import { useEffect, useRef, useState } from "preact/hooks";
import {
  encryptDataWithStoredPassword,
  getEncryptionPassword,
} from "../../helpers.ts";

interface AddObligationDialogProps {
  onClose: () => void;
  userId?: string;
}

type FieldErrorState = {
  description: boolean;
  amount: boolean;
};

export default function AddObligationDialog(
  { onClose, userId }: AddObligationDialogProps,
) {
  // Theme classes are defined in styles.css with @media (prefers-color-scheme: dark)
  const formRef = useRef<HTMLFormElement>(null);
  const firstInputRef = useRef<HTMLInputElement>(null);
  const [loading, setLoading] = useState(false);
  const [fieldErrors, setFieldErrors] = useState<FieldErrorState>({
    description: false,
    amount: false,
  });
  const today = new Date().toISOString().split("T")[0];

  const addNewObligation = async () => {
    if (!formRef.current) return;

    // Collect form data
    const formData = new FormData(formRef.current);
    const description = formData.get("description")?.toString().trim() || "";
    const amount = formData.get("amount")?.toString().trim() || "";
    const frequency = formData.get("frequency")?.toString() || "Monthly";
    const dueDate = formData.get("due_date")?.toString() || today;
    const sender = typeof location !== "undefined" ? location.pathname : "/";

    const validation = {
      description: !description,
      amount: !amount,
    };
    setFieldErrors(validation);

    if (validation.description || validation.amount) {
      return;
    }

    setLoading(true);
    localStorage.setItem(
      "lock-route",
      "/calendar/budget-obligations?modal=off",
    );

    // Build submission data
    const submitData = new FormData();
    submitData.set("sender", sender);
    submitData.set("frequency", frequency);
    submitData.set("due_date", dueDate);

    // Encrypt if password is available
    const encryptionPassword = userId ? getEncryptionPassword(userId) : null;

    if (encryptionPassword && (description || amount)) {
      try {
        const dataToEncrypt = {
          description,
          amount: parseFloat(amount) || 0,
        };

        const encryptedData = await encryptDataWithStoredPassword(
          userId!,
          JSON.stringify(dataToEncrypt),
        );

        if (encryptedData) {
          submitData.set("encrypted_data", encryptedData);
          // Send empty plaintext when encrypted
          submitData.set("description", "");
          submitData.set("amount", "0");
        } else {
          throw new Error("Encryption returned empty result");
        }
      } catch (_err) {
        setLoading(false);
        return;
      }
    } else {
      submitData.set("description", description);
      submitData.set("amount", amount);
      submitData.set("encrypted_data", "");
    }

    // Submit via fetch - let redirects follow automatically
    try {
      const response = await fetch("/api/create/obligation", {
        method: "POST",
        body: submitData,
        credentials: "same-origin",
      });

      // Fetch followed the redirect, now navigate to final URL or sender
      if (response.ok) {
        globalThis.location.href = "/calendar/budget-obligations?modal=off";
      } else {
        const errorData = await response.json().catch(() => ({}));
        throw new Error(errorData.error || "Failed to create obligation");
      }
    } catch (_err) {
      setLoading(false);
    }
  };

  const clearFieldError = (field: keyof FieldErrorState) => {
    setFieldErrors((prev) => prev[field] ? { ...prev, [field]: false } : prev);
  };

  const getInputErrorClass = (hasError: boolean) =>
    hasError ? "border-red-500 ring-1 ring-red-300" : "";

  useEffect(() => {
    firstInputRef.current?.focus();
  }, []);

  return (
    <div
      class="theme-dialog-overlay"
      style={{ paddingTop: "calc(50vh - 400px)" }}
    >
      <div class="theme-dialog-container flex flex-col gap-2">
        <form ref={formRef}>
          <h2 class="theme-dialog-title">Add Obligation</h2>
          <div class="flex flex-col gap-1 my-4">
            <input
              ref={firstInputRef}
              class={`theme-dialog-input ${
                getInputErrorClass(fieldErrors.description)
              }`}
              name="description"
              placeholder="Description"
              required
              onInput={() => clearFieldError("description")}
            />
            <div
              class={`text-red-500 text-xs min-h-4 ${
                fieldErrors.description ? "visible" : "invisible"
              }`}
              aria-live="polite"
            >
              Description is required.
            </div>
          </div>
          <div class="flex flex-col gap-1 my-4">
            <input
              class={`theme-dialog-input ${
                getInputErrorClass(fieldErrors.amount)
              }`}
              name="amount"
              placeholder="Amount"
              type="number"
              step="0.01"
              required
              onInput={() => clearFieldError("amount")}
            />
            <div
              class={`text-red-500 text-xs min-h-4 ${
                fieldErrors.amount ? "visible" : "invisible"
              }`}
              aria-live="polite"
            >
              Amount is required.
            </div>
          </div>
          <div class="flex flex-col gap-1 my-4">
            <select
              class="theme-dialog-select"
              name="frequency"
              defaultValue="Monthly"
            >
              <option value="One-time">One-time</option>
              <option value="Biweekly">Biweekly</option>
              <option value="Weekly">Weekly</option>
              <option value="Monthly">Monthly</option>
              <option value="Quarterly">Quarterly</option>
              <option value="Yearly">Yearly</option>
            </select>
          </div>
          <div class="flex flex-col gap-1 my-4">
            <input
              class="theme-dialog-input"
              name="due_date"
              type="date"
              defaultValue={today}
              required
            />
          </div>
        </form>

        <div class="flex justify-end gap-2 mt-2">
          <button
            type="button"
            class={`theme-dialog-cancel-button w-40 ${
              loading ? "opacity-70" : ""
            }`}
            onClick={() => {
              localStorage.setItem(
                "lock-route",
                "/calendar/budget-obligations?modal=off",
              );
              setLoading(true);
              onClose();
            }}
            disabled={loading}
          >
            Cancel
          </button>
          <button
            type="button"
            class={`theme-dialog-submit-button w-40 ${
              loading ? "opacity-70" : ""
            }`}
            disabled={loading}
            onClick={addNewObligation}
          >
            {loading ? "Adding..." : "Add"}
          </button>
        </div>
      </div>
    </div>
  );
}