/*
Copyright 2016 The Kubernetes Authors.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package templates

import (
	"bytes"
	"fmt"
	"strings"
	"text/template"
	"unicode"

	"github.com/spf13/cobra"
	flag "github.com/spf13/pflag"
)

// Content of this package was borrowed from openshift/origin.

type CommandGroup struct {
	Message  string
	Commands []*cobra.Command
}

type CommandGroups []CommandGroup

func (g CommandGroups) Add(c *cobra.Command) {
	for _, group := range g {
		for _, command := range group.Commands {
			c.AddCommand(command)
		}
	}
}

func (g CommandGroups) Has(c *cobra.Command) bool {
	for _, group := range g {
		for _, command := range group.Commands {
			if command == c {
				return true
			}
		}
	}
	return false
}

func AddAdditionalCommands(g CommandGroups, message string, cmds []*cobra.Command) CommandGroups {
	group := CommandGroup{Message: message}
	for _, c := range cmds {
		// Don't show commands that has no short description
		if !g.Has(c) && len(c.Short) != 0 {
			group.Commands = append(group.Commands, c)
		}
	}
	if len(group.Commands) == 0 {
		return g
	}
	return append(g, group)
}

func filter(cmds []*cobra.Command, names ...string) []*cobra.Command {
	out := []*cobra.Command{}
	for _, c := range cmds {
		if c.Hidden {
			continue
		}
		skip := false
		for _, name := range names {
			if name == c.Name() {
				skip = true
				break
			}
		}
		if skip {
			continue
		}
		out = append(out, c)
	}
	return out
}

type FlagExposer interface {
	ExposeFlags(cmd *cobra.Command, flags ...string) FlagExposer
}

func ActsAsRootCommand(cmd *cobra.Command, filters []string, groups ...CommandGroup) FlagExposer {
	if cmd == nil {
		panic("nil root command")
	}
	cmd.SetHelpTemplate(MainHelpTemplate())
	templater := &templater{
		RootCmd:       cmd,
		UsageTemplate: MainUsageTemplate(),
		CommandGroups: groups,
		Filtered:      filters,
	}
	cmd.SetUsageFunc(templater.UsageFunc())
	return templater
}

func UseOptionsTemplates(cmd *cobra.Command) {
	cmd.SetHelpTemplate(OptionsHelpTemplate())
	templater := &templater{
		UsageTemplate: OptionsUsageTemplate(),
	}
	cmd.SetUsageFunc(templater.UsageFunc())
}

type templater struct {
	UsageTemplate string
	RootCmd       *cobra.Command
	CommandGroups
	Filtered []string
}

func (templater *templater) ExposeFlags(cmd *cobra.Command, flags ...string) FlagExposer {
	cmd.SetUsageFunc(templater.UsageFunc(flags...))
	return templater
}

func (templater *templater) UsageFunc(exposedFlags ...string) func(*cobra.Command) error {
	return func(c *cobra.Command) error {
		t := template.New("custom")

		t.Funcs(template.FuncMap{
			"trim":                strings.TrimSpace,
			"trimRight":           func(s string) string { return strings.TrimRightFunc(s, unicode.IsSpace) },
			"trimLeft":            func(s string) string { return strings.TrimLeftFunc(s, unicode.IsSpace) },
			"gt":                  cobra.Gt,
			"eq":                  cobra.Eq,
			"rpad":                rpad,
			"appendIfNotPresent":  appendIfNotPresent,
			"flagsNotIntersected": flagsNotIntersected,
			"visibleFlags":        visibleFlags,
			"flagsUsages":         flagsUsages,
			"indentLines":         indentLines,
			"cmdGroups":           templater.cmdGroups,
			"rootCmd":             templater.rootCmdName,
			"isRootCmd":           templater.isRootCmd,
			"optionsCmdFor":       templater.optionsCmdFor,
			"usageLine":           templater.usageLine,
			"exposed": func(c *cobra.Command) *flag.FlagSet {
				exposed := flag.NewFlagSet("exposed", flag.ContinueOnError)
				if len(exposedFlags) > 0 {
					for _, name := range exposedFlags {
						if flag := c.Flags().Lookup(name); flag != nil {
							exposed.AddFlag(flag)
						}
					}
				}
				return exposed
			},
		})

		template.Must(t.Parse(templater.UsageTemplate))
		return t.Execute(c.OutOrStdout(), c)
	}
}

func (templater *templater) cmdGroups(c *cobra.Command, all []*cobra.Command) []CommandGroup {
	if len(templater.CommandGroups) > 0 && c == templater.RootCmd {
		all = filter(all, templater.Filtered...)
		return AddAdditionalCommands(templater.CommandGroups, "Other Commands:", all)
	}
	all = filter(all, "options")
	return []CommandGroup{
		{
			Message:  "Available Commands:",
			Commands: all,
		},
	}
}

func (t *templater) rootCmdName(c *cobra.Command) string {
	return t.rootCmd(c).CommandPath()
}

func (t *templater) isRootCmd(c *cobra.Command) bool {
	return t.rootCmd(c) == c
}

func (t *templater) parents(c *cobra.Command) []*cobra.Command {
	parents := []*cobra.Command{c}
	for current := c; !t.isRootCmd(current) && current.HasParent(); {
		current = current.Parent()
		parents = append(parents, current)
	}
	return parents
}

func (t *templater) rootCmd(c *cobra.Command) *cobra.Command {
	if c != nil && !c.HasParent() {
		return c
	}
	if t.RootCmd == nil {
		panic("nil root cmd")
	}
	return t.RootCmd
}

func (t *templater) optionsCmdFor(c *cobra.Command) string {
	if !c.Runnable() {
		return ""
	}
	rootCmdStructure := t.parents(c)
	for i := len(rootCmdStructure) - 1; i >= 0; i-- {
		cmd := rootCmdStructure[i]
		if _, _, err := cmd.Find([]string{"options"}); err == nil {
			return cmd.CommandPath() + " options"
		}
	}
	return ""
}

func (t *templater) usageLine(c *cobra.Command) string {
	usage := c.UseLine()
	suffix := "[options]"
	if c.HasFlags() && !strings.Contains(usage, suffix) {
		usage += " " + suffix
	}
	return usage
}

func flagsUsages(f *flag.FlagSet) string {
	x := new(bytes.Buffer)

	f.VisitAll(func(flag *flag.Flag) {
		if flag.Hidden {
			return
		}
		format := "--%s=%s: %s\n"

		if flag.Value.Type() == "string" {
			format = "--%s='%s': %s\n"
		}

		if len(flag.Shorthand) > 0 {
			format = "  -%s, " + format
		} else {
			format = "   %s   " + format
		}

		fmt.Fprintf(x, format, flag.Shorthand, flag.Name, flag.DefValue, flag.Usage)
	})

	return x.String()
}

func rpad(s string, padding int) string {
	template := fmt.Sprintf("%%-%ds", padding)
	return fmt.Sprintf(template, s)
}

func indentLines(s string, indentation int) string {
	r := []string{}
	for _, line := range strings.Split(s, "\n") {
		indented := strings.Repeat(" ", indentation) + line
		r = append(r, indented)
	}
	return strings.Join(r, "\n")
}

func appendIfNotPresent(s, stringToAppend string) string {
	if strings.Contains(s, stringToAppend) {
		return s
	}
	return s + " " + stringToAppend
}

func flagsNotIntersected(l *flag.FlagSet, r *flag.FlagSet) *flag.FlagSet {
	f := flag.NewFlagSet("notIntersected", flag.ContinueOnError)
	l.VisitAll(func(flag *flag.Flag) {
		if r.Lookup(flag.Name) == nil {
			f.AddFlag(flag)
		}
	})
	return f
}

func visibleFlags(l *flag.FlagSet) *flag.FlagSet {
	hidden := "help"
	f := flag.NewFlagSet("visible", flag.ContinueOnError)
	l.VisitAll(func(flag *flag.Flag) {
		if flag.Name != hidden {
			f.AddFlag(flag)
		}
	})
	return f
}