import React, { useState, useEffect, useRef } from 'react'
import axios from 'axios'

function formatRelative(isoString) {
  const diff = Date.now() - new Date(isoString).getTime()
  const s = Math.floor(diff / 1000)
  if (s < 60)  return 'just now'
  const m = Math.floor(s / 60)
  if (m < 60)  return `${m}m ago`
  const h = Math.floor(m / 60)
  if (h < 24)  return `${h}h ago`
  const d = Math.floor(h / 24)
  return `${d}d ago`
}

export default function PostComments({ postId, isLoggedIn, isOwn = false, initialCount = 0 }) {
  const [comments,    setComments]    = useState([])
  const [loading,     setLoading]     = useState(false)
  const [submitting,  setSubmitting]  = useState(false)
  const [body,        setBody]        = useState('')
  const [error,       setError]       = useState(null)
  const [page,        setPage]        = useState(1)
  const [hasMore,     setHasMore]     = useState(false)
  const [loaded,      setLoaded]      = useState(false)
  const textareaRef = useRef(null)

  const fetchComments = async (p = 1) => {
    setLoading(true)
    try {
      const { data } = await axios.get(`/api/posts/${postId}/comments`, { params: { page: p } })
      setComments((prev) => p === 1 ? data.data : [...prev, ...data.data])
      setHasMore(data.meta.current_page < data.meta.last_page)
      setPage(p)
    } catch {
      //
    } finally {
      setLoading(false)
      setLoaded(true)
    }
  }

  useEffect(() => {
    fetchComments(1)
  }, [postId])

  const handleSubmit = async (e) => {
    e.preventDefault()
    if (!body.trim()) return
    setSubmitting(true)
    setError(null)
    try {
      const { data } = await axios.post(`/api/posts/${postId}/comments`, { body })
      setComments((prev) => [...prev, data.comment])
      setBody('')
    } catch (err) {
      setError(err.response?.data?.message ?? 'Failed to post comment.')
    } finally {
      setSubmitting(false)
    }
  }

  const handleDelete = async (commentId) => {
    if (!window.confirm('Delete this comment?')) return
    try {
      await axios.delete(`/api/posts/${postId}/comments/${commentId}`)
      setComments((prev) => prev.filter((c) => c.id !== commentId))
    } catch {
      //
    }
  }

  const handleHighlight = async (comment) => {
    try {
      if (comment.is_highlighted) {
        await axios.delete(`/api/posts/${postId}/comments/${comment.id}/highlight`)
        setComments((prev) =>
          prev.map((c) => c.id === comment.id ? { ...c, is_highlighted: false } : c),
        )
      } else {
        await axios.post(`/api/posts/${postId}/comments/${comment.id}/highlight`)
        // Only one can be highlighted — clear others and set this one
        setComments((prev) =>
          prev.map((c) => ({ ...c, is_highlighted: c.id === comment.id })),
        )
      }
    } catch {
      //
    }
  }

  // Highlighted comment always first (server also orders this way, but keep client in sync)
  const sorted = [...comments].sort((a, b) =>
    (b.is_highlighted ? 1 : 0) - (a.is_highlighted ? 1 : 0),
  )

  return (
    <div className="space-y-3">
      {/* Comment list */}
      {!loaded && loading && (
        <div className="space-y-2">
          {[1, 2].map((i) => (
            <div key={i} className="flex gap-2 animate-pulse">
              <div className="w-7 h-7 rounded-full bg-white/10 shrink-0" />
              <div className="flex-1 space-y-1">
                <div className="h-2.5 bg-white/10 rounded w-24" />
                <div className="h-2 bg-white/6 rounded w-3/4" />
              </div>
            </div>
          ))}
        </div>
      )}

      {loaded && sorted.map((c) => (
        <div
          key={c.id}
          className={`flex gap-2 group ${c.is_highlighted ? 'rounded-xl bg-sky-500/5 border border-sky-500/15 px-3 py-2 -mx-3' : ''}`}
        >
          {/* Avatar */}
          <a href={`/@${c.author.username}`} className="shrink-0">
            <img
              src={c.author.avatar ?? '/images/avatar_default.webp'}
              alt={c.author.name}
              className="w-7 h-7 rounded-full object-cover ring-1 ring-white/10"
              loading="lazy"
            />
          </a>
          {/* Body */}
          <div className="flex-1 min-w-0">
            <div className="flex items-baseline gap-2 flex-wrap">
              <a
                href={`/@${c.author.username}`}
                className="text-xs font-semibold text-white/80 hover:text-sky-400 transition-colors"
              >
                {c.author.name || `@${c.author.username}`}
              </a>
              <span className="text-[10px] text-slate-600">{formatRelative(c.created_at)}</span>
              {c.is_highlighted && (
                <span className="text-[10px] text-sky-400 font-medium flex items-center gap-1">
                  <i className="fa-solid fa-star fa-xs" />
                  Highlighted by author
                </span>
              )}
            </div>
            <div
              className="text-sm text-slate-300 mt-0.5 [&_a]:text-sky-400 [&_a]:hover:underline"
              dangerouslySetInnerHTML={{ __html: c.body }}
            />
          </div>
          {/* Actions: highlight (owner) + delete */}
          <div className="flex items-start gap-1 opacity-0 group-hover:opacity-100 transition-all ml-1">
            {isOwn && (
              <button
                onClick={() => handleHighlight(c)}
                title={c.is_highlighted ? 'Remove highlight' : 'Highlight comment'}
                className={`text-xs transition-colors px-1 py-0.5 rounded ${
                  c.is_highlighted
                    ? 'text-sky-400 hover:text-slate-400'
                    : 'text-slate-600 hover:text-sky-400'
                }`}
              >
                <i className={`${c.is_highlighted ? 'fa-solid' : 'fa-regular'} fa-star`} />
              </button>
            )}
            {isLoggedIn && (
              <button
                onClick={() => handleDelete(c.id)}
                className="text-slate-600 hover:text-rose-400 transition-all text-xs"
                title="Delete comment"
              >
                <i className="fa-solid fa-trash-can" />
              </button>
            )}
          </div>
        </div>
      ))}

      {loaded && hasMore && (
        <button
          onClick={() => fetchComments(page + 1)}
          disabled={loading}
          className="text-xs text-sky-400 hover:text-sky-300 transition-colors"
        >
          {loading ? 'Loading…' : 'Load more comments'}
        </button>
      )}

      {/* Composer */}
      {isLoggedIn ? (
        <form onSubmit={handleSubmit} className="flex gap-2 mt-2">
          <textarea
            ref={textareaRef}
            value={body}
            onChange={(e) => setBody(e.target.value)}
            placeholder="Write a comment…"
            maxLength={1000}
            rows={1}
            className="flex-1 bg-white/5 border border-white/10 rounded-xl px-3 py-2 text-sm text-white resize-none placeholder-slate-600 focus:outline-none focus:border-sky-500/50 transition-colors"
            onKeyDown={(e) => {
              if (e.key === 'Enter' && !e.shiftKey) {
                e.preventDefault()
                handleSubmit(e)
              }
            }}
          />
          <button
            type="submit"
            disabled={submitting || !body.trim()}
            className="px-3 py-2 rounded-xl bg-sky-600 hover:bg-sky-500 disabled:opacity-40 disabled:cursor-not-allowed text-white text-sm transition-colors"
          >
            {submitting ? <i className="fa-solid fa-spinner fa-spin" /> : <i className="fa-solid fa-paper-plane" />}
          </button>
        </form>
      ) : (
        <p className="text-xs text-slate-500 mt-2">
          <a href="/login" className="text-sky-400 hover:underline">Sign in</a> to comment.
        </p>
      )}

      {error && <p className="text-xs text-rose-400">{error}</p>}
    </div>
  )
}