import { createHash } from 'node:crypto';
import Boom from '@hapi/boom';
import { z } from 'zod';
import { db } from '../db/knex.js';
import { auditFromRequest } from '../middleware/audit.js';
import { agreementHtml } from '../pdf/agreementHtml.js';
import { renderPdf } from '../pdf/render.js';
import { refreshAgreementPdfs } from './agreementPdfRefresh.js';
import { readPngDataUrl } from './png.js';
import { recordAudit } from './audit.js';
import { finalizeSubmittedApplication } from './applicationApproval.js';
import {
  applicationFromRequest,
  assertCompleteApplication,
  presentApplication,
} from './applications.js';
import { notifySubmission } from './mail.js';
import { getSignatory } from './settings.js';
import { deleteObject, getObject, getPresignedUrl, putObject } from './storage.js';

const PNG_LIMIT = 200 * 1024;

const signSchema = z.discriminatedUnion('type', [
  z.object({
    type: z.literal('DRAWN'),
    image: z.string().min(1),
  }),
  z.object({
    type: z.literal('TYPED'),
    typedName: z.string().trim().min(1).max(255),
  }),
]);

/**
 * @param {Record<string, unknown>} application
 */
export async function presentWithPdf(application) {
  await refreshAgreementPdfs(application);
  const body = presentApplication(application);
  const finalKey = application.final_pdf_key ? String(application.final_pdf_key) : null;
  const signedKey = application.signed_pdf_key ? String(application.signed_pdf_key) : null;

  if (signedKey) {
    body.signedPdfUrl = await getPresignedUrl(signedKey);
  }

  if (finalKey) {
    body.finalPdfUrl = await getPresignedUrl(finalKey);
  }

  // Prefer the final CREST-signed PDF for previews (same as admin).
  const previewKey = finalKey || signedKey;
  if (previewKey) {
    body.pdfUrl = previewKey === finalKey ? body.finalPdfUrl : body.signedPdfUrl;
  }

  if (application.cancelled_cheque_key) {
    body.cancelledChequeUrl = await getPresignedUrl(String(application.cancelled_cheque_key));
  }

  return body;
}

/**
 * @param {Record<string, unknown>} application
 */
async function crestSignatory(application) {
  if (application.status !== 'APPROVED') {
    return null;
  }

  const settings = await getSignatory();
  let signatureDataUrl = '';

  if (settings.signatureKey) {
    const bytes = await getObject(settings.signatureKey);
    signatureDataUrl = `data:image/png;base64,${Buffer.from(bytes).toString('base64')}`;
  }

  return {
    name: settings.name,
    designation: settings.designation,
    signatureDataUrl,
  };
}

/**
 * @param {Record<string, unknown>} application
 * @param {{ draft: boolean, physicianSignature?: { type: string, imageDataUrl?: string, typedName?: string, signedAt?: string } | null }} options
 */
async function renderAgreement(application, options) {
  const html = agreementHtml({
    application: presentApplication(application),
    signatory: await crestSignatory(application),
    physicianSignature: options.physicianSignature,
    draft: options.draft,
  });
  return renderPdf(html);
}

/**
 * The database runs in UTC, but the driver writes JS Dates in the writing
 * machine's time zone; an explicit UTC string keeps signing times comparable.
 * @param {Date} date
 */
function utcDateTime(date) {
  return date.toISOString().slice(0, 19).replace('T', ' ');
}

/**
 * @param {string} image
 */
function readPng(image) {
  return readPngDataUrl(image, PNG_LIMIT, 'The signature image must be 200KB or smaller');
}

/**
 * @param {import('@hapi/hapi').Request} request
 */
export async function previewApplication(request) {
  const application = await applicationFromRequest(request);

  if (application.status !== 'DRAFT' && application.status !== 'REJECTED') {
    throw Boom.conflict('This application can no longer be edited');
  }

  assertCompleteApplication(application);
  const pdf = await renderAgreement(application, { draft: true, physicianSignature: null });
  const key = `applications/${application.public_id}/v${application.version}/draft.pdf`;
  await putObject(key, pdf, 'application/pdf');
  await db('applications').where({ id: application.id }).update({ draft_pdf_key: key });
  await auditFromRequest(request, {
    actorType: 'PHYSICIAN',
    actorId: application.id,
    action: 'APPLICATION_PREVIEWED',
    entityType: 'applications',
    entityId: application.id,
  });

  return { url: await getPresignedUrl(key) };
}

/**
 * @param {import('@hapi/hapi').Request} request
 */
export async function signApplication(request) {
  const application = await applicationFromRequest(request);

  if (application.status !== 'DRAFT') {
    throw Boom.conflict('This application can no longer be signed');
  }

  assertCompleteApplication(application);
  const parsed = signSchema.safeParse(request.payload);

  if (!parsed.success) {
    throw Boom.badRequest('A signature is required');
  }

  const signature = parsed.data;
  const png = signature.type === 'DRAWN' ? readPng(signature.image) : null;
  const signedAt = new Date();
  const signedAtUtc = utcDateTime(signedAt);
  const physicianSignature =
    signature.type === 'DRAWN'
      ? {
          type: 'DRAWN',
          imageDataUrl: `data:image/png;base64,${png.toString('base64')}`,
          signedAt: signedAtUtc,
        }
      : { type: 'TYPED', typedName: signature.typedName, signedAt: signedAtUtc };
  const pdf = await renderAgreement(application, { draft: false, physicianSignature });
  const sha256 = createHash('sha256').update(pdf).digest('hex');
  const pdfKey = `applications/${application.public_id}/v${application.version}/signed.pdf`;
  const imageKey = `applications/${application.public_id}/v${application.version}/signature.png`;
  let storedImage = false;
  let storedPdf = false;

  try {
    if (png) {
      await putObject(imageKey, png, 'image/png');
      storedImage = true;
    }

    await putObject(pdfKey, pdf, 'application/pdf');
    storedPdf = true;
    await db.transaction(async (trx) => {
      const current = await trx('applications').where({ id: application.id }).forUpdate().first();

      if (!current || current.status !== 'DRAFT') {
        throw Boom.conflict('This application can no longer be signed');
      }

      await trx('signatures').insert({
        application_id: application.id,
        version: application.version,
        type: signature.type,
        image_key: png ? imageKey : null,
        typed_text: signature.type === 'TYPED' ? signature.typedName : null,
        signed_at: signedAtUtc,
        created_at: signedAtUtc,
        ip: request.info.remoteAddress,
        user_agent: request.headers['user-agent'] ?? null,
      });
      await trx('applications').where({ id: application.id }).update({
        status: 'SUBMITTED',
        submitted_at: signedAt,
        signed_pdf_key: pdfKey,
        signed_pdf_sha256: sha256,
      });
      await recordAudit(
        {
          actorType: 'PHYSICIAN',
          actorId: application.id,
          action: 'APPLICATION_SIGNED',
          entityType: 'applications',
          entityId: application.id,
          ip: request.info.remoteAddress,
          metadata: { sha256 },
        },
        trx,
      );
    });
  } catch (error) {
    if (storedPdf) {
      await deleteObject(pdfKey).catch(() => {});
    }

    if (storedImage) {
      await deleteObject(imageKey).catch(() => {});
    }

    throw error;
  }

  const saved = await db('applications').where({ id: application.id }).first();

  try {
    const finalized = await finalizeSubmittedApplication(request, saved, {
      decidedBy: null,
      actorType: 'SYSTEM',
      actorId: null,
      action: 'APPLICATION_AUTO_APPROVED',
    });
    const body = await presentWithPdf(finalized.application);
    body.surveyToken = finalized.surveyToken;
    return body;
  } catch (error) {
    request.log(['warn', 'auto-approve'], error);
    await notifySubmission(saved);
    return presentWithPdf(saved);
  }
}

/**
 * @param {import('@hapi/hapi').Request} request
 */
export async function editApplication(request) {
  const application = await applicationFromRequest(request);

  if (application.status === 'SUBMITTED' || application.status === 'APPROVED') {
    throw Boom.conflict('This application can no longer be edited');
  }

  if (application.status === 'DRAFT') {
    return presentWithPdf(application);
  }

  await db.transaction(async (trx) => {
    await trx('signatures')
      .where({ application_id: application.id })
      .whereNull('voided_at')
      .update({ voided_at: new Date() });
    await trx('applications')
      .where({ id: application.id })
      .update({
        status: 'DRAFT',
        version: Number(application.version) + 1,
      });
    await recordAudit(
      {
        actorType: 'PHYSICIAN',
        actorId: application.id,
        action: 'APPLICATION_EDITED',
        entityType: 'applications',
        entityId: application.id,
        ip: request.info.remoteAddress,
      },
      trx,
    );
  });

  const saved = await db('applications').where({ id: application.id }).first();
  return presentWithPdf(saved);
}