package cli

import (
	"fmt"
	"os"
	"strings"
)

// Usage()
func (cli *CliParser) Usage() string {
	var sb strings.Builder

	program, _ := cli.GetVersionSection("program")
	publicCount := cli.publicOptionCount()
	if publicCount > 0 {
		fmt.Fprintf(&sb, "USAGE: %s [<options>] %s\n", program, cli.getArgsTemplate())
	} else {
		fmt.Fprintf(&sb, "USAGE: %s %s\n", program, cli.getArgsTemplate())
	}

	if len(cli.argSpecs) > 0 || len(cli.options) > 0 {
		fmt.Fprintf(&sb, "where:\n")
		if len(cli.argSpecs) > 0 {
			for _, argSpec := range cli.argSpecs {
				arg := argSpec.getBase()
				fmt.Fprintf(&sb, "  <%s>  %s\n", arg.name, arg.description)
			}
		}
		if publicCount > 0 {
			fmt.Fprintf(&sb, "  <options>\n")
			templates, maxWidth := cli.makeOptionTemplateList()
			for i, opti := range cli.options {
				if opti.isHidden() {
					continue
				}
				opt := opti.getBase()
				aliases := opt.aliases
				if len(aliases) > 0 && opt.isArray {
					// Skip the last alias because it is the implicit plural alias
					aliases = aliases[0 : len(aliases)-1]
				}
				if len(aliases) > 0 {
					fmt.Fprintf(&sb, "    %-*s  %s (alias: %s)", maxWidth, templates[i], opt.description, strings.Join(aliases, ", "))
				} else {
					fmt.Fprintf(&sb, "    %-*s  %s", maxWidth, templates[i], opt.description)
				}
				if value := opti.getDefaultValue(); value != "" {
					fmt.Fprintf(&sb, " (default: %q)", value)
				}
				sb.WriteByte('\n')
			}
		}
	}
	return sb.String()
}

func (cli *CliParser) publicOptionCount() (count int) {
	for _, opti := range cli.options {
		opt := opti.getBase()
		if !opt.hidden {
			count++
		}
	}
	return
}

func (cli *CliParser) makeOptionTemplateList() (templates []string, maxWidth int) {
	maxWidth = 0
	templates = make([]string, len(cli.options))
	for i, opti := range cli.options {
		if opti.isHidden() {
			templates[i] = ""
		} else {
			templates[i] = opti.getTemplate()
			if len(templates[i]) > maxWidth {
				maxWidth = len(templates[i])
			}
		}
	}
	return templates, maxWidth
}

// PrintUsage()
func (cli *CliParser) PrintUsage() {
	os.Stdout.WriteString(cli.Usage())
}