"use client";

import { useEffect, useId, useRef } from "react";
import type { FormEvent, RefObject } from "react";
import { Send, Square } from "lucide-react";

import { Button } from "@/components/ui/button";
import type { AIMode } from "./workspace-mode";
import { submitComposer } from "./composer-events";

export function shouldSubmitOnEnter(event: {
  key: string;
  shiftKey: boolean;
  isComposing: boolean;
}): boolean {
  return event.key === "Enter" && !event.shiftKey && !event.isComposing;
}

interface WorkspaceComposerProps {
  mode: AIMode;
  input: string;
  onInputChange: (value: string) => void;
  onSubmit: (event: FormEvent<HTMLFormElement>) => void;
  busy?: boolean;
  onStop?: () => void;
  inputRef?: RefObject<HTMLTextAreaElement | null>;
  active?: boolean;
}

export function WorkspaceComposer({
  mode,
  input,
  onInputChange,
  onSubmit,
  busy = false,
  onStop,
  inputRef,
  active = true,
}: WorkspaceComposerProps) {
  const localRef = useRef<HTMLTextAreaElement>(null);
  const ref = inputRef ?? localRef;
  const hintId = useId();
  const isChat = mode === "chat";

  useEffect(() => {
    if (!active || !ref.current) return;
    ref.current.style.height = "auto";
    ref.current.style.height = `${Math.min(ref.current.scrollHeight, 200)}px`;
  }, [input, active, ref]);

  return (
    <div className="shrink-0 border-t bg-background px-4 py-4">
      <form
        aria-label={isChat ? "Chat composer" : "Agent builder composer"}
        onSubmit={(event) => {
          submitComposer(event, input, busy, onSubmit, () =>
            ref.current?.focus(),
          );
        }}
        className="mx-auto flex max-w-3xl items-end gap-3"
      >
        <textarea
          ref={ref}
          data-composer-mode={mode}
          value={input}
          onChange={(event) => onInputChange(event.target.value)}
          onKeyDown={(event) => {
            if (
              shouldSubmitOnEnter({
                key: event.key,
                shiftKey: event.shiftKey,
                isComposing: event.nativeEvent.isComposing,
              })
            ) {
              event.preventDefault();
              event.currentTarget.form?.requestSubmit();
            }
          }}
          placeholder={isChat ? "Ask anything…" : "Describe a reusable agent…"}
          aria-label={isChat ? "Chat message" : "Agent instructions"}
          aria-describedby={hintId}
          rows={1}
          readOnly={busy}
          className="max-h-[200px] min-h-[44px] flex-1 resize-none rounded-xl border bg-muted/30 px-4 py-3 text-sm outline-none placeholder:text-muted-foreground focus:ring-2 focus:ring-ring read-only:opacity-60"
        />
        {busy && onStop ? (
          <Button
            type="button"
            size="icon"
            variant="outline"
            className="h-11 w-11 shrink-0 rounded-xl"
            aria-label="Stop generating"
            onClick={() => {
              onStop();
              ref.current?.focus();
            }}
          >
            <Square className="size-4" aria-hidden="true" />
          </Button>
        ) : (
          <Button
            type="submit"
            size="icon"
            className="h-11 w-11 shrink-0 rounded-xl"
            disabled={busy || !input.trim()}
            aria-label={isChat ? "Send message" : "Check builder availability"}
          >
            <Send className="size-4" aria-hidden="true" />
          </Button>
        )}
      </form>
      <p
        id={hintId}
        className="mx-auto mt-2 max-w-3xl text-center text-[10px] text-muted-foreground"
      >
        {isChat ? "AI can make mistakes. " : "Builder is not connected yet. "}
        Enter to send · Shift+Enter for a new line.
      </p>
    </div>
  );
}