// Copyright 2017 The Gitea Authors. All rights reserved.
// SPDX-License-Identifier: MIT

package issues

import (
	"context"
	"fmt"
	"strings"
	"time"

	"code.gitea.io/gitea/models/db"
	repo_model "code.gitea.io/gitea/models/repo"
	"code.gitea.io/gitea/modules/setting"
	api "code.gitea.io/gitea/modules/structs"
	"code.gitea.io/gitea/modules/timeutil"
	"code.gitea.io/gitea/modules/util"

	"xorm.io/builder"
)

// ErrMilestoneNotExist represents a "MilestoneNotExist" kind of error.
type ErrMilestoneNotExist struct {
	ID     int64
	RepoID int64
	Name   string
}

// IsErrMilestoneNotExist checks if an error is a ErrMilestoneNotExist.
func IsErrMilestoneNotExist(err error) bool {
	_, ok := err.(ErrMilestoneNotExist)
	return ok
}

func (err ErrMilestoneNotExist) Error() string {
	if len(err.Name) > 0 {
		return fmt.Sprintf("milestone does not exist [name: %s, repo_id: %d]", err.Name, err.RepoID)
	}
	return fmt.Sprintf("milestone does not exist [id: %d, repo_id: %d]", err.ID, err.RepoID)
}

func (err ErrMilestoneNotExist) Unwrap() error {
	return util.ErrNotExist
}

// Milestone represents a milestone of repository.
type Milestone struct {
	ID              int64                  `xorm:"pk autoincr"`
	RepoID          int64                  `xorm:"INDEX"`
	Repo            *repo_model.Repository `xorm:"-"`
	Name            string
	Content         string `xorm:"TEXT"`
	RenderedContent string `xorm:"-"`
	IsClosed        bool
	NumIssues       int
	NumClosedIssues int
	NumOpenIssues   int  `xorm:"-"`
	Completeness    int  // Percentage(1-100).
	IsOverdue       bool `xorm:"-"`

	CreatedUnix    timeutil.TimeStamp `xorm:"INDEX created"`
	UpdatedUnix    timeutil.TimeStamp `xorm:"INDEX updated"`
	DeadlineUnix   timeutil.TimeStamp
	ClosedDateUnix timeutil.TimeStamp
	DeadlineString string `xorm:"-"`

	TotalTrackedTime int64 `xorm:"-"`
	TimeSinceUpdate  int64 `xorm:"-"`
}

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

// BeforeUpdate is invoked from XORM before updating this object.
func (m *Milestone) BeforeUpdate() {
	if m.NumIssues > 0 {
		m.Completeness = m.NumClosedIssues * 100 / m.NumIssues
	} else {
		m.Completeness = 0
	}
}

// AfterLoad is invoked from XORM after setting the value of a field of
// this object.
func (m *Milestone) AfterLoad() {
	if !m.UpdatedUnix.IsZero() {
		m.TimeSinceUpdate = time.Now().Unix() - m.UpdatedUnix.AsTime().Unix()
	}
	m.NumOpenIssues = m.NumIssues - m.NumClosedIssues
	if m.DeadlineUnix.Year() == 9999 {
		return
	}

	m.DeadlineString = m.DeadlineUnix.Format("2006-01-02")
	if m.IsClosed {
		m.IsOverdue = m.ClosedDateUnix >= m.DeadlineUnix
	} else {
		m.IsOverdue = timeutil.TimeStampNow() >= m.DeadlineUnix
	}
}

// State returns string representation of milestone status.
func (m *Milestone) State() api.StateType {
	if m.IsClosed {
		return api.StateClosed
	}
	return api.StateOpen
}

// NewMilestone creates new milestone of repository.
func NewMilestone(m *Milestone) (err error) {
	ctx, committer, err := db.TxContext(db.DefaultContext)
	if err != nil {
		return err
	}
	defer committer.Close()

	m.Name = strings.TrimSpace(m.Name)

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

	if _, err = db.Exec(ctx, "UPDATE `repository` SET num_milestones = num_milestones + 1 WHERE id = ?", m.RepoID); err != nil {
		return err
	}
	return committer.Commit()
}

// HasMilestoneByRepoID returns if the milestone exists in the repository.
func HasMilestoneByRepoID(ctx context.Context, repoID, id int64) (bool, error) {
	return db.GetEngine(ctx).ID(id).Where("repo_id=?", repoID).Exist(new(Milestone))
}

// GetMilestoneByRepoID returns the milestone in a repository.
func GetMilestoneByRepoID(ctx context.Context, repoID, id int64) (*Milestone, error) {
	m := new(Milestone)
	has, err := db.GetEngine(ctx).ID(id).Where("repo_id=?", repoID).Get(m)
	if err != nil {
		return nil, err
	} else if !has {
		return nil, ErrMilestoneNotExist{ID: id, RepoID: repoID}
	}
	return m, nil
}

// GetMilestoneByRepoIDANDName return a milestone if one exist by name and repo
func GetMilestoneByRepoIDANDName(repoID int64, name string) (*Milestone, error) {
	var mile Milestone
	has, err := db.GetEngine(db.DefaultContext).Where("repo_id=? AND name=?", repoID, name).Get(&mile)
	if err != nil {
		return nil, err
	}
	if !has {
		return nil, ErrMilestoneNotExist{Name: name, RepoID: repoID}
	}
	return &mile, nil
}

// UpdateMilestone updates information of given milestone.
func UpdateMilestone(m *Milestone, oldIsClosed bool) error {
	ctx, committer, err := db.TxContext(db.DefaultContext)
	if err != nil {
		return err
	}
	defer committer.Close()

	if m.IsClosed && !oldIsClosed {
		m.ClosedDateUnix = timeutil.TimeStampNow()
	}

	if err := updateMilestone(ctx, m); err != nil {
		return err
	}

	// if IsClosed changed, update milestone numbers of repository
	if oldIsClosed != m.IsClosed {
		if err := updateRepoMilestoneNum(ctx, m.RepoID); err != nil {
			return err
		}
	}

	return committer.Commit()
}

func updateMilestone(ctx context.Context, m *Milestone) error {
	m.Name = strings.TrimSpace(m.Name)
	_, err := db.GetEngine(ctx).ID(m.ID).AllCols().Update(m)
	if err != nil {
		return err
	}
	return UpdateMilestoneCounters(ctx, m.ID)
}

// UpdateMilestoneCounters calculates NumIssues, NumClosesIssues and Completeness
func UpdateMilestoneCounters(ctx context.Context, id int64) error {
	e := db.GetEngine(ctx)
	_, err := e.ID(id).
		SetExpr("num_issues", builder.Select("count(*)").From("issue").Where(
			builder.Eq{"milestone_id": id},
		)).
		SetExpr("num_closed_issues", builder.Select("count(*)").From("issue").Where(
			builder.Eq{
				"milestone_id": id,
				"is_closed":    true,
			},
		)).
		Update(&Milestone{})
	if err != nil {
		return err
	}
	_, err = e.Exec("UPDATE `milestone` SET completeness=100*num_closed_issues/(CASE WHEN num_issues > 0 THEN num_issues ELSE 1 END) WHERE id=?",
		id,
	)
	return err
}

// ChangeMilestoneStatusByRepoIDAndID changes a milestone open/closed status if the milestone ID is in the repo.
func ChangeMilestoneStatusByRepoIDAndID(repoID, milestoneID int64, isClosed bool) error {
	ctx, committer, err := db.TxContext(db.DefaultContext)
	if err != nil {
		return err
	}
	defer committer.Close()

	m := &Milestone{
		ID:     milestoneID,
		RepoID: repoID,
	}

	has, err := db.GetEngine(ctx).ID(milestoneID).Where("repo_id = ?", repoID).Get(m)
	if err != nil {
		return err
	} else if !has {
		return ErrMilestoneNotExist{ID: milestoneID, RepoID: repoID}
	}

	if err := changeMilestoneStatus(ctx, m, isClosed); err != nil {
		return err
	}

	return committer.Commit()
}

// ChangeMilestoneStatus changes the milestone open/closed status.
func ChangeMilestoneStatus(m *Milestone, isClosed bool) (err error) {
	ctx, committer, err := db.TxContext(db.DefaultContext)
	if err != nil {
		return err
	}
	defer committer.Close()

	if err := changeMilestoneStatus(ctx, m, isClosed); err != nil {
		return err
	}

	return committer.Commit()
}

func changeMilestoneStatus(ctx context.Context, m *Milestone, isClosed bool) error {
	m.IsClosed = isClosed
	if isClosed {
		m.ClosedDateUnix = timeutil.TimeStampNow()
	}

	count, err := db.GetEngine(ctx).ID(m.ID).Where("repo_id = ? AND is_closed = ?", m.RepoID, !isClosed).Cols("is_closed", "closed_date_unix").Update(m)
	if err != nil {
		return err
	}
	if count < 1 {
		return nil
	}
	return updateRepoMilestoneNum(ctx, m.RepoID)
}

// DeleteMilestoneByRepoID deletes a milestone from a repository.
func DeleteMilestoneByRepoID(repoID, id int64) error {
	m, err := GetMilestoneByRepoID(db.DefaultContext, repoID, id)
	if err != nil {
		if IsErrMilestoneNotExist(err) {
			return nil
		}
		return err
	}

	repo, err := repo_model.GetRepositoryByID(db.DefaultContext, m.RepoID)
	if err != nil {
		return err
	}

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

	sess := db.GetEngine(ctx)

	if _, err = sess.ID(m.ID).Delete(new(Milestone)); err != nil {
		return err
	}

	numMilestones, err := CountMilestones(ctx, GetMilestonesOption{
		RepoID: repo.ID,
		State:  api.StateAll,
	})
	if err != nil {
		return err
	}
	numClosedMilestones, err := CountMilestones(ctx, GetMilestonesOption{
		RepoID: repo.ID,
		State:  api.StateClosed,
	})
	if err != nil {
		return err
	}
	repo.NumMilestones = int(numMilestones)
	repo.NumClosedMilestones = int(numClosedMilestones)

	if _, err = sess.ID(repo.ID).Cols("num_milestones, num_closed_milestones").Update(repo); err != nil {
		return err
	}

	if _, err = db.Exec(ctx, "UPDATE `issue` SET milestone_id = 0 WHERE milestone_id = ?", m.ID); err != nil {
		return err
	}
	return committer.Commit()
}

// MilestoneList is a list of milestones offering additional functionality
type MilestoneList []*Milestone

func (milestones MilestoneList) getMilestoneIDs() []int64 {
	ids := make([]int64, 0, len(milestones))
	for _, ms := range milestones {
		ids = append(ids, ms.ID)
	}
	return ids
}

// GetMilestonesOption contain options to get milestones
type GetMilestonesOption struct {
	db.ListOptions
	RepoID   int64
	State    api.StateType
	Name     string
	SortType string
}

func (opts GetMilestonesOption) toCond() builder.Cond {
	cond := builder.NewCond()
	if opts.RepoID != 0 {
		cond = cond.And(builder.Eq{"repo_id": opts.RepoID})
	}

	switch opts.State {
	case api.StateClosed:
		cond = cond.And(builder.Eq{"is_closed": true})
	case api.StateAll:
		break
	// api.StateOpen:
	default:
		cond = cond.And(builder.Eq{"is_closed": false})
	}

	if len(opts.Name) != 0 {
		cond = cond.And(db.BuildCaseInsensitiveLike("name", opts.Name))
	}

	return cond
}

// GetMilestones returns milestones filtered by GetMilestonesOption's
func GetMilestones(opts GetMilestonesOption) (MilestoneList, int64, error) {
	sess := db.GetEngine(db.DefaultContext).Where(opts.toCond())

	if opts.Page != 0 {
		sess = db.SetSessionPagination(sess, &opts)
	}

	switch opts.SortType {
	case "furthestduedate":
		sess.Desc("deadline_unix")
	case "leastcomplete":
		sess.Asc("completeness")
	case "mostcomplete":
		sess.Desc("completeness")
	case "leastissues":
		sess.Asc("num_issues")
	case "mostissues":
		sess.Desc("num_issues")
	case "id":
		sess.Asc("id")
	default:
		sess.Asc("deadline_unix").Asc("id")
	}

	miles := make([]*Milestone, 0, opts.PageSize)
	total, err := sess.FindAndCount(&miles)
	return miles, total, err
}

// SearchMilestones search milestones
func SearchMilestones(repoCond builder.Cond, page int, isClosed bool, sortType, keyword string) (MilestoneList, error) {
	miles := make([]*Milestone, 0, setting.UI.IssuePagingNum)
	sess := db.GetEngine(db.DefaultContext).Where("is_closed = ?", isClosed)
	if len(keyword) > 0 {
		sess = sess.And(builder.Like{"UPPER(name)", strings.ToUpper(keyword)})
	}
	if repoCond.IsValid() {
		sess.In("repo_id", builder.Select("id").From("repository").Where(repoCond))
	}
	if page > 0 {
		sess = sess.Limit(setting.UI.IssuePagingNum, (page-1)*setting.UI.IssuePagingNum)
	}

	switch sortType {
	case "furthestduedate":
		sess.Desc("deadline_unix")
	case "leastcomplete":
		sess.Asc("completeness")
	case "mostcomplete":
		sess.Desc("completeness")
	case "leastissues":
		sess.Asc("num_issues")
	case "mostissues":
		sess.Desc("num_issues")
	default:
		sess.Asc("deadline_unix")
	}
	return miles, sess.Find(&miles)
}

// GetMilestonesByRepoIDs returns a list of milestones of given repositories and status.
func GetMilestonesByRepoIDs(repoIDs []int64, page int, isClosed bool, sortType string) (MilestoneList, error) {
	return SearchMilestones(
		builder.In("repo_id", repoIDs),
		page,
		isClosed,
		sortType,
		"",
	)
}

// MilestonesStats represents milestone statistic information.
type MilestonesStats struct {
	OpenCount, ClosedCount int64
}

// Total returns the total counts of milestones
func (m MilestonesStats) Total() int64 {
	return m.OpenCount + m.ClosedCount
}

// GetMilestonesStatsByRepoCond returns milestone statistic information for dashboard by given conditions.
func GetMilestonesStatsByRepoCond(repoCond builder.Cond) (*MilestonesStats, error) {
	var err error
	stats := &MilestonesStats{}

	sess := db.GetEngine(db.DefaultContext).Where("is_closed = ?", false)
	if repoCond.IsValid() {
		sess.And(builder.In("repo_id", builder.Select("id").From("repository").Where(repoCond)))
	}
	stats.OpenCount, err = sess.Count(new(Milestone))
	if err != nil {
		return nil, err
	}

	sess = db.GetEngine(db.DefaultContext).Where("is_closed = ?", true)
	if repoCond.IsValid() {
		sess.And(builder.In("repo_id", builder.Select("id").From("repository").Where(repoCond)))
	}
	stats.ClosedCount, err = sess.Count(new(Milestone))
	if err != nil {
		return nil, err
	}

	return stats, nil
}

// GetMilestonesStatsByRepoCondAndKw returns milestone statistic information for dashboard by given repo conditions and name keyword.
func GetMilestonesStatsByRepoCondAndKw(repoCond builder.Cond, keyword string) (*MilestonesStats, error) {
	var err error
	stats := &MilestonesStats{}

	sess := db.GetEngine(db.DefaultContext).Where("is_closed = ?", false)
	if len(keyword) > 0 {
		sess = sess.And(builder.Like{"UPPER(name)", strings.ToUpper(keyword)})
	}
	if repoCond.IsValid() {
		sess.And(builder.In("repo_id", builder.Select("id").From("repository").Where(repoCond)))
	}
	stats.OpenCount, err = sess.Count(new(Milestone))
	if err != nil {
		return nil, err
	}

	sess = db.GetEngine(db.DefaultContext).Where("is_closed = ?", true)
	if len(keyword) > 0 {
		sess = sess.And(builder.Like{"UPPER(name)", strings.ToUpper(keyword)})
	}
	if repoCond.IsValid() {
		sess.And(builder.In("repo_id", builder.Select("id").From("repository").Where(repoCond)))
	}
	stats.ClosedCount, err = sess.Count(new(Milestone))
	if err != nil {
		return nil, err
	}

	return stats, nil
}

// CountMilestones returns number of milestones in given repository with other options
func CountMilestones(ctx context.Context, opts GetMilestonesOption) (int64, error) {
	return db.GetEngine(ctx).
		Where(opts.toCond()).
		Count(new(Milestone))
}

// CountMilestonesByRepoCond map from repo conditions to number of milestones matching the options`
func CountMilestonesByRepoCond(repoCond builder.Cond, isClosed bool) (map[int64]int64, error) {
	sess := db.GetEngine(db.DefaultContext).Where("is_closed = ?", isClosed)
	if repoCond.IsValid() {
		sess.In("repo_id", builder.Select("id").From("repository").Where(repoCond))
	}

	countsSlice := make([]*struct {
		RepoID int64
		Count  int64
	}, 0, 10)
	if err := sess.GroupBy("repo_id").
		Select("repo_id AS repo_id, COUNT(*) AS count").
		Table("milestone").
		Find(&countsSlice); err != nil {
		return nil, err
	}

	countMap := make(map[int64]int64, len(countsSlice))
	for _, c := range countsSlice {
		countMap[c.RepoID] = c.Count
	}
	return countMap, nil
}

// CountMilestonesByRepoCondAndKw map from repo conditions and the keyword of milestones' name to number of milestones matching the options`
func CountMilestonesByRepoCondAndKw(repoCond builder.Cond, keyword string, isClosed bool) (map[int64]int64, error) {
	sess := db.GetEngine(db.DefaultContext).Where("is_closed = ?", isClosed)
	if len(keyword) > 0 {
		sess = sess.And(builder.Like{"UPPER(name)", strings.ToUpper(keyword)})
	}
	if repoCond.IsValid() {
		sess.In("repo_id", builder.Select("id").From("repository").Where(repoCond))
	}

	countsSlice := make([]*struct {
		RepoID int64
		Count  int64
	}, 0, 10)
	if err := sess.GroupBy("repo_id").
		Select("repo_id AS repo_id, COUNT(*) AS count").
		Table("milestone").
		Find(&countsSlice); err != nil {
		return nil, err
	}

	countMap := make(map[int64]int64, len(countsSlice))
	for _, c := range countsSlice {
		countMap[c.RepoID] = c.Count
	}
	return countMap, nil
}

func updateRepoMilestoneNum(ctx context.Context, repoID int64) error {
	_, err := db.GetEngine(ctx).Exec("UPDATE `repository` SET num_milestones=(SELECT count(*) FROM milestone WHERE repo_id=?),num_closed_milestones=(SELECT count(*) FROM milestone WHERE repo_id=? AND is_closed=?) WHERE id=?",
		repoID,
		repoID,
		true,
		repoID,
	)
	return err
}

//  _____               _            _ _____ _
// |_   _| __ __ _  ___| | _____  __| |_   _(_)_ __ ___   ___  ___
//   | || '__/ _` |/ __| |/ / _ \/ _` | | | | | '_ ` _ \ / _ \/ __|
//   | || | | (_| | (__|   <  __/ (_| | | | | | | | | | |  __/\__ \
//   |_||_|  \__,_|\___|_|\_\___|\__,_| |_| |_|_| |_| |_|\___||___/
//

func (milestones MilestoneList) loadTotalTrackedTimes(ctx context.Context) error {
	type totalTimesByMilestone struct {
		MilestoneID int64
		Time        int64
	}
	if len(milestones) == 0 {
		return nil
	}
	trackedTimes := make(map[int64]int64, len(milestones))

	// Get total tracked time by milestone_id
	rows, err := db.GetEngine(ctx).Table("issue").
		Join("INNER", "milestone", "issue.milestone_id = milestone.id").
		Join("LEFT", "tracked_time", "tracked_time.issue_id = issue.id").
		Where("tracked_time.deleted = ?", false).
		Select("milestone_id, sum(time) as time").
		In("milestone_id", milestones.getMilestoneIDs()).
		GroupBy("milestone_id").
		Rows(new(totalTimesByMilestone))
	if err != nil {
		return err
	}

	defer rows.Close()

	for rows.Next() {
		var totalTime totalTimesByMilestone
		err = rows.Scan(&totalTime)
		if err != nil {
			return err
		}
		trackedTimes[totalTime.MilestoneID] = totalTime.Time
	}

	for _, milestone := range milestones {
		milestone.TotalTrackedTime = trackedTimes[milestone.ID]
	}
	return nil
}

func (m *Milestone) loadTotalTrackedTime(ctx context.Context) error {
	type totalTimesByMilestone struct {
		MilestoneID int64
		Time        int64
	}
	totalTime := &totalTimesByMilestone{MilestoneID: m.ID}
	has, err := db.GetEngine(ctx).Table("issue").
		Join("INNER", "milestone", "issue.milestone_id = milestone.id").
		Join("LEFT", "tracked_time", "tracked_time.issue_id = issue.id").
		Where("tracked_time.deleted = ?", false).
		Select("milestone_id, sum(time) as time").
		Where("milestone_id = ?", m.ID).
		GroupBy("milestone_id").
		Get(totalTime)
	if err != nil {
		return err
	} else if !has {
		return nil
	}
	m.TotalTrackedTime = totalTime.Time
	return nil
}

// LoadTotalTrackedTimes loads for every milestone in the list the TotalTrackedTime by a batch request
func (milestones MilestoneList) LoadTotalTrackedTimes() error {
	return milestones.loadTotalTrackedTimes(db.DefaultContext)
}

// LoadTotalTrackedTime loads the tracked time for the milestone
func (m *Milestone) LoadTotalTrackedTime() error {
	return m.loadTotalTrackedTime(db.DefaultContext)
}
