package dbAccess

import (
	"git.fjla.uk/owlboard/timetable-mgr/helpers"
	"git.fjla.uk/owlboard/timetable-mgr/log"
	"go.uber.org/zap"

	"context"
	"time"

	"go.mongodb.org/mongo-driver/mongo"
	"go.mongodb.org/mongo-driver/mongo/options"
)

// Provide the DB Connection to other functions
var MongoClient (*mongo.Client)

// Builds the DB URI based on the loaded configuration parameters
func getDbUri(cfg *helpers.Configuration) string {
	var uri = "mongodb://" + cfg.DbUser + ":" + cfg.DbPass + "@" + cfg.DbHost + ":" + cfg.DbPort + "?authSource=owlboard"
	return uri
}

// Configure bsonOpts
var bsonOpts = &options.BSONOptions{
	UseJSONStructTags: true,
}

func InitDataAccess(cfg *helpers.Configuration) {
	log.Debug("Starting database connection")
	url := getDbUri(cfg)

	const maxRetries = 8

	for attempt := 1; attempt <= maxRetries; attempt++ {
		log.Info("Attempting to connect to database", zap.Int("attempt", attempt), zap.Int("max-tries", maxRetries))
		ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
		defer cancel()

		client, err := mongo.Connect(ctx, options.Client().ApplyURI(url).SetBSONOptions(bsonOpts))
		if err != nil {
			log.Warn("Error connecting to database", zap.Int("attempt", attempt), zap.Int("max-tries", maxRetries))
			cancel()
			if attempt != maxRetries {
				helpers.BackoffDelay(attempt)
			}
			continue
		}

		err = client.Ping(ctx, nil)
		if err != nil {
			log.Warn("Error pinging database", zap.Int("attempt", attempt), zap.Int("max-tries", maxRetries))
			cancel()
			if attempt != maxRetries {
				helpers.BackoffDelay(attempt)
			}
			continue
		}

		MongoClient = client
		log.Info("Database connection successful")
		return
	}

	log.Fatal("Failed to connect to database on multiple attempts", zap.Int("attempts", maxRetries))
}

// Closes the connection to the database - used for cleanup functions
func CloseMongoClient() {
	if MongoClient != nil {
		ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
		defer cancel()
		if err := MongoClient.Disconnect(ctx); err != nil {
			log.Warn("Error disconnecting MongoDB client: " + err.Error())
		} else {
			log.Info("MongoDB client disconnected.")
		}
	}
}