// Copyright 2021 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 private includes all internal routes. The package name internal is ideal but Golang is not allowed, so we use private as package name instead.
package private

import (
	"fmt"
	"net/http"
	"strconv"
	"strings"

	issues_model "code.gitea.io/gitea/models/issues"
	repo_model "code.gitea.io/gitea/models/repo"
	gitea_context "code.gitea.io/gitea/modules/context"
	"code.gitea.io/gitea/modules/git"
	"code.gitea.io/gitea/modules/log"
	"code.gitea.io/gitea/modules/private"
	repo_module "code.gitea.io/gitea/modules/repository"
	"code.gitea.io/gitea/modules/setting"
	"code.gitea.io/gitea/modules/util"
	"code.gitea.io/gitea/modules/web"
	repo_service "code.gitea.io/gitea/services/repository"
)

// HookPostReceive updates services and users
func HookPostReceive(ctx *gitea_context.PrivateContext) {
	opts := web.GetForm(ctx).(*private.HookOptions)

	// We don't rely on RepoAssignment here because:
	// a) we don't need the git repo in this function
	// b) our update function will likely change the repository in the db so we will need to refresh it
	// c) we don't always need the repo

	ownerName := ctx.Params(":owner")
	repoName := ctx.Params(":repo")

	// defer getting the repository at this point - as we should only retrieve it if we're going to call update
	var repo *repo_model.Repository

	updates := make([]*repo_module.PushUpdateOptions, 0, len(opts.OldCommitIDs))
	wasEmpty := false

	for i := range opts.OldCommitIDs {
		refFullName := opts.RefFullNames[i]

		// Only trigger activity updates for changes to branches or
		// tags.  Updates to other refs (eg, refs/notes, refs/changes,
		// or other less-standard refs spaces are ignored since there
		// may be a very large number of them).
		if strings.HasPrefix(refFullName, git.BranchPrefix) || strings.HasPrefix(refFullName, git.TagPrefix) {
			if repo == nil {
				repo = loadRepository(ctx, ownerName, repoName)
				if ctx.Written() {
					// Error handled in loadRepository
					return
				}
				wasEmpty = repo.IsEmpty
			}

			option := &repo_module.PushUpdateOptions{
				RefFullName:  refFullName,
				OldCommitID:  opts.OldCommitIDs[i],
				NewCommitID:  opts.NewCommitIDs[i],
				PusherID:     opts.UserID,
				PusherName:   opts.UserName,
				RepoUserName: ownerName,
				RepoName:     repoName,
			}
			updates = append(updates, option)
			if repo.IsEmpty && option.IsBranch() && (option.BranchName() == "master" || option.BranchName() == "main") {
				// put the master/main branch first
				copy(updates[1:], updates)
				updates[0] = option
			}
		}
	}

	if repo != nil && len(updates) > 0 {
		if err := repo_service.PushUpdates(updates); err != nil {
			log.Error("Failed to Update: %s/%s Total Updates: %d", ownerName, repoName, len(updates))
			for i, update := range updates {
				log.Error("Failed to Update: %s/%s Update: %d/%d: Branch: %s", ownerName, repoName, i, len(updates), update.BranchName())
			}
			log.Error("Failed to Update: %s/%s Error: %v", ownerName, repoName, err)

			ctx.JSON(http.StatusInternalServerError, private.HookPostReceiveResult{
				Err: fmt.Sprintf("Failed to Update: %s/%s Error: %v", ownerName, repoName, err),
			})
			return
		}
	}

	// Handle Push Options
	if len(opts.GitPushOptions) > 0 {
		// load the repository
		if repo == nil {
			repo = loadRepository(ctx, ownerName, repoName)
			if ctx.Written() {
				// Error handled in loadRepository
				return
			}
			wasEmpty = repo.IsEmpty
		}

		repo.IsPrivate = opts.GitPushOptions.Bool(private.GitPushOptionRepoPrivate, repo.IsPrivate)
		repo.IsTemplate = opts.GitPushOptions.Bool(private.GitPushOptionRepoTemplate, repo.IsTemplate)
		if err := repo_model.UpdateRepositoryCols(ctx, repo, "is_private", "is_template"); err != nil {
			log.Error("Failed to Update: %s/%s Error: %v", ownerName, repoName, err)
			ctx.JSON(http.StatusInternalServerError, private.HookPostReceiveResult{
				Err: fmt.Sprintf("Failed to Update: %s/%s Error: %v", ownerName, repoName, err),
			})
		}
	}

	results := make([]private.HookPostReceiveBranchResult, 0, len(opts.OldCommitIDs))

	// We have to reload the repo in case its state is changed above
	repo = nil
	var baseRepo *repo_model.Repository

	// Now handle the pull request notification trailers
	for i := range opts.OldCommitIDs {
		refFullName := opts.RefFullNames[i]
		newCommitID := opts.NewCommitIDs[i]

		// post update for agit pull request
		if git.SupportProcReceive && strings.HasPrefix(refFullName, git.PullPrefix) {
			if repo == nil {
				repo = loadRepository(ctx, ownerName, repoName)
				if ctx.Written() {
					return
				}
			}

			pullIndexStr := strings.TrimPrefix(refFullName, git.PullPrefix)
			pullIndexStr = strings.Split(pullIndexStr, "/")[0]
			pullIndex, _ := strconv.ParseInt(pullIndexStr, 10, 64)
			if pullIndex <= 0 {
				continue
			}

			pr, err := issues_model.GetPullRequestByIndex(ctx, repo.ID, pullIndex)
			if err != nil && !issues_model.IsErrPullRequestNotExist(err) {
				log.Error("Failed to get PR by index %v Error: %v", pullIndex, err)
				ctx.JSON(http.StatusInternalServerError, private.Response{
					Err: fmt.Sprintf("Failed to get PR by index %v Error: %v", pullIndex, err),
				})
				return
			}
			if pr == nil {
				continue
			}

			results = append(results, private.HookPostReceiveBranchResult{
				Message: setting.Git.PullRequestPushMessage && repo.AllowsPulls(),
				Create:  false,
				Branch:  "",
				URL:     fmt.Sprintf("%s/pulls/%d", repo.HTMLURL(), pr.Index),
			})
			continue
		}

		branch := git.RefEndName(opts.RefFullNames[i])

		// If we've pushed a branch (and not deleted it)
		if newCommitID != git.EmptySHA && strings.HasPrefix(refFullName, git.BranchPrefix) {

			// First ensure we have the repository loaded, we're allowed pulls requests and we can get the base repo
			if repo == nil {
				repo = loadRepository(ctx, ownerName, repoName)
				if ctx.Written() {
					return
				}

				if !repo.AllowsPulls() {
					// We can stop there's no need to go any further
					ctx.JSON(http.StatusOK, private.HookPostReceiveResult{
						RepoWasEmpty: wasEmpty,
					})
					return
				}
				baseRepo = repo

				if repo.IsFork {
					if err := repo.GetBaseRepo(); err != nil {
						log.Error("Failed to get Base Repository of Forked repository: %-v Error: %v", repo, err)
						ctx.JSON(http.StatusInternalServerError, private.HookPostReceiveResult{
							Err:          fmt.Sprintf("Failed to get Base Repository of Forked repository: %-v Error: %v", repo, err),
							RepoWasEmpty: wasEmpty,
						})
						return
					}
					baseRepo = repo.BaseRepo
				}
			}

			// If our branch is the default branch of an unforked repo - there's no PR to create or refer to
			if !repo.IsFork && branch == baseRepo.DefaultBranch {
				results = append(results, private.HookPostReceiveBranchResult{})
				continue
			}

			pr, err := issues_model.GetUnmergedPullRequest(ctx, repo.ID, baseRepo.ID, branch, baseRepo.DefaultBranch, issues_model.PullRequestFlowGithub)
			if err != nil && !issues_model.IsErrPullRequestNotExist(err) {
				log.Error("Failed to get active PR in: %-v Branch: %s to: %-v Branch: %s Error: %v", repo, branch, baseRepo, baseRepo.DefaultBranch, err)
				ctx.JSON(http.StatusInternalServerError, private.HookPostReceiveResult{
					Err: fmt.Sprintf(
						"Failed to get active PR in: %-v Branch: %s to: %-v Branch: %s Error: %v", repo, branch, baseRepo, baseRepo.DefaultBranch, err),
					RepoWasEmpty: wasEmpty,
				})
				return
			}

			if pr == nil {
				if repo.IsFork {
					branch = fmt.Sprintf("%s:%s", repo.OwnerName, branch)
				}
				results = append(results, private.HookPostReceiveBranchResult{
					Message: setting.Git.PullRequestPushMessage && repo.AllowsPulls(),
					Create:  true,
					Branch:  branch,
					URL:     fmt.Sprintf("%s/compare/%s...%s", baseRepo.HTMLURL(), util.PathEscapeSegments(baseRepo.DefaultBranch), util.PathEscapeSegments(branch)),
				})
			} else {
				results = append(results, private.HookPostReceiveBranchResult{
					Message: setting.Git.PullRequestPushMessage && repo.AllowsPulls(),
					Create:  false,
					Branch:  branch,
					URL:     fmt.Sprintf("%s/pulls/%d", baseRepo.HTMLURL(), pr.Index),
				})
			}
		}
	}
	ctx.JSON(http.StatusOK, private.HookPostReceiveResult{
		Results:      results,
		RepoWasEmpty: wasEmpty,
	})
}
