// Copyright 2026 The Gitea Authors. All rights reserved.
// SPDX-License-Identifier: MIT

package app

import (
	"errors"
	"io"
	"strconv"
	"time"

	"gitea.dev/tea/internal/clierr"
	"github.com/spf13/cobra"
	"github.com/spf13/cobra/doc"
)

func (a *application) manCommand() *cobra.Command {
	var output string
	command := &cobra.Command{
		Use: "man [command...]", Short: "Generate the full manual or a command's man page", Hidden: true,
		Annotations: textOutput("man pages are troff"),
		RunE: func(cmd *cobra.Command, args []string) error {
			// Use built-ins only so personal aliases and settings cannot change the manual.
			root := NewRoot(Dependencies{})
			target, remaining, err := root.Find(args)
			if err != nil || len(remaining) != 0 {
				return clierr.Wrap(clierr.Usage, errors.New("unknown manual command; use tea help to list commands"))
			}
			date := ManualDate(a.deps.Getenv)
			return writeOutput(cmd, output, func(writer io.Writer) error {
				var render func(*cobra.Command) error
				render = func(page *cobra.Command) error {
					if err := cmd.Context().Err(); err != nil {
						return err
					}
					page.DisableAutoGenTag = true
					// GenMan fills an empty Title from the command path by mutating the header, so each page needs its own.
					header := &doc.GenManHeader{Section: "1", Date: &date, Source: "Tea", Manual: "Tea Manual"}
					if err := doc.GenMan(page, header, writer); err != nil {
						return err
					}
					if len(args) == 0 {
						for _, child := range page.Commands() {
							if child.Hidden {
								continue
							}
							if err := render(child); err != nil {
								return err
							}
						}
					}
					return nil
				}
				return render(target)
			})
		},
	}
	command.Flags().StringVarP(&output, "output-file", "o", "", "Write the man page to a new file (default stdout)")
	return command
}

// ManualDate dates man pages from SOURCE_DATE_EPOCH, falling back to a fixed date so the
// manual stays reproducible when the variable is unset.
func ManualDate(getenv func(string) string) time.Time {
	if seconds, err := strconv.ParseInt(getenv("SOURCE_DATE_EPOCH"), 10, 64); err == nil {
		return time.Unix(seconds, 0).UTC()
	}
	return time.Date(2026, time.January, 1, 0, 0, 0, 0, time.UTC)
}