const http = require('http');
const https = require('https');

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

async function fetchApiSourcesData(pool) {
  const [apiSources] = await pool.query(
    'SELECT id, name, api_url, 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 api_sources ORDER BY modified_at DESC, id DESC'
  );

  return { apiSources: apiSources };
}

async function fetchApiSourceById(pool, id) {
  const [rows] = await pool.query(
    'SELECT id, name, api_url, 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 api_sources WHERE id = ?',
    [id]
  );

  return rows[0] || null;
}

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

    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 request = transport.get(url, {
      headers: {
        Accept: 'application/json, text/plain;q=0.9, */*;q=0.8',
        'User-Agent': 'Pulse Signage API Reader'
      }
    }, 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(apiUrl) {
  const response = await loadUrlText(apiUrl);
  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 name = String(req.body.name || fallback.name || '').trim();
  const apiUrl = String(req.body.api_url || req.body.apiUrl || fallback.api_url || '').trim();
  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;
  }

  return {
    name: name,
    apiUrl: parsedUrl.toString(),
    updateIntervalValue: Math.floor(updateIntervalValue),
    updateIntervalUnit: updateIntervalUnit
  };
}

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