[#96] added input suggestions (#304)

* (feat): issue templates based on CONTRIBUTION.md

* (chore): vi does not behave the same with vim users ☹️

* (feat): render struct

* (feat): implementing controls

* tab for complete (and complete the completion)
* arrows to navigate between suggestions
* cancel last suggestion to typed answer
* keeping previous scenarios intact

* (feat): usage example

* (feat): add to readme

* (fix): suggestions

* (fix): tab and help on the same brackets

* (feat): when tab with input suggestion, select next

* (feat): select and multiselect cycle next with tab

.github/ISSUE_TEMPLATE/ask-for-help.md

@@ -0,0 +1,10 @@
+---
+name: Ask for help
+about: Suggest an idea for this project or ask for help
+title: ''
+labels: 'Help Wanted'
+assignees: ''
+
+---
+
+

.github/ISSUE_TEMPLATE/bug_report.md

@@ -0,0 +1,16 @@
+---
+name: Bug report
+about: Create a report to help us improve
+title: ''
+labels: 'Bug'
+assignees: ''
+
+---
+
+**What operating system and terminal are you using?**
+
+**An example that showcases the bug.**
+
+**What did you expect to see?**
+
+**What did you see instead?**

.github/ISSUE_TEMPLATE/others-suggestions.md

@@ -0,0 +1,10 @@
+---
+name: Others/suggestions
+about: Suggestions and other topics
+title: ''
+labels: ''
+assignees: ''
+
+---
+
+

README.md

@@ -62,6 +62,7 @@ func main() {
 1. [Running the Prompts](#running-the-prompts)
 1. [Prompts](#prompts)
    1. [Input](#input)
+      1. [Suggestion Options](#suggestion-options)
    1. [Multiline](#multiline)
    1. [Password](#password)
    1. [Confirm](#confirm)
@@ -137,6 +138,23 @@ prompt := &survey.Input{
 survey.AskOne(prompt, &name)
 ```
 
+#### Suggestion Options
+
+<img src="https://i.imgur.com/Q7POpA1.gif" width="800px"/>
+
+```golang
+file := ""
+prompt := &survey.Input{
+    Message: "inform a file to save:",
+    Suggest: func (toComplete string) []string {
+        files, _ := filepath.Glob(toComplete + "*")
+        return files
+    },
+}
+}
+survey.AskOne(prompt, &file)
+```
+
 ### Multiline
 
 <img src="https://thumbs.gfycat.com/ImperfectShimmeringBeagle-size_restricted.gif" width="400px"/>

editor_test.go

@@ -102,6 +102,10 @@ func TestEditorRender(t *testing.T) {
 }
 
 func TestEditorPrompt(t *testing.T) {
+	if os.Getenv("SKIP_EDITOR_PROMPT_TESTS") != "" {
+		t.Skip("editor prompt tests skipped by dev")
+	}
+
 	if _, err := exec.LookPath("vi"); err != nil {
 		t.Skip("vi not found in PATH")
 	}

examples/inputfilesuggestion.go

@@ -0,0 +1,42 @@
+package main
+
+import (
+	"fmt"
+	"path/filepath"
+
+	"github.com/AlecAivazis/survey/v2"
+)
+
+func suggestFiles(toComplete string) []string {
+	files, _ := filepath.Glob(toComplete + "*")
+	return files
+}
+
+// the questions to ask
+var q = []*survey.Question{
+	{
+		Name: "file",
+		Prompt: &survey.Input{
+			Message: "Which file should be read?",
+			Suggest: suggestFiles,
+			Help:    "Any file; do not need to exist yet",
+		},
+		Validate: survey.Required,
+	},
+}
+
+func main() {
+	answers := struct {
+		File string
+	}{}
+
+	// ask the question
+	err := survey.Ask(q, &answers)
+
+	if err != nil {
+		fmt.Println(err.Error())
+		return
+	}
+	// print the answers
+	fmt.Printf("File chosen %s.\n", answers.File)
+}

input.go

@@ -1,5 +1,10 @@
 package survey
 
+import (
+	"github.com/AlecAivazis/survey/v2/core"
+	"github.com/AlecAivazis/survey/v2/terminal"
+)
+
 /*
 Input is a regular text input that prints each character the user types on the screen
 and accepts the input with the enter key. Response type is a string.
@@ -10,18 +15,26 @@ and accepts the input with the enter key. Response type is a string.
 */
 type Input struct {
 	Renderer
-	Message string
-	Default string
-	Help    string
+	Message       string
+	Default       string
+	Help          string
+	Suggest       func(toComplete string) []string
+	typedAnswer   string
+	answer        string
+	options       []core.OptionAnswer
+	selectedIndex int
+	showingHelp   bool
 }
 
 // data available to the templates when processing
 type InputTemplateData struct {
 	Input
-	Answer     string
-	ShowAnswer bool
-	ShowHelp   bool
-	Config     *PromptConfig
+	ShowAnswer    bool
+	ShowHelp      bool
+	Answer        string
+	PageEntries   []core.OptionAnswer
+	SelectedIndex int
+	Config        *PromptConfig
 }
 
 // Templates with Color formatting. See Documentation: https://github.com/mgutz/ansi#style-format
@@ -31,11 +44,92 @@ var InputQuestionTemplate = `
 {{- color "default+hb"}}{{ .Message }} {{color "reset"}}
 {{- if .ShowAnswer}}
   {{- color "cyan"}}{{.Answer}}{{color "reset"}}{{"\n"}}
+{{- else if .PageEntries -}}
+  {{- .Answer}} [Use arrows to move, enter to select, type to continue]
+  {{- "\n"}}
+  {{- range $ix, $choice := .PageEntries}}
+    {{- if eq $ix $.SelectedIndex }}{{color $.Config.Icons.SelectFocus.Format }}{{ $.Config.Icons.SelectFocus.Text }} {{else}}{{color "default"}}  {{end}}
+    {{- $choice.Value}}
+    {{- color "reset"}}{{"\n"}}
+  {{- end}}
 {{- else }}
-  {{- if and .Help (not .ShowHelp)}}{{color "cyan"}}[{{ print .Config.HelpInput }} for help]{{color "reset"}} {{end}}
+  {{- if or (and .Help (not .ShowHelp)) .Suggest }}{{color "cyan"}}[
+    {{- if and .Help (not .ShowHelp)}}{{ print .Config.HelpInput }} for help {{- if and .Suggest}}, {{end}}{{end -}}
+    {{- if and .Suggest }}{{color "cyan"}}{{ print .Config.SuggestInput }} for suggestions{{end -}}
+  ]{{color "reset"}} {{end}}
   {{- if .Default}}{{color "white"}}({{.Default}}) {{color "reset"}}{{end}}
+  {{- .Answer -}}
 {{- end}}`
 
+func (i *Input) OnChange(key rune, config *PromptConfig) (bool, error) {
+	if key == terminal.KeyEnter || key == '\n' {
+		if i.answer != config.HelpInput || i.Help == "" {
+			// we're done
+			return true, nil
+		} else {
+			i.answer = ""
+			i.showingHelp = true
+		}
+	} else if key == terminal.KeyDeleteWord || key == terminal.KeyDeleteLine {
+		i.answer = ""
+	} else if key == terminal.KeyEscape && i.Suggest != nil {
+		if len(i.options) > 0 {
+			i.answer = i.typedAnswer
+		}
+		i.options = nil
+	} else if key == terminal.KeyArrowUp && len(i.options) > 0 {
+		if i.selectedIndex == 0 {
+			i.selectedIndex = len(i.options) - 1
+		} else {
+			i.selectedIndex--
+		}
+		i.answer = i.options[i.selectedIndex].Value
+	} else if (key == terminal.KeyArrowDown || key == terminal.KeyTab) && len(i.options) > 0 {
+		if i.selectedIndex == len(i.options)-1 {
+			i.selectedIndex = 0
+		} else {
+			i.selectedIndex++
+		}
+		i.answer = i.options[i.selectedIndex].Value
+	} else if key == terminal.KeyTab && i.Suggest != nil {
+		options := i.Suggest(i.answer)
+		i.selectedIndex = 0
+		i.typedAnswer = i.answer
+		if len(options) > 0 {
+			i.answer = options[0]
+			if len(options) == 1 {
+				i.options = nil
+			} else {
+				i.options = core.OptionAnswerList(options)
+			}
+		}
+	} else if key == terminal.KeyDelete || key == terminal.KeyBackspace {
+		if i.answer != "" {
+			i.answer = i.answer[0 : len(i.answer)-1]
+		}
+	} else if key >= terminal.KeySpace {
+		i.answer += string(key)
+		i.typedAnswer = i.answer
+		i.options = nil
+	}
+
+	pageSize := config.PageSize
+	opts, idx := paginate(pageSize, i.options, i.selectedIndex)
+	err := i.Render(
+		InputQuestionTemplate,
+		InputTemplateData{
+			Input:         *i,
+			Answer:        i.answer,
+			ShowHelp:      i.showingHelp,
+			SelectedIndex: idx,
+			PageEntries:   opts,
+			Config:        config,
+		},
+	)
+
+	return err != nil, err
+}
+
 func (i *Input) Prompt(config *PromptConfig) (interface{}, error) {
 	// render the template
 	err := i.Render(
@@ -55,41 +149,39 @@ func (i *Input) Prompt(config *PromptConfig) (interface{}, error) {
 	defer rr.RestoreTermMode()
 
 	cursor := i.NewCursor()
+	cursor.Hide()       // hide the cursor
+	defer cursor.Show() // show the cursor when we're done
 
-	line := []rune{}
-	// get the next line
+	// start waiting for input
 	for {
-		line, err = rr.ReadLine(0)
+		r, _, err := rr.ReadRune()
 		if err != nil {
-			return string(line), err
+			return "", err
 		}
-		// terminal will echo the \n so we need to jump back up one row
-		cursor.Up(1)
-
-		if string(line) == config.HelpInput && i.Help != "" {
-			err = i.Render(
-				InputQuestionTemplate,
-				InputTemplateData{
-					Input:    *i,
-					ShowHelp: true,
-					Config:   config,
-				},
-			)
-			if err != nil {
-				return "", err
-			}
-			continue
+		if r == terminal.KeyInterrupt {
+			return "", terminal.InterruptErr
+		}
+		if r == terminal.KeyEndTransmission {
+			break
+		}
+
+		b, err := i.OnChange(r, config)
+		if err != nil {
+			return "", err
+		}
+
+		if b {
+			break
 		}
-		break
 	}
 
 	// if the line is empty
-	if line == nil || len(line) == 0 {
+	if len(i.answer) == 0 {
 		// use the default value
 		return i.Default, err
 	}
 
-	lineStr := string(line)
+	lineStr := i.answer
 
 	i.AppendRenderedText(lineStr)
 
@@ -102,7 +194,6 @@ func (i *Input) Cleanup(config *PromptConfig, val interface{}) error {
 		InputQuestionTemplate,
 		InputTemplateData{
 			Input:      *i,
-			Answer:     val.(string),
 			ShowAnswer: true,
 			Config:     config,
 		},