Added support for OpenSERP API

Author: shadowy-pycoder

README.md

@@ -26,8 +26,10 @@ CGO_ENABLED=0 go install -ldflags "-s -w" -trimpath github.com/shadowy-pycoder/g
 This will install the `goso` binary to your `$GOPATH/bin` directory.
 
 
+## Search Engine Setup
 
-This tool uses [Custom Search JSON API](https://developers.google.com/custom-search/v1/overview) from Google to obtain most relevant results from Stack Overflow. So, to make it work, you need to obtain an API key from Google and also a [Search Engine ID](https://developers.google.com/custom-search/v1/overview#search_engine_id).
+###  Google Search JSON API
+This approach employs [Custom Search JSON API](https://developers.google.com/custom-search/v1/overview) from Google to obtain most relevant results from Stack Overflow. So, to make it work, you need to get an API key from Google and also a [Search Engine ID](https://developers.google.com/custom-search/v1/overview#search_engine_id). That gives you `100 requests per day`, which I believe is enough for most use cases.
 
 Setup your `Search Engine ID` like this:
 
@@ -39,6 +41,33 @@ echo "export GOSO_API_KEY=<YOUR_API_KEY>" >> $HOME/.profile
 echo "export GOSO_SE=<YOUR_SEARCH_ENGINE_ID>" >> $HOME/.profile
 source $HOME/.profile
 ```
+
+###  OpenSerp API
+`goso` also supports [OpenSERP (Search Engine Results Page)](https://github.com/karust/openserp) from [Karust](https://github.com/karust). This is a completely *FREE* alternative to the Google Search JSON API, though it works a little bit slower, but gives basically the same results. 
+
+So, to make it work, you need tu run OperSERP server locally. You can do it like this:
+
+With Docker:
+```shell
+docker run -p 127.0.0.1:7000:7000 -it karust/openserp serve -a 0.0.0.0 -p 7000
+```
+
+Or as a CLI command:
+
+```shell
+openserp serve 
+```
+You can learn more on how to install OpenSERP [here](https://github.com/karust/openserp).
+
+Once you have it running, add variables to your environment:
+```shell
+echo "export GOSO_OS_HOST=127.0.0.1" >> $HOME/.profile
+echo "export GOSO_OS_PORT=7000" >> $HOME/.profile
+source $HOME/.profile
+```
+These variables will have priority over the `GOSO_API_KEY` and `GOSO_SE`.
+
+
 ## Usage
 
 ```shell

cmd/goso/cli.go

@@ -104,21 +104,34 @@ func root(args []string) error {
 		return fmt.Errorf("-a should be within [min=1, max=10]")
 	}
 	conf.AnswerNum = *aNum
-	apiKey, set := os.LookupEnv("GOSO_API_KEY")
-	if !set {
-		return fmt.Errorf("api key is not set")
-	}
-	conf.ApiKey = apiKey
-	se, set := os.LookupEnv("GOSO_SE")
-	if !set {
-		return fmt.Errorf("search engine is not set")
+	var fetchFunc func(*goso.Config, map[int]*goso.Result) error
+	osHost, hostSet := os.LookupEnv("GOSO_OS_HOST")
+	osPort, portSet := os.LookupEnv("GOSO_OS_PORT")
+	if hostSet && portSet {
+		conf.OpenSerpHost = osHost
+		conf.OpenSerpPort, err = strconv.Atoi(osPort)
+		if err != nil {
+			return fmt.Errorf("failed parsing `GOSO_OS_PORT`")
+		}
+		fetchFunc = goso.FetchOpenSerp
+	} else {
+		apiKey, set := os.LookupEnv("GOSO_API_KEY")
+		if !set {
+			return fmt.Errorf("`GOSO_API_KEY` is not set")
+		}
+		conf.ApiKey = apiKey
+		se, set := os.LookupEnv("GOSO_SE")
+		if !set {
+			return fmt.Errorf("`GOSO_SE` is not set")
+		}
+		conf.SearchEngine = se
+		fetchFunc = goso.FetchGoogle
 	}
-	conf.SearchEngine = se
 	conf.Query = strings.Join(flags.Args(), " ")
 	if conf.Query == "" {
 		return fmt.Errorf("query is empty")
 	}
-	answers, err := goso.GetAnswers(conf, goso.FetchGoogle, goso.FetchStackOverflow)
+	answers, err := goso.GetAnswers(conf, fetchFunc, goso.FetchStackOverflow)
 	if err != nil {
 		return err
 	}

goso.go

@@ -236,6 +236,14 @@ type StackOverflowResult struct {
 	QuotaRemaining int  `json:"quota_remaining"`
 }
 
+type OpenSerpResult struct {
+	Rank        int    `json:"rank"`
+	URL         string `json:"url"`
+	Title       string `json:"title"`
+	Description string `json:"description"`
+	Ad          bool   `json:"ad"`
+}
+
 type Config struct {
 	ApiKey       string
 	SearchEngine string
@@ -244,6 +252,8 @@ type Config struct {
 	Lexer        string
 	QuestionNum  int
 	AnswerNum    int
+	OpenSerpHost string
+	OpenSerpPort int
 	Client       *http.Client
 }
 type Answer struct {
@@ -365,6 +375,38 @@ func FetchGoogle(conf *Config, results map[int]*Result) error {
 	return nil
 }
 
+func FetchOpenSerp(conf *Config, results map[int]*Result) error {
+	url := fmt.Sprintf("http://%s:%d/google/search?lang=EN&limit=%d&text=%s&site=stackoverflow.com",
+		conf.OpenSerpHost, conf.OpenSerpPort, conf.QuestionNum, netUrl.QueryEscape(conf.Query))
+	req, err := http.NewRequest(http.MethodGet, url, nil)
+	if err != nil {
+		return err
+	}
+	res, err := conf.Client.Do(req)
+	if err != nil {
+		return fmt.Errorf("failed connecting to OpenSerp API: check your internet connection")
+	}
+	defer res.Body.Close()
+	if res.StatusCode > 299 {
+		return fmt.Errorf("failed connecting to OpenSerp API: %s", res.Status)
+	}
+	var osResp []OpenSerpResult
+	err = json.NewDecoder(res.Body).Decode(&osResp)
+	if err != nil {
+		return err
+	}
+	for _, item := range osResp {
+		u, _ := netUrl.Parse(item.URL)
+		questionId, _ := strconv.Atoi(strings.Split(u.Path, "/")[2])
+		results[questionId] = &Result{
+			Title:      item.Title,
+			Link:       item.URL,
+			QuestionId: questionId,
+		}
+	}
+	return nil
+}
+
 func FetchStackOverflow(conf *Config, results map[int]*Result) error {
 	questions := make([]string, len(results))
 	var idx int