// lib/letter-runner.ts
// SERVER-ONLY — orchestrates the full Phase 6 letter workflow for a given
// resolution. Called by:
//
//   1. app/api/resolutions/sign/[token]/route.ts  — when last signer signs
//      (this is the FINAL send: assemble the signed letter + email everyone)
//
//   2. app/api/resolutions/[id]/letter/route.ts   — GET on demand (preview /
//      re-download) without sending emails
//
// What this module does:
//   1. Fetch resolution + company + attendees + signers from PB
//   2. Download each signed signer's signature PNG to a temp file
//   3. Call generateLetter() to assemble + render the PDF
//   4. Upload the PDF to PB under resolution.signed_letter
//   5. Optionally send the PDF to every signer + company primary email
//   6. Return a summary { ok, final_letter_file_id, emailed_to, errors }
//
// Failure mode: if ANY step fails, we still try to upload what we have and
// surface the partial result. We never throw — callers need to record the
// outcome on the resolution record so we can retry later.

import "server-only";
import { promises as fs } from "node:fs";
import * as path from "node:path";
import {
  pbFetch,
  createRecordMultipart,
  updateRecord,
} from "@/lib/pb";
import {
  generateLetter,
  saveSignatureToTempFile,
  type LetterContext,
  type LetterAttendee,
  type LetterSigner,
  type LetterCompany,
} from "@/lib/letter";
import { sendFinalLetterEmail, type EmailResult } from "@/lib/email";

const RES_COL = "pbc_266170881";
const ATTENDEE_COL = "pbc_1608833669";
const SIGNERS_COL = "pbc_1655122391";
const COMPANIES_COL = "pbc_3748838150"; // ysterbaard_companies

/**
 * Fold `director_role` to a single canonical key so casing / wording drift
 * between the wizard, older fixtures and the PB select options can never make a
 * real director silently vanish from the letter.
 *
 *   "resigned" | "RESIGNED DIRECTOR" | "Resigned_Director"  -> "resigned"
 *   "appointed" | "NEW DIRECTOR"     | "New Director"       -> "appointed"
 *   "existing"  | "EXISTING DIRECTOR"                      -> "existing"
 *   "external"                                            -> "external"
 */
export function normaliseRole(role: string | null | undefined): string {
  const key = (role ?? "").toLowerCase().replace(/[^a-z]/g, "");
  switch (key) {
    case "resigned":
    case "resigneddirector":
    case "resignation":
      return "resigned";
    case "appointed":
    case "appointment":
    case "newdirector":
    case "newappointment":
      return "appointed";
    case "existing":
    case "existingdirector":
      return "existing";
    case "external":
      return "external";
    default:
      return key;
  }
}

/**
 * PocketBase `date` fields come back as full ISO timestamps, e.g.
 * "2026-10-09 00:00:00.000Z". That string was being substituted straight into
 * the letter ("DATE EMAIL WAS SENT" → "2026-10-09 00:00:00.000Z") and into the
 * attachment filename, which is not a presentable date for a legal document.
 * Render it as "9 October 2026" instead.
 *
 * The date is parsed as UTC (PB stores midnight UTC), so we read the UTC parts
 * rather than letting the machine's local timezone shift it by a day.
 */
export function formatSaDate(value: string | null | undefined): string {
  if (!value) return "";
  // PB sends "2026-10-09 00:00:00.000Z" — space-separated, already Z-suffixed.
  // Normalise the space to "T" and only add a Z if there is no zone marker,
  // otherwise "...000Z" becomes "...000ZZ" and Date() returns NaN.
  let iso = value.trim().replace(" ", "T");
  if (!/(Z|[+-]\d{2}:?\d{2})$/.test(iso)) iso += "Z";
  const d = new Date(iso);
  if (Number.isNaN(d.getTime())) return String(value); // unparseable — pass through
  return d.toLocaleDateString("en-ZA", {
    day: "numeric",
    month: "long",
    year: "numeric",
    timeZone: "UTC",
  });
}

export interface AssembleLetterResult {
  ok: boolean;
  resolution_id: string;
  /** Filename of the final PDF (suggested). */
  filename: string;
  /** Number of signatures embedded. */
  signatures_embedded: number;
  /** Any unfilled placeholders detected (should be empty for a healthy template). */
  unfilled_placeholders: string[];
  /** PB record id for the uploaded final letter (empty if upload failed). */
  final_letter_record_id: string | null;
  /** Per-recipient email results (only populated when send=true). */
  emailed: Array<{ to: string; result: EmailResult }>;
  /** Non-fatal errors (each step's error message, if any). */
  errors: string[];
}

/**
 * End-to-end: assemble the signed letter for a resolution, upload to PB,
 * and optionally send it to every signer.
 *
 * @param resolutionId The PB id of the resolution to assemble
 * @param opts.send Set false to skip email send (useful for preview)
 */
export async function assembleAndDistributeLetter(
  resolutionId: string,
  opts: { send: boolean }
): Promise<AssembleLetterResult> {
  const errors: string[] = [];

  // 1. Load resolution + company + attendees + signers
  const ctx = await loadLetterContext(resolutionId).catch((err) => {
    errors.push(`load context: ${err instanceof Error ? err.message : String(err)}`);
    return null;
  });
  if (!ctx) {
    return blankResult(resolutionId, errors);
  }

  // 2. Generate letter (PDF)
  let pdf: Buffer;
  let filename: string;
  let signatures_embedded: number;
  let unfilled_placeholders: string[];
  try {
    const out = await generateLetter(ctx);
    pdf = out.pdf;
    filename = out.filename;
    signatures_embedded = out.signatures_embedded;
    unfilled_placeholders = out.unfilled_placeholders;
  } catch (err) {
    errors.push(`generate letter: ${err instanceof Error ? err.message : String(err)}`);
    return {
      ok: false,
      resolution_id: resolutionId,
      filename: "",
      signatures_embedded: 0,
      unfilled_placeholders: [],
      final_letter_record_id: null,
      emailed: [],
      errors,
    };
  }

  // 3. Upload to PB as a file field on the resolution.
  //
  // The field is `signed_letter`. This code used to append to `final_letter`,
  // which does not exist on `ysterbaard_resolutions` — PocketBase rejected the
  // unknown field and the failure was swallowed into `errors`, so the assembled
  // signed PDF was never actually stored.
  //
  // GUARD — never clobber a filed document with a blank regeneration.
  //
  // Most resolutions are signed on paper and filed by hand, not through the app.
  // If this runs with zero in-app signatures embedded (signatures_embedded === 0)
  // while a signed_letter is ALREADY stored, the freshly rendered PDF is a blank
  // template. Writing it over the operator's real signed document is silent,
  // irreversible data loss — the filed PDF is gone and the record now looks
  // "filed" while showing bare signature lines.
  //
  // So: only auto-write when the slot is empty, or when this assembly actually
  // contains signatures. The email step below still sends the assembled PDF, so
  // nothing is lost by skipping the write.
  let final_letter_record_id: string | null = null;
  try {
    const existing = await pbFetch<{ signed_letter?: string }>(
      `/api/collections/${RES_COL}/records/${encodeURIComponent(resolutionId)}`,
      { fields: "signed_letter" }
    ).catch(() => ({ signed_letter: "" }));
    const hasFiledCopy = typeof existing?.signed_letter === "string" && existing.signed_letter !== "";

    if (hasFiledCopy && signatures_embedded === 0) {
      errors.push(
        `kept existing signed_letter: this run embedded 0 signatures, so the ` +
          `regenerated PDF is an unsigned template and would have replaced the ` +
          `filed signed document`
      );
    } else {
      const form = new FormData();
      const file = new File([pdf], filename, { type: "application/pdf" });
      form.append("signed_letter", file, filename);

      // PB requires multipart PATCH to update a single record with files
      const url = `${process.env.PB_URL}/api/collections/${RES_COL}/records/${encodeURIComponent(resolutionId)}`;
      const token = process.env.PB_TOKEN;
      const res = await fetch(url, {
        method: "PATCH",
        headers: token ? { Authorization: token } : {},
        body: form,
        cache: "no-store",
      });
      if (!res.ok) {
        const text = await res.text();
        throw new Error(`HTTP ${res.status}: ${text.slice(0, 300)}`);
      }
      const updated = (await res.json()) as { signed_letter?: string };
      final_letter_record_id = updated.signed_letter ?? null;
    }
  } catch (err) {
    errors.push(`upload signed letter: ${err instanceof Error ? err.message : String(err)}`);
  }

  // 4. Send emails (if requested)
  const emailed: Array<{ to: string; result: EmailResult }> = [];
  if (opts.send) {
    // Write PDF to temp file (email helper takes a path)
    const tmpPath = path.join("/tmp", `letter-${resolutionId}-${Date.now()}.pdf`);
    await fs.writeFile(tmpPath, pdf);
    try {
      // Collect recipients: every signer + the company primary contact
      const recipients = new Set<string>();
      for (const s of ctx.signers) {
        if (s.attendee.email) recipients.add(s.attendee.email);
      }
      // We don't have a company-primary-email field on the resolution itself,
      // but the company's enterprise contact lives in the company record.
      // For now, just send to signers — Phase 7 can extend to company primary.

      for (const to of recipients) {
        const signer = ctx.signers.find((s) => s.attendee.email === to);
        const signerName = signer
          ? `${signer.attendee.name} ${signer.attendee.surname}`.trim()
          : "Signatory";
        const result = await sendFinalLetterEmail({
          to,
          signer_name: signerName,
          resolution_title: ctx.company.name,
          company_name: ctx.company.name,
          pdf_path: tmpPath,
          pdf_filename: filename,
        });
        emailed.push({ to, result });
        if (!result.ok) {
          errors.push(`email to ${to}: ${result.error ?? `exit ${result.exit_code}`}`);
        }
      }
    } finally {
      await fs.unlink(tmpPath).catch(() => {});
    }
  }

  return {
    ok: errors.length === 0,
    resolution_id: resolutionId,
    filename,
    signatures_embedded,
    unfilled_placeholders,
    final_letter_record_id,
    emailed,
    errors,
  };
}

// ─── Context loader ──────────────────────────────────────────────────────

export async function loadLetterContext(
  resolutionId: string
): Promise<LetterContext> {
  // Fetch resolution with company expand
  const resList = await pbFetch<{
    items: Array<{
      id: string;
      status: string;
      meeting_date: string;
      company: string;
      expand?: {
        company?: {
          id: string;
          enterprise_name: string;
          enterprise_no?: string;
          // Physical address fields
          physical_address_line_1?: string;
          physical_address_line_2?: string;
          physical_town_city?: string;
          physical_province?: string;
          physical_postal_code?: string;
          company_email?: string;
        };
      };
    }>;
  }>(`/api/collections/${RES_COL}/records`, {
    perPage: 1,
    filter: `id="${resolutionId.replace(/"/g, "''")}"`,
    expand: "company",
  });
  const res = resList.items[0];
  if (!res) throw new Error(`Resolution ${resolutionId} not found`);
  const company = res.expand?.company;
  if (!company) throw new Error(`Resolution ${resolutionId} has no expanded company`);

  const attendees = await pbFetch<{
    items: Array<{
      id: string;
      name: string;
      surname: string;
      email: string | null;
      director_role: string;
      attended: boolean;
      must_sign: boolean;
      director?: string | null;
      effective_date?: string;
      expand?: {
        director?: {
          id: string;
          /** Full SA ID number. This is the real field on `ysterbaard_directors`.
           *  There is no `id_number` field — reading that returned undefined and
           *  silently dropped every ID from the letter. */
          id_no?: string | null;
          id_no_masked?: string | null;
          /** Cell number. */
          telephone?: string | null;
        };
      };
    }>;
  }>(`/api/collections/${ATTENDEE_COL}/records`, {
    perPage: 500,
    filter: `resolution="${resolutionId}"`,
    expand: "director",
  });

  const signers = await pbFetch<{
    items: Array<{
      id: string;
      status: string;
      attendee: string;
      sign_token: string;
      email_to: string;
      sent_at: string | null;
      signed_at: string | null;
      signature?: string;
      expand?: {
        attendee?: {
          id: string;
          name: string;
          surname: string;
          email: string | null;
          director_role: string;
          director?: string | null;
          effective_date?: string;
        };
      };
    }>;
  }>(`/api/collections/${SIGNERS_COL}/records`, {
    perPage: 500,
    filter: `resolution="${resolutionId}"`,
    expand: "attendee",
  });

  // Build attendees list with ID numbers
  const letterAttendees: LetterAttendee[] = attendees.items.map((a) => ({
    id: a.id,
    name: a.name,
    surname: a.surname,
    email: a.email,
    director_role: a.director_role,
    attended: a.attended,
    must_sign: a.must_sign,
    director_id_number:
      a.expand?.director?.id_no ||
      a.expand?.director?.id_no_masked ||
      null,
    // Cell number for the signature block. It lives on the DIRECTOR record
    // (field: `telephone`), not on the attendee — the attendee only carries a
    // copy of the email.
    telephone: a.expand?.director?.telephone ?? null,
    effective_date: a.effective_date ? formatSaDate(a.effective_date) : null,
  }));

  // Build signers list, downloading signature PNGs to temp
  const letterSigners: LetterSigner[] = await Promise.all(
    signers.items.map(async (s) => {
      const att = s.expand?.attendee;
      const attId = att?.id ?? s.attendee;
      const attendee =
        letterAttendees.find((la) => la.id === attId) ?? {
          id: attId,
          name: att?.name ?? "",
          surname: att?.surname ?? "",
          email: att?.email ?? null,
          director_role: att?.director_role ?? "DIRECTOR",
          attended: true,
          must_sign: true,
          director_id_number: null,
          telephone: null,
          effective_date: null,
        };
      let signature_path: string | null = null;
      if (s.signature && s.status === "signed") {
        signature_path = await downloadSignerSignature(s.id, s.signature);
      }
      return {
        id: s.id,
        attendee_id: attId,
        status: s.status as "pending" | "signed" | "expired",
        signature_path,
        signed_at: s.signed_at,
        attendee,
      };
    })
  );

  // Resigning + newly-appointed labels.
  //
  // CRITICAL: the canonical values written by the app are LOWERCASE and short
  // — app/api/resolutions/create/route.ts writes "resigned" / "appointed" /
  // "existing" / "external". Older code (and scripts/smoke_phase6.py) compared
  // against "RESIGNED DIRECTOR" / "NEW DIRECTOR", which never match real data.
  // That made `resigners` empty, both labels fell back to the "None this
  // meeting" sentinel, and _neutralise_empty_sections() then DELETED the
  // resignation and appointment sections from the letter entirely.
  //
  // normaliseRole() therefore folds case and separators so every spelling the
  // DB or an old fixture might contain resolves to the same role.
  const resigners = letterAttendees.filter(
    (a) => normaliseRole(a.director_role) === "resigned"
  );
  const newlyAppointed = letterAttendees.filter(
    (a) => normaliseRole(a.director_role) === "appointed"
  );

  // Address formatting — use the structured address fields from
  // ysterbaard_companies (physical_address_line_1/2/_town_city/_province/_postal_code).
  const c = company;
  const addressLines = [
    c.physical_address_line_1,
    c.physical_address_line_2,
    [c.physical_town_city, c.physical_province, c.physical_postal_code]
      .filter(Boolean)
      .join(", "),
  ].filter(Boolean) as string[];
  const address = addressLines.join(", ");
  const address_city = c.physical_town_city ?? "";

  const letterCompany: LetterCompany = {
    name: c.enterprise_name,
    enterprise_no: c.enterprise_no ?? "",
    address,
    address_city,
  };

  return {
    letter_type: "director_change",
    resolution_id: resolutionId,
    meeting_date: formatSaDate(res.meeting_date),
    company: letterCompany,
    attendees: letterAttendees,
    signers: letterSigners,
    resigning_director_label:
      resigners.length > 0
        ? resigners
            .map((a) =>
              `${a.name} ${a.surname}${a.director_id_number ? ` (${a.director_id_number})` : ""}`.trim()
            )
            .join(" and ")
        // When there are no resignations this meeting, set a sentinel
        // string that subst.py recognises. The python subst uses this
        // string to neutralise §2 / OR1 / OR2 paragraphs (replacing the
        // imperative "the resignation of [X]" prose with a one-line
        // "None this meeting" notice instead of leaving a literal
        // placeholder in the rendered PDF).
        : "None this meeting",
    newly_appointed_director_label:
      newlyAppointed.length > 0
        ? newlyAppointed
            .map((a) =>
              `${a.name} ${a.surname}${a.director_id_number ? ` (${a.director_id_number})` : ""}`.trim()
            )
            .join(" and ")
        // Same sentinel — subst.py neutralises §3 / OR3 / OR4 paragraphs.
        : "None this meeting",
  };
}

/**
 * Download a signer's signature PNG from PocketBase file storage to a temp
 * file. PB file URLs are like `/api/files/<collection>/<record>/`.
 * We fetch them with the admin token.
 */
async function downloadSignerSignature(
  signerId: string,
  signatureField: string
): Promise<string | null> {
  // signatureField is the filename (PB stores files by name)
  // The record id is needed for the URL — but PB returns just the filename
  // from the field accessor. We need the parent collection's id.
  const token = process.env.PB_TOKEN;
  const signersUrl = `${process.env.PB_URL}/api/collections/${SIGNERS_COL}/records/${signerId}`;
  try {
    const recRes = await fetch(signersUrl, {
      headers: { Authorization: token ?? "" },
      cache: "no-store",
    });
    if (!recRes.ok) return null;
    const rec = (await recRes.json()) as { collectionId: string; id: string };
    const fileUrl = `${process.env.PB_URL}/api/files/${rec.collectionId}/${rec.id}/${signatureField}`;
    const fileRes = await fetch(fileUrl, {
      headers: { Authorization: token ?? "" },
      cache: "no-store",
    });
    if (!fileRes.ok) return null;
    const buf = Buffer.from(await fileRes.arrayBuffer());
    return await saveSignatureToTempFile(signerId, buf);
  } catch {
    return null;
  }
}

function blankResult(
  resolutionId: string,
  errors: string[]
): AssembleLetterResult {
  return {
    ok: false,
    resolution_id: resolutionId,
    filename: "",
    signatures_embedded: 0,
    unfilled_placeholders: [],
    final_letter_record_id: null,
    emailed: [],
    errors,
  };
}