document.addEventListener("DOMContentLoaded", () => {
  const dataElement = document.getElementById("maintenance-data");
  let equipmentByScenario = {};
  let maintenanceByScenario = {};

  if (dataElement) {
    try {
      const parsed = JSON.parse(dataElement.textContent || "{}");
      if (parsed && typeof parsed === "object") {
        if (parsed.equipment && typeof parsed.equipment === "object") {
          equipmentByScenario = parsed.equipment;
        }
        if (parsed.maintenance && typeof parsed.maintenance === "object") {
          maintenanceByScenario = parsed.maintenance;
        }
      }
    } catch (error) {
      console.error("Unable to parse maintenance data", error);
    }
  }

  const filterSelect = document.getElementById("maintenance-scenario-filter");
  const tableWrapper = document.getElementById("maintenance-table-wrapper");
  const tableBody = document.getElementById("maintenance-table-body");
  const emptyState = document.getElementById("maintenance-empty");
  const form = document.getElementById("maintenance-form");
  const feedbackEl = document.getElementById("maintenance-feedback");
  const formScenarioSelect = document.getElementById(
    "maintenance-form-scenario"
  );
  const equipmentSelect = document.getElementById("maintenance-form-equipment");
  const equipmentEmptyState = document.getElementById(
    "maintenance-equipment-empty"
  );

  const showFeedback = (message, type = "success") => {
    if (!feedbackEl) {
      return;
    }
    feedbackEl.textContent = message;
    feedbackEl.classList.remove("hidden", "success", "error");
    feedbackEl.classList.add(type);
  };

  const hideFeedback = () => {
    if (!feedbackEl) {
      return;
    }
    feedbackEl.classList.add("hidden");
    feedbackEl.textContent = "";
  };

  const formatCost = (value) =>
    Number(value).toLocaleString(undefined, {
      minimumFractionDigits: 2,
      maximumFractionDigits: 2,
    });

  const formatDate = (value) => {
    if (!value) {
      return "—";
    }
    const parsed = new Date(value);
    if (Number.isNaN(parsed.getTime())) {
      return value;
    }
    return parsed.toLocaleDateString();
  };

  const renderMaintenanceRows = (scenarioId) => {
    if (!tableBody || !tableWrapper || !emptyState) {
      return;
    }

    const key = String(scenarioId);
    const records = maintenanceByScenario[key] || [];

    tableBody.innerHTML = "";

    if (!records.length) {
      emptyState.textContent =
        "No maintenance entries recorded for this scenario yet.";
      emptyState.classList.remove("hidden");
      tableWrapper.classList.add("hidden");
      return;
    }

    emptyState.classList.add("hidden");
    tableWrapper.classList.remove("hidden");

    records.forEach((record) => {
      const row = document.createElement("tr");
      row.innerHTML = `
        <td>${formatDate(record.maintenance_date)}</td>
        <td>${record.equipment_name || "—"}</td>
        <td>${formatCost(record.cost)}</td>
        <td>${record.description || "—"}</td>
      `;
      tableBody.appendChild(row);
    });
  };

  const populateEquipmentOptions = (scenarioId) => {
    if (!equipmentSelect) {
      return;
    }

    equipmentSelect.innerHTML =
      '<option value="" disabled selected>Select equipment</option>';
    equipmentSelect.disabled = true;

    if (equipmentEmptyState) {
      equipmentEmptyState.classList.add("hidden");
    }

    if (!scenarioId) {
      return;
    }

    const list = equipmentByScenario[String(scenarioId)] || [];
    if (!list.length) {
      if (equipmentEmptyState) {
        equipmentEmptyState.textContent =
          "Add equipment for this scenario before scheduling maintenance.";
        equipmentEmptyState.classList.remove("hidden");
      }
      return;
    }

    list.forEach((item) => {
      const option = document.createElement("option");
      option.value = item.id;
      option.textContent = item.name || `Equipment ${item.id}`;
      equipmentSelect.appendChild(option);
    });

    equipmentSelect.disabled = false;
  };

  if (filterSelect) {
    filterSelect.addEventListener("change", (event) => {
      const value = event.target.value;
      if (!value) {
        if (emptyState && tableWrapper && tableBody) {
          emptyState.textContent =
            "Choose a scenario to review upcoming or completed maintenance.";
          emptyState.classList.remove("hidden");
          tableWrapper.classList.add("hidden");
          tableBody.innerHTML = "";
        }
        return;
      }
      renderMaintenanceRows(value);
    });
  }

  if (formScenarioSelect) {
    formScenarioSelect.addEventListener("change", (event) => {
      const value = event.target.value;
      populateEquipmentOptions(value);
    });
  }

  const submitMaintenance = async (event) => {
    event.preventDefault();
    hideFeedback();

    if (!form) {
      return;
    }

    const formData = new FormData(form);
    const scenarioId = formData.get("scenario_id");
    const equipmentId = formData.get("equipment_id");
    const payload = {
      scenario_id: scenarioId ? Number(scenarioId) : null,
      equipment_id: equipmentId ? Number(equipmentId) : null,
      maintenance_date: formData.get("maintenance_date"),
      cost: Number(formData.get("cost")),
      description: formData.get("description") || null,
    };

    if (!payload.scenario_id || !payload.equipment_id) {
      showFeedback(
        "Select a scenario and equipment before submitting.",
        "error"
      );
      return;
    }

    try {
      const response = await fetch("/api/maintenance/", {
        method: "POST",
        headers: { "Content-Type": "application/json" },
        body: JSON.stringify(payload),
      });

      if (!response.ok) {
        const errorDetail = await response.json().catch(() => ({}));
        throw new Error(
          errorDetail.detail || "Unable to add maintenance entry."
        );
      }

      const result = await response.json();
      const mapKey = String(result.scenario_id);

      if (!Array.isArray(maintenanceByScenario[mapKey])) {
        maintenanceByScenario[mapKey] = [];
      }

      const equipmentList = equipmentByScenario[mapKey] || [];
      const matchedEquipment = equipmentList.find(
        (item) => Number(item.id) === Number(result.equipment_id)
      );
      result.equipment_name = matchedEquipment ? matchedEquipment.name : "";

      maintenanceByScenario[mapKey].push(result);

      form.reset();
      populateEquipmentOptions(null);
      showFeedback("Maintenance entry saved.", "success");

      if (filterSelect && filterSelect.value === String(result.scenario_id)) {
        renderMaintenanceRows(filterSelect.value);
      }
    } catch (error) {
      showFeedback(error.message || "An unexpected error occurred.", "error");
    }
  };

  if (form) {
    form.addEventListener("submit", submitMaintenance);
  }

  if (filterSelect && filterSelect.value) {
    renderMaintenanceRows(filterSelect.value);
  }

  if (formScenarioSelect && formScenarioSelect.value) {
    populateEquipmentOptions(formScenarioSelect.value);
  }
});