// Copyright 2017 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 (
	"fmt"

	"code.gitea.io/gitea/modules/setting"
)

// RepoWatchMode specifies what kind of watch the user has on a repository
type RepoWatchMode int8

const (
	// RepoWatchModeNone don't watch
	RepoWatchModeNone RepoWatchMode = iota // 0
	// RepoWatchModeNormal watch repository (from other sources)
	RepoWatchModeNormal // 1
	// RepoWatchModeDont explicit don't auto-watch
	RepoWatchModeDont // 2
	// RepoWatchModeAuto watch repository (from AutoWatchOnChanges)
	RepoWatchModeAuto // 3
)

// Watch is connection request for receiving repository notification.
type Watch struct {
	ID     int64         `xorm:"pk autoincr"`
	UserID int64         `xorm:"UNIQUE(watch)"`
	RepoID int64         `xorm:"UNIQUE(watch)"`
	Mode   RepoWatchMode `xorm:"SMALLINT NOT NULL DEFAULT 1"`
}

// getWatch gets what kind of subscription a user has on a given repository; returns dummy record if none found
func getWatch(e Engine, userID, repoID int64) (Watch, error) {
	watch := Watch{UserID: userID, RepoID: repoID}
	has, err := e.Get(&watch)
	if err != nil {
		return watch, err
	}
	if !has {
		watch.Mode = RepoWatchModeNone
	}
	return watch, nil
}

// Decodes watchability of RepoWatchMode
func isWatchMode(mode RepoWatchMode) bool {
	return mode != RepoWatchModeNone && mode != RepoWatchModeDont
}

// IsWatching checks if user has watched given repository.
func IsWatching(userID, repoID int64) bool {
	watch, err := getWatch(x, userID, repoID)
	return err == nil && isWatchMode(watch.Mode)
}

func watchRepoMode(e Engine, watch Watch, mode RepoWatchMode) (err error) {
	if watch.Mode == mode {
		return nil
	}
	if mode == RepoWatchModeAuto && (watch.Mode == RepoWatchModeDont || isWatchMode(watch.Mode)) {
		// Don't auto watch if already watching or deliberately not watching
		return nil
	}

	hadrec := watch.Mode != RepoWatchModeNone
	needsrec := mode != RepoWatchModeNone
	repodiff := 0

	if isWatchMode(mode) && !isWatchMode(watch.Mode) {
		repodiff = 1
	} else if !isWatchMode(mode) && isWatchMode(watch.Mode) {
		repodiff = -1
	}

	watch.Mode = mode

	if !hadrec && needsrec {
		watch.Mode = mode
		if _, err = e.Insert(watch); err != nil {
			return err
		}
	} else if needsrec {
		watch.Mode = mode
		if _, err := e.ID(watch.ID).AllCols().Update(watch); err != nil {
			return err
		}
	} else if _, err = e.Delete(Watch{ID: watch.ID}); err != nil {
		return err
	}
	if repodiff != 0 {
		_, err = e.Exec("UPDATE `repository` SET num_watches = num_watches + ? WHERE id = ?", repodiff, watch.RepoID)
	}
	return err
}

// WatchRepoMode watch repository in specific mode.
func WatchRepoMode(userID, repoID int64, mode RepoWatchMode) (err error) {
	var watch Watch
	if watch, err = getWatch(x, userID, repoID); err != nil {
		return err
	}
	return watchRepoMode(x, watch, mode)
}

func watchRepo(e Engine, userID, repoID int64, doWatch bool) (err error) {
	var watch Watch
	if watch, err = getWatch(e, userID, repoID); err != nil {
		return err
	}
	if !doWatch && watch.Mode == RepoWatchModeAuto {
		err = watchRepoMode(e, watch, RepoWatchModeDont)
	} else if !doWatch {
		err = watchRepoMode(e, watch, RepoWatchModeNone)
	} else {
		err = watchRepoMode(e, watch, RepoWatchModeNormal)
	}
	return err
}

// WatchRepo watch or unwatch repository.
func WatchRepo(userID, repoID int64, watch bool) (err error) {
	return watchRepo(x, userID, repoID, watch)
}

func getWatchers(e Engine, repoID int64) ([]*Watch, error) {
	watches := make([]*Watch, 0, 10)
	return watches, e.Where("`watch`.repo_id=?", repoID).
		And("`watch`.mode<>?", RepoWatchModeDont).
		And("`user`.is_active=?", true).
		And("`user`.prohibit_login=?", false).
		Join("INNER", "`user`", "`user`.id = `watch`.user_id").
		Find(&watches)
}

// GetWatchers returns all watchers of given repository.
func GetWatchers(repoID int64) ([]*Watch, error) {
	return getWatchers(x, repoID)
}

// GetWatchers returns range of users watching given repository.
func (repo *Repository) GetWatchers(page int) ([]*User, error) {
	users := make([]*User, 0, ItemsPerPage)
	sess := x.Where("watch.repo_id=?", repo.ID).
		Join("LEFT", "watch", "`user`.id=`watch`.user_id").
		And("`watch`.mode<>?", RepoWatchModeDont)
	if page > 0 {
		sess = sess.Limit(ItemsPerPage, (page-1)*ItemsPerPage)
	}
	return users, sess.Find(&users)
}

func notifyWatchers(e Engine, act *Action) error {
	// Add feeds for user self and all watchers.
	watches, err := getWatchers(e, act.RepoID)
	if err != nil {
		return fmt.Errorf("get watchers: %v", err)
	}

	// Add feed for actioner.
	act.UserID = act.ActUserID
	if _, err = e.InsertOne(act); err != nil {
		return fmt.Errorf("insert new actioner: %v", err)
	}

	act.loadRepo()
	// check repo owner exist.
	if err := act.Repo.getOwner(e); err != nil {
		return fmt.Errorf("can't get repo owner: %v", err)
	}

	// Add feed for organization
	if act.Repo.Owner.IsOrganization() && act.ActUserID != act.Repo.Owner.ID {
		act.ID = 0
		act.UserID = act.Repo.Owner.ID
		if _, err = e.InsertOne(act); err != nil {
			return fmt.Errorf("insert new actioner: %v", err)
		}
	}

	for i := range watches {
		if act.ActUserID == watches[i].UserID {
			continue
		}

		act.ID = 0
		act.UserID = watches[i].UserID
		act.Repo.Units = nil

		switch act.OpType {
		case ActionCommitRepo, ActionPushTag, ActionDeleteTag, ActionDeleteBranch:
			if !act.Repo.checkUnitUser(e, act.UserID, false, UnitTypeCode) {
				continue
			}
		case ActionCreateIssue, ActionCommentIssue, ActionCloseIssue, ActionReopenIssue:
			if !act.Repo.checkUnitUser(e, act.UserID, false, UnitTypeIssues) {
				continue
			}
		case ActionCreatePullRequest, ActionMergePullRequest, ActionClosePullRequest, ActionReopenPullRequest:
			if !act.Repo.checkUnitUser(e, act.UserID, false, UnitTypePullRequests) {
				continue
			}
		}

		if _, err = e.InsertOne(act); err != nil {
			return fmt.Errorf("insert new action: %v", err)
		}
	}
	return nil
}

// NotifyWatchers creates batch of actions for every watcher.
func NotifyWatchers(act *Action) error {
	return notifyWatchers(x, act)
}

func watchIfAuto(e Engine, userID, repoID int64, isWrite bool) error {
	if !isWrite || !setting.Service.AutoWatchOnChanges {
		return nil
	}
	watch, err := getWatch(e, userID, repoID)
	if err != nil {
		return err
	}
	if watch.Mode != RepoWatchModeNone {
		return nil
	}
	return watchRepoMode(e, watch, RepoWatchModeAuto)
}

// WatchIfAuto subscribes to repo if AutoWatchOnChanges is set
func WatchIfAuto(userID int64, repoID int64, isWrite bool) error {
	return watchIfAuto(x, userID, repoID, isWrite)
}