import { useEffect, useLayoutEffect, useRef, useState } from "react";
import { createPortal } from "react-dom";
import {
  Sparkles,
  Wand2,
  Expand,
  Shrink,
  Mic2,
  BookCopy,
  AlertCircle,
  RefreshCw,
  ChevronRight,
  X,
  Square,
  Send,
} from "lucide-react";
import { cn } from "@/lib/utils";
import type { RewriteAction, RewriteTone } from "../../api/rewrite";
import type { RewriteStatus } from "../../hooks/useWritingRewrite";

// ── Types ─────────────────────────────────────────────────────────────────────

interface MenuPos {
  x: number;
  y: number;
}

// ── Tone options ───────────────────────────────────────────────────────────────

const TONE_OPTIONS: { value: RewriteTone; label: string }[] = [
  { value: "professional", label: "更专业" },
  { value: "casual",       label: "更口语化" },
  { value: "readable",     label: "更易读" },
  { value: "academic",     label: "更学术" },
  { value: "expressive",   label: "更有文采" },
];

// ── Action rows ────────────────────────────────────────────────────────────────

const ACTION_ROWS: {
  action: RewriteAction;
  label: string;
  icon: React.ElementType;
}[] = [
  { action: "polish",  label: "润色",  icon: Wand2 },
  { action: "expand",  label: "扩写",  icon: Expand },
  { action: "shorten", label: "缩写",  icon: Shrink },
  { action: "tone",    label: "改语气", icon: Mic2 },
  { action: "imitate", label: "仿写",  icon: BookCopy },
];

// ── Main component ─────────────────────────────────────────────────────────────

interface WritingAiMenuProps {
  pos: MenuPos;
  status: RewriteStatus;
  error: string | null;
  onAction: (action: RewriteAction, tone?: RewriteTone, customInstruction?: string, referenceText?: string) => void;
  onAbort: () => void;
  onRetry: () => void;
  onClose: () => void;
}

export function WritingAiMenu({
  pos,
  status,
  error,
  onAction,
  onAbort,
  onRetry,
  onClose,
}: WritingAiMenuProps) {
  const [toneOpen, setToneOpen] = useState(false);
  const [imitateDialogOpen, setImitateDialogOpen] = useState(false);
  const [referenceText, setReferenceText] = useState("");
  const [instruction, setInstruction] = useState("");
  const inputRef = useRef<HTMLInputElement>(null);
  const imitateTextareaRef = useRef<HTMLTextAreaElement>(null);

  // autoFocus is unreliable when the menu opens during a mousedown event sequence;
  // explicit focus via setTimeout(0) runs after the browser finishes that sequence.
  useEffect(() => {
    const id = setTimeout(() => inputRef.current?.focus(), 0);
    return () => clearTimeout(id);
  }, []);

  // Focus the dialog textarea when the imitate dialog opens.
  useEffect(() => {
    if (!imitateDialogOpen) return;
    const id = setTimeout(() => imitateTextareaRef.current?.focus(), 0);
    return () => clearTimeout(id);
  }, [imitateDialogOpen]);

  const isLoading = status === "loading";
  const isError   = status === "error";

  // Measure actual height after render and compute safe position before browser paint
  const menuWidth = 240;
  const containerRef = useRef<HTMLDivElement>(null);
  const [computedPos, setComputedPos] = useState<{ left: number; top: number } | null>(null);

  useLayoutEffect(() => {
    const el = containerRef.current;
    if (!el) return;
    const h = el.getBoundingClientRect().height;
    const safeX = Math.min(Math.max(pos.x, 8), window.innerWidth - menuWidth - 8);
    const spaceBelow = window.innerHeight - pos.y - 8;
    const spaceAbove = pos.y - 8;
    let safeY: number;
    if (spaceBelow >= h) {
      safeY = pos.y + 4;
    } else if (spaceAbove >= h) {
      safeY = pos.y - h - 4;
    } else if (spaceBelow >= spaceAbove) {
      safeY = Math.max(8, window.innerHeight - h - 8);
    } else {
      safeY = 8;
    }
    setComputedPos({ left: safeX, top: safeY });
  }, [pos.x, pos.y]);

  const fireAction = (action: RewriteAction, tone?: RewriteTone) => {
    onAction(action, tone, instruction.trim() || undefined);
  };

  const fireImitate = () => {
    const ref = referenceText.trim();
    if (!ref) return;
    setImitateDialogOpen(false);
    onAction("imitate", undefined, instruction.trim() || undefined, ref);
  };

  const handleInputEnter = () => {
    const trimmed = instruction.trim();
    onAction("polish", undefined, trimmed || undefined);
  };

  return createPortal(
    <>
      {/* Backdrop */}
      <div className="fixed inset-0 z-[9990]" onMouseDown={onClose} />

      <div
        ref={containerRef}
        style={{
          position: "fixed",
          left: computedPos?.left ?? pos.x,
          top: computedPos?.top ?? (pos.y + 4),
          width: menuWidth,
          zIndex: 9999,
          visibility: computedPos ? "visible" : "hidden",
        }}
        className="rounded-xl border bg-popover shadow-lg animate-in fade-in zoom-in-95 duration-100 overflow-hidden"
      >
        {/* Header */}
        <div className="flex items-center justify-between px-3 py-2 border-b bg-muted/30">
          <span className="flex items-center gap-1.5 text-xs font-semibold text-foreground">
            <Sparkles className="h-3.5 w-3.5 text-amber-500" />
            AI 改写
          </span>
          <button
            type="button"
            onClick={onClose}
            className="rounded p-0.5 hover:bg-accent text-muted-foreground hover:text-foreground transition-colors"
          >
            <X className="h-3.5 w-3.5" />
          </button>
        </div>

        {/* ── Loading state ──────────────────────────────────────── */}
        {isLoading && (
          <div className="flex flex-col items-center gap-4 px-4 py-6">
            {/* Bouncing dots */}
            <div className="flex items-center gap-2">
              {[0, 160, 320].map((delay) => (
                <span
                  key={delay}
                  className="h-1.5 w-1.5 rounded-full bg-primary animate-bouncing"
                  style={{ animationDelay: `${delay}ms` }}
                />
              ))}
              <span className="ml-1 text-xs text-muted-foreground">AI 正在生成…</span>
            </div>

            {/* Stop button — breathing animation */}
            <button
              type="button"
              onClick={onAbort}
              className={cn(
                "animate-breathe-stop",
                "flex items-center gap-1.5 px-5 py-2 text-xs font-medium rounded-lg",
                "border border-red-300/70 bg-red-50/60 text-red-600",
                "dark:border-red-800/50 dark:bg-red-950/20 dark:text-red-400",
                "hover:bg-red-100/90 dark:hover:bg-red-950/40 transition-colors",
              )}
            >
              <Square className="h-3 w-3 fill-current" />
              停止生成
            </button>
          </div>
        )}

        {/* ── Error state ─────────────────────────────────────────── */}
        {isError && (
          <div className="px-3 py-3 space-y-2">
            <p className="flex items-center gap-1.5 text-xs text-destructive">
              <AlertCircle className="h-3.5 w-3.5 shrink-0" />
              {error ?? "改写失败"}
            </p>
            <button
              type="button"
              onClick={onRetry}
              className="flex items-center gap-1.5 text-xs text-primary hover:underline"
            >
              <RefreshCw className="h-3 w-3" />
              重试
            </button>
          </div>
        )}

        {/* ── Idle state: input + action list ─────────────────────── */}
        {!isLoading && !isError && (
          <>
            {/* Custom instruction input */}
            <div className="px-2.5 pt-2.5 pb-2">
              <input
                ref={inputRef}
                type="text"
                value={instruction}
                onChange={(e) => setInstruction(e.target.value)}
                onKeyDown={(e) => {
                  if (e.key === "Enter" && !e.shiftKey) {
                    e.preventDefault();
                    handleInputEnter();
                  }
                }}
                placeholder="告诉 AI 你想要什么…"
                className={cn(
                  "w-full text-xs rounded-md px-2.5 py-1.5 outline-none transition-colors",
                  "bg-muted/50 border border-input focus:border-primary/60",
                  "placeholder:text-muted-foreground/50",
                )}
              />
            </div>

            {/* Divider */}
            <div className="border-t border-border/50 mx-1" />

            {/* Preset actions */}
            <div className="p-1 space-y-0.5">
              {ACTION_ROWS.map(({ action, label, icon: Icon }) => {
                const isTone = action === "tone";
                const isImitate = action === "imitate";
                const hasSub = isTone;
                const isExpanded = isTone && toneOpen;
                return (
                  <div key={action}>
                    <button
                      type="button"
                      onClick={() => {
                        if (isTone) {
                          setToneOpen((v) => !v);
                        } else if (isImitate) {
                          setToneOpen(false);
                          setImitateDialogOpen(true);
                        } else {
                          fireAction(action);
                        }
                      }}
                      className={cn(
                        "flex w-full items-center gap-2 px-2.5 py-1.5 text-xs rounded-md transition-colors text-left",
                        "hover:bg-accent hover:text-accent-foreground",
                        isExpanded && "bg-accent text-accent-foreground",
                      )}
                    >
                      <Icon className="h-3.5 w-3.5 shrink-0 text-muted-foreground" />
                      <span className="flex-1">{label}</span>
                      {hasSub && (
                        <ChevronRight
                          className={cn(
                            "h-3.5 w-3.5 text-muted-foreground transition-transform duration-200",
                            isExpanded && "rotate-90",
                          )}
                        />
                      )}
                    </button>

                    {/* Tone sub-list */}
                    {isTone && toneOpen && (
                      <div className="ml-5 border-l pl-2 my-0.5 space-y-0.5">
                        {TONE_OPTIONS.map(({ value, label: toneLabel }) => (
                          <button
                            key={value}
                            type="button"
                            onClick={() => fireAction("tone", value)}
                            className="flex w-full items-center px-2 py-1.5 text-xs rounded-md hover:bg-accent hover:text-accent-foreground transition-colors"
                          >
                            {toneLabel}
                          </button>
                        ))}
                      </div>
                    )}
                  </div>
                );
              })}
            </div>
          </>
        )}
      </div>

      {/* ── Imitate dialog：弹窗内多行输入范文，回车 / 发送即仿写 ───────────── */}
      {imitateDialogOpen && (
        <div className="fixed inset-0 z-[10000] flex items-center justify-center p-4">
          <div
            className="absolute inset-0 bg-black/40 animate-in fade-in duration-100"
            onMouseDown={() => setImitateDialogOpen(false)}
          />
          <div
            className="relative w-full max-w-md rounded-xl border bg-popover shadow-2xl animate-in fade-in zoom-in-95 duration-100 overflow-hidden"
            onMouseDown={(e) => e.stopPropagation()}
          >
            {/* Header */}
            <div className="flex items-center justify-between px-4 py-3 border-b bg-muted/30">
              <span className="flex items-center gap-1.5 text-sm font-semibold text-foreground">
                <BookCopy className="h-4 w-4 text-amber-500" />
                仿写
              </span>
              <button
                type="button"
                onClick={() => setImitateDialogOpen(false)}
                className="rounded p-0.5 hover:bg-accent text-muted-foreground hover:text-foreground transition-colors"
              >
                <X className="h-4 w-4" />
              </button>
            </div>

            {/* Body */}
            <div className="p-4 space-y-3">
              <textarea
                ref={imitateTextareaRef}
                value={referenceText}
                onChange={(e) => setReferenceText(e.target.value)}
                onKeyDown={(e) => {
                  // Enter 提交，Shift+Enter 换行
                  if (e.key === "Enter" && !e.shiftKey) {
                    e.preventDefault();
                    fireImitate();
                  } else if (e.key === "Escape") {
                    e.preventDefault();
                    setImitateDialogOpen(false);
                  }
                }}
                rows={8}
                placeholder="粘贴范文，AI 将模仿其文风、句式与语气改写所选文字…（回车提交，Shift+Enter 换行）"
                className={cn(
                  "w-full resize-none text-sm rounded-md px-3 py-2 outline-none transition-colors leading-relaxed",
                  "bg-muted/50 border border-input focus:border-primary/60",
                  "placeholder:text-muted-foreground/50",
                )}
              />
            </div>

            {/* Footer */}
            <div className="flex items-center justify-end gap-2 px-4 py-3 border-t bg-muted/20">
              <button
                type="button"
                onClick={() => setImitateDialogOpen(false)}
                className="px-3 py-1.5 text-xs font-medium rounded-md border border-input hover:bg-accent hover:text-accent-foreground transition-colors"
              >
                取消
              </button>
              <button
                type="button"
                onClick={fireImitate}
                disabled={!referenceText.trim()}
                className={cn(
                  "flex items-center justify-center gap-1.5 px-4 py-1.5 text-xs font-medium rounded-md transition-colors",
                  "bg-primary text-primary-foreground hover:bg-primary/90",
                  "disabled:opacity-40 disabled:cursor-not-allowed",
                )}
              >
                <Send className="h-3.5 w-3.5" />
                发送
              </button>
            </div>
          </div>
        </div>
      )}
    </>,
    document.body,
  );
}