package merge

import (
	"encoding/json"
	"fmt"
	"io/ioutil"
	"os"
	"time"

	"code.obermui.de/6543/GitLab_MergeDevel2Default/utils"

	"github.com/AlecAivazis/survey/v2"
	"github.com/gobwas/glob"
	"github.com/xanzy/go-gitlab"
)

var (
	Version = "dev"
)

type Cache struct {
	token          string `json:"token"`
	baseURL        string `json:"baseURL"`
	orgName        string `json:"orgName"`
	repoExclude    string `json:"repoExclude"`
	pullBaseBranch string `json:"pullBaseBranch"`
}

type pullCache struct {
	repoID int
	iid    int
	webURL string
}

const (
	perPage         = 10
	waitSecForMerge = 3
)

func loadCache() (cache *Cache) {
	// default values
	cache = &Cache{
		token:          "XXXXXXXXXXXXXXXXXX",
		baseURL:        "https://gitlab.com",
		orgName:        "organisation",
		repoExclude:    "exclude*",
		pullBaseBranch: "devel*",
	}

	data, err := ioutil.ReadFile(".cache.json")
	if err != nil {
		return
	}
	var c Cache
	if err := json.Unmarshal(data, &c); err != nil {
		return
	}
	return &c
}

func saveCache(cache *Cache) {
	data, err := json.Marshal(cache)
	if err != nil {
		fmt.Printf("ERROR: marshal cache: %v\n", err)
	}
	err = ioutil.WriteFile(".cache.json", data, 0600)
	if err != nil {
		fmt.Printf("ERROR: save cache: %v\n", err)
	}
}

// RunMerge run script for merge subcommand
func RunMerge() {
	values := loadCache()

	// ask for infos
	if err := survey.AskOne(&survey.Input{Message: "GitLab Base URL:", Default: values.baseURL}, &values.baseURL); err != nil {
		os.Exit(1)
	}
	if err := survey.AskOne(&survey.Input{Message: "GitLab Token:", Default: values.token}, &values.token); err != nil {
		os.Exit(1)
	}
	if err := survey.AskOne(&survey.Input{Message: "Group Name:", Default: values.orgName}, &values.orgName); err != nil {
		os.Exit(1)
	}
	if err := survey.AskOne(&survey.Input{Message: "Ignore Repo with patter:", Default: values.repoExclude}, &values.repoExclude); err != nil {
		os.Exit(1)
	}
	if err := survey.AskOne(&survey.Input{Message: "Merge Branches with patter:", Default: values.pullBaseBranch}, &values.pullBaseBranch); err != nil {
		os.Exit(1)
	}

	saveCache(values)

	// Compile glob regex
	excludeRule, err := glob.Compile(values.repoExclude)
	if err != nil {
		utils.Error(2, "not able to compile regex '%s'", values.repoExclude)
	}
	baseBranchRule, err := glob.Compile(values.pullBaseBranch)
	if err != nil {
		utils.Error(3, "not able to compile regex '%s'", values.pullBaseBranch)
	}

	//  connect to gitlab
	client, err := gitlab.NewClient(values.token, gitlab.WithBaseURL(values.baseURL))
	if err != nil {
		utils.Error(4, "Could not create Client: %v\n", err)
	}

	// discover GroupID by name
	org, _, err := client.Groups.GetGroup(values.orgName)
	if err != nil {
		utils.Error(5, "Error cant get information for Organisation \"%s\": %v", values.orgName, err)
	}
	fmt.Printf("Found \"%s\"\n", org.WebURL)

	var repoList []*gitlab.Project
	var page = 1
	fmt.Printf("Retrieving repository list...\n")
	for {
		fmt.Printf("%d", page)
		repos, _, err := client.Groups.ListGroupProjects(org.ID, &gitlab.ListGroupProjectsOptions{
			ListOptions:      gitlab.ListOptions{PerPage: 10, Page: page},
			Archived:         utils.OptBool(false),
			IncludeSubgroups: utils.OptBool(false),
		})
		if err != nil {
			utils.Error(5, "Could not obtain repo list: %v\n", err)
		}

		repoList = append(repoList, repos...)
		if len(repos) < 10 {
			break
		}
		page++
	}
	fmt.Println()

	var pullsToMergeCache []*pullCache
	for i := range repoList {
		if !excludeRule.Match(repoList[i].Name) {
			// for each NOT excluded repo ...
			pullsToMergeCache = append(pullsToMergeCache,
				threatRepo(baseBranchRule, client, repoList[i]),
			)
		}
	}

	fmt.Printf("\n\nwait 3sec for gitlab before merge created pulls\n")
	time.Sleep(waitSecForMerge * time.Second)
	mergePulls(client, pullsToMergeCache)
}

// threatRepo create (if needed) & merge "develop[ment]" branch in DefaultBranch
// and return pulls to merge
func threatRepo(baseBranchRule glob.Glob, client *gitlab.Client, repo *gitlab.Project) *pullCache {
	fmt.Printf("Handle Repository '%s'\n", repo.Name)

	var branchList []*gitlab.Branch
	var page = 1
	for {
		bL, _, err := client.Branches.ListBranches(repo.ID, &gitlab.ListBranchesOptions{
			ListOptions: gitlab.ListOptions{
				Page:    page,
				PerPage: perPage,
			},
		})
		if err != nil {
			utils.Error(10, "Could not obtain branch list from '%s': %v\n", repo.Name, err)
		}

		branchList = append(branchList, bL...)
		if len(bL) < 10 {
			break
		}
		page++
	}

	fmt.Printf("  found %d branches:", len(branchList))
	fmt.Printf("  ")
	for _, b := range branchList {
		fmt.Printf("'%s' ", b.Name)
	}
	fmt.Println()

	for _, baseBranch := range branchList {
		if baseBranchRule.Match(baseBranch.Name) && !baseBranch.Default {
			fmt.Printf("  found branch '%s'\n", baseBranch.Name)

			// check if source is ahead target branch
			diff, _, err := client.Repositories.Compare(repo.ID, &gitlab.CompareOptions{
				From: &repo.DefaultBranch,
				To:   &baseBranch.Name,
			})
			if err != nil {
				utils.Error(10, "Could not compare '%s'...'%s' at '%s': %v\n", repo.DefaultBranch, baseBranch.Name, repo.Name, err)
			}

			if len(diff.Commits) == 0 {
				fmt.Printf("  branch '%s' is not ahead of '%s', skiping\n", baseBranch.Name, repo.DefaultBranch)
				return nil
			}

			// check if pull already exist
			pullList, _, err := client.MergeRequests.ListProjectMergeRequests(repo.ID, &gitlab.ListProjectMergeRequestsOptions{
				SourceBranch: &baseBranch.Name,
				TargetBranch: &repo.DefaultBranch,
				State:        utils.OptString("opened"),
			})
			if err != nil {
				utils.Error(11, "Could not obtain merge request list from '%s': %v\n", repo.Name, err)
			}

			// if not create one
			if len(pullList) == 0 {
				fmt.Printf("  no existing pull for %s, creating one ...\n", baseBranch.Name)
				pull, _, err := client.MergeRequests.CreateMergeRequest(repo.ID, &gitlab.CreateMergeRequestOptions{
					Title:              utils.OptString(fmt.Sprintf("%s <- %s", repo.DefaultBranch, baseBranch.Name)),
					Description:        utils.OptString("Auto created by https://code.obermui.de/6543/GitLab_MergeDevel2Default"),
					SourceBranch:       &baseBranch.Name,
					TargetBranch:       &repo.DefaultBranch,
					AllowCollaboration: utils.OptBool(true),
				})
				if err != nil {
					fmt.Printf("  could not create merge request '%s <- %s', skiping '%s'\n", repo.DefaultBranch, baseBranch.Name, repo.Name)
					return nil
				}
				pullList = []*gitlab.MergeRequest{pull}
			} else {
				// check if changes exist for pull
				changes, _, err := client.MergeRequests.GetMergeRequestChanges(repo.ID, pullList[0].IID, nil)
				if err != nil {
					fmt.Printf("  could not obtain changes of merge request '%s', skiping '%s'\n", pullList[0].WebURL, repo.Name)
					return nil
				}

				if len(changes.Changes) == 0 {
					fmt.Printf("  pull '%s' does not conatin changes, skiping\n", changes.WebURL)
					return nil
				}
			}

			// since we had a match go to next repo ... and return pull
			return &pullCache{
				repoID: repo.ID,
				iid:    pullList[0].IID,
				webURL: pullList[0].WebURL,
			}
		}
	}
	return nil
}

func mergePulls(c *gitlab.Client, pulls []*pullCache) {
	for i := range pulls {
		if pull, _, err := c.MergeRequests.AcceptMergeRequest(pulls[i].repoID, pulls[i].iid, nil); err != nil {
			fmt.Printf("  pull '%s' can not be merged: %v\n", pulls[i].webURL, err)
		} else {
			fmt.Printf("  pull '%s' got merged successfully\n", pull.WebURL)

			if err, _ := c.Branches.DeleteBranch(pulls[i].repoID, pull.SourceBranch); err != nil {
				fmt.Printf("  branch '%s' can not be deleted: %v\n", pull.SourceBranch, err)
			} else {
				fmt.Printf("  branch '%s' successfully deleted\n", pull.SourceBranch)
			}
		}
	}
}