// Copyright 2019 The Gitea Authors. All rights reserved.
// Use of this source code is governed by a MIT-style
// license that can be found in the LICENSE file.

package migrations

import (
	"fmt"

	"github.com/go-xorm/xorm"
	"xorm.io/core"

	"code.gitea.io/gitea/models"
	"code.gitea.io/gitea/modules/generate"
	"code.gitea.io/gitea/modules/log"
	"code.gitea.io/gitea/modules/util"
)

func hashAppToken(x *xorm.Engine) error {
	// AccessToken see models/token.go
	type AccessToken struct {
		ID             int64 `xorm:"pk autoincr"`
		UID            int64 `xorm:"INDEX"`
		Name           string
		Sha1           string
		Token          string `xorm:"-"`
		TokenHash      string // sha256 of token - we will ensure UNIQUE later
		TokenSalt      string
		TokenLastEight string `xorm:"token_last_eight"`

		CreatedUnix       util.TimeStamp `xorm:"INDEX created"`
		UpdatedUnix       util.TimeStamp `xorm:"INDEX updated"`
		HasRecentActivity bool           `xorm:"-"`
		HasUsed           bool           `xorm:"-"`
	}

	// First remove the index
	sess := x.NewSession()
	defer sess.Close()
	if err := sess.Begin(); err != nil {
		return err
	}

	var err error
	if models.DbCfg.Type == core.POSTGRES || models.DbCfg.Type == core.SQLITE {
		_, err = sess.Exec("DROP INDEX IF EXISTS UQE_access_token_sha1")
	} else if models.DbCfg.Type == core.MSSQL {
		_, err = sess.Exec(`DECLARE @ConstraintName VARCHAR(256)
		DECLARE @SQL NVARCHAR(256)
		SELECT @ConstraintName = obj.name FROM sys.columns col LEFT OUTER JOIN sys.objects obj ON obj.object_id = col.default_object_id AND obj.type = 'D' WHERE col.object_id = OBJECT_ID('access_token') AND obj.name IS NOT NULL AND col.name = 'sha1'
		SET @SQL = N'ALTER TABLE [access_token] DROP CONSTRAINT [' + @ConstraintName + N']'
		EXEC sp_executesql @SQL`)
	} else if models.DbCfg.Type == core.MYSQL {
		indexes, err := sess.QueryString(`SHOW INDEX FROM access_token WHERE KEY_NAME = 'UQE_access_token_sha1'`)
		if err != nil {
			return err
		}

		if len(indexes) >= 1 {
			_, err = sess.Exec("DROP INDEX UQE_access_token_sha1 ON access_token")
			if err != nil {
				return err
			}
		}
	} else {
		_, err = sess.Exec("DROP INDEX UQE_access_token_sha1 ON access_token")
	}
	if err != nil {
		return fmt.Errorf("Drop index failed: %v", err)
	}

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

	if err := sess.Begin(); err != nil {
		return err
	}

	if err := sess.Sync2(new(AccessToken)); err != nil {
		return fmt.Errorf("Sync2: %v", err)
	}

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

	if err := sess.Begin(); err != nil {
		return err
	}

	// transform all tokens to hashes
	const batchSize = 100
	for start := 0; ; start += batchSize {
		tokens := make([]*AccessToken, 0, batchSize)
		if err := sess.Limit(batchSize, start).Find(&tokens); err != nil {
			return err
		}
		if len(tokens) == 0 {
			break
		}

		for _, token := range tokens {
			// generate salt
			salt, err := generate.GetRandomString(10)
			if err != nil {
				return err
			}
			token.TokenSalt = salt
			token.TokenHash = hashToken(token.Sha1, salt)
			if len(token.Sha1) < 8 {
				log.Warn("Unable to transform token %s with name %s belonging to user ID %d, skipping transformation", token.Sha1, token.Name, token.UID)
				continue
			}
			token.TokenLastEight = token.Sha1[len(token.Sha1)-8:]
			token.Sha1 = "" // ensure to blank out column in case drop column doesn't work

			if _, err := sess.ID(token.ID).Cols("token_hash, token_salt, token_last_eight, sha1").Update(token); err != nil {
				return fmt.Errorf("couldn't add in sha1, token_hash, token_salt and token_last_eight: %v", err)
			}

		}
	}

	// Commit and begin new transaction for dropping columns
	if err := sess.Commit(); err != nil {
		return err
	}
	if err := sess.Begin(); err != nil {
		return err
	}

	if err := dropTableColumns(sess, "access_token", "sha1"); err != nil {
		return err
	}
	if err := sess.Commit(); err != nil {
		return err
	}
	return resyncHashAppTokenWithUniqueHash(x)
}

func resyncHashAppTokenWithUniqueHash(x *xorm.Engine) error {
	// AccessToken see models/token.go
	type AccessToken struct {
		TokenHash string `xorm:"UNIQUE"` // sha256 of token - we will ensure UNIQUE later
	}
	sess := x.NewSession()
	defer sess.Close()
	if err := sess.Begin(); err != nil {
		return err
	}
	if err := sess.Sync2(new(AccessToken)); err != nil {
		return fmt.Errorf("Sync2: %v", err)
	}
	return sess.Commit()
}