'use strict';

const mdl_EmailTemplate = require('../../models/email_templates/email_templates.mdl');
const mdl_EmailBroadcast = require('../../models/email_templates/email_broadcast.mdl');
const R           = require('../../utils/response.util');
const logActivity = require('../../utils/logActivity.util');

const TYPE_PATTERN = /^[A-Z][A-Z0-9_]*$/;
const VALID_CATEGORIES = ['announcement', 'advertisement', 'system', 'other'];

// ─── GET /admin/email-templates ───────────────────────────────────────────────

exports.getEmailTemplates = async (req, res) => {
  try {
    const templates = await mdl_EmailTemplate.findAll({
      order: [['category', 'ASC'], ['is_system', 'DESC'], ['type', 'ASC']],
    });
    return R.success(res, 'Email templates retrieved.', templates);
  } catch (err) {
    console.error('[ADMIN][GET EMAIL TEMPLATES]', err);
    return R.error(res, 'Could not retrieve email templates.', 500);
  }
};

// ─── GET /admin/email-templates/:id ───────────────────────────────────────────

exports.getEmailTemplate = async (req, res) => {
  try {
    const template = await mdl_EmailTemplate.findByPk(req.params.id);
    if (!template) return R.error(res, 'Email template not found.', 404);
    return R.success(res, 'Email template retrieved.', template);
  } catch (err) {
    console.error('[ADMIN][GET EMAIL TEMPLATE]', err);
    return R.error(res, 'Could not retrieve email template.', 500);
  }
};

// ─── POST /admin/email-templates ──────────────────────────────────────────────

exports.createEmailTemplate = async (req, res) => {
  try {
    const { type, label, category, subject, html_body, body_markdown, publish } = req.body;
    if (!type || !label || !subject || !html_body) {
      return R.error(res, 'type, label, subject and html_body are required.', 400);
    }
    if (!TYPE_PATTERN.test(type)) {
      return R.error(res, 'type must be uppercase letters, numbers or underscores, starting with a letter (e.g. INVOICE_RECEIPT).', 400);
    }
    if (category !== undefined && !VALID_CATEGORIES.includes(category)) {
      return R.error(res, `category must be one of: ${VALID_CATEGORIES.join(', ')}.`, 400);
    }

    const exists = await mdl_EmailTemplate.findOne({ where: { type } });
    if (exists) return R.error(res, `An email template with type "${type}" already exists.`, 409);

    // "Send Now" writes straight to the live columns sendEmail() reads.
    // "Save as Draft" keeps the content out of the live columns entirely, so
    // there's nothing for sendEmail() to pick up until it's published.
    const isPublishing = publish === true || publish === 'true';

    const template = await mdl_EmailTemplate.create({
      type,
      label,
      category: category || 'other',
      status:          isPublishing ? 'sent' : 'draft',
      subject:         isPublishing ? subject : null,
      html_body:       isPublishing ? html_body : null,
      body_markdown:   isPublishing ? (body_markdown ?? null) : null,
      draft_subject:   isPublishing ? null : subject,
      draft_html_body: isPublishing ? null : html_body,
      draft_body_markdown: isPublishing ? null : (body_markdown ?? null),
      last_sent_at:    isPublishing ? new Date() : null,
      is_system: false, // only seed data may be system-protected
    });

    logActivity(req.user?.user_id, 'create_email_template', { entityType: 'email_template', details: { type, label, category: template.category, status: template.status } });

    return R.success(res, 'Email template created.', template, 201);
  } catch (err) {
    console.error('[ADMIN][CREATE EMAIL TEMPLATE]', err);
    return R.error(res, 'Could not create email template.', 500);
  }
};

// ─── PUT /admin/email-templates/:id ───────────────────────────────────────────

exports.updateEmailTemplate = async (req, res) => {
  try {
    const template = await mdl_EmailTemplate.findByPk(req.params.id);
    if (!template) return R.error(res, 'Email template not found.', 404);

    const { type, label, category, subject, html_body, body_markdown, publish } = req.body;

    if (template.is_system && type !== undefined && type !== template.type) {
      return R.error(res, 'The type of a system email template cannot be changed.', 400);
    }
    if (type !== undefined && !TYPE_PATTERN.test(type)) {
      return R.error(res, 'type must be uppercase letters, numbers or underscores, starting with a letter (e.g. INVOICE_RECEIPT).', 400);
    }
    if (category !== undefined && !VALID_CATEGORIES.includes(category)) {
      return R.error(res, `category must be one of: ${VALID_CATEGORIES.join(', ')}.`, 400);
    }

    if (!template.is_system && type !== undefined && type !== template.type) {
      const exists = await mdl_EmailTemplate.findOne({ where: { type } });
      if (exists) return R.error(res, `An email template with type "${type}" already exists.`, 409);
    }

    if (subject !== undefined && !subject.trim())     return R.error(res, 'subject cannot be empty.', 400);
    if (html_body !== undefined && !html_body.trim()) return R.error(res, 'html_body cannot be empty.', 400);

    // "Send" publishes subject/html_body straight to the live columns that
    // sendEmail() reads and clears any pending draft. A plain save (no
    // publish flag) writes into draft_subject/draft_html_body instead, so
    // real outgoing mail keeps using the last-published content until an
    // admin comes back and explicitly sends again.
    const isPublishing   = publish === true || publish === 'true';
    const nextSubject    = subject       ?? template.draft_subject       ?? template.subject;
    const nextHtmlBody   = html_body     ?? template.draft_html_body     ?? template.html_body;
    const nextMarkdown   = body_markdown ?? template.draft_body_markdown ?? template.body_markdown;

    await template.update({
      type:      (!template.is_system && type !== undefined) ? type : template.type,
      label:     label     ?? template.label,
      category:  category  ?? template.category,
      ...(isPublishing
        ? {
            status:              'sent',
            subject:             nextSubject,
            html_body:           nextHtmlBody,
            body_markdown:       nextMarkdown,
            draft_subject:       null,
            draft_html_body:     null,
            draft_body_markdown: null,
            last_sent_at:        new Date(),
          }
        : {
            draft_subject:       nextSubject,
            draft_html_body:     nextHtmlBody,
            draft_body_markdown: nextMarkdown,
          }),
    });

    logActivity(req.user?.user_id, 'update_email_template', { entityType: 'email_template', entityId: template.email_template_id, details: { type: template.type, published: isPublishing } });

    return R.success(res, 'Email template updated.', template);
  } catch (err) {
    console.error('[ADMIN][UPDATE EMAIL TEMPLATE]', err);
    return R.error(res, 'Could not update email template.', 500);
  }
};

// ─── DELETE /admin/email-templates/:id ────────────────────────────────────────

exports.deleteEmailTemplate = async (req, res) => {
  try {
    const template = await mdl_EmailTemplate.findByPk(req.params.id);
    if (!template) return R.error(res, 'Email template not found.', 404);
    if (template.is_system) return R.error(res, 'Built-in system email templates cannot be deleted.', 400);

    const broadcastCount = await mdl_EmailBroadcast.count({ where: { email_template_id: template.email_template_id } });
    if (broadcastCount > 0) {
      return R.error(res, `Cannot delete — ${broadcastCount} broadcast(s) reference this template. Its send history would be lost.`, 409);
    }

    await template.destroy();
    logActivity(req.user?.user_id, 'delete_email_template', { entityType: 'email_template', details: { type: template.type } });
    return R.success(res, 'Email template deleted.');
  } catch (err) {
    console.error('[ADMIN][DELETE EMAIL TEMPLATE]', err);
    return R.error(res, 'Could not delete email template.', 500);
  }
};