import React, { useEffect, useState } from "react";
import { Link } from "react-router-dom";
import { apiFetch } from "../api";
import { useAuth } from "../state";

const emptyForm = {
  name: "",
  host: "",
  port: 5432,
  dbname: "",
  username: "",
  password: "",
  sslmode: "prefer",
  use_pg_stat_statements: true,
  tags: {},
};

const emptyEditForm = {
  id: null,
  name: "",
  host: "",
  port: 5432,
  dbname: "",
  username: "",
  password: "",
  sslmode: "prefer",
  use_pg_stat_statements: true,
};

export function TargetsPage() {
  const { tokens, refresh, me } = useAuth();
  const [targets, setTargets] = useState([]);
  const [form, setForm] = useState(emptyForm);
  const [editForm, setEditForm] = useState(emptyEditForm);
  const [editing, setEditing] = useState(false);
  const [error, setError] = useState("");
  const [loading, setLoading] = useState(true);
  const [testState, setTestState] = useState({ loading: false, message: "", ok: null });
  const [saveState, setSaveState] = useState({ loading: false, message: "" });

  const canManage = me?.role === "admin" || me?.role === "operator";

  const load = async () => {
    setLoading(true);
    try {
      setTargets(await apiFetch("/targets", {}, tokens, refresh));
      setError("");
    } catch (e) {
      setError(String(e.message || e));
    } finally {
      setLoading(false);
    }
  };

  useEffect(() => {
    load();
  }, []);

  const createTarget = async (e) => {
    e.preventDefault();
    try {
      await apiFetch("/targets", { method: "POST", body: JSON.stringify(form) }, tokens, refresh);
      setForm(emptyForm);
      await load();
    } catch (e) {
      setError(String(e.message || e));
    }
  };

  const testConnection = async () => {
    setTestState({ loading: true, message: "", ok: null });
    try {
      const result = await apiFetch(
        "/targets/test-connection",
        {
          method: "POST",
          body: JSON.stringify({
            host: form.host,
            port: form.port,
            dbname: form.dbname,
            username: form.username,
            password: form.password,
            sslmode: form.sslmode,
          }),
        },
        tokens,
        refresh
      );
      setTestState({ loading: false, message: `${result.message} (PostgreSQL ${result.server_version})`, ok: true });
    } catch (e) {
      setTestState({ loading: false, message: String(e.message || e), ok: false });
    }
  };

  const deleteTarget = async (id) => {
    if (!confirm("Delete target?")) return;
    try {
      await apiFetch(`/targets/${id}`, { method: "DELETE" }, tokens, refresh);
      await load();
    } catch (e) {
      setError(String(e.message || e));
    }
  };

  const startEdit = (target) => {
    setEditing(true);
    setSaveState({ loading: false, message: "" });
    setEditForm({
      id: target.id,
      name: target.name,
      host: target.host,
      port: target.port,
      dbname: target.dbname,
      username: target.username,
      password: "",
      sslmode: target.sslmode,
      use_pg_stat_statements: target.use_pg_stat_statements !== false,
    });
  };

  const cancelEdit = () => {
    setEditing(false);
    setEditForm(emptyEditForm);
    setSaveState({ loading: false, message: "" });
  };

  const saveEdit = async (e) => {
    e.preventDefault();
    if (!editForm.id) return;
    setSaveState({ loading: true, message: "" });
    try {
      const payload = {
        name: editForm.name,
        host: editForm.host,
        port: Number(editForm.port),
        dbname: editForm.dbname,
        username: editForm.username,
        sslmode: editForm.sslmode,
        use_pg_stat_statements: !!editForm.use_pg_stat_statements,
      };
      if (editForm.password.trim()) payload.password = editForm.password;

      await apiFetch(`/targets/${editForm.id}`, { method: "PUT", body: JSON.stringify(payload) }, tokens, refresh);
      setSaveState({ loading: false, message: "Target updated." });
      setEditing(false);
      setEditForm(emptyEditForm);
      await load();
    } catch (e) {
      setSaveState({ loading: false, message: String(e.message || e) });
    }
  };

  return (
    <div className="targets-page">
      <h2>Targets Management</h2>
      {error && <div className="card error">{error}</div>}

      {canManage && (
        <details className="card collapsible">
          <summary className="collapse-head">
            <div>
              <h3>New Target</h3>
            </div>
            <span className="collapse-chevron" aria-hidden="true">v</span>
          </summary>

          <form className="target-form grid two" onSubmit={createTarget}>
            <div className="field">
              <label>Name</label>
              <input placeholder="e.g. Prod-DB" value={form.name} onChange={(e) => setForm({ ...form, name: e.target.value })} required />
            </div>
            <div className="field">
              <label>Host</label>
              <input placeholder="e.g. 172.16.0.106 or db.internal" value={form.host} onChange={(e) => setForm({ ...form, host: e.target.value })} required />
            </div>
            <div className="field">
              <label>Port</label>
              <input placeholder="5432" value={form.port} onChange={(e) => setForm({ ...form, port: Number(e.target.value) })} type="number" required />
            </div>
            <div className="field">
              <label>DB Name</label>
              <input placeholder="e.g. postgres or appdb" value={form.dbname} onChange={(e) => setForm({ ...form, dbname: e.target.value })} required />
            </div>
            <div className="field">
              <label>Username</label>
              <input placeholder="e.g. postgres" value={form.username} onChange={(e) => setForm({ ...form, username: e.target.value })} required />
            </div>
            <div className="field">
              <label>Password</label>
              <input placeholder="Password" type="password" value={form.password} onChange={(e) => setForm({ ...form, password: e.target.value })} required />
            </div>
            <div className="field">
              <label>SSL Mode</label>
              <select value={form.sslmode} onChange={(e) => setForm({ ...form, sslmode: e.target.value })}>
                <option value="disable">disable</option>
                <option value="prefer">prefer</option>
                <option value="require">require</option>
              </select>
              <small>
                If you see "rejected SSL upgrade", switch to <code>disable</code>.
              </small>
            </div>
            <div className="field field-full toggle-field">
              <label>Query Insights Source</label>
              <label className="toggle-check">
                <input
                  type="checkbox"
                  checked={!!form.use_pg_stat_statements}
                  onChange={(e) => setForm({ ...form, use_pg_stat_statements: e.target.checked })}
                />
                <span className="toggle-ui" aria-hidden="true" />
                <span className="toggle-copy">
                  <strong>Use pg_stat_statements for this target</strong>
                  <small>Disable this if the extension is unavailable on the target.</small>
                </span>
              </label>
            </div>
            <div className="field submit-field field-full">
              <div className="form-actions">
                <button type="button" className="secondary-btn" onClick={testConnection} disabled={testState.loading}>
                  {testState.loading ? "Testing..." : "Test connection"}
                </button>
                <button className="primary-btn">Create target</button>
              </div>
            </div>
          </form>
          {testState.message && (
            <div className={`test-connection-result ${testState.ok ? "ok" : "fail"}`}>{testState.message}</div>
          )}
        </details>
      )}

      {canManage && editing && (
        <section className="card">
          <h3>Edit Target</h3>
          <form className="target-form grid two" onSubmit={saveEdit}>
            <div className="field">
              <label>Name</label>
              <input value={editForm.name} onChange={(e) => setEditForm({ ...editForm, name: e.target.value })} required />
            </div>
            <div className="field">
              <label>Host</label>
              <input value={editForm.host} onChange={(e) => setEditForm({ ...editForm, host: e.target.value })} required />
            </div>
            <div className="field">
              <label>Port</label>
              <input type="number" value={editForm.port} onChange={(e) => setEditForm({ ...editForm, port: Number(e.target.value) })} required />
            </div>
            <div className="field">
              <label>DB Name</label>
              <input value={editForm.dbname} onChange={(e) => setEditForm({ ...editForm, dbname: e.target.value })} required />
            </div>
            <div className="field">
              <label>Username</label>
              <input value={editForm.username} onChange={(e) => setEditForm({ ...editForm, username: e.target.value })} required />
            </div>
            <div className="field">
              <label>New Password (optional)</label>
              <input type="password" placeholder="Leave empty to keep current" value={editForm.password} onChange={(e) => setEditForm({ ...editForm, password: e.target.value })} />
            </div>
            <div className="field">
              <label>SSL Mode</label>
              <select value={editForm.sslmode} onChange={(e) => setEditForm({ ...editForm, sslmode: e.target.value })}>
                <option value="disable">disable</option>
                <option value="prefer">prefer</option>
                <option value="require">require</option>
              </select>
            </div>
            <div className="field field-full toggle-field">
              <label>Query Insights Source</label>
              <label className="toggle-check">
                <input
                  type="checkbox"
                  checked={!!editForm.use_pg_stat_statements}
                  onChange={(e) => setEditForm({ ...editForm, use_pg_stat_statements: e.target.checked })}
                />
                <span className="toggle-ui" aria-hidden="true" />
                <span className="toggle-copy">
                  <strong>Use pg_stat_statements for this target</strong>
                  <small>Disable this if the extension is unavailable on the target.</small>
                </span>
              </label>
            </div>
            <div className="field submit-field field-full">
              <div className="form-actions">
                <button type="button" className="secondary-btn" onClick={cancelEdit}>Cancel</button>
                <button className="primary-btn" disabled={saveState.loading}>{saveState.loading ? "Saving..." : "Save changes"}</button>
              </div>
            </div>
          </form>
          {saveState.message && <div className="test-connection-result">{saveState.message}</div>}
        </section>
      )}

      {canManage && (
        <details className="card collapsible tips">
          <summary className="collapse-head">
            <div>
              <h3>Troubleshooting</h3>
              <p>Quick checks for the most common connection issues.</p>
            </div>
            <span className="collapse-chevron" aria-hidden="true">v</span>
          </summary>
          <p>
            <code>Connection refused</code>: host/port is wrong or database is unreachable.
          </p>
          <p>
            <code>rejected SSL upgrade</code>: set SSL mode to <code>disable</code>.
          </p>
          <p>
            <code>localhost</code> points to the backend container itself, not your host machine.
          </p>
        </details>
      )}

      <div className="card targets-table">
        {loading ? (
          <p>Loading targets...</p>
        ) : (
          <table>
            <thead>
              <tr>
                <th>Name</th>
                <th>Host</th>
                <th>DB</th>
                <th>Query Insights</th>
                <th>Actions</th>
              </tr>
            </thead>
            <tbody>
              {targets.map((t) => (
                <tr key={t.id}>
                  <td>{t.name}</td>
                  <td>{t.host}:{t.port}</td>
                  <td>{t.dbname}</td>
                  <td>
                    <span className={`status-chip ${t.use_pg_stat_statements ? "ok" : "warning"}`}>
                      {t.use_pg_stat_statements ? "Enabled" : "Disabled"}
                    </span>
                  </td>
                  <td>
                    <Link className="table-link" to={`/targets/${t.id}`}>Details</Link>{" "}
                    {canManage && <button className="secondary-btn small-btn" onClick={() => startEdit(t)}>Edit</button>}
                    {canManage && <button className="danger-btn" onClick={() => deleteTarget(t.id)}>Delete</button>}
                  </td>
                </tr>
              ))}
            </tbody>
          </table>
        )}
      </div>
    </div>
  );
}