Add API package, rudimentary implemenation

cmd/list.go

@@ -53,7 +53,7 @@ var (
 			} else if aliases {
 				versions = list.GetAliasedVersions()
 			} else {
-				versions = list.GetAvailableVersions()
+				versions = list.GetAvailableVersionsFromApi()
 			}
 
 			// filter out pre-release versions if needed

pkg/api/api.go

@@ -0,0 +1,80 @@
+package api
+
+import (
+	"encoding/json"
+	"fmt"
+	"net/http"
+
+	"github.com/tfversion/tfversion/pkg/helpers"
+)
+
+const (
+	// TerraformReleasesApiUrl is the URL to list available Terraform releases.
+	TerraformReleasesApiUrl = "https://api.releases.hashicorp.com/v1/releases/terraform"
+	ReleasesPerPage         = 20
+)
+
+type Build struct {
+	Arch string `json:"arch"`
+	Os   string `json:"os"`
+	Url  string `json:"url"`
+}
+
+type Status struct {
+	State            string `json:"state"`
+	TimestampUpdated string `json:"timestamp_updated"`
+}
+
+type Release struct {
+	Builds           []Build `json:"builds"`
+	Name             string  `json:"name"`
+	Status           Status  `json:"status"`
+	Version          string  `json:"version"`
+	IsPreRelease     bool    `json:"is_prerelease"`
+	TimestampCreated string  `json:"timestamp_created"`
+	TimestampUpdated string  `json:"timestamp_updated"`
+}
+
+func ListReleases(after string) ([]*Release, error) {
+	url := fmt.Sprintf("%s?limit=%v&after=%s", TerraformReleasesApiUrl, ReleasesPerPage, after)
+	resp, err := http.Get(url)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+
+	var releases []*Release
+	err = json.NewDecoder(resp.Body).Decode(&releases)
+	if err != nil {
+		return nil, err
+	}
+
+	// append next page if there are still results
+	if len(releases) > 0 {
+		lastRelease := releases[len(releases)-1]
+		nextPage, err := ListReleases(lastRelease.TimestampCreated)
+		if err != nil {
+			return nil, err
+		}
+		releases = append(releases, nextPage...)
+	}
+
+	return releases, nil
+}
+
+// TODO: use this method to validate a specific version before downloading and use builds[0].url for downloading
+func GetRelease(version string) (*Release, error) {
+	url := fmt.Sprintf("%s/%s", TerraformReleasesApiUrl, version)
+	resp, err := http.Get(url)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+
+	var release *Release
+	if err := json.NewDecoder(resp.Body).Decode(&release); err != nil {
+		helpers.ExitWithError("parsing Terraform release", err)
+	}
+
+	return release, nil
+}

pkg/list/list.go

@@ -6,8 +6,10 @@
 	"os"
 	"path/filepath"
 	"strings"
+	"time"
 
 	"github.com/tfversion/tfversion/pkg/alias"
+	"github.com/tfversion/tfversion/pkg/api"
 	"github.com/tfversion/tfversion/pkg/download"
 	"github.com/tfversion/tfversion/pkg/helpers"
 	"golang.org/x/net/html"
@@ -68,6 +70,23 @@
 	return reversedVersions
 }
 
+func GetAvailableVersionsFromApi() []string {
+	currentTime := time.Now().UTC().Format(time.RFC3339)
+	releases, err := api.ListReleases(currentTime)
+	if err != nil {
+		helpers.ExitWithError("getting Terraform releases from API", err)
+	}
+
+	var availableVersions []string
+	for _, r := range releases {
+		availableVersions = append(availableVersions, r.Version)
+	}
+
+	// TODO: sort the list
+
+	return availableVersions
+}
+
 // GetAvailableVersions returns the available Terraform versions from the official Terraform releases page
 func GetAvailableVersions() []string {
 	resp, err := http.Get(download.TerraformReleasesUrl)