package app

import (
	"encoding/json"
	"fmt"
	"path/filepath"
	"strings"
	"time"

	transportcfgpkg "selective-vpn-api/app/transportcfg"
)

func appendSingBoxHistory(rec singBoxProfileHistoryRecord) error {
	profileID := sanitizeID(rec.ProfileID)
	if profileID == "" {
		return fmt.Errorf("empty profile id")
	}
	rec.ProfileID = profileID
	if strings.TrimSpace(rec.At) == "" {
		rec.At = time.Now().UTC().Format(time.RFC3339Nano)
	}
	if strings.TrimSpace(rec.ID) == "" {
		rec.ID = "h-" + newTransportToken(8)
	}
	if rec.Action == "" {
		rec.Action = "unknown"
	}
	if rec.Status == "" {
		rec.Status = "success"
	}

	data, err := json.MarshalIndent(rec, "", "  ")
	if err != nil {
		return err
	}
	stamp := transportcfgpkg.SanitizeHistoryStamp(rec.At, time.Now().UTC())
	fileName := fmt.Sprintf("%s-%s-%s-%s.json", stamp, rec.ProfileID, rec.Action, rec.ID)
	return transportcfgpkg.WriteFileAtomic(filepath.Join(singBoxHistoryRootDir, fileName), append(data, '\n'), 0o644)
}

func loadSingBoxHistoryRecords(profileID string, limit int) ([]singBoxProfileHistoryRecord, error) {
	rawRecords, err := transportcfgpkg.ReadJSONFiles(singBoxHistoryRootDir)
	if err != nil {
		return nil, err
	}
	id := sanitizeID(profileID)
	out := make([]singBoxProfileHistoryRecord, 0, len(rawRecords))
	for _, data := range rawRecords {
		var rec singBoxProfileHistoryRecord
		if err := json.Unmarshal(data, &rec); err != nil {
			continue
		}
		if sanitizeID(rec.ProfileID) != id {
			continue
		}
		out = append(out, rec)
	}
	transportcfgpkg.SortRecordsDescByAt(out, func(rec singBoxProfileHistoryRecord) string { return rec.At })
	if limit > 0 && len(out) > limit {
		out = out[:limit]
	}
	return out, nil
}

func selectSingBoxRollbackCandidate(records []singBoxProfileHistoryRecord, historyID string) (singBoxProfileHistoryRecord, bool) {
	return transportcfgpkg.SelectRecordCandidate(
		records,
		historyID,
		func(rec singBoxProfileHistoryRecord) string { return rec.ID },
		func(rec singBoxProfileHistoryRecord) bool { return rec.Action == "apply" && rec.Status == "success" },
	)
}

func decodeHistoryPrevConfig(rec singBoxProfileHistoryRecord) ([]byte, bool, error) {
	return transportcfgpkg.DecodeBase64Optional(rec.PrevConfigB64, rec.PrevConfigExist)
}

func joinSingBoxIssueMessages(issues []SingBoxProfileIssue) string {
	parts := make([]string, 0, len(issues))
	for _, it := range issues {
		parts = append(parts, it.Message)
	}
	return transportcfgpkg.JoinMessages(parts)
}