// Copyright (C) 2021 nytpu
// SPDX-License-Identifier: AGPL-3.0-only
// For more license details, see LICENSE or <https://www.gnu.org/licenses/agpl-3.0.html>.

// comitium is a feed aggregator for gemini. see README.md for more details and
// doc/comitium.1.scd for a manual page.
package main

// generate the translations:
//go:generate go-localize -input localizations_src -output localizations

import (
	"fmt"
	"net/url"
	"os"
	"path/filepath"
	"strconv"

	"github.com/mitchellh/go-homedir"
	"golang.nytpu.com/comitium/localizations"
	"golang.org/x/text/language"

	"golang.nytpu.com/comitium/core"
	"golang.nytpu.com/comitium/fetch"
)

var supportedLangs = []language.Tag{
	language.MustParse("en-US"), // default fallback
	language.MustParse("fr-FR"),
	language.MustParse("it-IT"),
}

func main() {
	// figure out what language to use (just getting $LANG if set since flags
	// aren't parsed yet)
	localizer := getLang()

	argCheck(os.Args, 2, true, localizer.Get("errors.no_command"))

	c, ok := commands[os.Args[1]]
	if !ok {
		fmt.Fprint(os.Stderr, core.TranslateStringLocalizer(localizer, "%s\n\n", "errors.bad_command", nil))
		usage()
		os.Exit(1)
	}

	c.AddFlagSet(globalFs)
	c.Parse(os.Args[2:])

	// figure out what language to use now that flags are parsed
	localizer = getLang()

	// these are special cases where we shouldn't try to touch data paths
	if os.Args[1] == "help" {
		usage()
		os.Exit(0)
	}
	if os.Args[1] == "version" {
		fmt.Printf(core.TranslateStringLocalizer(
			localizer, "%s\n", "errors.version",
			&localizations.Replacements{"version": core.Version, "commit": core.Commit},
		))
		os.Exit(0)
	}

	// dataPath is the location where all the data (list of subs, cached hashes,
	// etcetera) are stored
	dataPath := getDataPath(localizer)
	// make sure it exists so we can start working with files in it
	os.MkdirAll(dataPath, os.ModePerm)

	days, err := getHist()
	if err != nil {
		fmt.Fprint(os.Stderr, err)
		os.Exit(1)
	}

	err = core.Init(dataPath, localizer, days)
	if err != nil {
		fmt.Fprintf(os.Stderr, core.TranslateStringLocalizer(
			localizer, "%s\n",
			"errors.core_init", &localizations.Replacements{"error": err},
		))
		os.Exit(1)
	}

	switch os.Args[1] {
	case "refresh":
		argCheck(c.Args(), 0, false, localizer.Get("errors.no_argument", &localizations.Replacements{"command": "'refresh'"}))
		core.Timeout = *refreshTimeoutFlag
		fetch.RefreshAll(&core.Data, *refreshWorkersFlag)
	case "regenerate":
		argCheck(c.Args(), 0, false, localizer.Get("errors.no_argument", &localizations.Replacements{"command": "'regenerate'"}))
	case "add":
		argCheck(c.Args(), 1, true, localizer.Get("errors.no_url_add"))

		remote, err := url.Parse(c.Arg(0))
		if err != nil {
			fmt.Fprintf(os.Stderr, core.TranslateString(
				"%s\n", "errors.url_parse",
				&localizations.Replacements{"error": err},
			))
			os.Exit(1)
		}

		if *addPageFlag {
			err = fetch.Page(&core.Data, remote, c.Arg(1))
		} else {
			err = fetch.Feed(&core.Data, remote, c.Arg(1))
		}
		if err != nil {
			fmt.Fprintf(os.Stderr, core.TranslateString(
				"%s\n", "errors.url_add",
				&localizations.Replacements{"error": err},
			))
			os.Exit(1)
		}
	case "remove":
		argCheck(c.Args(), 1, false, localizer.Get("errors.no_url_remove"))
		if (!*removeFeedsFlag && !*removePagesFlag) || *removeFeedsFlag {
			delete(core.Data.Feeds, c.Arg(0))
		}
		if (!*removeFeedsFlag && !*removePagesFlag) || *removePagesFlag {
			delete(core.Data.Pages, c.Arg(0))
		}
	}
	err = core.Data.WriteSubs(dataPath)
	if err != nil {
		fmt.Fprintf(os.Stderr, core.TranslateString(
			"%s\n", "errors.saving",
			&localizations.Replacements{"file": "subscriptions.gmi", "error": err},
		))
		os.Exit(1)
	}
	err = core.Data.WriteFeed(dataPath)
	if err != nil {
		fmt.Fprintf(os.Stderr, core.TranslateString(
			"%s\n", "errors.saving",
			&localizations.Replacements{"file": "feed.gmi", "error": err},
		))
		os.Exit(1)
	}
	err = core.Data.WriteJSON(dataPath)
	if err != nil {
		fmt.Fprintf(os.Stderr, core.TranslateString(
			"%s\n", "errors.saving",
			&localizations.Replacements{"file": "comtitium.json", "error": err},
		))
		os.Exit(1)
	}
}

// argCheck makes sure that the target number of arguments are given.  If
// not, msg is displayed alongside usage information and then the program exits
// with failure.
func argCheck(args []string, target int, lt bool, msg string) {
	if (lt && len(args) < target) || (!lt && len(args) != target) {
		fmt.Fprint(os.Stderr, msg, "\n\n")
		usage()
		os.Exit(1)
	}
}

// verifyPath will expand ~ if neccessary and will clean the path.
func verifyPath(p string) string {
	if n, err := homedir.Expand(p); err != nil {
		return filepath.Clean(p)
	} else {
		return filepath.Clean(n)
	}
}

// getDataPath will return a data path in a gracefully degrading tree, picking
// the first that exists:
// --data flag, $COMITIUM_DATA, $XDG_DATA_HOME/comitium,
// $HOME/.local/share/comitium, $HOME/.comitium, $PWD (last resort)
func getDataPath(localizer *localizations.Localizer) string {
	if *dataFlag != "" {
		return verifyPath(*dataFlag)
	}

	if env := os.Getenv("COMITIUM_DATA"); env != "" {
		return verifyPath(env)
	}
	if env := os.Getenv("XDG_DATA_HOME"); env != "" {
		return verifyPath(env + "/comitium")
	}

	home, err := homedir.Dir()
	if err == nil {
		if _, err := os.Stat(verifyPath(home + "/.local")); !os.IsNotExist(err) {
			return verifyPath(home + "/.local/share/comitium")
		}
		return verifyPath(home + "/.comitium")
	}

	fmt.Fprintln(os.Stderr, localizer.Get("errors.no_data_dir"))
	return verifyPath("comitium")
}

// getLang will return the localizer for the user's lang
func getLang() *localizations.Localizer {
	matcher := language.NewMatcher(supportedLangs)
	var lang language.Tag
	if *langFlag != "" {
		lang, _ = language.MatchStrings(matcher, *langFlag)
	} else if env := os.Getenv("LANG"); env != "" {
		lang, _ = language.MatchStrings(matcher, env)
	}
	return localizations.New(lang.String(), supportedLangs[0].String())
}

func getHist() (days int, err error) {
	if env := os.Getenv("COMITIUM_HISTORY"); env != "" && *histFlag != 31 {
		return strconv.Atoi(env)
	}
	return *histFlag, nil
}

func usage() {
	fmt.Fprintf(os.Stderr, "Usage:\n")
	fmt.Fprintf(os.Stderr, "  %v <command> [FLAGS] [ARGUMENTS]\n\n", os.Args[0])

	fmt.Fprint(os.Stderr, "Commands:\n")
	for _, v := range commandInfo {
		// FIXME: find a way to dynamically match the spacing that
		// flag.PrintDefaults() outputs (instead of hardcoding "-20")
		fmt.Fprintf(os.Stderr, "  %-20s%s\n", v.Name, v.Usage)
	}

	fmt.Fprintf(os.Stderr, "\nGlobal Flags:\n%v", globalFs.FlagUsages())
	// command-specific flags should be printed here
	fmt.Fprintf(os.Stderr, "Flags for \"add\":\n%v", commands["add"].FlagUsages())
	fmt.Fprintf(os.Stderr, "Flags for \"refresh\":\n%v", commands["refresh"].FlagUsages())
	fmt.Fprintf(os.Stderr, "Flags for \"remove\":\n%v\n", commands["remove"].FlagUsages())

	fmt.Fprint(os.Stderr, "For more help, see comitium(1).\n")
}