package db

import (
	"context"
	"encoding/json"
	"fmt"
	"net/url"
	"os"

	"codeberg.org/u1f320/pronouns.cc/backend/log"
	"emperror.dev/errors"
	"github.com/Masterminds/squirrel"
	"github.com/jackc/pgx/v5/pgconn"
	"github.com/jackc/pgx/v5/pgxpool"
	"github.com/mediocregopher/radix/v4"
	"github.com/minio/minio-go/v7"
	"github.com/minio/minio-go/v7/pkg/credentials"
	"github.com/prometheus/client_golang/prometheus"
)

var sq = squirrel.StatementBuilder.PlaceholderFormat(squirrel.Dollar)

const ErrNothingToUpdate = errors.Sentinel("nothing to update")

type Execer interface {
	Exec(ctx context.Context, sql string, arguments ...interface{}) (commandTag pgconn.CommandTag, err error)
}

type DB struct {
	*pgxpool.Pool

	Redis radix.Client

	minio       *minio.Client
	minioBucket string
	baseURL     *url.URL

	TotalRequests prometheus.Counter
}

func New() (*DB, error) {
	log.Debug("creating postgres client")
	pool, err := pgxpool.New(context.Background(), os.Getenv("DATABASE_URL"))
	if err != nil {
		return nil, errors.Wrap(err, "creating postgres client")
	}

	log.Debug("creating redis client")
	redis, err := (&radix.PoolConfig{}).New(context.Background(), "tcp", os.Getenv("REDIS"))
	if err != nil {
		return nil, errors.Wrap(err, "creating redis client")
	}

	log.Debug("creating minio client")
	minioClient, err := minio.New(os.Getenv("MINIO_ENDPOINT"), &minio.Options{
		Creds:  credentials.NewStaticV4(os.Getenv("MINIO_ACCESS_KEY_ID"), os.Getenv("MINIO_ACCESS_KEY_SECRET"), ""),
		Secure: os.Getenv("MINIO_SSL") == "true",
	})
	if err != nil {
		return nil, errors.Wrap(err, "creating minio client")
	}

	baseURL, err := url.Parse(os.Getenv("BASE_URL"))
	if err != nil {
		return nil, errors.Wrap(err, "parsing base URL")
	}

	db := &DB{
		Pool:  pool,
		Redis: redis,

		minio:       minioClient,
		minioBucket: os.Getenv("MINIO_BUCKET"),
		baseURL:     baseURL,
	}

	log.Debug("initializing metrics")
	err = db.initMetrics()
	if err != nil {
		return nil, errors.Wrap(err, "initializing metrics")
	}

	return db, nil
}

// MultiCmd executes the given Redis commands in order.
// If any return an error, the function is aborted.
func (db *DB) MultiCmd(ctx context.Context, cmds ...radix.Action) error {
	for _, cmd := range cmds {
		err := db.Redis.Do(ctx, cmd)
		if err != nil {
			return err
		}
	}
	return nil
}

// SetJSON sets the given key to v marshaled as JSON.
func (db *DB) SetJSON(ctx context.Context, key string, v any, args ...string) error {
	b, err := json.Marshal(v)
	if err != nil {
		return errors.Wrap(err, "marshaling json")
	}

	cmdArgs := make([]string, 0, len(args)+2)
	cmdArgs = append(cmdArgs, key, string(b))
	cmdArgs = append(cmdArgs, args...)

	err = db.Redis.Do(ctx, radix.Cmd(nil, "SET", cmdArgs...))
	if err != nil {
		return errors.Wrap(err, "writing to Redis")
	}
	return nil
}

// GetJSON gets the given key as a JSON object.
func (db *DB) GetJSON(ctx context.Context, key string, v any) error {
	var b []byte

	err := db.Redis.Do(ctx, radix.Cmd(&b, "GET", key))
	if err != nil {
		return errors.Wrap(err, "reading from Redis")
	}

	if b == nil {
		return nil
	}

	if v == nil {
		return fmt.Errorf("nil pointer passed into GetJSON")
	}

	err = json.Unmarshal(b, v)
	if err != nil {
		return errors.Wrap(err, "unmarshaling json")
	}
	return nil
}

// GetDelJSON gets the given key as a JSON object and deletes it.
func (db *DB) GetDelJSON(ctx context.Context, key string, v any) error {
	var b []byte

	err := db.Redis.Do(ctx, radix.Cmd(&b, "GETDEL", key))
	if err != nil {
		return errors.Wrap(err, "reading from Redis")
	}

	if b == nil {
		return nil
	}

	if v == nil {
		return fmt.Errorf("nil pointer passed into GetDelJSON")
	}

	err = json.Unmarshal(b, v)
	if err != nil {
		return errors.Wrap(err, "unmarshaling json")
	}
	return nil
}

// NotNull is a little helper that returns an *empty slice* when the slice's length is 0.
// This is to prevent nil slices from being marshaled as JSON null
func NotNull[T any](slice []T) []T {
	if len(slice) == 0 {
		return []T{}
	}
	return slice
}