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|
package input
import (
"bytes"
"fmt"
"strconv"
)
// Select asks the user to select a item from the given list by the number.
// It shows the given query and list to user. The response is returned as string
// from the list. By default, it checks the input is the number and is not
// out of range of the list and if not returns error. If Loop is true, it continue to
// ask until it receives valid input.
//
// If the user sends SIGINT (Ctrl+C) while reading input, it catches
// it and return it as a error.
func (i *UI) Select(query string, list []string, opts *Options) (string, error) {
// Set default val
i.once.Do(i.setDefault)
// Input must not be empty if no default is specified.
// Because Select ask user to input by number.
// If empty, can not transform it to int.
opts.Required = true
// Find default index which opts.Default indicates
defaultIndex := -1
defaultVal := opts.Default
if defaultVal != "" {
for i, item := range list {
if item == defaultVal {
defaultIndex = i
}
}
// DefaultVal is set but doesn't exist in list
if defaultIndex == -1 {
// This error message is not for user
// Should be found while development
return "", fmt.Errorf("opt.Default is specified but item does not exist in list")
}
}
// Construct the query & display it to user
var buf bytes.Buffer
buf.WriteString(fmt.Sprintf("%s\n\n", query))
for i, item := range list {
buf.WriteString(fmt.Sprintf("%d. %s\n", i+1, item))
}
buf.WriteString("\n")
fmt.Fprintf(i.Writer, buf.String())
// resultStr and resultErr are return val of this function
var resultStr string
var resultErr error
for {
// Construct the asking line to input
var buf bytes.Buffer
buf.WriteString("Enter a number")
// Add default val if provided
if defaultIndex >= 0 && !opts.HideDefault {
buf.WriteString(fmt.Sprintf(" (Default is %d)", defaultIndex+1))
}
buf.WriteString(": ")
fmt.Fprintf(i.Writer, buf.String())
// Read user input from reader.
line, err := i.read(opts.readOpts())
if err != nil {
resultErr = err
break
}
// line is empty but default is provided returns it
if line == "" && defaultIndex >= 0 {
resultStr = list[defaultIndex]
break
}
if line == "" && opts.Required {
if !opts.Loop {
resultErr = ErrEmpty
break
}
fmt.Fprintf(i.Writer, "Input must not be empty. Answer by a number.\n\n")
continue
}
// Convert user input string to int val
n, err := strconv.Atoi(line)
if err != nil {
if !opts.Loop {
resultErr = ErrNotNumber
break
}
fmt.Fprintf(i.Writer,
"%q is not a valid input. Answer by a number.\n\n", line)
continue
}
// Check answer is in range of list
if n < 1 || len(list) < n {
if !opts.Loop {
resultErr = ErrOutOfRange
break
}
fmt.Fprintf(i.Writer,
"%q is not a valid choice. Choose a number from 1 to %d.\n\n",
line, len(list))
continue
}
// validate input by custom function
validate := opts.validateFunc()
if err := validate(line); err != nil {
if !opts.Loop {
resultErr = err
break
}
fmt.Fprintf(i.Writer, "Failed to validate input string: %s\n\n", err)
continue
}
// Reach here means it gets ideal input.
resultStr = list[n-1]
break
}
// Insert the new line for next output
fmt.Fprintf(i.Writer, "\n")
return resultStr, resultErr
}
|
