package common

import (
	"encoding/json"
	"fmt"
)

const aaRoundSelectionKey = "aa_round_selection"

type AARoundSelection struct {
	PeakGroupID   uint32 `json:"peak_group_id"`
	ClientVersion string `json:"client_version"`
}

func SetAARoundSelection(peakGroupID uint32) (*AARoundSelection, error) {
	catalog, err := LoadMonsterSettingsCatalog()
	if err != nil {
		return nil, err
	}
	valid := false
	for _, group := range catalog.Modes["aa"] {
		if group.ID == peakGroupID {
			valid = true
			break
		}
	}
	if !valid {
		return nil, fmt.Errorf("AA round %d is not present in this Client's resources", peakGroupID)
	}
	cfg, err := LoadRuntimeConfig()
	if err != nil {
		return nil, err
	}
	selection := &AARoundSelection{
		PeakGroupID:   peakGroupID,
		ClientVersion: cfg.ClientVersion,
	}
	if err := updateAARoundSelection(selection); err != nil {
		return nil, err
	}
	return selection, nil
}

// ReadAARoundSelection is read-only. The selected round remains active until
// Srtool changes or clears it, or the configured Client version changes.
func ReadAARoundSelection() (*AARoundSelection, error) {
	cfg, err := LoadRuntimeConfig()
	if err != nil {
		return nil, err
	}
	root, err := readCurrencyWarsPersistentRoot()
	if err != nil {
		return nil, err
	}
	return activeAARoundSelection(root, cfg), nil
}

func ClearAARoundSelection() error {
	persistentWriteMu.Lock()
	defer persistentWriteMu.Unlock()
	unlock, err := lockPersistentFile()
	if err != nil {
		return err
	}
	defer unlock()
	root, err := readCurrencyWarsPersistentRoot()
	if err != nil {
		return err
	}
	_, hasRound := root[aaRoundSelectionKey]
	_, hasLegacyRoom := root["aa_room_selection"]
	if !hasRound && !hasLegacyRoom {
		return nil
	}
	delete(root, aaRoundSelectionKey)
	delete(root, "aa_room_selection")
	return writeJSONAtomic("persistent", root)
}

func updateAARoundSelection(selection *AARoundSelection) error {
	raw, err := json.Marshal(selection)
	if err != nil {
		return err
	}
	persistentWriteMu.Lock()
	defer persistentWriteMu.Unlock()
	unlock, err := lockPersistentFile()
	if err != nil {
		return err
	}
	defer unlock()
	root, err := readCurrencyWarsPersistentRoot()
	if err != nil {
		return err
	}
	delete(root, "aa_room_selection")
	root[aaRoundSelectionKey] = raw
	return writeJSONAtomic("persistent", root)
}

func activeAARoundSelection(root map[string]json.RawMessage, cfg RuntimeConfig) *AARoundSelection {
	raw, exists := root[aaRoundSelectionKey]
	if !exists {
		return nil
	}
	var selection AARoundSelection
	if json.Unmarshal(raw, &selection) != nil || selection.PeakGroupID == 0 || selection.ClientVersion != cfg.ClientVersion {
		return nil
	}
	return &selection
}