package repoter

import (
	"context"
	"encoding/json"
	"fmt"
	"os"
	"path/filepath"

	"github.com/Azure/azure-sdk-for-go/sdk/azidentity"
	awsconfig "github.com/aws/aws-sdk-go-v2/config"
	"github.com/glebarez/sqlite"
	"github.com/tidbcloud/metering/pkg/common/config"
	"github.com/tidbcloud/metering/pkg/common/constants"
	"github.com/tidbcloud/metering/pkg/common/models"
	"github.com/tidbcloud/metering/pkg/common/utils"
	"github.com/tidbcloud/metering/pkg/common/utils/storage"
	awsobj "github.com/tidbcloud/metering/pkg/common/utils/storage/aws"
	azblob "github.com/tidbcloud/metering/pkg/common/utils/storage/azure"
	gcpobj "github.com/tidbcloud/metering/pkg/common/utils/storage/gcp"
	"gorm.io/gorm"
)

const (
	repotercachepath   = "repotercache"
	checkpointfilename = "checkpoint.json"
)

// BillingRepoterLoader load billing repoter from azure blob and save checkpoint to azure blob
type BillingRepoterLoad struct {
	conf      *config.ServiceConfig
	objcli    storage.StorageProvider
	cachepath string
}

func NewBillingRepoterLoad(conf *config.ServiceConfig) *BillingRepoterLoad {
	return &BillingRepoterLoad{
		conf: conf,
	}
}

func (b *BillingRepoterLoad) Init() (*BillingRepoterLoad, error) {
	abspath, err := utils.EnsureCache(b.conf.TrafficMeteringConfig.CachePath, repotercachepath)
	if err != nil {
		return b, err
	}
	b.cachepath = abspath
	switch b.conf.Vendor {
	case constants.VendorAzure:
		{
			err := b.ensureAzureClient()
			if err != nil {
				return b, err
			}
		}
	case constants.VendorAWS:
		{
			err := b.ensureAWSClient()
			if err != nil {
				return b, err
			}
		}
	case constants.VendorGCP:
		{
			err := b.ensureGCPClient()
			if err != nil {
				return b, err
			}
		}
	default:
		return b, fmt.Errorf("invalid vendor: %s", b.conf.Vendor)
	}

	return b, nil
}
func (b *BillingRepoterLoad) ensureAzureClient() error {
	cred, err := azidentity.NewDefaultAzureCredential(nil)
	if err != nil {
		return err
	}
	b.objcli, err = azblob.NewAzureProviderBlob(cred, b.conf.TrafficMeteringConfig.Provider.Azure.BillingProvider.StorageAccountName, b.conf.TrafficMeteringConfig.Provider.Azure.BillingProvider.ContainerName)
	if err != nil {
		return err
	}
	return nil
}

func (b *BillingRepoterLoad) ensureAWSClient() error {
	cfg, err := awsconfig.LoadDefaultConfig(context.TODO())
	if err != nil {
		return fmt.Errorf("unable to get aws config: %v", err)
	}
	cfg.Region = b.conf.Region
	if b.conf.TrafficMeteringConfig.Provider.AWS.StoreProvider.RoleArn != "" {
		b.objcli = awsobj.NewAwsProviderS3(cfg, b.conf.TrafficMeteringConfig.Provider.AWS.StoreProvider.BucketName).AssumeRole(context.TODO(), b.conf.TrafficMeteringConfig.Provider.AWS.StoreProvider.RoleArn)

	} else {
		b.objcli = awsobj.NewAwsProviderS3(cfg, b.conf.TrafficMeteringConfig.Provider.AWS.StoreProvider.BucketName)
	}
	return nil
}

func (b *BillingRepoterLoad) ensureGCPClient() error {
	b.objcli = gcpobj.NewGcpProviderGcs(b.conf.TrafficMeteringConfig.Provider.GCP.StoreProvider.ProjectId, b.conf.TrafficMeteringConfig.Provider.GCP.StoreProvider.BucketName)
	return nil
}

// LoadRepoterWithTs load  billing repoter sqlite from object blob
func (b *BillingRepoterLoad) LoadRepoterWithTs(ctx context.Context, destfilename string, timestemp int64) ([]*models.BillingReport, error) {

	blobs, err := b.objcli.ListObjectByName(ctx, destfilename)
	if err != nil {
		return nil, err
	}
	if len(blobs) == 0 {
		return nil, nil
	}
	if len(blobs) > 1 {
		return nil, fmt.Errorf("more than one file found in azure blob")
	}
	//download blob to cache
	destFile := filepath.Join(b.cachepath, filepath.Base(destfilename))
	err = b.objcli.DownloadObjects(ctx, blobs, b.cachepath)
	if err != nil {
		return nil, err
	}
	//load file
	db, err := ensureSQLite(destFile)
	if err != nil {
		return nil, err
	}
	//close db after load, release sqlite file fd
	defer b.CloseDB(db)
	// load repoter from sqlite
	res, err := loadRepoterFromSQLite(db, timestemp)
	if err != nil {
		return nil, err
	}
	return res, nil
}
func ensureSQLite(dbfile string) (*gorm.DB, error) {
	db, err := gorm.Open(sqlite.Open(dbfile), &gorm.Config{})
	if err != nil {
		return nil, err
	}
	err = db.AutoMigrate(&models.BillingReport{})
	if err != nil {
		return nil, err
	}
	return db, nil
}

func (b *BillingRepoterLoad) CloseDB(db *gorm.DB) {
	//close db
	if db != nil {
		pool, err := db.DB()
		if err != nil {
			return
		}
		err = pool.Close()
		if err != nil {
			return
		}
	}
}

func loadRepoterFromSQLite(db *gorm.DB, timestemp int64) ([]*models.BillingReport, error) {
	var res []*models.BillingReport
	err := db.Where("created_at > ?", timestemp).Find(&res).Error
	if err != nil {
		return nil, err
	}
	return res, nil
}

// LoadCheckpoint load  checkpoint from object storage
func (b *BillingRepoterLoad) LoadCheckpoint(ctx context.Context, destfilename string) (int64, error) {
	checkpointname := filepath.Join(filepath.Dir(destfilename), checkpointfilename)
	blobs, err := b.objcli.ListObjectByName(ctx, checkpointname)
	if err != nil {
		return 0, err
	}
	// if no checkpoint file found, return 0
	if len(blobs) == 0 {
		return 0, nil
	}
	if len(blobs) > 1 {
		return 0, fmt.Errorf("more than one file found in azure blob")
	}
	//download blob to cache
	destFile := filepath.Join(b.cachepath, filepath.Base(checkpointname))
	err = b.objcli.DownloadObjects(ctx, blobs, b.cachepath)
	if err != nil {
		return 0, err
	}
	//load file
	return ensureJsonCheckpoint(destFile)
}

// SaveCheckpoint save checkpoint to object storage
func (b *BillingRepoterLoad) SaveCheckpoint(ctx context.Context, destfilename string, checkpoint int64) error {
	checkpointname := filepath.Join(filepath.Dir(destfilename), checkpointfilename)
	destcheckponitfile := filepath.Join(b.cachepath, checkpointfilename)
	err := saveJsonCheckpoint(destcheckponitfile, checkpoint)
	if err != nil {
		return err
	}
	//upload checkpoint to object storage
	return b.objcli.UploadObject(ctx, checkpointname, destcheckponitfile)
}

func ensureJsonCheckpoint(filepath string) (int64, error) {
	f, err := os.Open(filepath)
	if err != nil {
		return 0, err
	}
	defer f.Close()
	var res models.ReportCheckPoint
	err = json.NewDecoder(f).Decode(&res)
	if err != nil {
		return 0, err
	}
	return res.Timestamp, nil

}

func saveJsonCheckpoint(filepath string, checkpoint int64) error {
	f, err := os.Create(filepath)
	if err != nil {
		return err
	}
	defer f.Close()
	res := models.ReportCheckPoint{
		Timestamp: checkpoint,
	}
	return json.NewEncoder(f).Encode(res)
}