// Copyright (c) 2012-present The upper.io/db authors. All rights reserved.
//
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
//
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

// Package ql wraps the modernc.org/ql/driver QL driver. See
// https://github.com/upper/db/adapter/ql for documentation, particularities and usage
// examples.
package ql

import (
	"context"
	"database/sql"
	"strings"

	db "github.com/upper/db/v4"
	"github.com/upper/db/v4/internal/sqladapter"
	"github.com/upper/db/v4/internal/sqladapter/compat"
	"github.com/upper/db/v4/internal/sqladapter/exql"
	"github.com/upper/db/v4/internal/sqlbuilder"
	_ "modernc.org/ql/driver" // QL driver
)

// database is the actual implementation of Database
type database struct {
}

func (*database) Template() *exql.Template {
	return template
}

func (*database) OpenDSN(sess sqladapter.Session, dsn string) (*sql.DB, error) {
	return sql.Open("ql2", dsn)
}

func (*database) Collections(sess sqladapter.Session) (collections []string, err error) {
	q := sess.SQL().
		Select("Name").
		From("__Table")

	iter := q.Iterator()
	defer iter.Close()

	for iter.Next() {
		var tableName string
		if err := iter.Scan(&tableName); err != nil {
			return nil, err
		}
		if strings.HasPrefix(tableName, "__") {
			continue
		}
		collections = append(collections, tableName)
	}
	if err := iter.Err(); err != nil {
		return nil, err
	}

	return collections, nil
}

func (*database) CompileStatement(sess sqladapter.Session, stmt *exql.Statement, args []interface{}) (string, []interface{}, error) {
	compiled, err := stmt.Compile(template)
	if err != nil {
		return "", nil, err
	}

	query, args := sqlbuilder.Preprocess(compiled, args)
	query = sqladapter.ReplaceWithDollarSign(query)
	return query, args, nil
}

func (*database) StatementExec(sess sqladapter.Session, ctx context.Context, query string, args ...interface{}) (res sql.Result, err error) {
	if sess.Transaction() != nil {
		return compat.ExecContext(sess.Driver().(*sql.Tx), ctx, query, args)
	}

	sqlTx, err := compat.BeginTx(sess.Driver().(*sql.DB), ctx, nil)
	if err != nil {
		return nil, err
	}

	if res, err = compat.ExecContext(sqlTx, ctx, query, args); err != nil {
		return nil, err
	}

	if err = sqlTx.Commit(); err != nil {
		return nil, err
	}

	return res, err
}

func (*database) NewCollection() sqladapter.CollectionAdapter {
	return &collectionAdapter{}
}

func (*database) LookupName(sess sqladapter.Session) (string, error) {
	connURL, err := ParseURL(sess.ConnectionURL().String())
	if err != nil {
		return "", err
	}
	return connURL.Database, nil
}

func (*database) TableExists(sess sqladapter.Session, name string) error {
	q := sess.SQL().Select("Name").
		From("__Table").
		Where("Name == ?", name)

	iter := q.Iterator()
	defer iter.Close()

	if iter.Next() {
		var name string
		if err := iter.Scan(&name); err != nil {
			return err
		}
		return nil
	}
	if err := iter.Err(); err != nil {
		return err
	}

	return db.ErrCollectionDoesNotExist
}

func (*database) PrimaryKeys(sess sqladapter.Session, tableName string) ([]string, error) {
	return []string{"id()"}, nil
}