// 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 models

import (
	"fmt"

	"code.gitea.io/gitea/modules/base"
	"code.gitea.io/gitea/modules/git"
	"code.gitea.io/gitea/modules/log"
	"github.com/unknwon/com"
	"xorm.io/xorm"
)

// PullRequestsOptions holds the options for PRs
type PullRequestsOptions struct {
	Page        int
	State       string
	SortType    string
	Labels      []string
	MilestoneID int64
}

func listPullRequestStatement(baseRepoID int64, opts *PullRequestsOptions) (*xorm.Session, error) {
	sess := x.Where("pull_request.base_repo_id=?", baseRepoID)

	sess.Join("INNER", "issue", "pull_request.issue_id = issue.id")
	switch opts.State {
	case "closed", "open":
		sess.And("issue.is_closed=?", opts.State == "closed")
	}

	if labelIDs, err := base.StringsToInt64s(opts.Labels); err != nil {
		return nil, err
	} else if len(labelIDs) > 0 {
		sess.Join("INNER", "issue_label", "issue.id = issue_label.issue_id").
			In("issue_label.label_id", labelIDs)
	}

	if opts.MilestoneID > 0 {
		sess.And("issue.milestone_id=?", opts.MilestoneID)
	}

	return sess, nil
}

// GetUnmergedPullRequestsByHeadInfo returns all pull requests that are open and has not been merged
// by given head information (repo and branch).
func GetUnmergedPullRequestsByHeadInfo(repoID int64, branch string) ([]*PullRequest, error) {
	prs := make([]*PullRequest, 0, 2)
	return prs, x.
		Where("head_repo_id = ? AND head_branch = ? AND has_merged = ? AND issue.is_closed = ?",
			repoID, branch, false, false).
		Join("INNER", "issue", "issue.id = pull_request.issue_id").
		Find(&prs)
}

// GetUnmergedPullRequestsByBaseInfo returns all pull requests that are open and has not been merged
// by given base information (repo and branch).
func GetUnmergedPullRequestsByBaseInfo(repoID int64, branch string) ([]*PullRequest, error) {
	prs := make([]*PullRequest, 0, 2)
	return prs, x.
		Where("base_repo_id=? AND base_branch=? AND has_merged=? AND issue.is_closed=?",
			repoID, branch, false, false).
		Join("INNER", "issue", "issue.id=pull_request.issue_id").
		Find(&prs)
}

// PullRequests returns all pull requests for a base Repo by the given conditions
func PullRequests(baseRepoID int64, opts *PullRequestsOptions) ([]*PullRequest, int64, error) {
	if opts.Page <= 0 {
		opts.Page = 1
	}

	countSession, err := listPullRequestStatement(baseRepoID, opts)
	if err != nil {
		log.Error("listPullRequestStatement: %v", err)
		return nil, 0, err
	}
	maxResults, err := countSession.Count(new(PullRequest))
	if err != nil {
		log.Error("Count PRs: %v", err)
		return nil, maxResults, err
	}

	prs := make([]*PullRequest, 0, ItemsPerPage)
	findSession, err := listPullRequestStatement(baseRepoID, opts)
	sortIssuesSession(findSession, opts.SortType, 0)
	if err != nil {
		log.Error("listPullRequestStatement: %v", err)
		return nil, maxResults, err
	}
	findSession.Limit(ItemsPerPage, (opts.Page-1)*ItemsPerPage)
	return prs, maxResults, findSession.Find(&prs)
}

// PullRequestList defines a list of pull requests
type PullRequestList []*PullRequest

func (prs PullRequestList) loadAttributes(e Engine) error {
	if len(prs) == 0 {
		return nil
	}

	// Load issues.
	issueIDs := prs.getIssueIDs()
	issues := make([]*Issue, 0, len(issueIDs))
	if err := e.
		Where("id > 0").
		In("id", issueIDs).
		Find(&issues); err != nil {
		return fmt.Errorf("find issues: %v", err)
	}

	set := make(map[int64]*Issue)
	for i := range issues {
		set[issues[i].ID] = issues[i]
	}
	for i := range prs {
		prs[i].Issue = set[prs[i].IssueID]
	}
	return nil
}

func (prs PullRequestList) getIssueIDs() []int64 {
	issueIDs := make([]int64, 0, len(prs))
	for i := range prs {
		issueIDs = append(issueIDs, prs[i].IssueID)
	}
	return issueIDs
}

// LoadAttributes load all the prs attributes
func (prs PullRequestList) LoadAttributes() error {
	return prs.loadAttributes(x)
}

func (prs PullRequestList) invalidateCodeComments(e Engine, doer *User, repo *git.Repository, branch string) error {
	if len(prs) == 0 {
		return nil
	}
	issueIDs := prs.getIssueIDs()
	var codeComments []*Comment
	if err := e.
		Where("type = ? and invalidated = ?", CommentTypeCode, false).
		In("issue_id", issueIDs).
		Find(&codeComments); err != nil {
		return fmt.Errorf("find code comments: %v", err)
	}
	for _, comment := range codeComments {
		if err := comment.CheckInvalidation(repo, doer, branch); err != nil {
			return err
		}
	}
	return nil
}

// InvalidateCodeComments will lookup the prs for code comments which got invalidated by change
func (prs PullRequestList) InvalidateCodeComments(doer *User, repo *git.Repository, branch string) error {
	return prs.invalidateCodeComments(x, doer, repo, branch)
}

// TestPullRequests checks and tests untested patches of pull requests.
// TODO: test more pull requests at same time.
func TestPullRequests() {
	prs := make([]*PullRequest, 0, 10)

	err := x.Where("status = ?", PullRequestStatusChecking).Find(&prs)
	if err != nil {
		log.Error("Find Checking PRs: %v", err)
		return
	}

	var checkedPRs = make(map[int64]struct{})

	// Update pull request status.
	for _, pr := range prs {
		checkedPRs[pr.ID] = struct{}{}
		if err := pr.GetBaseRepo(); err != nil {
			log.Error("GetBaseRepo: %v", err)
			continue
		}
		if pr.manuallyMerged() {
			continue
		}
		if err := pr.testPatch(x); err != nil {
			log.Error("testPatch: %v", err)
			continue
		}

		pr.checkAndUpdateStatus()
	}

	// Start listening on new test requests.
	for prID := range pullRequestQueue.Queue() {
		log.Trace("TestPullRequests[%v]: processing test task", prID)
		pullRequestQueue.Remove(prID)

		id := com.StrTo(prID).MustInt64()
		if _, ok := checkedPRs[id]; ok {
			continue
		}

		pr, err := GetPullRequestByID(id)
		if err != nil {
			log.Error("GetPullRequestByID[%s]: %v", prID, err)
			continue
		} else if pr.manuallyMerged() {
			continue
		} else if err = pr.testPatch(x); err != nil {
			log.Error("testPatch[%d]: %v", pr.ID, err)
			continue
		}

		pr.checkAndUpdateStatus()
	}
}

// InitTestPullRequests runs the task to test all the checking status pull requests
func InitTestPullRequests() {
	go TestPullRequests()
}