package main

import (
	"bufio"
	"encoding/json"
	"fmt"
	"io"
	"log"
	"net/url"
	"os"
	"path"
	"path/filepath"
	"strings"
	"time"

	"github.com/kortschak/arrgh"
)

func main() {
	r, err := arrgh.NewRemoteSession("http://public.opencpu.org", "", 10*time.Second)
	if err != nil {
		log.Fatal(err)
	}
	defer r.Close()

	// Send a query to get a session result for the linear
	// regression: coef(lm(speed~dist, data=cars)).
	resp, err := r.Post(
		"library/base/R/identity",
		"application/x-www-form-urlencoded",
		nil,
		strings.NewReader("x="+url.QueryEscape("coef(lm(speed ~ dist, data = cars))")),
	)
	if err != nil {
		log.Fatal(err)
	}
	defer resp.Body.Close()

	// Get each part of the session result and display it,
	// keeping the location of the linear regression.
	sc := bufio.NewScanner(resp.Body)
	var val string
	for sc.Scan() {
		// API root path stripping here depends on consistency
		// between os.Separator and the URL path separator.
		p, err := filepath.Rel(r.Root(), sc.Text())
		if err != nil {
			log.Fatal(err)
		}
		if path.Base(p) == ".val" {
			val = p
		}
		fmt.Printf("%s:\n", p)

		resp, err := r.Get(p, nil)
		if err != nil {
			log.Fatal(err)
		}
		io.Copy(os.Stdout, resp.Body)
		fmt.Print("\n\n")
		resp.Body.Close()
	}

	// Get the linear regression result as JSON.
	res, err := r.Get(path.Join(val, "json"), url.Values{"digits": []string{"10"}})
	if err != nil {
		log.Fatal(err)
	}
	defer res.Body.Close()

	// Decode the result into a [2]float64.
	var lm [2]float64
	dec := json.NewDecoder(res.Body)
	err = dec.Decode(&lm)
	if err != nil {
		log.Fatal(err)
	}

	fmt.Printf("lm: intercept=%f dist=%f\n", lm[0], lm[1])
}

tmp/x0113a3ca85/R/identity:
function (x) 
x
<bytecode: 0x55d13e1f40a0>
<environment: namespace:base>


tmp/x0113a3ca85/R/.val:
(Intercept)        dist 
  8.2839056   0.1655676 


tmp/x0113a3ca85/stdout:
(Intercept)        dist 
  8.2839056   0.1655676 


tmp/x0113a3ca85/source:
identity(x = coef(lm(speed ~ dist, data = cars)))

tmp/x0113a3ca85/console:
> identity(x = coef(lm(speed ~ dist, data = cars)))
(Intercept)        dist 
  8.2839056   0.1655676 

tmp/x0113a3ca85/info:
R version 3.4.1 (2017-06-30)
Platform: x86_64-pc-linux-gnu (64-bit)
Running under: Ubuntu 16.04.2 LTS

Matrix products: default
BLAS: /usr/lib/openblas-base/libblas.so.3
LAPACK: /usr/lib/libopenblasp-r0.2.18.so

locale:
 [1] LC_CTYPE=en_US.UTF-8    LC_NUMERIC=C            LC_TIME=en_US.UTF-8    
 [4] LC_COLLATE=en_US.UTF-8  LC_MONETARY=en_US.UTF-8 LC_MESSAGES=C          
 [7] LC_PAPER=C              LC_NAME=C               LC_ADDRESS=C           
[10] LC_TELEPHONE=C          LC_MEASUREMENT=C        LC_IDENTIFICATION=C    

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base     

other attached packages:
[1] opencpu_2.0.3.1

loaded via a namespace (and not attached):
 [1] Rcpp_0.12.11     lattice_0.20-35  mime_0.5         plyr_1.8.4      
 [5] grid_3.4.1       gtable_0.2.0     sys_1.4          jsonlite_1.5    
 [9] unix_1.3         magrittr_1.5     scales_0.4.1     evaluate_0.10.2 
[13] ggplot2_2.2.1    rlang_0.1.1      stringi_1.1.5    curl_2.7        
[17] lazyeval_0.2.0   webutils_0.6     tools_3.4.1      stringr_1.2.0   
[21] munsell_0.4.3    parallel_3.4.1   sendmailR_1.2-1  compiler_3.4.1  
[25] colorspace_1.3-2 base64enc_0.1-3  openssl_0.9.6    tibble_1.3.3    


tmp/x0113a3ca85/files/DESCRIPTION:
Package: x0113a3ca85
Type: Session
Version: 2.0.3.1
Author: OpenCPU
Date: 2017-07-07
Description: This file is automatically generated by OpenCPU.


lm: intercept=8.283906 dist=0.165568

go get github.com/kortschak/arrgh