const fs = require('fs');
const path = require('path');

// General-purpose helpers used across the admin UI.
function registerGeneralHelpers(Handlebars) {
  Handlebars.registerHelper('eq', function (left, right) {
    return left === right;
  });

  Handlebars.registerHelper('gt', function (left, right) {
    return left > right;
  });

  Handlebars.registerHelper('lt', function (left, right) {
    return left < right;
  });

  Handlebars.registerHelper('json', function (value) {
    return new Handlebars.SafeString(JSON.stringify(value).replace(/</g, '\\u003c'));
  });

  Handlebars.registerHelper('truncateText', function (value, maxLength) {
    const text = String(value || '').trim();
    const limit = Number(maxLength);
    if (!text || !Number.isFinite(limit) || limit <= 0 || text.length <= limit) {
      return text;
    }

    return `${text.slice(0, Math.max(0, limit - 1)).trimEnd()}…`;
  });

  Handlebars.registerHelper('textLengthAttrs', function (maxLength) {
    const limit = Number(maxLength);
    if (!Number.isFinite(limit) || limit < 1) {
      return '';
    }

    return new Handlebars.SafeString(`maxlength="${Handlebars.escapeExpression(String(Math.floor(limit)))}" data-limit-text-length`);
  });
}

// URL helpers for generating links and external URL checks.
function registerUrlHelpers(Handlebars) {

  Handlebars.registerHelper('isExternalUrl', function (value) {
    return /^https?:\/\//i.test(String(value || ''));
  });

  Handlebars.registerHelper('assetHref', function (value) {
    const href = String(value || '').trim();
    if (!href) {
      return '';
    }
    if (/^https?:\/\//i.test(href) || href.startsWith('/')) {
      return href;
    }
    return `/assets/${href}`;
  });

  Handlebars.registerHelper('playerUrl', function (slug) {
    const base = String(arguments[1] || '').trim().replace(/\/$/, '');
    if (!base) {
      return '';
    }

    return `${base}/screen/${encodeURIComponent(slug)}`;
  });
}

// Permission helpers delegate to the RBAC layer.
function registerPermissionHelpers(Handlebars, deps) {
  const hasPermission = deps && deps.hasPermission;
  const hasAnyPermission = deps && deps.hasAnyPermission;

  Handlebars.registerHelper('hasPermission', function (currentUser, permissionKey) {
    return hasPermission(currentUser, permissionKey);
  });

  Handlebars.registerHelper('anyPermission', function (currentUser) {
    const args = Array.prototype.slice.call(arguments, 1);
    args.pop();
    return hasAnyPermission(currentUser, args);
  });
}

function registerUserHelpers(Handlebars) {
  Handlebars.registerHelper('userInitial', function (name) {
    const text = String(name || '').trim();
    return text ? text.charAt(0).toUpperCase() : 'A';
  });
}

// Action button helpers keep form submit controls consistent.
function registerActionHelpers(Handlebars) {
  Handlebars.registerHelper('saveActionButtons', function (options) {
    const hash = options && options.hash ? options.hash : {};
    const formId = String(hash.formId || '').trim();

    const save = {
      label: String(hash.saveLabel || 'Save'),
      className: String(hash.saveButtonClass || 'btn btn-success'),
      actionName: String(hash.saveActionName || 'save_action'),
      actionValue: String(hash.saveActionValue || 'save'),
      closeLabel: String(hash.saveAndCloseLabel || 'Save and Close'),
      closeValue: String(hash.saveAndCloseValue || 'close'),
      newLabel: String(hash.saveAndNewLabel || 'Save and New'),
      newValue: String(hash.saveAndNewValue || 'new')
    };

    const showSaveAndClose = hash.showSaveAndClose === undefined ? true : String(hash.showSaveAndClose).toLowerCase() !== 'false';
    const showSaveAndNew = hash.showSaveAndNew === undefined ? true : String(hash.showSaveAndNew).toLowerCase() !== 'false';
    const showDelete = hash.showDelete === undefined ? true : String(hash.showDelete).toLowerCase() !== 'false';
    const hasSecondaryActions = showSaveAndClose || showSaveAndNew;
    const ariaLabel = String(hash.ariaLabel || 'Save actions');
    const saveUrl = String(hash.saveUrl || '').trim();

    const cancel = {
      label: String(hash.cancelLabel || 'Cancel'),
      className: String(hash.cancelClass || 'btn btn-warning'),
      url: String(hash.cancelUrl || '').trim(),
      confirmMessage: String(hash.cancelConfirmMessage || hash.cancelConfirm || 'You have unsaved changes. Leave this page?')
    };

    const deleteAction = {
      label: String(hash.deleteLabel || 'Delete'),
      className: String(hash.deleteClass || 'btn btn-danger'),
      url: String(hash.deleteUrl || '').trim(),
      formId: String(hash.deleteFormId || '').trim(),
      confirmMessage: String(hash.deleteConfirmMessage || '').trim(),
      disabled: hash.deleteDisabled === undefined ? false : String(hash.deleteDisabled).toLowerCase() !== 'false',
      title: String(hash.deleteTitle || '')
    };

    const resolvedDeleteUrl = deleteAction.url || (!deleteAction.disabled && saveUrl ? saveUrl.replace(/\/+$/, '') + '/delete' : '');
    const resolvedDeleteFormId = deleteAction.formId || '';

    if (!formId) {
      return '';
    }

    const escape = Handlebars.escapeExpression;
    const formAttr = ` form="${escape(formId)}"`;

    const parts = [
      '<div class="btn-group save-action-group" role="group">',
      `<button type="submit" class="${escape(save.className)}"${formAttr} name="${escape(save.actionName)}" value="${escape(save.actionValue)}">${escape(save.label)}</button>`,
      hasSecondaryActions ? `<button type="button" class="btn btn-success dropdown-toggle dropdown-toggle-split rounded-0" data-bs-toggle="dropdown" aria-expanded="false"><span class="visually-hidden">${escape(ariaLabel)}</span></button>` : '',
      hasSecondaryActions ? '<div class="dropdown-menu dropdown-menu-end">' : '',
      hasSecondaryActions && showSaveAndClose ? `<button type="submit" class="dropdown-item"${formAttr} name="${escape(save.actionName)}" value="${escape(save.closeValue)}">${escape(save.closeLabel)}</button>` : '',
      hasSecondaryActions && showSaveAndNew ? `<button type="submit" class="dropdown-item"${formAttr} name="${escape(save.actionName)}" value="${escape(save.newValue)}">${escape(save.newLabel)}</button>` : '',
      hasSecondaryActions ? '</div>' : '',
    ];

    if (cancel.url) {
      parts.push(`<a class="${escape(cancel.className)}" href="${escape(cancel.url)}" data-confirm-unsaved="${escape(cancel.confirmMessage)}">${escape(cancel.label)}</a>`);
    }

    if (showDelete && (deleteAction.disabled || resolvedDeleteUrl)) {
      const deleteActionAttr = resolvedDeleteUrl && !resolvedDeleteFormId ? ` data-delete-action-url="${escape(resolvedDeleteUrl)}"` : '';
      const deleteFormAttr = resolvedDeleteFormId ? ` form="${escape(resolvedDeleteFormId)}"` : '';
      const confirmAttr = deleteAction.confirmMessage ? ` data-confirm-message="${escape(deleteAction.confirmMessage)}"` : '';
      const titleAttr = deleteAction.disabled && deleteAction.title ? ` title="${escape(deleteAction.title)}"` : '';
      parts.push(`<button type="${resolvedDeleteFormId ? 'submit' : 'button'}" class="${escape(deleteAction.className)}"${deleteFormAttr}${deleteActionAttr}${confirmAttr}${deleteAction.disabled ? ' disabled' : ''}${titleAttr}>${escape(deleteAction.label)}</button>`);
    }

    parts.push('</div>');

    return new Handlebars.SafeString(parts.join(''));
  });
}

// Shared partials are registered once at startup.
function registerPartials(Handlebars, viewsRoot) {
  Handlebars.registerPartial('modal-shell', fs.readFileSync(path.join(viewsRoot, 'shared', 'modal-shell.hbs'), 'utf8'));
  Handlebars.registerPartial('media-picker-modal', fs.readFileSync(path.join(viewsRoot, 'shared', 'media-picker-modal.hbs'), 'utf8'));
  Handlebars.registerPartial('table-pagination', fs.readFileSync(path.join(viewsRoot, 'shared', 'table', 'table-pagination.hbs'), 'utf8'));
  Handlebars.registerPartial('playlists/form', fs.readFileSync(path.join(viewsRoot, 'signage', 'playlists', 'form.hbs'), 'utf8'));
  Handlebars.registerPartial('signage/playlists/slide-row', fs.readFileSync(path.join(viewsRoot, 'signage', 'playlists', 'slide-row.hbs'), 'utf8'));
  Handlebars.registerPartial('signage/playlists/schedule-rule-card', fs.readFileSync(path.join(viewsRoot, 'signage', 'playlists', 'schedule-rule-card.hbs'), 'utf8'));
  Handlebars.registerPartial('signage/templates/animation-advanced-modal', fs.readFileSync(path.join(viewsRoot, 'signage', 'templates', 'animation-advanced-modal.hbs'), 'utf8'));
  Handlebars.registerPartial('data-sources/api-sources/form', fs.readFileSync(path.join(viewsRoot, 'data-sources', 'api-sources', 'form.hbs'), 'utf8'));
  Handlebars.registerPartial('data-sources/rss-feeds/form', fs.readFileSync(path.join(viewsRoot, 'data-sources', 'rss-feeds', 'form.hbs'), 'utf8'));
  Handlebars.registerPartial('data-sources/weather/preview', fs.readFileSync(path.join(viewsRoot, 'data-sources', 'weather', 'preview.hbs'), 'utf8'));
  Handlebars.registerPartial('data-sources/weather/forecast-preview', fs.readFileSync(path.join(viewsRoot, 'data-sources', 'weather', 'forecast-preview.hbs'), 'utf8'));
}

// One entry point keeps Handlebars bootstrap centralized.
function registerHandlebars(Handlebars, deps) {
  const viewsRoot = String(deps && deps.viewsRoot || '').trim();
  const hasPermission = deps && deps.hasPermission;
  const hasAnyPermission = deps && deps.hasAnyPermission;

  if (!Handlebars || !viewsRoot || typeof hasPermission !== 'function' || typeof hasAnyPermission !== 'function') {
    throw new Error('registerHandlebars requires Handlebars, viewsRoot, hasPermission, and hasAnyPermission.');
  }

  registerGeneralHelpers(Handlebars);
  registerUrlHelpers(Handlebars);
  registerPermissionHelpers(Handlebars, { hasPermission: hasPermission, hasAnyPermission: hasAnyPermission });
  registerUserHelpers(Handlebars);
  registerActionHelpers(Handlebars);
  registerPartials(Handlebars, viewsRoot);
}

module.exports = {
  registerHandlebars: registerHandlebars
};