package main

import (
	"fmt"
	"net/url"
	"regexp"
	"time"
)

var reGitLabMR = regexp.MustCompile(`^https://([^/]+)/([^?#]+)/-/merge_requests/([0-9]+)(?:\?[^#]*)?(?:#.*)?$`)

type GitLab struct{}

var _ Forge = GitLab{}

func (GitLab) FetchStatus(urls []string) (string, error) {
	for _, u := range urls {
		m := reGitLabMR.FindStringSubmatch(u)
		if m == nil {
			continue
		}
		authority := m[1]
		projectID := m[2]
		mrnum := m[3]

		urlStr := "https://" + authority + "/api/v4/projects/" + url.QueryEscape(projectID) + "/merge_requests/" + mrnum

		var obj struct {
			// State values are "opened", "closed", "locked", and "merged".
			State           string `json:"state"`
			MergeCommitSha  string `json:"merge_commit_sha"`
			SquashCommitSha string `json:"squash_commit_sha"`
		}
		if err := httpGetJSON(urlStr, nil, &obj); err != nil {
			return "", err
		}

		ret := obj.State
		if ret == "opened" {
			ret = statusOpen
		}

		if ret == "merged" {
			ret = statusMerged
			var mergeCommit string
			if obj.MergeCommitSha != "" {
				mergeCommit = obj.MergeCommitSha
			}
			if obj.SquashCommitSha != "" {
				mergeCommit = obj.SquashCommitSha
			}
			if mergeCommit != "" {
				tag, err := getGitTagThatContainsAll("https://"+authority+"/"+projectID+".git", mergeCommit)
				if err != nil {
					return "", err
				}
				if tag != "" {
					ret = fmt.Sprintf(statusReleasedFmt, tag)
				}
			}
		}

		return ret, nil
	}
	return "", nil
}

func (GitLab) FetchSubmittedAt(urls []string) (time.Time, error) {
	for _, u := range urls {
		m := reGitLabMR.FindStringSubmatch(u)
		if m == nil {
			continue
		}
		authority := m[1]
		projectID := m[2]
		mrnum := m[3]

		urlStr := "https://" + authority + "/api/v4/projects/" + url.QueryEscape(projectID) + "/merge_requests/" + mrnum

		var obj struct {
			CreatedAt time.Time `json:"created_at"`
		}
		if err := httpGetJSON(urlStr, nil, &obj); err != nil {
			return time.Time{}, err
		}
		return obj.CreatedAt, nil
	}
	return time.Time{}, nil
}

func (GitLab) FetchLastUpdated(urls []string) (time.Time, User, error) {
	for _, u := range urls {
		m := reGitLabMR.FindStringSubmatch(u)
		if m == nil {
			continue
		}
		authority := m[1]
		projectID := m[2]
		mrnum := m[3]

		urlStr := "https://" + authority + "/api/v4/projects/" + url.QueryEscape(projectID) + "/merge_requests/" + mrnum

		var obj struct {
			ID int `json:"id"`

			UpdatedAt time.Time `json:"updated_at"`

			CreatedAt time.Time `json:"created_at"`
			CreatedBy struct {
				Username string `json:"username"`
				WebURL   string `json:"web_url"`
			} `json:"author"`

			MergedAt time.Time `json:"merged_at"`
			MergedBy struct {
				Username string `json:"username"`
				WebURL   string `json:"web_url"`
			} `json:"merged_by"`
		}
		if err := httpGetJSON(urlStr, nil, &obj); err != nil {
			return time.Time{}, User{}, err
		}

		retUpdatedAt := obj.UpdatedAt
		var retUser User

		if retUser == (User{}) && withinOneSecond(obj.CreatedAt, retUpdatedAt) {
			retUser.Name = obj.CreatedBy.Username
			retUser.URL = obj.CreatedBy.WebURL
		}
		if retUser == (User{}) && withinOneSecond(obj.MergedAt, retUpdatedAt) {
			retUser.Name = obj.MergedBy.Username
			retUser.URL = obj.MergedBy.WebURL
		}
		if retUser == (User{}) {
			var notes struct {
				Notes []struct {
					UpdatedAt time.Time `json:"updated_at"`
					Author    struct {
						Username string `json:"username"`
						WebURL   string `json:"web_url"`
					} `json:"author"`
				} `json:"notes"`
			}
			if err := httpGetJSON(fmt.Sprintf("https://%s/%s/noteable/merge_request/%d/notes", authority, projectID, obj.ID), map[string]string{"X-Last-Fetched-At": "0"}, &notes); err != nil {
				return time.Time{}, User{}, err
			}
			for _, note := range notes.Notes {
				if withinOneSecond(note.UpdatedAt, retUpdatedAt) {
					retUser.Name = note.Author.Username
					retUser.URL = note.Author.WebURL
					break
				}
			}
		}

		return retUpdatedAt, retUser, nil
	}
	return time.Time{}, User{}, nil
}