/// <reference path="../pb_data/types.d.ts" />
/**
 * Shared helpers for audit_log.pb.js. Loaded with
 * `require(`${__hooks}/audit_log_utils.js`)` from INSIDE each handler —
 * PB runs handlers in isolated VMs, so top-level code in the .pb.js file
 * is not visible to them.
 *
 * Not named *.pb.js on purpose: PB must not auto-load it as a hook file.
 */

// Fields that change on their own (search indexing, AI enrichment,
// timers) or are covered by a dedicated event. Logging them would bury
// the human edits.
const IGNORED_FIELDS = {
  id: 1, created: 1, updated: 1, collectionId: 1, collectionName: 1, expand: 1,
  meiliesearch: 1, ai_insights: 1, ai_item_insights: 1, ai_status: 1, ai_error: 1,
  ai_processed_at: 1, migration_meta: 1, migration_source: 1, migrated_at: 1,
  wfdash_quote_id: 1, wfdash_order_id: 1, claim_expires_at: 1, sending_started_at: 1,
  email_tracking_id: 1, has_new_reply: 1, last_reply_at: 1, pdf_generated_at: 1,
  quote_matching_attempted: 1, delivery_note_matching_attempted: 1,
  duplicate_order_matching_attempted: 1, order_number_duplicate_checked: 1,
  email_opened: 1, email_opened_at: 1, email_delivered: 1, email_delivered_at: 1, ai_check: 1,
};

// Key fields recorded when a line is added or removed, so the trail can
// say "added M16 bolt × 10 @ R3.11" without a separate lookup.
const SNAPSHOT_FIELDS = {
  quote_items: ["description", "quantity", "cost_price", "selling_price", "markup", "supplier"],
  order_items: ["description", "quantity", "cost_price", "selling_price", "markup", "supplier", "item_status"],
  quote_attachments: ["filename", "kind"],
};

const MAX_VALUE_CHARS = 300;

function toPlain(record) {
  if (!record) return null;
  // Record implements json.Marshaler, so this yields the same public
  // shape the REST API returns (json fields parsed, files as names).
  return JSON.parse(JSON.stringify(record));
}

function isEmpty(v) {
  return v === null || v === undefined || v === "" ||
    (Array.isArray(v) && v.length === 0);
}

function clip(v) {
  if (v === null || v === undefined) return null;
  if (typeof v === "string") {
    return v.length > MAX_VALUE_CHARS ? v.slice(0, MAX_VALUE_CHARS) + "…" : v;
  }
  if (typeof v === "number" || typeof v === "boolean") return v;
  const s = JSON.stringify(v);
  return s.length > MAX_VALUE_CHARS ? s.slice(0, MAX_VALUE_CHARS) + "…" : v;
}

function same(a, b) {
  if (isEmpty(a) && isEmpty(b)) return true;
  return JSON.stringify(a) === JSON.stringify(b);
}

function isPlainObject(v) {
  return v !== null && typeof v === "object" && !Array.isArray(v);
}

/** [{ field, from, to }] for every changed, non-ignored field. */
function diff(before, after) {
  const changes = [];
  const keys = {};
  Object.keys(before || {}).forEach((k) => { keys[k] = 1; });
  Object.keys(after || {}).forEach((k) => { keys[k] = 1; });
  Object.keys(keys).sort().forEach((field) => {
    if (IGNORED_FIELDS[field]) return;
    const from = before ? before[field] : undefined;
    const to = after ? after[field] : undefined;
    if (same(from, to)) return;
    // JSON blobs (e.g. order_item_details): diff one level down so an
    // invoice stamp reads as `order_item_details.invoice`, not a wall
    // of JSON.
    if (isPlainObject(from) || isPlainObject(to)) {
      const f = isPlainObject(from) ? from : {};
      const t = isPlainObject(to) ? to : {};
      const sub = {};
      Object.keys(f).forEach((k) => { sub[k] = 1; });
      Object.keys(t).forEach((k) => { sub[k] = 1; });
      Object.keys(sub).sort().forEach((k) => {
        if (!same(f[k], t[k])) {
          changes.push({ field: field + "." + k, from: clip(f[k]), to: clip(t[k]) });
        }
      });
      return;
    }
    // Append-only text (notes feeds): keep just the appended tail.
    if (typeof from === "string" && typeof to === "string" && from && to.indexOf(from) === 0) {
      changes.push({ field: field, from: null, to: clip(to.slice(from.length).trim()), appended: true });
      return;
    }
    changes.push({ field: field, from: clip(from), to: clip(to) });
  });
  return changes;
}

function snapshotChanges(collection, data, side) {
  const fields = SNAPSHOT_FIELDS[collection] || [];
  const out = [];
  fields.forEach((field) => {
    const v = data ? data[field] : undefined;
    if (isEmpty(v)) return;
    out.push(side === "from"
      ? { field: field, from: clip(v), to: null }
      : { field: field, from: null, to: clip(v) });
  });
  return out;
}

function header(info, name) {
  const h = (info && info.headers) || {};
  // PB exposes request headers lowercased with "-" turned into "_".
  const raw = String(h[name.replace(/-/g, "_")] || h[name] || "").trim();
  // The WFDASH server URI-encodes the name hints (header values must be
  // ASCII). Plain values pass through unchanged.
  try {
    return decodeURIComponent(raw);
  } catch (_) {
    return raw;
  }
}

function displayName(user) {
  return user.getString("name") || user.getString("email") || user.id;
}

/**
 * Who made the change.
 *  - A dashboard user writing straight to PB: their verified auth record.
 *  - The WFDASH server / n8n (superuser key): the X-Audit-* headers the
 *    caller attached. Only trusted on superuser requests, so a normal
 *    user can't impersonate someone else. X-Audit-Auth carries the
 *    browser user's PB token, which we verify here rather than trusting
 *    a name.
 */
function resolveActor(e) {
  let info = null;
  try { info = e.requestInfo(); } catch (_) { info = null; }
  const auth = e.auth;
  const isSuper = !!(auth && auth.isSuperuser && auth.isSuperuser());

  if (auth && !isSuper) {
    return {
      id: auth.id,
      name: displayName(auth),
      email: auth.getString("email"),
      source: header(info, "x-audit-source") || "web",
    };
  }

  const source = header(info, "x-audit-source") || (isSuper ? "api" : "unknown");
  const token = header(info, "x-audit-auth");
  if (isSuper && token) {
    try {
      const user = e.app.findAuthRecordByToken(token, "auth");
      if (user && !(user.isSuperuser && user.isSuperuser())) {
        return { id: user.id, name: displayName(user), email: user.getString("email"), source: source };
      }
    } catch (_) {
      // Expired / invalid token — fall through to the name hints.
    }
  }
  if (isSuper) {
    const name = header(info, "x-audit-actor-name");
    const email = header(info, "x-audit-actor-email");
    return {
      id: header(info, "x-audit-actor-id"),
      name: name || email || (source === "api" ? "Automation (admin API)" : "System"),
      email: email,
      source: source,
    };
  }
  return { id: "", name: "Unknown", email: "", source: source };
}

function findDeliveryNoteId(app, number) {
  if (!number) return "";
  try {
    return app.findFirstRecordByData("delivery_notes", "delivery_note_number", number).id;
  } catch (_) {
    return "";
  }
}

/** Where the change shows up: { parentType, parentId, label, refs }. */
function resolveParent(app, collection, data) {
  const d = data || {};
  const refs = [];
  if (d.delivery_note_number) refs.push("dn:" + d.delivery_note_number);
  switch (collection) {
    case "quotes":
      return { parentType: "quote", parentId: d.id, label: d.quote_number || "", refs: refs };
    case "quote_items":
      return { parentType: "quote", parentId: d.quote, label: d.description || "", refs: refs };
    case "quote_attachments":
      return { parentType: "quote", parentId: d.quote, label: d.filename || "", refs: refs };
    case "orders":
      if (d.quote) refs.push("quote:" + d.quote);
      return { parentType: "order", parentId: d.id, label: d.order_number || "", refs: refs };
    case "order_items":
      if (d.order) {
        return { parentType: "order", parentId: d.order, label: d.description || "", refs: refs };
      }
      // Ad-hoc delivery-note lines have no parent order.
      return {
        parentType: "delivery_note",
        parentId: findDeliveryNoteId(app, d.delivery_note_number),
        label: d.description || "",
        refs: refs,
      };
    case "delivery_notes":
      if (d.order) refs.push("order:" + d.order);
      return { parentType: "delivery_note", parentId: d.id, label: d.delivery_note_number || "", refs: refs };
  }
  return null;
}

/**
 * Write one audit row. Never throws — an audit failure must not undo
 * or fail the user's actual save.
 */
function log(e, action, before, after) {
  try {
    const collection = (after || before).collectionName;
    const data = after || before;
    const parent = resolveParent(e.app, collection, data);
    if (!parent || !parent.parentId) return;

    let changes;
    let finalAction = action;
    if (action === "update") {
      changes = diff(before, after);
      if (changes.length === 0) return;
    } else if (action === "create") {
      changes = snapshotChanges(collection, after, "to");
      if (collection === "quote_attachments") {
        finalAction = after.kind === "pdf" ? "pdf_generated" : "attachment_added";
      }
    } else {
      changes = snapshotChanges(collection, before, "from");
    }

    const actor = resolveActor(e);
    const col = e.app.findCollectionByNameOrId("audit_log");
    const row = new Record(col);
    row.set("collection_name", collection);
    row.set("record_id", data.id);
    row.set("parent_type", parent.parentType);
    row.set("parent_id", parent.parentId);
    row.set("action", finalAction);
    row.set("label", String(parent.label || "").slice(0, 500));
    row.set("changes", changes);
    row.set("actor_id", String(actor.id || "").slice(0, 32));
    row.set("actor_name", String(actor.name || "").slice(0, 200));
    row.set("actor_email", String(actor.email || "").slice(0, 200));
    row.set("source", String(actor.source || "").slice(0, 32));
    row.set("refs", parent.refs.join(" ").slice(0, 500));
    e.app.save(row);
  } catch (err) {
    console.log("[audit_log] failed to record " + action + ": " + err);
  }
}

module.exports = { toPlain: toPlain, diff: diff, log: log };