"use client";

import { useState } from "react";
import { useMutation } from "@tanstack/react-query";
import { useRouter } from "next/navigation";
import { DISPLAY_NAME_MAX_LENGTH } from "@/lib/constants";
import { getSupabaseBrowserClient } from "@/lib/supabase/client";
import { AvatarColorPicker } from "./avatar-color-picker";

function validateDisplayName(name: string): string | null {
  const trimmed = name.trim();
  if (trimmed.length === 0) return "Display name is required";
  if (trimmed.length > DISPLAY_NAME_MAX_LENGTH)
    return `Display name must be ${DISPLAY_NAME_MAX_LENGTH} characters or less`;
  if (/<|>/.test(trimmed)) return "Display name cannot contain < or >";
  return null;
}

export function DisplayNameForm() {
  const router = useRouter();
  const [displayName, setDisplayName] = useState("");
  const [avatarColor, setAvatarColor] = useState<string | null>(null);
  const [validationError, setValidationError] = useState<string | null>(null);

  const signUpMutation = useMutation({
    mutationFn: async ({ name, color }: { name: string; color: string | null }) => {
      const supabase = getSupabaseBrowserClient();

      const { data: authData, error: authError } = await supabase.auth.signInAnonymously();
      if (authError) throw authError;
      if (!authData.user) throw new Error("Sign-in failed: no user returned");

      const { error: insertError } = await supabase.from("users").insert({
        id: authData.user.id,
        display_name: name,
        avatar_color: color,
      });
      if (insertError) throw insertError;

      return { userId: authData.user.id };
    },
    onSuccess: () => {
      router.push("/recovery");
    },
  });

  function handleSubmit(e: React.FormEvent) {
    e.preventDefault();
    const trimmed = displayName.trim();
    const error = validateDisplayName(trimmed);
    if (error) {
      setValidationError(error);
      return;
    }
    setValidationError(null);
    signUpMutation.mutate({ name: trimmed, color: avatarColor });
  }

  return (
    <form onSubmit={handleSubmit} className="space-y-6">
      <div>
        <label htmlFor="display-name" className="block text-sm font-medium mb-1">
          Display name
        </label>
        <input
          id="display-name"
          type="text"
          value={displayName}
          onChange={(e) => {
            setDisplayName(e.target.value);
            setValidationError(null);
          }}
          maxLength={DISPLAY_NAME_MAX_LENGTH}
          placeholder="What should we call you?"
          className="w-full rounded-lg border border-foreground/20 bg-background px-3 py-2 text-foreground placeholder:text-foreground/40 focus:outline-none focus:ring-2 focus:ring-blue-500"
          autoFocus
          autoComplete="off"
        />
        {validationError && <p className="mt-1 text-sm text-red-500">{validationError}</p>}
      </div>

      <AvatarColorPicker value={avatarColor} onChange={setAvatarColor} />

      {signUpMutation.error && (
        <p className="text-sm text-red-500" role="alert">
          {signUpMutation.error instanceof Error
            ? signUpMutation.error.message
            : "Something went wrong. Please try again."}
        </p>
      )}

      <button
        type="submit"
        disabled={signUpMutation.isPending}
        className="w-full rounded-lg bg-blue-600 px-4 py-2 font-medium text-white transition-colors hover:bg-blue-700 disabled:opacity-50"
      >
        {signUpMutation.isPending ? "Setting up..." : "Get started"}
      </button>
    </form>
  );
}