package main

import (
	"fmt"
	"io/ioutil"
	"log"
	"os"
	"path/filepath"
	"strconv"
	"time"

	"github.com/docker/cli/cli/command"
	"github.com/docker/cli/cli/command/commands"
	"github.com/spf13/cobra"
	"github.com/spf13/cobra/doc"
	"github.com/spf13/pflag"
)

const descriptionSourcePath = "man/src/"

func generateManPages(opts *options) error {
	header := &doc.GenManHeader{
		Title:   "DOCKER",
		Section: "1",
		Source:  "Docker Community",
		Manual:  "Docker User Manuals",
	}

	// If SOURCE_DATE_EPOCH is set, in order to allow reproducible package
	// builds, we explicitly set the build time to SOURCE_DATE_EPOCH.
	if epoch := os.Getenv("SOURCE_DATE_EPOCH"); epoch != "" {
		unixEpoch, err := strconv.ParseInt(epoch, 10, 64)
		if err != nil {
			return fmt.Errorf("invalid SOURCE_DATE_EPOCH: %v", err)
		}
		now := time.Unix(unixEpoch, 0)
		header.Date = &now
	}

	dockerCli, err := command.NewDockerCli()
	if err != nil {
		return err
	}
	cmd := &cobra.Command{Use: "docker"}
	commands.AddCommands(cmd, dockerCli)
	source := filepath.Join(opts.source, descriptionSourcePath)
	if err := loadLongDescription(cmd, source); err != nil {
		return err
	}

	cmd.DisableAutoGenTag = true
	cmd.DisableFlagsInUseLine = true
	return doc.GenManTreeFromOpts(cmd, doc.GenManTreeOptions{
		Header:           header,
		Path:             opts.target,
		CommandSeparator: "-",
	})
}

func loadLongDescription(cmd *cobra.Command, path string) error {
	for _, cmd := range cmd.Commands() {
		cmd.DisableFlagsInUseLine = true
		if cmd.Name() == "" {
			continue
		}
		fullpath := filepath.Join(path, cmd.Name()+".md")

		if cmd.HasSubCommands() {
			loadLongDescription(cmd, filepath.Join(path, cmd.Name()))
		}

		if _, err := os.Stat(fullpath); err != nil {
			log.Printf("WARN: %s does not exist, skipping\n", fullpath)
			continue
		}

		content, err := ioutil.ReadFile(fullpath)
		if err != nil {
			return err
		}
		cmd.Long = string(content)

		fullpath = filepath.Join(path, cmd.Name()+"-example.md")
		if _, err := os.Stat(fullpath); err != nil {
			continue
		}

		content, err = ioutil.ReadFile(fullpath)
		if err != nil {
			return err
		}
		cmd.Example = string(content)

	}
	return nil
}

type options struct {
	source string
	target string
}

func parseArgs() (*options, error) {
	opts := &options{}
	cwd, _ := os.Getwd()
	flags := pflag.NewFlagSet(os.Args[0], pflag.ContinueOnError)
	flags.StringVar(&opts.source, "root", cwd, "Path to project root")
	flags.StringVar(&opts.target, "target", "/tmp", "Target path for generated man pages")
	err := flags.Parse(os.Args[1:])
	return opts, err
}

func main() {
	opts, err := parseArgs()
	if err != nil {
		fmt.Fprintln(os.Stderr, err.Error())
	}
	fmt.Printf("Project root: %s\n", opts.source)
	fmt.Printf("Generating man pages into %s\n", opts.target)
	if err := generateManPages(opts); err != nil {
		fmt.Fprintf(os.Stderr, "Failed to generate man pages: %s\n", err.Error())
	}
}