// API source data access, pagination, and remote fetch helpers.

const http = require('http');
const https = require('https');
const { fetchPagedRows, validateMaxLength } = require('./utils');

const NAME_MAX_LENGTH = 255;
const URL_MAX_LENGTH = 1024;
const AUTH_MAX_LENGTH = 255;
const ITEMS_PATH_MAX_LENGTH = 255;

function normalizeUpdateIntervalUnit(value) {
  const unit = String(value || '').trim().toLowerCase();
  return unit === 'seconds' ? 'seconds' : 'minutes';
}

function normalizeAuthMethod(value) {
  const method = String(value || '').trim().toLowerCase();
  return ['basic', 'bearer', 'api_key_header'].includes(method) ? method : 'none';
}

function getItemsPath(source) {
  return String(source && (source.items_path || source.itemsPath) || '').trim();
}

function buildAuthHeaders(source) {
  const method = normalizeAuthMethod(source && (source.auth_method || source.authMethod));
  const headers = {};

  if (method === 'basic') {
    const username = String(source && (source.auth_username || source.authUsername) || '').trim();
    const password = String(source && (source.auth_password || source.authPassword) || '');
    if (username || password) {
      headers.Authorization = 'Basic ' + Buffer.from(username + ':' + password, 'utf8').toString('base64');
    }
  } else if (method === 'bearer') {
    const token = String(source && (source.auth_bearer_token || source.authBearerToken) || '').trim();
    if (token) {
      headers.Authorization = 'Bearer ' + token;
    }
  } else if (method === 'api_key_header') {
    const headerName = String(source && (source.auth_header_name || source.authHeaderName) || 'X-API-Key').trim() || 'X-API-Key';
    const headerValue = String(source && (source.auth_header_value || source.authHeaderValue) || '').trim();
    if (headerValue) {
      headers[headerName] = headerValue;
    }
  }

  return headers;
}

async function fetchApiSourcesData(pool) {
  const [apiSources] = await pool.query(
    'SELECT id, name, api_url, auth_method, auth_username, auth_password, auth_bearer_token, auth_header_name, auth_header_value, items_path, update_interval_value, update_interval_unit, last_pulled_at, last_pull_error, last_response_status, last_response_content_type, last_response_json, created_at, modified_at, created_by, modified_by FROM i_api_sources ORDER BY modified_at DESC, id DESC'
  );

  return { apiSources: apiSources };
}

async function fetchApiSourcesPage(pool, page, pageSize, searchTerm, sortKey, sortDirection) {
  const paged = await fetchPagedRows(pool, {
    selectSql: 'SELECT id, name, api_url, auth_method, auth_username, auth_password, auth_bearer_token, auth_header_name, auth_header_value, items_path, update_interval_value, update_interval_unit, last_pulled_at, last_pull_error, last_response_status, last_response_content_type, last_response_json, created_at, modified_at, created_by, modified_by FROM i_api_sources ORDER BY modified_at DESC, id DESC',
    countSql: 'SELECT COUNT(*) AS count FROM i_api_sources',
    searchColumns: ['name', 'api_url', 'last_pull_error'],
    searchTerm: searchTerm,
    sortColumns: {
      name: 'name',
      url: 'api_url',
      interval: ['update_interval_value', 'update_interval_unit'],
      last_pulled: 'last_pulled_at',
      last_response: 'last_response_status',
      created: 'created_at',
      modified: 'modified_at'
    },
    sortKey: sortKey,
    sortDirection: sortDirection,
    page: page,
    pageSize: pageSize
  });

  return Object.assign({ apiSources: paged.rows }, paged);
}

async function fetchApiSourceById(pool, id) {
  const [rows] = await pool.query(
    'SELECT id, name, api_url, auth_method, auth_username, auth_password, auth_bearer_token, auth_header_name, auth_header_value, items_path, update_interval_value, update_interval_unit, last_pulled_at, last_pull_error, last_response_status, last_response_content_type, last_response_json, created_at, modified_at, created_by, modified_by FROM i_api_sources WHERE id = ?',
    [id]
  );

  return rows[0] || null;
}

async function loadUrlText(urlValue, requestOptions) {
  const extraHeaders = requestOptions && requestOptions.headers ? requestOptions.headers : {};
  if (typeof fetch === 'function') {
    const response = await fetch(urlValue, {
      headers: Object.assign({
        Accept: 'application/json, text/plain;q=0.9, */*;q=0.8',
        'User-Agent': 'Pulse Signage API Reader'
      }, extraHeaders)
    });

    return {
      statusCode: response.status,
      contentType: response.headers.get('content-type') || '',
      bodyText: await response.text(),
      ok: response.ok
    };
  }

  return await new Promise(function (resolve, reject) {
    const url = new URL(urlValue);
    const transport = url.protocol === 'https:' ? https : http;
    const requestHeaders = Object.assign({
      Accept: 'application/json, text/plain;q=0.9, */*;q=0.8',
      'User-Agent': 'Pulse Signage API Reader'
    }, extraHeaders);
    const request = transport.get(url, Object.assign({}, requestOptions || {}, {
      headers: requestHeaders
    }), function (response) {
      response.setEncoding('utf8');
      let body = '';
      response.on('data', function (chunk) {
        body += chunk;
      });
      response.on('end', function () {
        resolve({
          statusCode: response.statusCode || 0,
          contentType: String(response.headers['content-type'] || ''),
          bodyText: body,
          ok: !response.statusCode || response.statusCode < 400
        });
      });
      response.on('error', reject);
    });

    request.on('error', reject);
  });
}

async function fetchApiSourceResponse(apiSource) {
  const source = apiSource && typeof apiSource === 'object' ? apiSource : { api_url: apiSource };
  const response = await loadUrlText(source.api_url, {
    headers: buildAuthHeaders(source)
  });
  if (!response.ok) {
    throw new Error(`Unable to load API response (${response.statusCode}).`);
  }

  const text = String(response.bodyText || '').trim();
  if (!text) {
    throw new Error('API response did not return JSON.');
  }

  let parsed;
  try {
    parsed = JSON.parse(text);
  } catch (_error) {
    throw new Error('API response was not valid JSON.');
  }

  return {
    responseJson: JSON.stringify(parsed, null, 2),
    responseStatus: response.statusCode,
    responseContentType: response.contentType
  };
}

function buildApiSourcePayload(req, existingApiSource) {
  const fallback = existingApiSource || {};
  const body = req && req.body ? req.body : {};
  function readBodyValue(fieldName, fallbackValue) {
    if (Object.prototype.hasOwnProperty.call(body, fieldName)) {
      return body[fieldName];
    }
    return fallbackValue;
  }

  const name = validateMaxLength(req.body.name || fallback.name || '', NAME_MAX_LENGTH, 'API source name');
  const apiUrl = validateMaxLength(req.body.api_url || req.body.apiUrl || fallback.api_url || '', URL_MAX_LENGTH, 'API source URL');
  const authMethod = normalizeAuthMethod(readBodyValue('auth_method', readBodyValue('authMethod', fallback.auth_method || 'none')));
  const authUsername = validateMaxLength(readBodyValue('auth_username', readBodyValue('authUsername', fallback.auth_username || '')) || '', AUTH_MAX_LENGTH, 'API source username');
  const authPassword = validateMaxLength(readBodyValue('auth_password', readBodyValue('authPassword', fallback.auth_password || '')) || '', AUTH_MAX_LENGTH, 'API source password');
  const authBearerToken = validateMaxLength(readBodyValue('auth_bearer_token', readBodyValue('authBearerToken', fallback.auth_bearer_token || '')) || '', AUTH_MAX_LENGTH, 'API source bearer token');
  const authHeaderName = validateMaxLength(readBodyValue('auth_header_name', readBodyValue('authHeaderName', fallback.auth_header_name || 'X-API-Key')) || 'X-API-Key', AUTH_MAX_LENGTH, 'API source header name') || 'X-API-Key';
  const authHeaderValue = validateMaxLength(readBodyValue('auth_header_value', readBodyValue('authHeaderValue', fallback.auth_header_value || '')) || '', AUTH_MAX_LENGTH, 'API source header value');
  const itemsPath = validateMaxLength(readBodyValue('items_path', readBodyValue('itemsPath', fallback.items_path || '')) || '', ITEMS_PATH_MAX_LENGTH, 'API source items path');
  const updateIntervalValue = Math.max(1, Number(req.body.update_interval_value || req.body.updateIntervalValue || fallback.update_interval_value || 60));
  const updateIntervalUnit = normalizeUpdateIntervalUnit(req.body.update_interval_unit || req.body.updateIntervalUnit || fallback.update_interval_unit || 'minutes');

  if (!name) {
    const error = new Error('API source name is required.');
    error.statusCode = 400;
    throw error;
  }

  if (!apiUrl) {
    const error = new Error('API source URL is required.');
    error.statusCode = 400;
    throw error;
  }

  let parsedUrl;
  try {
    parsedUrl = new URL(apiUrl);
  } catch (_error) {
    const error = new Error('Enter a valid API URL.');
    error.statusCode = 400;
    throw error;
  }

  if (parsedUrl.protocol !== 'http:' && parsedUrl.protocol !== 'https:') {
    const error = new Error('API URL must start with http or https.');
    error.statusCode = 400;
    throw error;
  }

  if (!Number.isFinite(updateIntervalValue)) {
    const error = new Error('Update interval must be a number.');
    error.statusCode = 400;
    throw error;
  }

  if (authMethod === 'basic' && !authUsername && !authPassword) {
    const error = new Error('Basic auth requires a username or password.');
    error.statusCode = 400;
    throw error;
  }

  if (authMethod === 'bearer' && !authBearerToken) {
    const error = new Error('Bearer auth requires a token.');
    error.statusCode = 400;
    throw error;
  }

  if (authMethod === 'api_key_header' && !authHeaderValue) {
    const error = new Error('API key auth requires a header value.');
    error.statusCode = 400;
    throw error;
  }

  return {
    name: name,
    apiUrl: parsedUrl.toString(),
    authMethod: authMethod,
    authUsername: authUsername,
    authPassword: authPassword,
    authBearerToken: authBearerToken,
    authHeaderName: authHeaderName,
    authHeaderValue: authHeaderValue,
    itemsPath: itemsPath,
    updateIntervalValue: Math.floor(updateIntervalValue),
    updateIntervalUnit: updateIntervalUnit
  };
}

module.exports = {
  fetchApiSourcesData: fetchApiSourcesData,
  fetchApiSourcesPage: fetchApiSourcesPage,
  fetchApiSourceById: fetchApiSourceById,
  fetchApiSourceResponse: fetchApiSourceResponse,
  buildApiSourcePayload: buildApiSourcePayload
};