import fs from "fs";
import path from "path";
import { PDFDocument, PDFFont, PDFForm, StandardFonts } from "pdf-lib";

/**
 * Fills the 2024 ADA Dental Claim Form (J43024) for payers that only accept
 * paper claims (e.g. BCBS MA). Field names come from the template's AcroForm;
 * signatures are left blank for wet signing; only item 53's date is filled (claim date).
 */

const TEMPLATE_PATH = path.join(__dirname, "../data/templates/ada-claim-form-2024.pdf");
const PROCEDURE_CODES_PATH = path.join(__dirname, "../data/procedureCodes.json");

const LINES_PER_FORM = 10;
const FONT_SIZE = 10;
const MIN_FONT_SIZE = 6;

export type AdaPayer = {
  name: string;
  address1: string;
  address2?: string;
  cityStateZip: string;
};

export const ADA_PAYERS: Record<string, AdaPayer> = {
  BCBS_MA: {
    name: "Blue Cross Blue Shield of MA",
    address1: "P.O. Box 986005",
    cityStateZip: "Boston, MA 02298",
  },
  ALTUS: {
    name: "Altus Dental",
    address1: "P.O. Box 1557",
    cityStateZip: "Providence, RI 02901-1557",
  },
  DELTA_INDIV: {
    name: "Delta Dental",
    address1: "P.O. Box 103",
    cityStateZip: "Stevens Point, WI 54481-0103",
  },
};

/** ADA payer key for a claim's insurance provider text (defaults to BCBS MA). */
export function adaPayerKeyForProvider(provider?: string | null): string {
  const p = provider ?? "";
  if (/altus/i.test(p)) return "ALTUS";
  if (/delta\s*(dental\s*)?indiv/i.test(p)) return "DELTA_INDIV";
  return "BCBS_MA";
}

export type AdaClaimInput = {
  claim: {
    id: number;
    createdAt?: Date | string | null;
    memberId?: string | null;
    remarks?: string | null;
    status?: string | null;
    preAuthNumber?: string | null;
    missingTeeth?: unknown;
    serviceLines: {
      procedureCode: string;
      procedureDate: Date | string;
      quad?: string | null;
      arch?: string | null;
      toothNumber?: string | null;
      toothSurface?: string | null;
      totalBilled: unknown;
    }[];
  };
  patient: {
    id: number;
    firstName: string;
    lastName: string;
    dateOfBirth?: Date | string | null;
    gender?: string | null;
    address?: string | null;
    city?: string | null;
    state?: string | null;
    zipCode?: string | null;
    insuranceId?: string | null;
    groupNumber?: string | null;
    policyHolder?: string | null;
    policyHolderRelationship?: string | null;
  };
  /** Policy holder's own patient record (Patient.policyHolderPatientId), when not self */
  policyHolderPatient?: {
    firstName: string;
    lastName: string;
    dateOfBirth?: Date | string | null;
    gender?: string | null;
    address?: string | null;
    city?: string | null;
    state?: string | null;
    zipCode?: string | null;
  } | null;
  office: {
    legalName?: string | null;
    officeName?: string | null;
    phoneNumber?: string | null;
    streetAddress?: string | null;
    city?: string | null;
    state?: string | null;
    zipCode?: string | null;
    billingName?: string | null;
    billingNpi?: string | null;
    billingLicense?: string | null;
    billingTaxId?: string | null;
  } | null;
  treatingProvider: {
    npiNumber: string;
    licenseNumber?: string | null;
  } | null;
  payer: AdaPayer;
  /** Appointment notes — item 43/44 (replacement of prosthesis) */
  appointmentNotes?: string | null;
};

let descriptionByCode: Map<string, string> | null = null;
function cdtDescription(code: string): string {
  if (!descriptionByCode) {
    descriptionByCode = new Map();
    try {
      const rows = JSON.parse(fs.readFileSync(PROCEDURE_CODES_PATH, "utf8")) as {
        "Procedure Code": string;
        Description: string;
      }[];
      for (const r of rows) descriptionByCode.set(r["Procedure Code"].toUpperCase(), r.Description);
    } catch {
      // descriptions are optional on the form
    }
  }
  return descriptionByCode.get(code.toUpperCase()) ?? "";
}

function fmtDate(d: Date | string | null | undefined): string {
  if (!d) return "";
  const date = d instanceof Date ? d : new Date(d);
  if (isNaN(date.getTime())) return "";
  const mm = String(date.getUTCMonth() + 1).padStart(2, "0");
  const dd = String(date.getUTCDate()).padStart(2, "0");
  return `${mm}/${dd}/${date.getUTCFullYear()}`;
}

/** Preauth forms show procedures as planned this many days after the preauth (appointment) date. */
const PREAUTH_PROCEDURE_DAYS_AFTER = 6;

/** Shifts a date-only value (stored as UTC midnight) by whole days. */
function addDays(d: Date | string | null | undefined, days: number): Date | null {
  if (!d) return null;
  const date = new Date(d instanceof Date ? d.getTime() : d);
  if (isNaN(date.getTime())) return null;
  date.setUTCDate(date.getUTCDate() + days);
  return date;
}

/** A timestamp as the office's local calendar date (fmtDate is for date-only values stored as UTC midnight). */
function fmtLocalDate(d: Date | string | null | undefined): string {
  if (!d) return "";
  const date = d instanceof Date ? d : new Date(d);
  if (isNaN(date.getTime())) return "";
  const mm = String(date.getMonth() + 1).padStart(2, "0");
  const dd = String(date.getDate()).padStart(2, "0");
  return `${mm}/${dd}/${date.getFullYear()}`;
}

const PROSTHESIS_WORDS = "crowns?|bridges?|dentures?|partials?|prosthes[ie]s|prosthetics?|pontics?|veneers?|onlays?|inlays?|fpd|rpd|implants?";
const REPLACE_WORDS = "replac(?:e|ed|es|ing|ement)|remake|re-make|redo|re-do";

/**
 * Item 43/44: does the note say an existing prosthesis is being replaced
 * (e.g. "replace old crown #3", "bridge replacement", "replacement of prosthesis")?
 * Returns the prior placement date when the note gives one as MM/DD/YYYY.
 */
export function prosthesisReplacement(notes?: string | null): { replacement: boolean; priorDate?: string } {
  const s = (notes ?? "").toLowerCase();
  const replaceThenProsthesis = new RegExp(`\\b(?:${REPLACE_WORDS})\\b[^.;\\n]{0,30}?\\b(?:${PROSTHESIS_WORDS})\\b`);
  const prosthesisThenReplace = new RegExp(`\\b(?:${PROSTHESIS_WORDS})\\b[^.;\\n]{0,15}?\\b(?:${REPLACE_WORDS})\\b`);
  // "replace missing #19 with bridge" is a new prosthesis for a lost tooth, not a replacement
  const hit = [s.match(replaceThenProsthesis), s.match(prosthesisThenReplace)].find(
    (m) => m && !/\b(?:missing|extracted|lost)\b/.test(m[0]),
  );
  if (!hit) return { replacement: false };
  const m = s.match(/\b(\d{1,2})[/-](\d{1,2})[/-](\d{4}|\d{2})\b/);
  if (!m) return { replacement: true };
  const year = m[3]!.length === 2 ? `20${m[3]}` : m[3]!;
  return { replacement: true, priorDate: `${m[1]!.padStart(2, "0")}/${m[2]!.padStart(2, "0")}/${year}` };
}

function fmtMoney(v: unknown): string {
  const n = Number(v ?? 0);
  return isNaN(n) ? "" : n.toFixed(2);
}

function cityStateZip(city?: string | null, state?: string | null, zip?: string | null): string {
  const left = [city?.trim(), state?.trim()].filter(Boolean).join(", ");
  return [left, zip?.trim()].filter(Boolean).join(" ");
}

/** Item 25: ADA area-of-oral-cavity codes. */
function oralCavityArea(quad?: string | null, arch?: string | null): string {
  switch ((quad ?? "").toUpperCase()) {
    case "UR": return "10";
    case "UL": return "20";
    case "LL": return "30";
    case "LR": return "40";
  }
  switch ((arch ?? "").toLowerCase()) {
    case "maxilla": return "01";
    case "mandible": return "02";
  }
  return "";
}

/** "M"/"F"/"U" from free-text gender. */
function genderCode(g?: string | null): "M" | "F" | "U" {
  const s = (g ?? "").trim().toLowerCase();
  if (s.startsWith("m")) return "M";
  if (s.startsWith("f")) return "F";
  return "U";
}

function splitPhone(phone?: string | null): [string, string, string] | null {
  const digits = (phone ?? "").replace(/\D/g, "").replace(/^1(?=\d{10}$)/, "");
  if (digits.length !== 10) return null;
  return [digits.slice(0, 3), digits.slice(3, 6), digits.slice(6)];
}

function normName(s: string): string {
  return s.toLowerCase().replace(/[^a-z]/g, " ").split(/\s+/).filter(Boolean).sort().join(" ");
}

function setText(form: PDFForm, name: string, value: string | null | undefined) {
  if (!value) return;
  const field = form.getTextField(name);
  field.setFontSize(FONT_SIZE);
  field.setText(value);
}

/** Left-aligned text shrunk (then truncated) to fit the field width. */
function setFittedText(form: PDFForm, font: PDFFont, name: string, value: string) {
  if (!value) return;
  const field = form.getTextField(name);
  const width = field.acroField.getWidgets()[0]!.getRectangle().width - 4;
  let size = FONT_SIZE;
  while (size > MIN_FONT_SIZE && font.widthOfTextAtSize(value, size) > width) size -= 0.5;
  let text = value;
  while (text.length > 1 && font.widthOfTextAtSize(text, size) > width) text = text.slice(0, -1);
  field.setAlignment(0);
  field.setFontSize(size);
  field.setText(text);
}

function check(form: PDFForm, name: string) {
  form.getCheckBox(name).check();
}

/** Field-name suffix for service line i (0-based): "1".."9", then "Row10" (Fee uses "10"). */
function lineSuffix(i: number, field: "fee" | "other"): string {
  if (i < 9) return String(i + 1);
  return field === "fee" ? "10" : "Row10";
}

async function fillOnePage(
  template: Uint8Array,
  input: AdaClaimInput,
  lines: AdaClaimInput["claim"]["serviceLines"],
): Promise<PDFDocument> {
  const doc = await PDFDocument.load(template);
  // Keep page 1 only (pages 2-3 are instructions / fraud warnings)
  while (doc.getPageCount() > 1) doc.removePage(doc.getPageCount() - 1);
  const form = doc.getForm();
  const helvetica = await doc.embedFont(StandardFonts.Helvetica);
  const { claim, patient, office, treatingProvider, payer } = input;
  const officeState = office?.state ?? "";

  // 1-2. Header
  if (claim.status === "PREAUTH") {
    check(form, "1 Check Box 1");
    setText(form, "2 PredeterminationPreauthorization Number", claim.preAuthNumber);
  } else {
    check(form, "1 Check Box 2");
  }

  // 3. Payer
  setText(form, "3 CompanyPlan Name", payer.name);
  setText(form, "3 Address 1", payer.address1);
  setText(form, "3 Address 2", payer.address2);
  setText(form, "3 City, State, Zip Code", payer.cityStateZip);

  // 12-23. Subscriber / patient
  const patientName = `${patient.lastName}, ${patient.firstName}`;
  const patientCsz = cityStateZip(
    patient.city,
    patient.state || (patient.address || patient.city ? officeState : ""),
    patient.zipCode,
  );
  const dob = fmtDate(patient.dateOfBirth);
  const gender = genderCode(patient.gender);
  const genderBox = { M: "Check Box1", F: "Check Box2", U: "Check Box3" }[gender];

  const holder = (patient.policyHolder ?? "").trim();
  const relationship = (patient.policyHolderRelationship ?? "").trim().toUpperCase();
  const isSelf = relationship
    ? relationship === "SELF"
    : !holder ||
      holder.toLowerCase() === "self" ||
      normName(holder) === normName(`${patient.firstName} ${patient.lastName}`);

  if (isSelf) {
    setText(form, "12 PolicyholderSubscriber Name Last First Middle Initial Suffix", patientName);
    setText(form, "12 Address 1", patient.address);
    setText(form, "12 City, State, Zip", patientCsz);
    setText(form, "13 Date of Birth MMDDCCYY", dob);
    check(form, `14 ${genderBox}`);
  } else if (input.policyHolderPatient) {
    // Subscriber is another patient in the system: fill 12-14 from their record
    const h = input.policyHolderPatient;
    setText(form, "12 PolicyholderSubscriber Name Last First Middle Initial Suffix", `${h.lastName}, ${h.firstName}`);
    setText(form, "12 Address 1", h.address);
    setText(
      form,
      "12 City, State, Zip",
      cityStateZip(h.city, h.state || (h.address || h.city ? officeState : ""), h.zipCode),
    );
    setText(form, "13 Date of Birth MMDDCCYY", fmtDate(h.dateOfBirth));
    const hGenderBox = { M: "Check Box1", F: "Check Box2", U: "Check Box3" }[genderCode(h.gender)];
    check(form, `14 ${hGenderBox}`);
  } else {
    // Subscriber typed by name only: DOB, gender and address are completed by hand.
    setText(form, "12 PolicyholderSubscriber Name Last First Middle Initial Suffix", holder);
  }
  // 18. Relationship to policyholder: Self, Spouse, Dependent Child, Other (left to right)
  const relationshipBox = isSelf
    ? "Check Box1"
    : { SPOUSE: "Check Box2", DEPENDENT: "Check Box3", OTHER: "Check Box4" }[relationship];
  if (relationshipBox) check(form, `18 ${relationshipBox}`);
  setText(form, "15 Policyho derSubscriber ID Assigned by Plan", claim.memberId || patient.insuranceId);
  setText(form, "16 PlanGroup Number", patient.groupNumber);

  setText(form, "20 Name Last First Middle Initial Suffix", patientName);
  setText(form, "20 Address 1", patient.address);
  setText(form, "20 City, State, Zip", patientCsz);
  setText(form, "21 Date of Birth MMDDCCYY", dob);
  check(form, `22 ${genderBox}`);

  // 24-31. Service lines (a preauth lists the planned date: 6 days after the preauth date)
  const isPreauth = claim.status === "PREAUTH";
  let total = 0;
  lines.forEach((line, i) => {
    const s = lineSuffix(i, "other");
    const tooth = (line.toothNumber ?? "").trim();
    setText(
      form,
      `24 Procedure Date MMDDCCYY${s}`,
      fmtDate(isPreauth ? addDays(line.procedureDate, PREAUTH_PROCEDURE_DAYS_AFTER) : line.procedureDate),
    );
    setText(form, `25 Area of Oral Cavity${s}`, oralCavityArea(line.quad, line.arch));
    setText(form, `27 Tooth Numbers or Letters${s}`, tooth);
    setText(form, `28 Tooth Surface${s}`, (line.toothSurface ?? "").trim());
    setText(form, `29 Procedure Code${s}`, line.procedureCode.trim().toUpperCase());
    setFittedText(form, helvetica, `30 Description${s}`, cdtDescription(line.procedureCode.trim()));
    setText(form, `31 Fee${lineSuffix(i, "fee")}`, fmtMoney(line.totalBilled));
    total += Number(line.totalBilled ?? 0) || 0;
  });
  setText(form, "32 Total Fee", total.toFixed(2));

  // 33. Missing teeth — { "T_14": "X", ... }; only permanent teeth 1-32 have boxes
  if (claim.missingTeeth && typeof claim.missingTeeth === "object") {
    for (const [key, val] of Object.entries(claim.missingTeeth as Record<string, unknown>)) {
      const n = Number(key.replace(/^T_/, ""));
      if (val === "X" && Number.isInteger(n) && n >= 1 && n <= 32) check(form, `33 box${n}`);
    }
  }

  // 35. Remarks
  setText(form, "35 Remarks", claim.remarks?.trim());

  // 38-40. Ancillary
  setText(form, "38 Place of Treatment", "11");
  check(form, "40 Check Box1");
  // 43-44. Replacement of prosthesis: Yes only when the appointment notes say so
  const replacement = prosthesisReplacement(input.appointmentNotes);
  if (replacement.replacement) {
    check(form, "43 Check Box2");
    setText(form, "44 Date of Prior Placement MMDDCCYY", replacement.priorDate);
  } else {
    check(form, "43 Check Box1");
  }

  // 48-52. Billing dentist: legal name, office name (DBA) and address (Settings > Office Contact)
  const officeCsz = cityStateZip(office?.city, office?.state, office?.zipCode);
  const legalName = (office?.legalName || office?.billingName || "").trim();
  const dbaName = office?.officeName?.trim() ?? "";
  const street = office?.streetAddress?.trim() ?? "";
  const billingLines = [legalName, dbaName !== legalName ? dbaName : "", street].filter(Boolean);
  setText(form, "48 Name", billingLines[0]);
  setText(form, "48 Address", billingLines[1]);
  setText(form, "48 Address 2", billingLines[2]);
  setText(form, "48 City, State, Zip", officeCsz);
  setText(form, "49 NPI", office?.billingNpi);
  setText(form, "50 License Number", office?.billingLicense);
  setText(form, "51 SSN or TIN", office?.billingTaxId);

  const phone = splitPhone(office?.phoneNumber);
  if (phone) {
    for (const item of ["52", "57"]) {
      setText(form, `${item} area code`, phone[0]);
      setText(form, `${item} phone 1`, phone[1]);
      setText(form, `${item} phone 2`, phone[2]);
    }
  }

  // 53. Signature stays blank; date = claim date (when the claim was made)
  setText(form, "53 Date", fmtLocalDate(claim.createdAt ?? new Date()));

  // 54-56. Treating dentist and location
  setText(form, "54 NPI", treatingProvider?.npiNumber);
  setText(form, "55 License Number", treatingProvider?.licenseNumber || office?.billingLicense);
  // 56. Treatment location: office address only
  setFittedText(form, helvetica, "56 Address 1", street);
  setFittedText(form, helvetica, "56 Address 2", officeCsz);

  form.updateFieldAppearances(helvetica);
  form.flatten();
  return doc;
}

/** Returns the filled form; claims with more than 10 lines continue on additional complete forms. */
export async function buildAdaClaimPdf(input: AdaClaimInput): Promise<Uint8Array> {
  const template = fs.readFileSync(TEMPLATE_PATH);
  const lines = input.claim.serviceLines;
  const out = await PDFDocument.create();
  for (let i = 0; i < Math.max(lines.length, 1); i += LINES_PER_FORM) {
    const filled = await fillOnePage(template, input, lines.slice(i, i + LINES_PER_FORM));
    const [page] = await out.copyPages(filled, [0]);
    out.addPage(page!);
  }
  out.setTitle(`ADA Claim Form - ${input.patient.lastName}, ${input.patient.firstName}`);
  return out.save();
}