const crypto = require('node:crypto');
const fs = require('node:fs');
const path = require('node:path');

const { logger } = require('generalFunctions');

function stableUid(input) {
  const digest = crypto.createHash('sha1').update(String(input)).digest('hex');
  return digest.slice(0, 12);
}

function slugify(input) {
  return String(input || '')
    .trim()
    .toLowerCase()
    .replace(/[^a-z0-9]+/g, '-')
    .replace(/(^-|-$)/g, '')
    .slice(0, 60);
}

// Map a node's lowercased softwareType to its Grafana template file in config/.
// Nodes report softwareType as the lowercased node name (e.g. 'rotatingmachine',
// 'machinegroupcontrol'), but several template files are camelCase and some node
// types share a template (rotatingMachine → machine, diffuser → aeration). The
// keys here are always lowercase; lookup lowercases the input first.
const TEMPLATE_FILE_BY_SOFTWARE_TYPE = {
  rotatingmachine: 'machine.json',
  machine: 'machine.json',
  machinegroupcontrol: 'machineGroup.json',
  machinegroup: 'machineGroup.json',
  pumpingstation: 'pumpingStation.json',
  valvegroupcontrol: 'valveGroupControl.json',
  diffuser: 'aeration.json',
  aeration: 'aeration.json',
  measurement: 'measurement.json',
  monster: 'monster.json',
  reactor: 'reactor.json',
  settler: 'settler.json',
  valve: 'valve.json',
  dashboardapi: 'dashboardapi.json',
};

function defaultBucketForPosition(positionVsParent) {
  const pos = String(positionVsParent || '').toLowerCase();
  if (pos === 'upstream') return 'lvl1';
  if (pos === 'downstream') return 'lvl3';
  return 'lvl2';
}

// Replace `{{name}}` placeholders in a raw JSON template string with values
// from `vars`. Unknown placeholders are left intact. Used to inject node-config
// derived constants (basin geometry, threshold y-positions) into a template
// before JSON.parse — so the resulting dashboard has concrete numbers in
// fieldConfig.thresholds and canvas element placements. Mustache-style braces
// keep these placeholders distinct from Grafana's own `${var}` dashboard
// variables (which are interpreted by Grafana at render time).
function substituteTemplateVars(rawJson, vars) {
  if (!vars || !Object.keys(vars).length) return rawJson;
  return rawJson.replace(/\{\{([a-zA-Z_][a-zA-Z0-9_]*)\}\}/g, (m, key) => (
    Object.prototype.hasOwnProperty.call(vars, key) ? String(vars[key]) : m
  ));
}

function updateTemplatingVar(dashboard, varName, value) {
  const list = dashboard?.templating?.list;
  if (!Array.isArray(list)) return;

  const variable = list.find((v) => v && v.name === varName);
  if (!variable) return;

  variable.current = variable.current || {};
  variable.current.text = value;
  variable.current.value = value;

  if (Array.isArray(variable.options) && variable.options.length > 0) {
    variable.options[0] = variable.options[0] || {};
    variable.options[0].text = value;
    variable.options[0].value = value;
  }

  variable.query = value;
}

/**
 * Dashboard domain service.
 * Builds Grafana dashboard payloads from EVOLV node config and child topology.
 */
class DashboardApi {
  constructor(config = {}) {
    this.config = {
      general: {
        name: config?.general?.name || 'dashboardapi',
        logging: {
          enabled: config?.general?.logging?.enabled ?? true,
          logLevel: config?.general?.logging?.logLevel || 'info',
        },
      },
      grafanaConnector: {
        protocol: config?.grafanaConnector?.protocol || 'http',
        host: config?.grafanaConnector?.host || 'localhost',
        port: Number(config?.grafanaConnector?.port || 3000),
        bearerToken: config?.grafanaConnector?.bearerToken || '',
        // folderTitle is the durable way to target a folder: Grafana folder
        // uids change whenever the instance is rebuilt, so a pinned folderUid
        // goes stale (every upsert then 400s "folder not found"). When set, the
        // uid is resolved (and the folder created if absent) by name at emit
        // time. folderUid stays supported as an explicit override / fallback.
        folderTitle: config?.grafanaConnector?.folderTitle || '',
        folderUid: config?.grafanaConnector?.folderUid || '',
      },
      defaultBucket: config?.defaultBucket || '',
      bucketMap: config?.bucketMap || {},
    };

    this.logger = new logger(
      this.config.general.logging.enabled,
      this.config.general.logging.logLevel,
      this.config.general.name
    );

    // Light state cache for manual regen (#41). Stores the latest child
    // source object per child id so `regenerate-dashboard` can re-emit
    // dashboards without waiting for children to re-register.
    this._lastChildSources = new Map();
  }

  recordChild(childSource) {
    const id = childSource?.config?.general?.id;
    if (id) this._lastChildSources.set(id, childSource);
  }

  cachedChildSources() {
    return Array.from(this._lastChildSources.values());
  }

  _templatesDir() {
    return path.join(__dirname, '..', 'config');
  }

  _templateFileForSoftwareType(softwareType) {
    const st = String(softwareType || '').trim();
    const candidates = [
      TEMPLATE_FILE_BY_SOFTWARE_TYPE[st.toLowerCase()],
      `${st}.json`,
      `${st.toLowerCase()}.json`,
    ].filter(Boolean);

    for (const filename of candidates) {
      const fullPath = path.join(this._templatesDir(), filename);
      if (fs.existsSync(fullPath)) return fullPath;
    }

    this.logger.warn(`No dashboard template found for softwareType=${st}`);
    return null;
  }

  loadTemplate(softwareType, templateVars = null) {
    const templatePath = this._templateFileForSoftwareType(softwareType);
    if (!templatePath) return null;
    let raw = fs.readFileSync(templatePath, 'utf8');
    // Always substitute — falls back to per-softwareType defaults so the
    // template is JSON-parseable even when no nodeConfig is provided (tests,
    // smoke-loading, etc.). _templateVarsForNode returns {} for types that
    // don't use placeholders, which is a no-op pass.
    const vars = templateVars || this._templateVarsForNode(softwareType, null);
    raw = substituteTemplateVars(raw, vars);
    return JSON.parse(raw);
  }

  // Per-softwareType numeric vars baked into the template before JSON.parse.
  // Today only pumpingStation needs this (basin geometry → bar-gauge thresholds
  // and canvas y-positions). Other types return {} and skip substitution.
  _templateVarsForNode(softwareType, nodeConfig) {
    const st = String(softwareType || '').toLowerCase();
    if (st !== 'pumpingstation') return {};

    // configManager.buildConfig nests basin geometry under `basin.*` and
    // safety percentages under `safety.*` (see generalFunctions/configManager).
    const basin  = nodeConfig?.basin  || {};
    const safety = nodeConfig?.safety || {};
    const heightBasin   = Number(basin.height)        || 4;
    const inflowLevel   = Number(basin.inflowLevel)   || 0;
    const outflowLevel  = Number(basin.outflowLevel)  || 0;
    const overflowLevel = Number(basin.overflowLevel) || heightBasin;
    const dryRunPct     = Number(safety.dryRunThresholdPercent)            || 30;
    const highPct       = Number(safety.highVolumeSafetyThresholdPercent)  || 90;

    // Mirror specificClass._computeSafetyPoints derivation (pumpingStation).
    const dryRunLevel    = outflowLevel  * (1 + dryRunPct / 100);
    const highSafetyLevel = overflowLevel * (highPct / 100);

    // Canvas tank: rim at y=20px, floor at y=540px (520px tall). Must match
    // hard-coded tank rectangle placement in config/pumpingStation.json
    // (basin row is h:20 grid rows; canvas root frame is 480x600 px).
    const TANK_TOP = 20, TANK_BOT = 540, TANK_H = TANK_BOT - TANK_TOP;
    const yFor = (v) => +(TANK_BOT - (v / heightBasin) * TANK_H).toFixed(2);
    const tyFor = (yLine) => +(yLine - 8).toFixed(2); // centre 16px text on the line

    const y_overflow    = yFor(overflowLevel);
    const y_highSafety  = yFor(highSafetyLevel);
    const y_inflow      = yFor(inflowLevel);
    const y_dryRun      = yFor(dryRunLevel);
    const y_outflow     = yFor(outflowLevel);

    // Label y-positions get min-gap enforcement so labels never overlap even
    // when thresholds sit nearly on top of each other (e.g. dryRun=2 % means
    // dryRunLevel sits right on outflowLevel; highSafety=98 % puts it under
    // overflow). Lines stay at proportional y; only the label text moves.
    // Two-pass (down + up) mirrors editor's basin-diagram.js placement logic.
    const GAP = 20;
    const labels = [
      { id: 'overflow',    y: tyFor(y_overflow)   },
      { id: 'highSafety',  y: tyFor(y_highSafety) },
      { id: 'inflow',      y: tyFor(y_inflow)     },
      { id: 'dryRun',      y: tyFor(y_dryRun)     },
      { id: 'outflow',     y: tyFor(y_outflow)    },
    ].sort((a, b) => a.y - b.y);
    for (let i = 1; i < labels.length; i++) {
      if (labels[i].y < labels[i - 1].y + GAP) labels[i].y = labels[i - 1].y + GAP;
    }
    for (let i = labels.length - 2; i >= 0; i--) {
      if (labels[i].y > labels[i + 1].y - GAP) labels[i].y = labels[i + 1].y - GAP;
    }
    const ty = Object.fromEntries(labels.map((l) => [l.id, +l.y.toFixed(2)]));

    return {
      heightBasin:    +heightBasin.toFixed(2),
      outflowLevel:   +outflowLevel.toFixed(3),
      inflowLevel:    +inflowLevel.toFixed(3),
      overflowLevel:  +overflowLevel.toFixed(3),
      dryRunLevel:    +dryRunLevel.toFixed(3),
      highSafetyLevel: +highSafetyLevel.toFixed(3),
      y_overflow, y_highSafety, y_inflow, y_dryRun, y_outflow,
      h_spill:      +(y_overflow   - TANK_TOP).toFixed(2),
      h_highSafety: +(y_highSafety - y_overflow).toFixed(2),
      h_operating:  +(y_outflow    - y_highSafety).toFixed(2),
      h_dead:       +(TANK_BOT     - y_outflow).toFixed(2),
      ty_overflow:    ty.overflow,
      ty_highSafety:  ty.highSafety,
      ty_inflow:      ty.inflow,
      ty_dryRun:      ty.dryRun,
      ty_outflow:     ty.outflow,
    };
  }

  // Collect every `meta.emittedFields` declared by panels in a template.
  // Used by #39's parent panel filter — a parent panel whose emittedFields
  // are fully covered by its children's panels is removed.
  collectEmittedFields(dashboard) {
    const out = new Set();
    for (const panel of dashboard?.panels || []) {
      const fields = panel?.meta?.emittedFields;
      if (Array.isArray(fields)) for (const f of fields) out.add(f);
    }
    return out;
  }

  grafanaUpsertUrl() {
    const { protocol, host, port } = this.config.grafanaConnector;
    return `${protocol}://${host}:${port}/api/dashboards/db`;
  }

  grafanaFoldersUrl() {
    const { protocol, host, port } = this.config.grafanaConnector;
    return `${protocol}://${host}:${port}/api/folders`;
  }

  _grafanaJsonHeaders() {
    const headers = { Accept: 'application/json', 'Content-Type': 'application/json' };
    const token = this.config.grafanaConnector.bearerToken;
    if (token) headers.Authorization = `Bearer ${token}`;
    return headers;
  }

  // Resolve the target Grafana folder uid by NAME, creating the folder if it
  // doesn't exist. This is the durable alternative to a pinned folderUid, which
  // goes stale on every Grafana rebuild (the new instance hands the same-named
  // folder a fresh uid, and every dashboard upsert then 400s "folder not
  // found"). Resolution is done once per process and cached.
  //
  // Degradation contract: any failure (no fetch, network error, non-OK
  // response) logs a warning and falls back to the configured folderUid, so the
  // node is never worse off than the pinned-uid behavior it replaces.
  async resolveFolderUid({ fetchImpl = globalThis.fetch } = {}) {
    const gc = this.config.grafanaConnector;
    const title = String(gc.folderTitle || '').trim();
    // No title configured → legacy behavior: use the explicit uid (may be '').
    if (!title) return gc.folderUid || '';
    if (this._resolvedFolderUid) return this._resolvedFolderUid;
    if (typeof fetchImpl !== 'function') {
      this.logger.warn('resolveFolderUid: no fetch implementation available; using configured folderUid');
      return gc.folderUid || '';
    }
    try {
      const uid = await this._lookupOrCreateFolder(title, fetchImpl);
      if (uid) {
        this._resolvedFolderUid = uid;
        return uid;
      }
    } catch (err) {
      this.logger.warn(`resolveFolderUid failed (${err?.message || err}); using configured folderUid`);
    }
    return gc.folderUid || '';
  }

  async _lookupOrCreateFolder(title, fetchImpl) {
    const url = this.grafanaFoldersUrl();
    const headers = this._grafanaJsonHeaders();

    const listRes = await fetchImpl(url, { method: 'GET', headers });
    if (listRes?.ok) {
      const folders = await listRes.json();
      const match = Array.isArray(folders)
        && folders.find((f) => String(f?.title || '').trim().toLowerCase() === title.toLowerCase());
      if (match?.uid) {
        this.logger.info({ event: 'folder-resolved', outcome: 'found', title, uid: match.uid });
        return match.uid;
      }
    } else {
      this.logger.warn(`resolveFolderUid: GET /api/folders -> ${listRes?.status}`);
    }

    const createRes = await fetchImpl(url, { method: 'POST', headers, body: JSON.stringify({ title }) });
    if (createRes?.ok) {
      const created = await createRes.json();
      this.logger.info({ event: 'folder-resolved', outcome: 'created', title, uid: created?.uid });
      return created?.uid || '';
    }
    this.logger.warn(`resolveFolderUid: POST /api/folders -> ${createRes?.status}`);
    return '';
  }

  buildDashboard({ nodeConfig, positionVsParent }) {
    const softwareType =
      nodeConfig?.functionality?.softwareType ||
      nodeConfig?.functionality?.software_type ||
      'measurement';
    const nodeId = nodeConfig?.general?.id || nodeConfig?.general?.name || softwareType;
    // Mirror outputUtils.formatMsg: telemetry is written under general.name when
    // set, falling back to `<softwareType>_<id>`. The dashboard's _measurement var
    // must match that exactly or every panel queries a non-existent series.
    const measurementName =
      nodeConfig?.general?.name || `${softwareType}_${nodeConfig?.general?.id || softwareType}`;
    const title = nodeConfig?.general?.name || String(nodeId);

    // Missing templates are treated as non-fatal: we skip only that dashboard.
    const templateVars = this._templateVarsForNode(softwareType, nodeConfig);
    const dashboard = this.loadTemplate(softwareType, templateVars);
    if (!dashboard) {
      this.logger.warn(`Skipping dashboard generation: no template for softwareType=${softwareType}`);
      return null;
    }
    const uid = stableUid(`${softwareType}:${nodeId}`);

    dashboard.id = null;
    dashboard.uid = uid;
    dashboard.title = title;
    dashboard.tags = Array.from(
      new Set([...(dashboard.tags || []), 'EVOLV', softwareType, String(positionVsParent || '')].filter(Boolean))
    );

    const bucket =
      this.config.defaultBucket ||
      this.config.bucketMap[String(positionVsParent)] ||
      defaultBucketForPosition(positionVsParent);

    updateTemplatingVar(dashboard, 'measurement', measurementName);
    updateTemplatingVar(dashboard, 'bucket', bucket);

    return { dashboard, uid, title, softwareType, nodeId, measurementName, bucket };
  }

  buildUpsertRequest({ dashboard, folderId, folderUid, overwrite = true }) {
    const out = { dashboard, overwrite };
    // Prefer folderUid (modern Grafana API). Fall back to folderId for older callers.
    const uid = folderUid ?? this.config?.grafanaConnector?.folderUid ?? '';
    if (uid) out.folderUid = uid;
    else if (typeof folderId === 'number') out.folderId = folderId;
    return out;
  }

  extractChildren(nodeSource) {
    const out = [];
    const reg = nodeSource?.childRegistrationUtils?.registeredChildren;
    if (reg && typeof reg.values === 'function') {
      for (const entry of reg.values()) {
        const child = entry?.child;
        if (!child?.config) continue;
        out.push({ childSource: child, positionVsParent: entry?.position || child.positionVsParent });
      }
      return out;
    }
    return out;
  }

  // Predicate from Gitea issue #32 spike (S1 findings). Given the diff payload
  // from Node-RED's flows:started event and a set of node ids that constitute
  // "my subtree", decides whether the subtree changed on this deploy.
  // `null` diff (first deploy / startup) → always regen (safe default).
  subtreeChanged(diff, subtreeIds) {
    if (!diff) return true;
    const mine = new Set(subtreeIds);
    for (const field of ['added', 'changed', 'removed', 'rewired']) {
      const arr = diff[field] || [];
      if (arr.some((id) => mine.has(id))) return true;
    }
    return false;
  }

  // Collect every node id in "this dashboardAPI + this child's full subtree" for
  // the diff predicate. Recurses the whole registered-child tree (not just
  // grandchildren) so a change anywhere below a wired root triggers a regen.
  // `visited` guards cycles / diamond topologies.
  subtreeIdsFor(dashboardApiNodeId, childSource) {
    const ids = new Set();
    if (dashboardApiNodeId) ids.add(dashboardApiNodeId);
    this._collectSubtreeIds(childSource, ids, new Set());
    return ids;
  }

  _collectSubtreeIds(nodeSource, ids, visited) {
    const id = nodeSource?.config?.general?.id;
    if (id) {
      if (visited.has(id)) return;
      visited.add(id);
      ids.add(id);
    }
    for (const { childSource } of this.extractChildren(nodeSource)) {
      this._collectSubtreeIds(childSource, ids, visited);
    }
  }

  // Compose a dashboard for a wired root and EVERY descendant in its registered-
  // child tree. Operators wire only subtree roots; dashboardAPI recurses the
  // parent-child relationships to discover the rest. Returns a flat, pre-order
  // array (root first) of buildDashboard results.
  generateDashboardsForGraph(rootSource, { includeChildren = true } = {}) {
    if (!rootSource?.config) {
      this.logger.warn('generateDashboardsForGraph skipped: root source missing config');
      return [];
    }

    const results = [];
    this._composeNode(rootSource, includeChildren, results, new Set());
    return results;
  }

  // Recursively compose `nodeSource` then its descendants. Per-parent dedup and
  // links are applied at every level (each parent is deduped against / links to
  // its own direct children). `visited` ensures one dashboard per node id even
  // when the topology has cycles or diamonds.
  _composeNode(nodeSource, includeChildren, results, visited) {
    const nodeId = nodeSource?.config?.general?.id;
    if (nodeId) {
      if (visited.has(nodeId)) return null;
      visited.add(nodeId);
    }

    const position = nodeSource?.positionVsParent || nodeSource?.config?.functionality?.positionVsParent;
    const nodeDash = this.buildDashboard({ nodeConfig: nodeSource.config, positionVsParent: position });
    if (!nodeDash) return null;
    results.push(nodeDash);

    if (!includeChildren) return nodeDash;

    const children = this.extractChildren(nodeSource);
    const childDashes = [];
    for (const { childSource } of children) {
      const childDash = this._composeNode(childSource, includeChildren, results, visited);
      if (childDash) childDashes.push(childDash);
    }

    this._dedupParentPanels(nodeDash, childDashes);
    this._linkToChildren(nodeDash, children);
    // Inject the per-pump fan-out panels AFTER dedup so they survive: these
    // panels intentionally aggregate child data onto the parent dashboard
    // (the operator wants every pump on one MGC graph), which is exactly what
    // the no-duplication rule strips elsewhere. Run last so nothing removes them.
    this._injectMachineGroupPumpPanels(nodeDash, children);

    return nodeDash;
  }

  // No-data-duplication rule (PRD F-5, #39): remove a parent's panels whose
  // emittedFields are fully covered by its direct children's panels, so the
  // same series isn't rendered twice across the parent/child dashboards.
  _dedupParentPanels(parentDash, childDashes) {
    if (childDashes.length === 0 || !parentDash.dashboard) return;

    const childCoveredFields = new Set();
    for (const dash of childDashes) {
      for (const f of this.collectEmittedFields(dash.dashboard)) childCoveredFields.add(f);
    }
    const before = parentDash.dashboard.panels.length;
    parentDash.dashboard.panels = parentDash.dashboard.panels.filter((p) => {
      if (p.type === 'row') return true; // never drop rows
      const fields = p?.meta?.emittedFields;
      if (!Array.isArray(fields) || fields.length === 0) return true; // no declaration, keep
      return !fields.every((f) => childCoveredFields.has(f));
    });
    if (this.logger?.debug && before !== parentDash.dashboard.panels.length) {
      this.logger.debug({
        event: 'parent-panels-deduped',
        before,
        after: parentDash.dashboard.panels.length,
        rootTitle: parentDash.title,
      });
    }
  }

  _linkToChildren(parentDash, children) {
    if (children.length === 0 || !parentDash.dashboard) return;

    parentDash.dashboard.links = Array.isArray(parentDash.dashboard.links) ? parentDash.dashboard.links : [];
    for (const { childSource } of children) {
      const childConfig = childSource.config;
      const childSoftwareType = childConfig?.functionality?.softwareType || 'measurement';
      const childNodeId = childConfig?.general?.id || childConfig?.general?.name || childSoftwareType;
      const childUid = stableUid(`${childSoftwareType}:${childNodeId}`);
      const childTitle = childConfig?.general?.name || String(childNodeId);

      parentDash.dashboard.links.push({
        type: 'link',
        title: childTitle,
        url: `/d/${childUid}/${slugify(childTitle)}`,
        tags: [],
        targetBlank: false,
        keepTime: true,
        keepVariables: true,
      });
    }
  }

  // Software types that count as a "pump" child of a machine group. Mirrors the
  // template-alias map: a rotatingMachine reports softwareType 'rotatingmachine'
  // in production, 'machine' in tests / shared template.
  static _PUMP_SOFTWARE_TYPES = new Set(['rotatingmachine', 'machine']);

  // Replicate the measurement-name convention from outputUtils.formatMsg /
  // buildDashboard so the dashboard queries the exact series each pump writes:
  // `general.name` when set, else `<softwareType>_<id>`.
  _measurementNameForConfig(config) {
    const softwareType = config?.functionality?.softwareType || 'measurement';
    return config?.general?.name || `${softwareType}_${config?.general?.id || softwareType}`;
  }

  // Datasource block reused for injected panels. Pull it off an existing panel
  // so the dashboard keeps a single influxdb datasource uid; fall back to the
  // template's known uid if every panel was deduped away.
  _datasourceFor(dashboard) {
    const withDs = (dashboard.panels || []).find((p) => p?.datasource?.type === 'influxdb');
    return withDs?.datasource || { type: 'influxdb', uid: 'cdzg44tv250jkd' };
  }

  // Build the per-pump + group-aggregate timeseries panels for a machineGroup
  // dashboard. The operator asked for one graph each of pump % control, pump
  // predicted flow, and pump predicted power, with the group total folded in,
  // the resolved demand overlaid on the flow graph, and the flow-capacity
  // envelope drawn as dashed min/max lines.
  //
  // Per-pump series live in each pump's OWN InfluxDB measurement (not the
  // MGC's), so the queries are generated at compose time from the known child
  // topology. Pump series are kept by `_measurement` (legend = pump name);
  // group series are kept by `_field` and renamed via byName overrides.
  _injectMachineGroupPumpPanels(parentDash, children) {
    if (!parentDash?.dashboard) return;
    const st = String(parentDash.softwareType || '').toLowerCase();
    if (st !== 'machinegroupcontrol' && st !== 'machinegroup') return;

    const pumps = (children || [])
      .map(({ childSource }) => childSource?.config)
      .filter((c) => c && DashboardApi._PUMP_SOFTWARE_TYPES.has(
        String(c?.functionality?.softwareType || '').toLowerCase()))
      .map((c) => ({ measurement: this._measurementNameForConfig(c), title: c?.general?.name || c?.general?.id }));

    if (pumps.length === 0) return; // No pumps wired → leave the static totals.

    const dashboard = parentDash.dashboard;
    const datasource = this._datasourceFor(dashboard);
    // The richer flow/power panels below supersede the static group-total
    // panels — drop them so the same series isn't drawn twice.
    dashboard.panels = (dashboard.panels || []).filter(
      (p) => p.title !== 'Total Flow' && p.title !== 'Total Power');

    const measFilter = pumps.map((p) => `r._measurement == "${p.measurement}"`).join(' or ');
    const nextId = Math.max(0, ...dashboard.panels.map((p) => Number(p.id) || 0)) + 1;

    dashboard.panels.push(
      this._pumpControlPanel({ datasource, measFilter, id: nextId, y: 6 }),
      this._pumpFlowPanel({ datasource, measFilter, id: nextId + 1, y: 14 }),
      this._pumpPowerPanel({ datasource, measFilter, id: nextId + 2, y: 22 }),
    );
  }

  // ── Injected-panel builders ──────────────────────────────────────────────
  // All three use `${bucket}` / `${measurement}` template vars (resolved by
  // Grafana from the dashboard's templating list) plus literal pump measurement
  // names. v.timeRangeStart/Stop/windowPeriod are Grafana-supplied.

  _baseTsPanel({ datasource, id, y, title, targets, overrides = [], defaults = {} }) {
    return {
      datasource,
      fieldConfig: {
        defaults: { custom: { drawStyle: 'line', lineWidth: 2, fillOpacity: 5, showPoints: 'never' }, ...defaults },
        overrides,
      },
      gridPos: { h: 8, w: 24, x: 0, y },
      id,
      options: { legend: { displayMode: 'list', placement: 'bottom' }, tooltip: { mode: 'multi' } },
      targets,
      title,
      type: 'timeseries',
      // Empty emittedFields: these panels intentionally duplicate child series
      // and must never be removed by the no-duplication dedup pass.
      meta: { emittedFields: [], dynamic: 'mgc-pump-fanout' },
    };
  }

  // Pump series kept by `_measurement` → one line per pump, legend = pump name.
  // `field` is exact-matched by default; pass `regex:true` to match a 4-segment
  // MeasurementContainer key whose childId varies per pump. rotatingMachine
  // writes its own predictions under childId = node id (e.g.
  // `flow.predicted.atequipment.<pumpId>`), NOT a fixed `default`, so the
  // flow/power series must match the position prefix, not an exact key.
  _perPumpTarget({ measFilter, field, refId, transform = '', regex = false }) {
    const fieldFilter = regex ? `r._field =~ /${field}/` : `r._field == "${field}"`;
    return {
      refId,
      query:
        `from(bucket: "\${bucket}")\n` +
        `  |> range(start: v.timeRangeStart, stop: v.timeRangeStop)\n` +
        `  |> filter(fn:(r) => (${measFilter}) and ${fieldFilter})\n` +
        `  |> aggregateWindow(every: v.windowPeriod, fn: mean, createEmpty: false)\n` +
        transform +
        `  |> keep(columns: ["_time", "_value", "_measurement"])`,
    };
  }

  // Group series kept by `_field` → legend = field name, renamed via byName
  // overrides. `fields` is OR-joined into one query.
  _groupFieldsTarget({ fields, refId }) {
    const filter = fields.map((f) => `r._field == "${f}"`).join(' or ');
    return {
      refId,
      query:
        `from(bucket: "\${bucket}")\n` +
        `  |> range(start: v.timeRangeStart, stop: v.timeRangeStop)\n` +
        `  |> filter(fn:(r) => r._measurement == "\${measurement}" and (${filter}))\n` +
        `  |> aggregateWindow(every: v.windowPeriod, fn: mean, createEmpty: false)\n` +
        `  |> keep(columns: ["_time", "_value", "_field"])`,
    };
  }

  _byName(name, properties) {
    return { matcher: { id: 'byName', options: name }, properties };
  }

  _pumpControlPanel({ datasource, measFilter, id, y }) {
    // Two series per pump so an operator can see at a glance whether each pump
    // actually moved to where the MGC told it:
    //   • realized position — the bare `ctrl` field (getCurrentPosition), solid.
    //   • commanded setpoint — `ctrl.predicted.atequipment.<pumpId>`, the % the
    //     pump computed from the MGC flow command (calcCtrl reverse curve),
    //     drawn dashed. childId varies per pump, so match the position prefix.
    // Both are already 0..100 %, so they map straight onto a % axis — no scaling.
    // Each series' `_measurement` is suffixed so the legend distinguishes the
    // two lines per pump ("Pump A (realized)" vs "Pump A (setpoint)").
    const label = (name) =>
      `  |> map(fn: (r) => ({ r with _measurement: r._measurement + " (${name})" }))\n`;
    return this._baseTsPanel({
      datasource, id, y,
      title: 'Pump % Control',
      defaults: { unit: 'percent', min: 0, max: 100 },
      targets: [
        this._perPumpTarget({ measFilter, field: 'ctrl', refId: 'A', transform: label('realized') }),
        this._perPumpTarget({
          measFilter, field: '^ctrl\\.predicted\\.atequipment\\.', refId: 'B',
          regex: true, transform: label('setpoint'),
        }),
      ],
      overrides: [{
        matcher: { id: 'byRegexp', options: '.*\\(setpoint\\)' },
        properties: [{ id: 'custom.lineStyle', value: { fill: 'dash', dash: [6, 6] } }],
      }],
    });
  }

  _pumpFlowPanel({ datasource, measFilter, id, y }) {
    return this._baseTsPanel({
      datasource, id, y,
      title: 'Pump Predicted Flow vs Demand',
      defaults: { unit: 'm3/h' },
      targets: [
        this._perPumpTarget({ measFilter, field: '^flow\\.predicted\\.atequipment\\.', refId: 'A', regex: true }),
        this._groupFieldsTarget({
          refId: 'B',
          fields: ['atEquipment_predicted_flow', 'demandFlow', 'demandPct', 'flowCapacityMin', 'flowCapacityMax'],
        }),
      ],
      overrides: [
        this._byName('atEquipment_predicted_flow', [
          { id: 'displayName', value: 'Total flow' },
          { id: 'custom.lineWidth', value: 3 },
        ]),
        this._byName('demandFlow', [
          { id: 'displayName', value: 'Flow demand (setpoint)' },
          { id: 'custom.lineStyle', value: { fill: 'dash', dash: [6, 6] } },
          { id: 'color', value: { mode: 'fixed', fixedColor: 'blue' } },
        ]),
        this._byName('demandPct', [
          { id: 'displayName', value: 'Demand %' },
          { id: 'unit', value: 'percent' },
          { id: 'custom.axisPlacement', value: 'right' },
          { id: 'custom.axisLabel', value: '% control' },
          { id: 'color', value: { mode: 'fixed', fixedColor: 'purple' } },
        ]),
        this._byName('flowCapacityMin', [
          { id: 'displayName', value: 'Capacity min' },
          { id: 'custom.lineStyle', value: { fill: 'dash', dash: [10, 10] } },
          { id: 'custom.fillOpacity', value: 0 },
          { id: 'color', value: { mode: 'fixed', fixedColor: 'orange' } },
        ]),
        this._byName('flowCapacityMax', [
          { id: 'displayName', value: 'Capacity max' },
          { id: 'custom.lineStyle', value: { fill: 'dash', dash: [10, 10] } },
          { id: 'custom.fillOpacity', value: 0 },
          { id: 'color', value: { mode: 'fixed', fixedColor: 'red' } },
        ]),
      ],
    });
  }

  _pumpPowerPanel({ datasource, measFilter, id, y }) {
    return this._baseTsPanel({
      datasource, id, y,
      title: 'Pump Predicted Power',
      defaults: { unit: 'kwatt' },
      targets: [
        this._perPumpTarget({ measFilter, field: '^power\\.predicted\\.atequipment\\.', refId: 'A', regex: true }),
        this._groupFieldsTarget({ refId: 'B', fields: ['atEquipment_predicted_power'] }),
      ],
      overrides: [
        this._byName('atEquipment_predicted_power', [
          { id: 'displayName', value: 'Total power' },
          { id: 'custom.lineWidth', value: 3 },
        ]),
      ],
    });
  }
}

module.exports = DashboardApi;