package sqlite

import (
	"context"
	"database/sql"
	"fmt"
	"math"
	"sync"
	"time"

	"forge.cadoles.com/arcad/edge/pkg/storage"
	"forge.cadoles.com/arcad/edge/pkg/storage/filter"
	filterSQL "forge.cadoles.com/arcad/edge/pkg/storage/filter/sql"
	"github.com/pkg/errors"
	"gitlab.com/wpetit/goweb/logger"

	_ "modernc.org/sqlite"
)

type DocumentStore struct {
	db       *sql.DB
	path     string
	openOnce sync.Once
	mutex    sync.RWMutex
}

// Delete implements storage.DocumentStore
func (s *DocumentStore) Delete(ctx context.Context, collection string, id storage.DocumentID) error {
	err := s.withTx(ctx, func(tx *sql.Tx) error {
		query := `
		DELETE FROM documents
		WHERE collection = $1 AND id = $2 
		`

		_, err := tx.ExecContext(ctx, query, collection, string(id))
		if err != nil {
			return errors.WithStack(err)
		}

		return nil
	})
	if err != nil {
		return errors.WithStack(err)
	}

	return nil
}

// Get implements storage.DocumentStore
func (s *DocumentStore) Get(ctx context.Context, collection string, id storage.DocumentID) (storage.Document, error) {
	var document storage.Document

	err := s.withTx(ctx, func(tx *sql.Tx) error {
		query := `
		SELECT id, data, created_at, updated_at 
		FROM documents 
		WHERE collection = $1 AND id = $2 
		`

		row := tx.QueryRowContext(ctx, query, collection, string(id))

		var (
			createdAt time.Time
			updatedAt time.Time
			data      JSONMap
		)

		err := row.Scan(&id, &data, &createdAt, &updatedAt)
		if err != nil {
			if errors.Is(err, sql.ErrNoRows) {
				return errors.WithStack(storage.ErrDocumentNotFound)
			}

			return errors.WithStack(err)
		}

		document = storage.Document(data)

		document[storage.DocumentAttrID] = id
		document[storage.DocumentAttrCreatedAt] = createdAt
		document[storage.DocumentAttrUpdatedAt] = updatedAt

		return nil
	})
	if err != nil {
		return nil, errors.WithStack(err)
	}

	return document, nil
}

// Query implements storage.DocumentStore
func (s *DocumentStore) Query(ctx context.Context, collection string, filter *filter.Filter, funcs ...storage.QueryOptionFunc) ([]storage.Document, error) {
	opts := &storage.QueryOptions{}
	for _, fn := range funcs {
		fn(opts)
	}

	var documents []storage.Document

	err := s.withTx(ctx, func(tx *sql.Tx) error {
		criteria := "1 = 1"
		args := make([]any, 0)

		var err error

		if filter != nil {
			criteria, args, err = filterSQL.ToSQL(
				filter.Root(),
				filterSQL.WithPreparedParameter("$", 2),
				filterSQL.WithTransform(transformOperator),
				filterSQL.WithKeyTransform(func(key string) string {
					return fmt.Sprintf("json_extract(data, '$.%s')", key)
				}),
			)
			if err != nil {
				return errors.WithStack(err)
			}
		}

		query := `
		SELECT id, data, created_at, updated_at 
		FROM documents 
		WHERE collection = $1 AND (` + criteria + `)
		`

		args = append([]interface{}{collection}, args...)

		if opts.OrderBy != nil {
			direction := storage.OrderDirectionAsc
			if opts.OrderDirection != nil {
				direction = *opts.OrderDirection
			}

			query, args = withOrderByClause(query, args, *opts.OrderBy, direction)
		}

		if opts.Offset != nil || opts.Limit != nil {
			offset := 0
			if opts.Offset != nil {
				offset = *opts.Offset
			}

			limit := math.MaxInt
			if opts.Limit != nil {
				limit = *opts.Limit
			}

			query, args = withLimitOffsetClause(query, args, limit, offset)
		}

		logger.Debug(
			ctx, "executing query",
			logger.F("query", query),
			logger.F("args", args),
		)

		rows, err := tx.QueryContext(ctx, query, args...)
		if err != nil {
			return errors.WithStack(err)
		}

		defer rows.Close()

		documents = make([]storage.Document, 0)

		for rows.Next() {
			var (
				id        storage.DocumentID
				createdAt time.Time
				updatedAt time.Time
				data      JSONMap
			)

			if err := rows.Scan(&id, &data, &createdAt, &updatedAt); err != nil {
				return errors.WithStack(err)
			}

			document := storage.Document(data)
			document[storage.DocumentAttrID] = id
			document[storage.DocumentAttrCreatedAt] = createdAt
			document[storage.DocumentAttrUpdatedAt] = updatedAt

			documents = append(documents, document)
		}

		if err := rows.Err(); err != nil {
			return errors.WithStack(err)
		}

		return nil
	})
	if err != nil {
		return nil, errors.WithStack(err)
	}

	return documents, nil
}

// Upsert implements storage.DocumentStore
func (s *DocumentStore) Upsert(ctx context.Context, collection string, document storage.Document) (storage.Document, error) {
	var upsertedDocument storage.Document

	err := s.withTx(ctx, func(tx *sql.Tx) error {
		query := `
		INSERT INTO documents (id, collection, data, created_at, updated_at) 
		VALUES($1, $2, $3, $4, $4)
		ON CONFLICT (id, collection) DO UPDATE SET
			data = $3, updated_at = $4
		RETURNING "id", "data", "created_at", "updated_at"
		`

		now := time.Now().UTC()

		id, exists := document.ID()
		if !exists || id == "" {
			id = storage.NewDocumentID()
		}

		args := []any{id, collection, JSONMap(document), now, now}

		logger.Debug(
			ctx, "executing query",
			logger.F("query", query),
			logger.F("args", args),
		)

		row := tx.QueryRowContext(ctx, query, args...)

		var (
			createdAt time.Time
			updatedAt time.Time
			data      JSONMap
		)

		err := row.Scan(&id, &data, &createdAt, &updatedAt)
		if err != nil {
			return errors.WithStack(err)
		}

		upsertedDocument = storage.Document(data)

		upsertedDocument[storage.DocumentAttrID] = id
		upsertedDocument[storage.DocumentAttrCreatedAt] = createdAt
		upsertedDocument[storage.DocumentAttrUpdatedAt] = updatedAt

		return nil
	})
	if err != nil {
		return nil, errors.WithStack(err)
	}

	return upsertedDocument, nil
}

func (s *DocumentStore) withTx(ctx context.Context, fn func(tx *sql.Tx) error) error {
	var db *sql.DB

	db, err := s.getDatabase(ctx)
	if err != nil {
		return errors.WithStack(err)
	}

	if err := withTx(ctx, db, fn); err != nil {
		return errors.WithStack(err)
	}

	return nil
}

func (s *DocumentStore) getDatabase(ctx context.Context) (*sql.DB, error) {
	s.mutex.RLock()
	if s.db != nil {
		defer s.mutex.RUnlock()

		var err error

		s.openOnce.Do(func() {
			if err = s.ensureTables(ctx, s.db); err != nil {
				err = errors.WithStack(err)

				return
			}
		})

		if err != nil {
			return nil, errors.WithStack(err)
		}

		return s.db, nil
	}

	s.mutex.RUnlock()

	var (
		db  *sql.DB
		err error
	)

	s.openOnce.Do(func() {
		db, err = sql.Open("sqlite", s.path)
		if err != nil {
			err = errors.WithStack(err)

			return
		}

		if err = s.ensureTables(ctx, db); err != nil {
			err = errors.WithStack(err)

			return
		}
	})

	if err != nil {
		return nil, errors.WithStack(err)
	}

	if db != nil {
		s.mutex.Lock()
		s.db = db
		s.mutex.Unlock()
	}

	s.mutex.RLock()
	defer s.mutex.RUnlock()

	return s.db, nil
}

func (s *DocumentStore) ensureTables(ctx context.Context, db *sql.DB) error {
	err := withTx(ctx, db, func(tx *sql.Tx) error {
		query := `
			CREATE TABLE IF NOT EXISTS documents (
				id TEXT PRIMARY KEY,
				collection TEXT NOT NULL,
				data TEXT,
				created_at TIMESTAMP NOT NULL,
				updated_at TIMESTAMP NOT NULL,
				UNIQUE(id, collection) ON CONFLICT REPLACE
			);
		`
		if _, err := tx.ExecContext(ctx, query); err != nil {
			return errors.WithStack(err)
		}

		query = `
			CREATE INDEX IF NOT EXISTS collection_idx ON documents (collection);
		`
		if _, err := tx.ExecContext(ctx, query); err != nil {
			return errors.WithStack(err)
		}

		return nil
	})
	if err != nil {
		return errors.WithStack(err)
	}

	return nil
}

func withOrderByClause(query string, args []any, orderBy string, orderDirection storage.OrderDirection) (string, []any) {
	direction := "ASC"
	if orderDirection == storage.OrderDirectionDesc {
		direction = "DESC"
	}

	var column string

	switch orderBy {
	case storage.DocumentAttrID:
		column = "id"

	case storage.DocumentAttrCreatedAt:
		column = "created_at"

	case storage.DocumentAttrUpdatedAt:
		column = "updated_at"

	default:
		column = fmt.Sprintf("json_extract(data, '$.' || $%d)", len(args)+1)
		args = append(args, orderBy)
	}

	query += fmt.Sprintf(` ORDER BY %s %s`, column, direction)

	return query, args
}

func withLimitOffsetClause(query string, args []any, limit int, offset int) (string, []any) {
	query += fmt.Sprintf(` LIMIT $%d OFFSET $%d`, len(args)+1, len(args)+2)
	args = append(args, limit, offset)

	return query, args
}

func NewDocumentStore(path string) *DocumentStore {
	return &DocumentStore{
		db:       nil,
		path:     path,
		openOnce: sync.Once{},
	}
}

func NewDocumentStoreWithDB(db *sql.DB) *DocumentStore {
	return &DocumentStore{
		db:       db,
		path:     "",
		openOnce: sync.Once{},
	}
}

var _ storage.DocumentStore = &DocumentStore{}