// Copyright (C) 2021 nytpu
// SPDX-License-Identifier: AGPL-3.0-or-later
// 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

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

	"github.com/mitchellh/go-homedir"

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

func main() {
	argCheck(os.Args, 2, true, "Please provide a command.")

	// these are special cases where we shouldn't bother to do anything else
	if os.Args[1] == "help" {
		usage()
		os.Exit(0)
	}
	if os.Args[1] == "version" {
		fmt.Printf("comitium v%v, commit %v\n", Version, Commit)
		os.Exit(0)
	}

	c, ok := commands[os.Args[1]]
	if !ok {
		fmt.Fprint(os.Stderr, "Unrecognized Command.\n\n")
		usage()
		os.Exit(1)
	}

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

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

	err := core.Init(dataPath)
	if err != nil {
		fmt.Fprintf(os.Stderr, "Error in initialization: %v\n", err)
		os.Exit(1)
	}

	switch os.Args[1] {
	case "refresh":
		argCheck(c.Args(), 0, false, "'refresh' doesn't take an argument!")
		fetch.RefreshAll(&core.Data, *refreshWorkersFlag)
		err = core.Data.WriteSubs(dataPath)
		if err != nil {
			fmt.Fprintf(os.Stderr, "Error saving subscriptions: %v\n", err)
			os.Exit(1)
		}
	case "list":
		argCheck(c.Args(), 0, false, "'list' doesn't take an argument!")
		core.Data.Export(os.Stdout)
	case "add":
		argCheck(c.Args(), 1, true, "Please provide a URL to add.")

		remote, err := url.Parse(c.Arg(0))
		if err != nil {
			fmt.Fprintf(os.Stderr, "Error parsing URL: %v\n", 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, "Error adding URL: %v\n", err)
			os.Exit(1)
		}
		err = core.Data.WriteSubs(dataPath)
		if err != nil {
			fmt.Fprintf(os.Stderr, "Error saving subscriptions: %v\n", err)
			os.Exit(1)
		}
	case "remove":
		argCheck(c.Args(), 1, true, "Please provide a URL to remove.")
		delete(core.Data.Feeds, c.Arg(0))
		delete(core.Data.Pages, c.Arg(0))
	}

	err = core.Data.WriteJSON(dataPath)
	if err != nil {
		fmt.Fprintf(os.Stderr, "Error saving subscriptions json: %v\n", 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() 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, "Error finding a suitable directory! Falling back to the current working directory. See \"comitium help\" or comitium(1) for more information.")
	return verifyPath("comitium")
}

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\n", commands["refresh"].FlagUsages())

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