package main

import (
	"context"
	"fmt"
	"maps"
	"os"
	"os/signal"
	"path"
	"regexp"
	"strings"
	"syscall"
)

func main() {
	ctx, can := signal.NotifyContext(context.Background(), syscall.SIGINT)
	defer can()

	if err := Run(ctx,
		os.Args[1],
		os.Args[2],
		os.Args[3:],
		nil,
	); err != nil {
		panic(err)
	}
}

func Run(ctx context.Context, outd, ind string, patterns []string, overrides map[string]string) error {
	entries, err := os.ReadDir(ind)
	if err != nil {
		return err
	}
	for _, entry := range entries {
		if err := one(ctx, outd, path.Join(ind, entry.Name()), patterns, overrides); err != nil {
			return err
		}
	}
	return nil
}

func one(ctx context.Context, outd, inf string, patterns []string, overrides map[string]string) error {
	f := path.Base(inf)
	for _, pattern := range patterns {
		re := regexp.MustCompile(pattern)
		if !re.MatchString(f) {
			continue
		}

		found := maps.Clone(overrides)
		groupNames := re.SubexpNames()
		groups := re.FindStringSubmatch(f)
		for i := 1; i < len(groupNames); i++ {
			k := groupNames[i]
			v := groups[i]
			found[k] = v
		}

		if found["title"] == "" || found["season"] == "" || found["episode"] == "" {
			continue
		}
		found["title"] = strings.Join(strings.Fields(found["title"]), "_")

		if err := mvNLn(ctx, outd, inf, found["title"], found["season"], found["episode"]); err != nil {
			return err
		}
		return nil
	}
	return nil
}

func mvNLn(ctx context.Context, outd, inf string, title, season, episode string) error {
	outf := path.Join(outd, fmt.Sprintf("%s_S%sE%s%s", title, season, episode, path.Ext(inf)))
	if err := os.Rename(inf, outf); err != nil {
		return err
	}
	return os.Symlink(outf, inf)
}