"use client"

/* eslint-disable @next/next/no-img-element -- favicon 来源由数据动态决定，静态 Image 配置无法预枚举域名。 */
import { useEffect, useRef, useState } from "react"

import {
  getIconCandidates,
  type IconCandidate,
} from "@/components/shared/icon-candidates"
import { SIMPLE_ICON_MAP } from "@/components/shared/simple-icon-map"
import { cn } from "@/lib/utils"
import type { NavLink } from "@/types/navigation"

type SiteIconProps = {
  link: Pick<NavLink, "title" | "url" | "icon">
  size?: number
  className?: string
}

type SiteIconContentProps = SiteIconProps & {
  candidates: IconCandidate[]
}

function SiteIconContent({
  link,
  candidates,
  size = 36,
  className,
}: SiteIconContentProps) {
  const [candidateIndex, setCandidateIndex] = useState(0)
  const [loadedImageSrc, setLoadedImageSrc] = useState<string | null>(null)
  const imageRef = useRef<HTMLImageElement | null>(null)
  const candidate = candidates[candidateIndex]
  const initialCandidate = candidates.at(-1)
  const initialValue =
    initialCandidate?.kind === "initial" ? initialCandidate.value : "?"
  const wrapperClassName = cn("site-icon", className)
  const style = { width: size, height: size }

  // 缓存命中的图片可能在 React 附加 onLoad/onError（如水合）之前就完成或失败，
  // 之后不再派发任何事件；挂载后按 complete/naturalWidth 补偿判定，
  // 避免透明图片永久停留在首字母占位，也避免坏图卡住候选链。
  // 候选推进有末位钳制，末位为首字母分支，不会形成无限循环。
  useEffect(() => {
    if (candidate.kind !== "image") return
    const image = imageRef.current
    if (!image?.complete) return
    if (image.naturalWidth > 0) {
      setLoadedImageSrc(candidate.src)
    } else {
      setCandidateIndex((index) => Math.min(index + 1, candidates.length - 1))
    }
  }, [candidate, candidates.length])

  if (candidate.kind === "simple") {
    const icon = SIMPLE_ICON_MAP[candidate.slug]
    return (
      <span className={wrapperClassName} style={style} aria-hidden="true">
        <svg
          viewBox="0 0 24 24"
          role="presentation"
          width={size}
          height={size}
          style={{ color: `#${icon.hex}` }}
        >
          <path d={icon.path} fill="currentColor" />
        </svg>
      </span>
    )
  }

  if (candidate.kind === "image") {
    const imageLoaded = loadedImageSrc === candidate.src

    return (
      <span
        className={cn(wrapperClassName, !imageLoaded && "site-icon--initial")}
        style={style}
        data-initial={!imageLoaded ? initialValue : undefined}
        aria-hidden="true"
      >
        <img
          className={cn(
            "site-icon__image",
            !imageLoaded && "site-icon__image--loading",
          )}
          src={candidate.src}
          alt={`${link.title} 图标`}
          width={size}
          height={size}
          ref={imageRef}
          onLoad={() => setLoadedImageSrc(candidate.src)}
          onError={() =>
            setCandidateIndex((index) =>
              Math.min(index + 1, candidates.length - 1),
            )
          }
        />
      </span>
    )
  }

  return (
    <span
      className={cn(wrapperClassName, "site-icon--initial")}
      style={style}
      aria-hidden="true"
    >
      {candidate.value}
    </span>
  )
}

export function SiteIcon({ link, size = 36, className }: SiteIconProps) {
  const candidates = getIconCandidates(link)
  const candidateKey = JSON.stringify([link.icon ?? "", link.title, link.url])

  // 链接变化时通过 key 重建候选状态，避免 effect 中同步 setState 和旧链接的失败记录泄漏。
  return (
    <SiteIconContent
      key={candidateKey}
      link={link}
      candidates={candidates}
      size={size}
      className={className}
    />
  )
}