package triageissue

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

	"github.com/google/go-github/v47/github"

	"edge-infra.dev/pkg/f8n/devinfra/jack/constants"
	guestservices "edge-infra.dev/pkg/f8n/devinfra/jack/guest_services"
	"edge-infra.dev/pkg/f8n/devinfra/jack/plugin"
)

var (
	// LabelApplied is a check to see if triage/needs-issue is already present on the PR
	labelApplied bool
	check        bool
)

const ghURL = "https://github.com/"

// checkForIssueInPR triggered when the PR is created. The function will scan the body and determine
// if the triage/needs-issue needs to be included or removed
func checkForIssueInPR(hp plugin.HandlerParams, event github.PullRequestEvent) error {
	// if a bot added a label we don't want to handle it twice
	if event.GetSender().GetType() == constants.Bot {
		return nil
	}

	body := event.GetPullRequest().GetBody()

	linkNum, _ := guestservices.ParsePRIssueLinkBody(body)
	labelCheck := labelCheck(body, linkNum)

	switch {
	case labelCheck:
		hp.Log.Info("adding needs-issue label")
		newLabels := []string{constants.TriageIssueLabel}
		labelApplied = true
		_, _, err := hp.Client.Issues().AddLabelsToIssue(hp.Ctx, hp.Org, hp.Repo, event.PullRequest.GetNumber(), newLabels)
		if err != nil {
			return err
		}
	case !labelCheck:
		_, err := http.Get(ghURL + constants.Address + linkNum)
		if err != nil {
			return err
		}
		hp.Log.Info("removing needs issue label")
		labelApplied = false
		err = removeTriageLabel(hp, event)
		if err != nil {
			return err
		}
		err = addIssueNumberToTitle(hp, event, linkNum, event.GetPullRequest().GetTitle())
		if err != nil {
			return err
		}
	}
	return nil
}

// labelCheck returns true when anything in the relevant issue is incorrect
func labelCheck(body, linkNum string) bool {
	_, err := strconv.Atoi(linkNum)

	if body == "" || linkNum == "" || linkNum == "ISSUE_NUMBER_HERE" || linkNum[0:1] == "0" || err != nil {
		check = true
	} else {
		check = false
	}
	return check
}

// addLabel is triggered whenever a user manually adds the triage/needs-issue label
func addLabel(hp plugin.HandlerParams, event github.PullRequestEvent) error {
	// if a bot added a label we don't want to handle it twice
	if event.GetSender().GetType() == constants.Bot {
		return nil
	}

	hp.Log.Info("add triage/needs_issue")

	body := event.GetPullRequest().GetBody()
	linkNum, _ := guestservices.ParsePRIssueLinkBody(body)

	if !labelCheck(body, linkNum) {
		hp.Log.Info("Link exists. Removing label again.")
		return removeLabel(hp, event)
	}

	if labelCheck(body, linkNum) {
		hp.Log.Info("adding needs-issue label")
		newLabels := []string{constants.TriageIssueLabel}
		labelApplied = true
		_, _, err := hp.Client.Issues().AddLabelsToIssue(hp.Ctx, hp.Org, hp.Repo, event.PullRequest.GetNumber(), newLabels)
		if err != nil {
			return err
		}
	}

	return nil
}

// removeLabel is triggered whenever the user manually removes the triage/needs-issue label
func removeLabel(hp plugin.HandlerParams, event github.PullRequestEvent) error {
	// if a bot added a label we don't want to handle it twice
	if event.GetSender().GetType() == constants.Bot {
		return nil
	}
	hp.Log.Info("remove triage/needs_issue")

	body := event.GetPullRequest().GetBody()
	linkNum, _ := guestservices.ParsePRIssueLinkBody(body)

	if labelCheck(body, linkNum) {
		hp.Log.Info("Link does not exist. Adding label back")
		return addLabel(hp, event)
	}

	_, err := http.Get(ghURL + constants.Address + linkNum)
	if err != nil {
		return err
	}
	hp.Log.Info("removing needs-issue label")
	labelApplied = false
	err = removeTriageLabel(hp, event)
	if err != nil {
		return err
	}
	return nil
}

// editedPRBody is called whenever the main PR comment body is altered.
// It runs through checks to determine how the body was changed and then applies/removes the label.
func editedPRBody(hp plugin.HandlerParams, event github.PullRequestEvent) error {
	// if a bot added a label we don't want to handle it twice
	if event.GetSender().GetType() == constants.Bot {
		return nil
	}

	body := event.GetPullRequest().GetBody()
	linkNum, _ := guestservices.ParsePRIssueLinkBody(body)
	doesNotHaveIssue := labelCheck(body, linkNum)

	// LabelApplied returns true if the label is already present on the PR
	// doesNotHaveIssue returns true if there isn't a correct issue in the PR
	switch {
	case labelApplied && !doesNotHaveIssue:
		_, err := http.Get(ghURL + constants.Address + linkNum)
		if err != nil {
			return err
		}
		labelApplied = false
		hp.Log.Info("removing needs-issue label")
		err = removeTriageLabel(hp, event)
		if err != nil {
			return err
		}
		if !isIssueNumberInTitle(event.GetPullRequest().GetTitle()) {
			err = addIssueNumberToTitle(hp, event, linkNum, event.GetPullRequest().GetTitle())
			if err != nil {
				return err
			}
		}
	case !labelApplied && doesNotHaveIssue:
		if labelCheck(body, linkNum) {
			newLabels := []string{constants.TriageIssueLabel}
			labelApplied = true
			hp.Log.Info("adding needs-issue label")
			_, _, err := hp.Client.Issues().AddLabelsToIssue(hp.Ctx, hp.Org, hp.Repo, event.PullRequest.GetNumber(), newLabels)
			if err != nil {
				return err
			}
		}
	case !doesNotHaveIssue:
		// compare the issue number to the title if same no change if different, update
		if compareTitleNumberToBody(event.GetPullRequest().GetTitle(), linkNum) != 0 {
			err := updateIssueNumberInTitle(hp, event, linkNum, event.GetPullRequest().GetTitle())
			if err != nil {
				return err
			}
		}
	}
	return nil
}

// remove the triage issue label if it exists in the prs labels
func removeTriageLabel(hp plugin.HandlerParams, pre github.PullRequestEvent) error {
	for _, x := range pre.PullRequest.Labels {
		if x.GetName() == constants.TriageIssueLabel {
			_, err := hp.Client.Issues().RemoveLabelForIssue(hp.Ctx, hp.Org, hp.Repo, pre.PullRequest.GetNumber(), constants.TriageIssueLabel)
			if err != nil {
				return err
			}
			break
		}
	}

	return nil
}

// append issue number to title
func addIssueNumberToTitle(hp plugin.HandlerParams, pre github.PullRequestEvent, linkNum string, title string) error {
	githubIssueBody := &github.IssueRequest{Title: github.String(linkNum + ": " + title)}
	_, _, err := hp.Client.Issues().Edit(hp.Ctx, hp.Org, hp.Repo, pre.PullRequest.GetNumber(), githubIssueBody)
	if err != nil {
		return err
	}
	return nil
}

// append issue number to title
func updateIssueNumberInTitle(hp plugin.HandlerParams, pre github.PullRequestEvent, linkNum string, title string) error {
	r := regexp.MustCompile(`(\d+):\s*(.*)`)
	matches := r.FindStringSubmatch(title)
	githubIssueBody := &github.IssueRequest{Title: github.String(linkNum + ": " + matches[2])}
	_, _, err := hp.Client.Issues().Edit(hp.Ctx, hp.Org, hp.Repo, pre.PullRequest.GetNumber(), githubIssueBody)
	if err != nil {
		return err
	}
	return nil
}

// checks if an issue number already exists within the title
func isIssueNumberInTitle(title string) bool {
	r := regexp.MustCompile(`[0-9]+:`)
	return len(r.FindStringSubmatch(title)) > 0
}

func compareTitleNumberToBody(title string, linkNum string) int {
	r := regexp.MustCompile(`(\d+):\s*(.*)`)
	matches := r.FindStringSubmatch(title)
	return strings.Compare(matches[1], linkNum)
}