
      </section>

      <div className="mt-4">
        {loading ? (
          <p className="py-6 text-center text-sm text-gray-400">불러오는 중…</p>
        ) : memos.length === 0 ? (
          <p className="py-6 text-center text-sm text-gray-300">
            등록된 메모가 없습니다. 통화 후 첫 메모를 남겨보세요.
          </p>
        ) : (
          <ul className="space-y-3">
            {memos.map((memo) => (
              <li key={memo.id} className="rounded-lg border border-gray-200 p-3">
                <div className="flex items-center justify-between gap-2">
                  <div className="flex items-baseline gap-2">
                    <span className="text-xs text-gray-400">{formatDateTime(memo.createdAt)}</span>
                    <span className="text-xs text-gray-300">·</span>
                    <span className="text-sm font-medium text-gray-900">{memo.contactName}</span>
                  </div>
                  <button
                    type="button"
                    onClick={() => void handleDelete(memo)}
                    className="rounded-md border border-gray-200 px-2 py-0.5 text-xs text-gray-500 hover:bg-gray-50"
                  >
                    삭제
                  </button>
                </div>
                <p className="mt-1.5 whitespace-pre-wrap text-sm text-gray-800">{memo.body}</p>
              </li>
            ))}
          </ul>
        )}
      </div>
    </div>
  )
}