1 | ;
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2 |
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3 | const compose = require('koa-compose');
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4 | const context = require('./context');
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5 | const rejectedPromise = require('./rejectedPromise');
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6 | const bind = require('./bind');
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7 |
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8 | /** Core client */
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9 | class HttpTransportClient {
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10 | /**
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11 | * Create a HttpTransport.
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12 | * @param {Transport} transport - Transport instance.
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13 | * @param {object} defaults - default configuration
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14 | */
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15 | constructor(transport, defaults) {
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16 | this._transport = transport;
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17 | this._instancePlugins = defaults.plugins || [];
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18 | this._defaults = defaults;
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19 | this._initContext();
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20 | bind(this);
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21 | }
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22 |
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23 | /**
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24 | * Registers a per request plugin
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25 | *
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26 | * @return a HttpTransport instance
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27 | * @param {function} fn - per request plugin
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28 | * @example
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29 | * const toError = require('@bbc/http-transport-to-error');
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30 | * const httpTransport = require('@bbc/http-transport');
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31 | *
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32 | * httpTransport.createClient()
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33 | * .use(toError(404));
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34 | */
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35 | use(plugin) {
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36 | validatePlugin(plugin);
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37 | this._ctx.addPlugin(plugin);
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38 | return this;
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39 | }
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40 |
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41 | /**
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42 | * Make a HTTP GET request
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43 | *
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44 | * @param {string} baseUrl
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45 | * @return a HttpTransport instance
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46 | * @example
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47 | * const httpTransport = require('@bbc/http-transport');
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48 | *
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49 | * const response = await httpTransport.createClient()
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50 | * .get(url)
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51 | * .asResponse();
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52 | */
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53 | get(baseUrl) {
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54 | this._ctx.req.method('GET').baseUrl(baseUrl);
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55 | return this;
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56 | }
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57 |
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58 | /**
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59 | * Make a HTTP POST request
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60 | *
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61 | * @param {string} baseUrl
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62 | * @param {object} request body
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63 | * @return a HttpTransport instance
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64 | * @example
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65 | * const httpTransport = require('@bbc/http-transport');
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66 | *
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67 | * const response = await httpTransport.createClient()
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68 | * .post(baseUrl, requestBody)
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69 | * .asResponse();
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70 | */
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71 | post(baseUrl, body) {
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72 | this._ctx.req
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73 | .method('POST')
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74 | .body(body)
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75 | .baseUrl(baseUrl);
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76 | return this;
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77 | }
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78 |
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79 | /**
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80 | * Make a HTTP PUT request
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81 | *
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82 | * @param {string} baseUrl
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83 | * @param {object} request body
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84 | * @return a HttpTransport instance
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85 | * @example
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86 | * const httpTransport = require('@bbc/http-transport');
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87 | *
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88 | * const response = await httpTransport.createClient()
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89 | * .put(baseUrl, requestBody)
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90 | * .asResponse();
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91 | */
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92 | put(baseUrl, body) {
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93 | this._ctx.req
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94 | .method('PUT')
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95 | .body(body)
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96 | .baseUrl(baseUrl);
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97 | return this;
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98 | }
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99 |
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100 | /**
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101 | * Make a HTTP DELETE request
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102 | *
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103 | * @param {string} baseUrl
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104 | * @return a HttpTransport instance
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105 | * @example
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106 | * const httpTransport = require('@bbc/http-transport');
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107 | *
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108 | * const response = await httpTransport.createClient()
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109 | * .delete(baseUrl)
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110 | * .asResponse();
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111 | */
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112 | delete(baseUrl) {
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113 | this._ctx.req.method('DELETE').baseUrl(baseUrl);
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114 | return this;
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115 | }
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116 |
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117 | /**
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118 | * Make a HTTP PATCH request
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119 | *
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120 | * @param {string} baseUrl
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121 | * @param {object} request body
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122 | * @return a HttpTransport instance
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123 | * @example
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124 | * const httpTransport = require('@bbc/http-transport');
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125 | *
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126 | * const response = await httpTransport.createClient()
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127 | * .put(baseUrl, requestBody)
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128 | * .asResponse();
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129 | */
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130 | patch(baseUrl, body) {
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131 | this._ctx.req
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132 | .method('PATCH')
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133 | .body(body)
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134 | .baseUrl(baseUrl);
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135 | return this;
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136 | }
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137 |
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138 | /**
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139 | * Make a HTTP HEAD request
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140 | *
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141 | * @param {string} baseUrl
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142 | * @return a HttpTransport instance
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143 | * @example
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144 | * const httpTransport = require('@bbc/http-transport');
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145 | *
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146 | * const response = await httpTransport.createClient()
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147 | * .head(baseUrl)
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148 | * .asResponse();
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149 | */
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150 | head(baseUrl) {
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151 | this._ctx.req.method('HEAD').baseUrl(baseUrl);
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152 | return this;
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153 | }
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154 |
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155 | /**
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156 | * Sets the request headers
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157 | *
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158 | * @param {string|object} name - header name or headers object
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159 | * @param {string|object} value - header value
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160 | * @return a HttpTransport instance
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161 | * @example
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162 | * const httpTransport = require('@bbc/http-transport');
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163 | *
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164 | * const response = await httpTransport.createClient()
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165 | * .headers({
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166 | * 'User-Agent' : 'someUserAgent'
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167 | * })
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168 | * .asResponse();
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169 | */
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170 | headers() {
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171 | const args = normalise(arguments);
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172 | Object.keys(args).forEach((key) => {
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173 | this._ctx.req.addHeader(key, args[key]);
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174 | });
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175 | return this;
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176 | }
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177 |
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178 | /**
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179 | * Sets the query strings
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180 | *
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181 | * @param {string|object} name - query name or query object
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182 | * @param {string|object} value - query value
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183 | * @return a HttpTransport instance
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184 | * @example
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185 | * const httpTransport = require('@bbc/http-transport');
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186 | *
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187 | * const response = await httpTransport.createClient()
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188 | * .query({
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189 | * 'perPage' : 1
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190 | * })
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191 | * .asResponse();
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192 | */
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193 | query() {
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194 | const args = normalise(arguments);
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195 | Object.keys(args).forEach((key) => {
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196 | this._ctx.req.addQuery(key, args[key]);
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197 | });
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198 | return this;
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199 | }
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200 |
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201 | /**
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202 | * Sets a request timeout
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203 | *
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204 | * @param {integer} time - timeout in seconds
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205 | * @return a HttpTransport instance
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206 | * @example
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207 | * const httpTransport = require('@bbc/http-transport');
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208 | *
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209 | * const response = await httpTransport.createClient()
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210 | * .timeout(1)
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211 | * .asResponse();
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212 | */
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213 | timeout(time) {
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214 | this._ctx.req.timeout(time);
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215 | return this;
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216 | }
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217 |
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218 | /**
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219 | * Set the number of retries on failure for the request
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220 | *
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221 | * @param {integer} retries - number of times to retry a failed request
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222 | * @return a HttpTransport instance
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223 | * @example
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224 | * const httpTransport = require('@bbc/http-transport');
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225 | *
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226 | * const response = await httpTransport.createClient()
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227 | * .retry(5) // for this request only
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228 | * .asResponse();
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229 | */
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230 | retry(retries) {
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231 | this._ctx.retries = retries;
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232 | return this;
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233 | }
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234 |
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235 | /**
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236 | * Set the delay between retries in ms
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237 | *
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238 | * @param {integer} delay - number of ms to wait between retries (default: 100)
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239 | * @return a HttpTransport instance
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240 | * @example
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241 | * const httpTransport = require('@bbc/http-transport');
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242 | *
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243 | * const response = await httpTransport.createClient()
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244 | * .retry(2)
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245 | * .retryDelay(200)
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246 | * .asResponse();
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247 | */
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248 | retryDelay(delay) {
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249 | this._ctx.retryDelay = delay;
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250 | return this;
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251 | }
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252 |
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253 | /**
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254 | * Initiates the request, returning the response body, if successful.
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255 | *
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256 | * @return a Promise. If the Promise fulfils,
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257 | * the fulfilment value is the response body. The body type defaults to string.
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258 | * If the content-type response header contains 'json'
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259 | * or the json: true option has been set on transport layer
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260 | * then the body type will be json.
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261 | *
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262 | * @example
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263 | * const httpTransport = require('@bbc/http-transport');
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264 | *
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265 | * const body = await httpTransport.createClient()
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266 | * .asBody();
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267 | *
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268 | * console.log(body);
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269 | */
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270 | async asBody() {
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271 | const res = await this.asResponse();
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272 | return res.body;
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273 | }
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274 |
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275 | /**
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276 | * Initiates the request, returning a http transport response object, if successful.
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277 | *
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278 | * @return a Promise. If the Promise fulfils,
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279 | * the fulfilment value is response object.
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280 | * @example
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281 | * const httpTransport = require('@bbc/http-transport');
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282 | *
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283 | * const response = await httpTransport.createClient()
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284 | * .asResponse()
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285 | *
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286 | * console.log(response);
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287 | *
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288 | */
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289 | async asResponse() {
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290 | const currentContext = this._ctx;
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291 | this._initContext();
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292 |
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293 | const ctx = await retry(this._executeRequest, currentContext);
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294 | return ctx.res;
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295 | }
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296 |
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297 | _getPlugins(ctx) {
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298 | return this._instancePlugins.concat(ctx.plugins);
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299 | }
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300 |
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301 | _applyPlugins(ctx, next) {
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302 | const fn = compose(this._getPlugins(ctx));
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303 | return fn(ctx, next);
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304 | }
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305 |
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306 | async _executeRequest(ctx) {
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307 | await this._applyPlugins(ctx, this._handleRequest);
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308 | return ctx;
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309 | }
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310 |
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311 | async _handleRequest(ctx, next) {
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312 | await this._transport.execute(ctx);
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313 | return next();
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314 | }
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315 |
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316 | _initContext() {
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317 | this._ctx = context.create(this._defaults);
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318 | this.headers('User-Agent', this._ctx.userAgent);
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319 | }
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320 | }
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321 |
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322 | function isCriticalError(err) {
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323 | if (err && err.statusCode < 500) {
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324 | return false;
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325 | }
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326 | return true;
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327 | }
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328 |
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329 | function toRetry(err) {
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330 | return {
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331 | reason: err.message,
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332 | statusCode: err.statusCode
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333 | };
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334 | }
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335 |
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336 | function retry(fn, ctx) {
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337 | ctx.retryAttempts = [];
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338 | const maxAttempts = ctx.retries;
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339 |
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340 | function attempt(i) {
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341 | return fn(ctx)
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342 | .catch((err) => {
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343 | if (maxAttempts > 0) {
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344 | const delayBy = rejectedPromise(ctx.retryDelay);
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345 | return delayBy(err);
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346 | }
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347 | throw err;
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348 | })
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349 | .catch((err) => {
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350 | if (i < maxAttempts && isCriticalError(err)) {
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351 | ctx.retryAttempts.push(toRetry(err));
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352 | return attempt(++i);
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353 | }
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354 | throw err;
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355 | });
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356 | }
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357 | return attempt(0);
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358 | }
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359 |
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360 | function toObject(arr) {
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361 | const obj = {};
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362 | for (let i = 0; i < arr.length; i += 2) {
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363 | obj[arr[i]] = arr[i + 1];
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364 | }
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365 | return obj;
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366 | }
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367 |
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368 | function isObject(value) {
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369 | return value !== null && typeof value === 'object';
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370 | }
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371 |
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372 | function normalise(args) {
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373 | args = Array.from(args);
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374 | if (isObject(args[0])) {
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375 | return args[0];
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376 | }
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377 | return toObject(args);
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378 | }
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379 |
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380 | function validatePlugin(plugin) {
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381 | if (typeof plugin !== 'function') throw new TypeError('Plugin is not a function');
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382 | }
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383 |
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384 | module.exports = HttpTransportClient;
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