// Copyright 2020 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 models

import (
	"context"
	"errors"
	"fmt"

	"code.gitea.io/gitea/models/db"
	repo_model "code.gitea.io/gitea/models/repo"
	user_model "code.gitea.io/gitea/models/user"
	"code.gitea.io/gitea/modules/lfs"
	"code.gitea.io/gitea/modules/log"
	"code.gitea.io/gitea/modules/timeutil"

	"xorm.io/builder"
)

// LFSMetaObject stores metadata for LFS tracked files.
type LFSMetaObject struct {
	ID           int64 `xorm:"pk autoincr"`
	lfs.Pointer  `xorm:"extends"`
	RepositoryID int64              `xorm:"UNIQUE(s) INDEX NOT NULL"`
	Existing     bool               `xorm:"-"`
	CreatedUnix  timeutil.TimeStamp `xorm:"created"`
}

func init() {
	db.RegisterModel(new(LFSMetaObject))
}

// LFSTokenResponse defines the JSON structure in which the JWT token is stored.
// This structure is fetched via SSH and passed by the Git LFS client to the server
// endpoint for authorization.
type LFSTokenResponse struct {
	Header map[string]string `json:"header"`
	Href   string            `json:"href"`
}

// ErrLFSObjectNotExist is returned from lfs models functions in order
// to differentiate between database and missing object errors.
var ErrLFSObjectNotExist = errors.New("LFS Meta object does not exist")

// NewLFSMetaObject stores a given populated LFSMetaObject structure in the database
// if it is not already present.
func NewLFSMetaObject(m *LFSMetaObject) (*LFSMetaObject, error) {
	var err error

	ctx, committer, err := db.TxContext()
	if err != nil {
		return nil, err
	}
	defer committer.Close()

	has, err := db.GetByBean(ctx, m)
	if err != nil {
		return nil, err
	}

	if has {
		m.Existing = true
		return m, committer.Commit()
	}

	if err = db.Insert(ctx, m); err != nil {
		return nil, err
	}

	return m, committer.Commit()
}

// GetLFSMetaObjectByOid selects a LFSMetaObject entry from database by its OID.
// It may return ErrLFSObjectNotExist or a database error. If the error is nil,
// the returned pointer is a valid LFSMetaObject.
func GetLFSMetaObjectByOid(repoID int64, oid string) (*LFSMetaObject, error) {
	if len(oid) == 0 {
		return nil, ErrLFSObjectNotExist
	}

	m := &LFSMetaObject{Pointer: lfs.Pointer{Oid: oid}, RepositoryID: repoID}
	has, err := db.GetEngine(db.DefaultContext).Get(m)
	if err != nil {
		return nil, err
	} else if !has {
		return nil, ErrLFSObjectNotExist
	}
	return m, nil
}

// RemoveLFSMetaObjectByOid removes a LFSMetaObject entry from database by its OID.
// It may return ErrLFSObjectNotExist or a database error.
func RemoveLFSMetaObjectByOid(repoID int64, oid string) (int64, error) {
	if len(oid) == 0 {
		return 0, ErrLFSObjectNotExist
	}

	ctx, committer, err := db.TxContext()
	if err != nil {
		return 0, err
	}
	defer committer.Close()

	m := &LFSMetaObject{Pointer: lfs.Pointer{Oid: oid}, RepositoryID: repoID}
	if _, err := db.DeleteByBean(ctx, m); err != nil {
		return -1, err
	}

	count, err := db.CountByBean(ctx, &LFSMetaObject{Pointer: lfs.Pointer{Oid: oid}})
	if err != nil {
		return count, err
	}

	return count, committer.Commit()
}

// GetLFSMetaObjects returns all LFSMetaObjects associated with a repository
func GetLFSMetaObjects(repoID int64, page, pageSize int) ([]*LFSMetaObject, error) {
	sess := db.GetEngine(db.DefaultContext)

	if page >= 0 && pageSize > 0 {
		start := 0
		if page > 0 {
			start = (page - 1) * pageSize
		}
		sess.Limit(pageSize, start)
	}
	lfsObjects := make([]*LFSMetaObject, 0, pageSize)
	return lfsObjects, sess.Find(&lfsObjects, &LFSMetaObject{RepositoryID: repoID})
}

// CountLFSMetaObjects returns a count of all LFSMetaObjects associated with a repository
func CountLFSMetaObjects(repoID int64) (int64, error) {
	return db.GetEngine(db.DefaultContext).Count(&LFSMetaObject{RepositoryID: repoID})
}

// LFSObjectAccessible checks if a provided Oid is accessible to the user
func LFSObjectAccessible(user *user_model.User, oid string) (bool, error) {
	if user.IsAdmin {
		count, err := db.GetEngine(db.DefaultContext).Count(&LFSMetaObject{Pointer: lfs.Pointer{Oid: oid}})
		return count > 0, err
	}
	cond := accessibleRepositoryCondition(user)
	count, err := db.GetEngine(db.DefaultContext).Where(cond).Join("INNER", "repository", "`lfs_meta_object`.repository_id = `repository`.id").Count(&LFSMetaObject{Pointer: lfs.Pointer{Oid: oid}})
	return count > 0, err
}

// LFSObjectIsAssociated checks if a provided Oid is associated
func LFSObjectIsAssociated(oid string) (bool, error) {
	return db.GetEngine(db.DefaultContext).Exist(&LFSMetaObject{Pointer: lfs.Pointer{Oid: oid}})
}

// LFSAutoAssociate auto associates accessible LFSMetaObjects
func LFSAutoAssociate(metas []*LFSMetaObject, user *user_model.User, repoID int64) error {
	ctx, committer, err := db.TxContext()
	if err != nil {
		return err
	}
	defer committer.Close()

	sess := db.GetEngine(ctx)

	oids := make([]interface{}, len(metas))
	oidMap := make(map[string]*LFSMetaObject, len(metas))
	for i, meta := range metas {
		oids[i] = meta.Oid
		oidMap[meta.Oid] = meta
	}

	if !user.IsAdmin {
		newMetas := make([]*LFSMetaObject, 0, len(metas))
		cond := builder.In(
			"`lfs_meta_object`.repository_id",
			builder.Select("`repository`.id").From("repository").Where(accessibleRepositoryCondition(user)),
		)
		err = sess.Cols("oid").Where(cond).In("oid", oids...).GroupBy("oid").Find(&newMetas)
		if err != nil {
			return err
		}
		if len(newMetas) != len(oidMap) {
			return fmt.Errorf("unable collect all LFS objects from database, expected %d, actually %d", len(oidMap), len(newMetas))
		}
		for i := range newMetas {
			newMetas[i].Size = oidMap[newMetas[i].Oid].Size
			newMetas[i].RepositoryID = repoID
		}
		if err = db.Insert(ctx, newMetas); err != nil {
			return err
		}
	} else {
		// admin can associate any LFS object to any repository, and we do not care about errors (eg: duplicated unique key),
		// even if error occurs, it won't hurt users and won't make things worse
		for i := range metas {
			_, err = sess.Insert(&LFSMetaObject{
				Pointer:      lfs.Pointer{Oid: metas[i].Oid, Size: metas[i].Size},
				RepositoryID: repoID,
			})
			if err != nil {
				log.Warn("failed to insert LFS meta object into database, err=%v", err)
			}
		}
	}
	return committer.Commit()
}

// IterateLFS iterates lfs object
func IterateLFS(f func(mo *LFSMetaObject) error) error {
	var start int
	const batchSize = 100
	e := db.GetEngine(db.DefaultContext)
	for {
		mos := make([]*LFSMetaObject, 0, batchSize)
		if err := e.Limit(batchSize, start).Find(&mos); err != nil {
			return err
		}
		if len(mos) == 0 {
			return nil
		}
		start += len(mos)

		for _, mo := range mos {
			if err := f(mo); err != nil {
				return err
			}
		}
	}
}

// CopyLFS copies LFS data from one repo to another
func CopyLFS(ctx context.Context, newRepo, oldRepo *repo_model.Repository) error {
	var lfsObjects []*LFSMetaObject
	if err := db.GetEngine(ctx).Where("repository_id=?", oldRepo.ID).Find(&lfsObjects); err != nil {
		return err
	}

	for _, v := range lfsObjects {
		v.ID = 0
		v.RepositoryID = newRepo.ID
		if _, err := db.GetEngine(ctx).Insert(v); err != nil {
			return err
		}
	}

	return nil
}