import { useState, useRef, useEffect } from "react";
import type { MessageType } from "@/types/MessageType";
import { postMessage } from "@/api";
import { cn } from "@/lib/utils";

interface Props {
  channelId: string;
  replyTo: string | null;
  onClearReply: () => void;
  onMessageSent: () => void;
}

const TYPE_META: Record<MessageType, { prefix: string; color: string; key: string }> = {
  text: { prefix: ">", color: "text-muted-foreground", key: "1" },
  code: { prefix: "//", color: "text-[var(--color-msg-code)]", key: "2" },
  result: { prefix: "=>", color: "text-[var(--color-msg-result)]", key: "3" },
  error: { prefix: "!!", color: "text-[var(--color-msg-error)]", key: "4" },
  plan: { prefix: "::", color: "text-[var(--color-msg-plan)]", key: "5" },
};

export function ComposeBox({
  channelId,
  replyTo,
  onClearReply,
  onMessageSent,
}: Props) {
  const [content, setContent] = useState("");
  const [msgType, setMsgType] = useState<MessageType>("text");
  const [sending, setSending] = useState(false);
  const [focused, setFocused] = useState(false);
  const inputRef = useRef<HTMLTextAreaElement>(null);
  const meta = TYPE_META[msgType];

  // Auto-resize textarea
  useEffect(() => {
    if (inputRef.current) {
      inputRef.current.style.height = "0";
      inputRef.current.style.height = `${Math.min(inputRef.current.scrollHeight, 120)}px`;
    }
  }, [content]);

  // Auto-focus on mount
  useEffect(() => {
    inputRef.current?.focus();
  }, []);

  async function handleSend() {
    if (!content.trim() || sending) return;
    setSending(true);
    try {
      await postMessage(channelId, {
        content: content.trim(),
        type: msgType,
        reply_to: replyTo ?? undefined,
      });
      setContent("");
      setMsgType("text");
      onClearReply();
      onMessageSent();
    } finally {
      setSending(false);
    }
  }

  function cycleType(direction: 1 | -1) {
    const types: MessageType[] = ["text", "code", "result", "error", "plan"];
    const idx = types.indexOf(msgType);
    const next = (idx + direction + types.length) % types.length;
    setMsgType(types[next]);
  }

  return (
    <div className={cn(
      "border-t-2 transition-colors px-3 py-2 md:px-4 pb-[env(safe-area-inset-bottom,8px)]",
      focused ? "border-primary bg-card" : "border-border bg-background",
    )}>
      {/* Reply chip */}
      {replyTo && (
        <div className="flex items-center gap-1.5 mb-1.5 text-[10px] font-mono">
          <span className="text-primary">^</span>
          <span className="text-muted-foreground">#{replyTo.slice(0, 8)}</span>
          <button
            type="button"
            onClick={onClearReply}
            className="text-muted-foreground hover:text-primary ml-1"
          >
            x
          </button>
        </div>
      )}

      <div className="flex items-end gap-2">
        {/* Type prefix — click to cycle */}
        <button
          type="button"
          onClick={() => cycleType(1)}
          className={cn(
            "font-mono text-sm font-bold pb-1 min-w-[20px] transition-colors select-none",
            meta.color,
          )}
          title={`${msgType} (Tab to cycle, Ctrl+1-5 to select)`}
        >
          {meta.prefix}
        </button>

        {/* Auto-growing textarea — no send button */}
        <textarea
          ref={inputRef}
          value={content}
          onChange={(e) => setContent(e.target.value)}
          onFocus={() => setFocused(true)}
          onBlur={() => setFocused(false)}
          onKeyDown={(e) => {
            if (e.key === "Enter" && !e.shiftKey) {
              e.preventDefault();
              handleSend();
            }
            if (e.key === "Tab" && !e.shiftKey) {
              e.preventDefault();
              cycleType(1);
            }
            if (e.key === "Tab" && e.shiftKey) {
              e.preventDefault();
              cycleType(-1);
            }
            // Ctrl+1-5 for type
            if (e.ctrlKey && e.key >= "1" && e.key <= "5") {
              e.preventDefault();
              const types: MessageType[] = ["text", "code", "result", "error", "plan"];
              setMsgType(types[parseInt(e.key) - 1]);
            }
          }}
          placeholder="message"
          disabled={sending}
          rows={1}
          className={cn(
            "flex-1 bg-transparent text-sm font-mono text-foreground placeholder:text-muted-foreground/30 resize-none focus:outline-none leading-relaxed py-0.5",
            sending && "opacity-30",
          )}
        />

        {/* Subtle type indicator — shows current type name */}
        <span className={cn(
          "text-[9px] font-mono uppercase tracking-widest pb-1 transition-opacity",
          meta.color,
          content ? "opacity-60" : "opacity-30",
        )}>
          {msgType}
        </span>
      </div>
    </div>
  );
}