package main

import (
	"cmp"
	"context"
	"encoding/json"
	"flag"
	"fmt"
	"io"
	"log/slog"
	"net/http"
	"os"
	"os/signal"
	"path/filepath"
	"time"
)

type DumpCard struct {
	ID     int `json:"card_id"`
	Rarity int `json:"rarity"`
	// Level      int `json:"talent_level"`
	// CreateTime int `json:"create_time"`
}

type DumpSupport struct {
	ID int `json:"support_card_id"`
	LB int `json:"limit_break_count"`
	// many other fields we don't need
}

type Collection struct {
	App       string                      `json:"app"`       // "gametora"
	Game      string                      `json:"game"`      // "umamusume"
	Type      string                      `json:"type"`      // "collection"
	Version   int                         `json:"version"`   // 4
	Timestamp string                      `json:"timestamp"` // time.Now().String()
	Servers   map[string]CollectionServer `json:"servers"`
}

type CollectionServer struct {
	CharCards map[string]int `json:"charCards"`
	Supports  map[string]int `json:"supports"`
	Veterans  struct{}       `json:"-"` // `json:"veterans"`
}

type Localize struct {
	CardID    int    `json:"card_id"` // character card, or trainee
	SupportID int    `json:"id"`      // support card
	TID       string `json:"tid"`
	// many other fields we don't need
}

func decode[T any](r io.Reader) ([]T, error) {
	var l []T
	d := json.NewDecoder(r)
	err := d.Decode(&l)
	return l, err
}

func tidMap(ctx context.Context, url string) (map[int]string, error) {
	req, err := http.NewRequestWithContext(ctx, "GET", url, nil)
	if err != nil {
		return nil, err
	}
	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		return nil, err
	}
	l, err := decode[Localize](resp.Body)
	m := make(map[int]string, len(l))
	for _, v := range l {
		m[cmp.Or(v.CardID, v.SupportID)] = v.TID
	}
	return m, err
}

func filejson[T any](path string) ([]T, error) {
	f, err := os.Open(path)
	if err != nil {
		return nil, err
	}
	return decode[T](f)
}

func main() {
	ts := time.Now().UTC().Format(time.DateOnly) // can't use RFC3339 because :s in filename
	var (
		dumpDir string
		out     string
	)
	flag.StringVar(&dumpDir, "dump", ".", "`dir`ectory containing umadump output files")
	flag.StringVar(&out, "o", fmt.Sprintf("uma-col-all-%s.json", ts), "output `file` (stdout if empty)")
	flag.Parse()

	ctx, stop := signal.NotifyContext(context.Background(), os.Interrupt)
	go func() {
		<-ctx.Done()
		stop()
	}()

	var err error
	w := os.Stdout
	if out != "" {
		w, err = os.Create(out)
		if err != nil {
			fatal("output", slog.Any("err", err))
		}
	}

	charas, err := filejson[DumpCard](filepath.Join(dumpDir, "card_data.json"))
	if err != nil {
		fatal("character dump", slog.Any("err", err))
	}
	supports, err := filejson[DumpSupport](filepath.Join(dumpDir, "support_card_data.json"))
	if err != nil {
		fatal("support card dump", slog.Any("err", err))
	}
	charaTID, err := tidMap(ctx, "https://gametora.com/loc/umamusume/character_cards.json")
	if err != nil {
		fatal("character localization file", slog.Any("err", err))
	}
	supportTID, err := tidMap(ctx, "https://gametora.com/loc/umamusume/support_cards.json")
	if err != nil {
		fatal("support card localization file", slog.Any("err", err))
	}

	charaLevels := make(map[string]int, len(charas))
	for _, v := range charas {
		charaLevels[charaTID[v.ID]] = v.Rarity
	}
	supportLevels := make(map[string]int, len(supports))
	for _, v := range supports {
		supportLevels[supportTID[v.ID]] = v.LB
	}

	collection := Collection{
		App:       "gametora",
		Game:      "umamusume",
		Type:      "collection",
		Version:   4,
		Timestamp: ts,
		Servers: map[string]CollectionServer{
			"en": {
				CharCards: charaLevels,
				Supports:  supportLevels,
			},
		},
	}
	b, err := json.Marshal(collection)
	if err != nil {
		panic(err)
	}
	if _, err := w.Write(b); err != nil {
		fatal("writing output", slog.Any("err", err))
	}
}

func fatal(msg string, args ...any) {
	slog.Error(msg, args...)
	os.Exit(1)
}