import { useState } from "react";
import { useNavigate } from "react-router-dom";
import { createSSHKey, deleteSSHKey, listSSHKeys, signPayload, verifySignature, type SSHKey } from "../api/ssh_keys";
import { EmptyState, ErrorState, LoadingState } from "../components/data-states";
import { Icon } from "../components/icon";
import { useAsyncData } from "../hooks/use-async-data";

export const SSHKeysPage = () => {
  const navigate = useNavigate();
  const { data: keys, status, error, reload: loadKeys } = useAsyncData<SSHKey[]>(listSSHKeys, []);
  const [newKeyName, setNewKeyName] = useState("");
  const [generating, setGenerating] = useState(false);
  const [signPayloads, setSignPayloads] = useState<Record<string, string>>({});
  const [signatures, setSignatures] = useState<Record<string, string>>({});
  const [signing, setSigning] = useState<Record<string, boolean>>({});
  const [verifyPayloads, setVerifyPayloads] = useState<Record<string, string>>({});
  const [verifySignatures, setVerifySignatures] = useState<Record<string, string>>({});
  const [verifyResults, setVerifyResults] = useState<Record<string, boolean | null>>({});
  const [verifying, setVerifying] = useState<Record<string, boolean>>({});
  const [mutationError, setMutationError] = useState<string | null>(null);

  const safeKeys = keys ?? [];

  async function handleGenerate(e: React.FormEvent) {
    e.preventDefault();
    if (!newKeyName.trim()) return;

    try {
      setGenerating(true);
      await createSSHKey({ name: newKeyName.trim() });
      setNewKeyName("");
      await loadKeys();
    } catch {
      setMutationError("Failed to generate SSH key");
    } finally {
      setGenerating(false);
    }
  }

  async function handleDelete(keyId: string) {
    if (!confirm("Are you sure you want to delete this SSH key?")) return;

    try {
      await deleteSSHKey(keyId);
      await loadKeys();
    } catch {
      setMutationError("Failed to delete SSH key");
    }
  }

  function copyToClipboard(text: string) {
    navigator.clipboard.writeText(text);
  }

  async function handleSign(keyId: string) {
    const payload = signPayloads[keyId];
    if (!payload?.trim()) return;

    try {
      setSigning((prev) => ({ ...prev, [keyId]: true }));
      const result = await signPayload(keyId, { payload: payload.trim() });
      setSignatures((prev) => ({ ...prev, [keyId]: result.signature }));
      setMutationError(null);
    } catch {
      setMutationError("Failed to sign payload");
    } finally {
      setSigning((prev) => ({ ...prev, [keyId]: false }));
    }
  }

  async function handleVerify(keyId: string) {
    const payload = verifyPayloads[keyId];
    const signature = verifySignatures[keyId];
    if (!payload?.trim() || !signature?.trim()) return;

    try {
      setVerifying((prev) => ({ ...prev, [keyId]: true }));
      const result = await verifySignature(keyId, {
        payload: payload.trim(),
        signature: signature.trim(),
      });
      setVerifyResults((prev) => ({ ...prev, [keyId]: result.valid }));
      setMutationError(null);
    } catch {
      setMutationError("Failed to verify signature");
    } finally {
      setVerifying((prev) => ({ ...prev, [keyId]: false }));
    }
  }

  if (status === "loading") return <LoadingState message="Loading SSH keys..." />;

  return (
    <section className="stack">
      <div className="page-header">
        <div>
          <p className="eyebrow">Settings</p>
          <h1>SSH Keys</h1>
        </div>
        <button className="secondary-button" type="button" onClick={() => navigate("/settings")}>
          Back to settings
        </button>
      </div>

      {mutationError && <div className="error">{mutationError}</div>}

      <form onSubmit={handleGenerate} className="stack">
        <div className="form-group">
          <label htmlFor="key-name">Key Name</label>
          <input
            id="key-name"
            type="text"
            value={newKeyName}
            onChange={(e) => setNewKeyName(e.target.value)}
            placeholder="e.g., GitHub Work"
            required
          />
        </div>
        <button type="submit" className="primary-button" disabled={generating}>
          {generating ? (
            <>
              <Icon name="loading" size="sm" />
              Generating...
            </>
          ) : (
            <>
              <Icon name="add" size="sm" />
              Generate SSH Key
            </>
          )}
        </button>
      </form>

      {status === "error" && <ErrorState message="Failed to load SSH keys" onRetry={loadKeys} />}

      <div className="keys-list">
        {safeKeys.length === 0 ? (
          <EmptyState message="No SSH keys yet. Generate one above." />
        ) : (
          safeKeys.map((key) => (
            <div key={key.id} className="key-card">
              <div className="key-header">
                <h3>{key.name}</h3>
                <button
                  onClick={() => handleDelete(key.id)}
                  className="danger-button"
                >
                  <Icon name="delete" size="sm" />
                  Delete
                </button>
              </div>
              <div className="key-meta">
                <span className="muted">
                  Created: {new Date(key.created_at).toLocaleDateString()}
                </span>
              </div>
              <div className="key-public">
                <code>{key.public_key.substring(0, 50)}...</code>
                <button
                  onClick={() => copyToClipboard(key.public_key)}
                  className="secondary-button"
                >
                  <Icon name="copy" size="sm" />
                  Copy Full Key
                </button>
              </div>

              <div className="key-signing">
                <h4>Sign Payload</h4>
                <div className="form-group">
                  <textarea
                    value={signPayloads[key.id] || ""}
                    onChange={(e) =>
                      setSignPayloads((prev) => ({ ...prev, [key.id]: e.target.value }))
                    }
                    placeholder="Enter payload to sign..."
                    rows={3}
                  />
                </div>
                <button
                  onClick={() => handleSign(key.id)}
                  disabled={signing[key.id] || !signPayloads[key.id]?.trim()}
                  className="primary-button"
                >
                  {signing[key.id] ? (
                    <>
                      <Icon name="loading" size="sm" />
                      Signing...
                    </>
                  ) : (
                    <>
                      <Icon name="edit" size="sm" />
                      Sign
                    </>
                  )}
                </button>
                {signatures[key.id] && (
                  <div className="signature-result">
                    <label>Signature (base64):</label>
                    <code>{signatures[key.id]}</code>
                    <button
                      onClick={() => copyToClipboard(signatures[key.id])}
                      className="secondary-button"
                    >
                      <Icon name="copy" size="sm" />
                      Copy Signature
                    </button>
                  </div>
                )}
              </div>

              <div className="key-verification">
                <h4>Verify Signature</h4>
                <div className="form-group">
                  <textarea
                    value={verifyPayloads[key.id] || ""}
                    onChange={(e) =>
                      setVerifyPayloads((prev) => ({ ...prev, [key.id]: e.target.value }))
                    }
                    placeholder="Enter payload..."
                    rows={2}
                  />
                </div>
                <div className="form-group">
                  <textarea
                    value={verifySignatures[key.id] || ""}
                    onChange={(e) =>
                      setVerifySignatures((prev) => ({ ...prev, [key.id]: e.target.value }))
                    }
                    placeholder="Enter base64 signature..."
                    rows={2}
                  />
                </div>
                <button
                  onClick={() => handleVerify(key.id)}
                  disabled={
                    verifying[key.id] ||
                    !verifyPayloads[key.id]?.trim() ||
                    !verifySignatures[key.id]?.trim()
                  }
                  className="primary-button"
                >
                  {verifying[key.id] ? (
                    <>
                      <Icon name="loading" size="sm" />
                      Verifying...
                    </>
                  ) : (
                    <>
                      <Icon name="success" size="sm" />
                      Verify
                    </>
                  )}
                </button>
                {verifyResults[key.id] !== undefined && verifyResults[key.id] !== null && (
                  <div className={`verify-result ${verifyResults[key.id] ? "valid" : "invalid"}`}>
                    {verifyResults[key.id] ? (
                      <>
                        <Icon name="success" size="sm" />
                        Signature is valid
                      </>
                    ) : (
                      <>
                        <Icon name="error" size="sm" />
                        Signature is invalid
                      </>
                    )}
                  </div>
                )}
              </div>
            </div>
          ))
        )}
      </div>
    </section>
  );
};