package edit

import (
	"fmt"
	"net/http"
	"sort"
	"strings"
	"sync"
	"time"

	"github.com/MakeNowJust/heredoc"
	"github.com/cli/cli/v2/api"
	fd "github.com/cli/cli/v2/internal/featuredetection"
	"github.com/cli/cli/v2/internal/gh"
	"github.com/cli/cli/v2/internal/ghrepo"
	"github.com/cli/cli/v2/internal/text"
	issueShared "github.com/cli/cli/v2/pkg/cmd/issue/shared"
	prShared "github.com/cli/cli/v2/pkg/cmd/pr/shared"
	"github.com/cli/cli/v2/pkg/cmdutil"
	"github.com/cli/cli/v2/pkg/iostreams"
	"github.com/spf13/cobra"
)

type EditOptions struct {
	HttpClient func() (*http.Client, error)
	IO         *iostreams.IOStreams
	BaseRepo   func() (ghrepo.Interface, error)
	Prompter   prShared.EditPrompter
	Detector   fd.Detector

	DetermineEditor    func() (string, error)
	FieldsToEditSurvey func(prShared.EditPrompter, *prShared.Editable) error
	EditFieldsSurvey   func(prShared.EditPrompter, *prShared.Editable, string) error
	FetchOptions       func(*api.Client, ghrepo.Interface, *prShared.Editable, gh.ProjectsV1Support) error

	IssueNumbers []int
	Interactive  bool

	SetParent       string
	RemoveParent    bool
	AddSubIssues    []string
	RemoveSubIssues []string
	AddBlockedBy    []string
	RemoveBlockedBy []string
	AddBlocking     []string
	RemoveBlocking  []string

	prShared.Editable
}

func NewCmdEdit(f *cmdutil.Factory, runF func(*EditOptions) error) *cobra.Command {
	opts := &EditOptions{
		IO:                 f.IOStreams,
		HttpClient:         f.HttpClient,
		DetermineEditor:    func() (string, error) { return cmdutil.DetermineEditor(f.Config) },
		FieldsToEditSurvey: prShared.FieldsToEditSurvey,
		EditFieldsSurvey:   prShared.EditFieldsSurvey,
		FetchOptions:       prShared.FetchOptions,
		Prompter:           f.Prompter,
	}

	var bodyFile string
	var removeMilestone bool

	cmd := &cobra.Command{
		Use:   "edit {<numbers> | <urls>}",
		Short: "Edit issues",
		Long: heredoc.Docf(`
			Edit one or more issues within the same repository.

			Editing issues' projects requires authorization with the %[1]sproject%[1]s scope.
			To authorize, run %[1]sgh auth refresh -s project%[1]s.

			The %[1]s--add-assignee%[1]s and %[1]s--remove-assignee%[1]s flags both support
			the following special values:
			- %[1]s@me%[1]s: assign or unassign yourself
			- %[1]s@copilot%[1]s: assign or unassign Copilot (not supported on GitHub Enterprise Server)
		`, "`"),
		Example: heredoc.Doc(`
			$ gh issue edit 23 --title "I found a bug" --body "Nothing works"
			$ gh issue edit 23 --add-label "bug,help wanted" --remove-label "core"
			$ gh issue edit 23 --add-assignee "@me" --remove-assignee monalisa,hubot
			$ gh issue edit 23 --add-assignee "@copilot"
			$ gh issue edit 23 --add-project "Roadmap" --remove-project v1,v2
			$ gh issue edit 23 --milestone "Version 1"
			$ gh issue edit 23 --remove-milestone
			$ gh issue edit 23 --body-file body.txt
			$ gh issue edit 23 34 --add-label "help wanted"
			$ gh issue edit 23 --type Bug
			$ gh issue edit 23 --set-parent 100
			$ gh issue edit 23 --remove-parent
			$ gh issue edit 100 --add-sub-issue 123,124
			$ gh issue edit 123 --add-blocked-by 200 --add-blocking 300,301
		`),
		Args: cobra.MinimumNArgs(1),
		RunE: func(cmd *cobra.Command, args []string) error {
			issueNumbers, baseRepo, err := issueShared.ParseIssuesFromArgs(args)
			if err != nil {
				return err
			}

			// If the args provided the base repo then use that directly.
			if baseRepo, present := baseRepo.Value(); present {
				opts.BaseRepo = func() (ghrepo.Interface, error) {
					return baseRepo, nil
				}
			} else {
				// support `-R, --repo` override
				opts.BaseRepo = f.BaseRepo
			}

			opts.IssueNumbers = issueNumbers

			flags := cmd.Flags()

			bodyProvided := flags.Changed("body")
			bodyFileProvided := bodyFile != ""

			if err := cmdutil.MutuallyExclusive(
				"specify only one of `--body` or `--body-file`",
				bodyProvided,
				bodyFileProvided,
			); err != nil {
				return err
			}
			if bodyProvided || bodyFileProvided {
				opts.Editable.Body.Edited = true
				if bodyFileProvided {
					b, err := cmdutil.ReadFile(bodyFile, opts.IO.In)
					if err != nil {
						return err
					}
					opts.Editable.Body.Value = string(b)
				}
			}

			if err := cmdutil.MutuallyExclusive(
				"specify only one of `--milestone` or `--remove-milestone`",
				flags.Changed("milestone"),
				removeMilestone,
			); err != nil {
				return err
			}

			if err := cmdutil.MutuallyExclusive(
				"specify only one of --set-parent or --remove-parent",
				flags.Changed("set-parent"),
				opts.RemoveParent,
			); err != nil {
				return err
			}

			if flags.Changed("title") {
				opts.Editable.Title.Edited = true
			}
			if flags.Changed("add-assignee") || flags.Changed("remove-assignee") {
				opts.Editable.Assignees.Edited = true
			}
			if flags.Changed("add-label") || flags.Changed("remove-label") {
				opts.Editable.Labels.Edited = true
			}
			if flags.Changed("add-project") || flags.Changed("remove-project") {
				opts.Editable.Projects.Edited = true
			}
			if flags.Changed("milestone") || removeMilestone {
				opts.Editable.Milestone.Edited = true

				// Note that when `--remove-milestone` is provided, the value of
				// `opts.Editable.Milestone.Value` will automatically be empty,
				// which results in milestone association removal. For reference,
				// see the `Editable.MilestoneId` method.
			}
			if flags.Changed("type") {
				opts.Editable.IssueType.Edited = true
			}
			if flags.Changed("set-parent") || opts.RemoveParent {
				opts.Editable.Parent.Edited = true
				if opts.RemoveParent {
					opts.Editable.Parent.Value = ""
				} else {
					opts.Editable.Parent.Value = opts.SetParent
				}
			}

			// Sub-issue and relationship flags are outside the Editable pattern
			// but still need to prevent interactive mode.
			hasRelationshipFlags := len(opts.AddSubIssues) > 0 || len(opts.RemoveSubIssues) > 0 ||
				len(opts.AddBlockedBy) > 0 || len(opts.RemoveBlockedBy) > 0 ||
				len(opts.AddBlocking) > 0 || len(opts.RemoveBlocking) > 0

			if !opts.Editable.Dirty() && !hasRelationshipFlags {
				opts.Interactive = true
			}

			if opts.Interactive && !opts.IO.CanPrompt() {
				return cmdutil.FlagErrorf("field to edit flag required when not running interactively")
			}

			if opts.Interactive && len(opts.IssueNumbers) > 1 {
				return cmdutil.FlagErrorf("multiple issues cannot be edited interactively")
			}

			if runF != nil {
				return runF(opts)
			}

			return editRun(opts)
		},
	}

	cmd.Flags().StringVarP(&opts.Editable.Title.Value, "title", "t", "", "Set the new title.")
	cmd.Flags().StringVarP(&opts.Editable.Body.Value, "body", "b", "", "Set the new body.")
	cmd.Flags().StringVarP(&bodyFile, "body-file", "F", "", "Read body text from `file` (use \"-\" to read from standard input)")
	cmd.Flags().StringSliceVar(&opts.Editable.Assignees.Add, "add-assignee", nil, "Add assigned users by their `login`. Use \"@me\" to assign yourself, or \"@copilot\" to assign Copilot.")
	cmd.Flags().StringSliceVar(&opts.Editable.Assignees.Remove, "remove-assignee", nil, "Remove assigned users by their `login`. Use \"@me\" to unassign yourself, or \"@copilot\" to unassign Copilot.")
	cmd.Flags().StringSliceVar(&opts.Editable.Labels.Add, "add-label", nil, "Add labels by `name`")
	cmd.Flags().StringSliceVar(&opts.Editable.Labels.Remove, "remove-label", nil, "Remove labels by `name`")
	cmd.Flags().StringSliceVar(&opts.Editable.Projects.Add, "add-project", nil, "Add the issue to projects by `title`")
	cmd.Flags().StringSliceVar(&opts.Editable.Projects.Remove, "remove-project", nil, "Remove the issue from projects by `title`")
	cmd.Flags().StringVarP(&opts.Editable.Milestone.Value, "milestone", "m", "", "Edit the milestone the issue belongs to by `name`")
	cmd.Flags().BoolVar(&removeMilestone, "remove-milestone", false, "Remove the milestone association from the issue")
	cmd.Flags().StringVar(&opts.Editable.IssueType.Value, "type", "", "Set the issue type by `name`")
	cmd.Flags().StringVar(&opts.SetParent, "set-parent", "", "Set the parent issue by `number` or URL")
	cmd.Flags().BoolVar(&opts.RemoveParent, "remove-parent", false, "Remove the parent issue")
	cmd.Flags().StringSliceVar(&opts.AddSubIssues, "add-sub-issue", nil, "Add sub-issues by `number` or URL")
	cmd.Flags().StringSliceVar(&opts.RemoveSubIssues, "remove-sub-issue", nil, "Remove sub-issues by `number` or URL")
	cmd.Flags().StringSliceVar(&opts.AddBlockedBy, "add-blocked-by", nil, "Add 'blocked by' relationships by issue `number` or URL")
	cmd.Flags().StringSliceVar(&opts.RemoveBlockedBy, "remove-blocked-by", nil, "Remove 'blocked by' relationships by issue `number` or URL")
	cmd.Flags().StringSliceVar(&opts.AddBlocking, "add-blocking", nil, "Add 'blocking' relationships by issue `number` or URL")
	cmd.Flags().StringSliceVar(&opts.RemoveBlocking, "remove-blocking", nil, "Remove 'blocking' relationships by issue `number` or URL")

	return cmd
}

func editRun(opts *EditOptions) error {
	httpClient, err := opts.HttpClient()
	if err != nil {
		return err
	}

	baseRepo, err := opts.BaseRepo()
	if err != nil {
		return err
	}

	// Prompt the user which fields they'd like to edit.
	editable := opts.Editable
	editable.IssueType.Allowed = true
	editable.Parent.Allowed = true
	if opts.Interactive {
		err = opts.FieldsToEditSurvey(opts.Prompter, &editable)
		if err != nil {
			return err
		}
	}

	if opts.Detector == nil {
		cachedClient := api.NewCachedHTTPClient(httpClient, time.Hour*24)
		opts.Detector = fd.NewDetector(cachedClient, baseRepo.RepoHost())
	}

	issueFeatures, err := opts.Detector.IssueFeatures()
	if err != nil {
		return err
	}

	lookupFields := []string{"id", "number", "title", "body", "url"}
	if editable.Assignees.Edited {
		// TODO ApiActorsSupported
		if issueFeatures.ApiActorsSupported {
			editable.ApiActorsSupported = true
			lookupFields = append(lookupFields, "assignedActors")
		} else {
			lookupFields = append(lookupFields, "assignees")
		}
	}
	if editable.Labels.Edited {
		lookupFields = append(lookupFields, "labels")
	}
	if editable.Projects.Edited {
		// TODO projectsV1Deprecation
		// Remove this section as we should no longer add projectCards
		projectsV1Support := opts.Detector.ProjectsV1()
		if projectsV1Support == gh.ProjectsV1Supported {
			lookupFields = append(lookupFields, "projectCards")
		}

		lookupFields = append(lookupFields, "projectItems")
	}
	if editable.Milestone.Edited {
		lookupFields = append(lookupFields, "milestone")
	}
	if editable.IssueType.Edited {
		lookupFields = append(lookupFields, "issueType")
	}
	if editable.Parent.Edited || opts.RemoveParent {
		lookupFields = append(lookupFields, "parent")
	}

	// Get all specified issues and make sure they are within the same repo.
	issues, err := issueShared.FindIssuesOrPRs(httpClient, baseRepo, opts.IssueNumbers, lookupFields)
	if err != nil {
		return err
	}

	// Fetch editable shared fields once for all issues.
	apiClient := api.NewClientFromHTTP(httpClient)

	// Wire up search function for assignees when ApiActorsSupported is available.
	// Interactive mode only supports a single issue, so we use its ID for the search query.
	if issueFeatures.ApiActorsSupported && opts.Interactive && len(issues) == 1 {
		editable.AssigneeSearchFunc = prShared.AssigneeSearchFunc(apiClient, baseRepo, issues[0].ID)
	}

	opts.IO.StartProgressIndicatorWithLabel("Fetching repository information")
	err = opts.FetchOptions(apiClient, baseRepo, &editable, opts.Detector.ProjectsV1())
	opts.IO.StopProgressIndicator()
	if err != nil {
		return err
	}

	// Update all issues in parallel.
	editedIssueChan := make(chan string, len(issues))
	failedIssueChan := make(chan string, len(issues))
	g := sync.WaitGroup{}

	// Only show progress if we will not prompt below or the survey will break up the progress indicator.
	if !opts.Interactive {
		opts.IO.StartProgressIndicatorWithLabel(fmt.Sprintf("Updating %d issues", len(issues)))
	}

	for _, issue := range issues {
		// Copy variables to capture in the go routine below.
		editable := editable.Clone()

		editable.Title.Default = issue.Title
		editable.Body.Default = issue.Body
		// We use Actors as the default assignees if Actors are assignable
		// on this GitHub host.
		// TODO ApiActorsSupported
		if editable.ApiActorsSupported {
			editable.Assignees.Default = issue.AssignedActors.DisplayNames()
			editable.Assignees.DefaultLogins = issue.AssignedActors.Logins()
		} else {
			editable.Assignees.Default = issue.Assignees.Logins()
		}
		editable.Labels.Default = issue.Labels.Names()
		editable.Projects.Default = append(issue.ProjectCards.ProjectNames(), issue.ProjectItems.ProjectTitles()...)
		projectItems := map[string]string{}
		for _, n := range issue.ProjectItems.Nodes {
			projectItems[n.Project.ID] = n.ID
		}
		editable.Projects.ProjectItems = projectItems
		if issue.Milestone != nil {
			editable.Milestone.Default = issue.Milestone.Title
		}
		if issue.IssueType != nil {
			editable.IssueType.Default = issue.IssueType.Name
		}
		if issue.Parent != nil {
			editable.Parent.Default = fmt.Sprintf("#%d", issue.Parent.Number)
		}

		// Allow interactive prompts for one issue; failed earlier if multiple issues specified.
		if opts.Interactive {
			editorCommand, err := opts.DetermineEditor()
			if err != nil {
				return err
			}
			err = opts.EditFieldsSurvey(opts.Prompter, &editable, editorCommand)
			if err != nil {
				return err
			}
		}

		// Look up the issue type ID using the map populated by FetchOptions
		var issueTypeID string
		if editable.IssueType.Edited && editable.IssueType.Value != "" {
			id, ok := editable.IssueTypeNameToID[editable.IssueType.Value]
			if !ok {
				return fmt.Errorf("type %q not found; available types: %s",
					editable.IssueType.Value,
					strings.Join(editable.IssueType.Options, ", "))
			}
			issueTypeID = id
		}

		g.Add(1)
		go func(issue *api.Issue) {
			defer g.Done()

			err := prShared.UpdateIssue(httpClient, baseRepo, issue.ID, issue.IsPullRequest(), editable)
			if err != nil {
				failedIssueChan <- fmt.Sprintf("failed to update %s: %s", issue.URL, err)
				return
			}

			// Issue type mutation
			if editable.IssueType.Edited && editable.IssueType.Value != "" {
				if err := api.UpdateIssueIssueType(apiClient, baseRepo.RepoHost(), issue.ID, issueTypeID); err != nil {
					failedIssueChan <- fmt.Sprintf("failed to update type for %s: %s", issue.URL, err)
					return
				}
			}

			// Parent mutation
			if editable.Parent.Edited {
				if err := applyEditParent(apiClient, baseRepo, issue, editable.Parent.Value); err != nil {
					failedIssueChan <- fmt.Sprintf("failed to update parent for %s: %s", issue.URL, err)
					return
				}
			}

			// Sub-issue mutations
			if err := applyEditSubIssues(apiClient, baseRepo, issue, opts); err != nil {
				failedIssueChan <- fmt.Sprintf("failed to update sub-issues for %s: %s", issue.URL, err)
				return
			}

			// Relationship mutations
			if err := applyEditRelationships(apiClient, baseRepo, issue, opts, issueFeatures); err != nil {
				failedIssueChan <- fmt.Sprintf("failed to update relationships for %s: %s", issue.URL, err)
				return
			}

			editedIssueChan <- issue.URL
		}(issue)
	}

	g.Wait()
	close(editedIssueChan)
	close(failedIssueChan)

	// Does nothing if progress was not started above.
	opts.IO.StopProgressIndicator()

	// Print a sorted list of successfully edited issue URLs to stdout.
	editedIssueURLs := make([]string, 0, len(issues))
	for editedIssueURL := range editedIssueChan {
		editedIssueURLs = append(editedIssueURLs, editedIssueURL)
	}

	sort.Strings(editedIssueURLs)
	for _, editedIssueURL := range editedIssueURLs {
		fmt.Fprintln(opts.IO.Out, editedIssueURL)
	}

	// Print a sorted list of failures to stderr.
	failedIssueErrors := make([]string, 0, len(issues))
	for failedIssueError := range failedIssueChan {
		failedIssueErrors = append(failedIssueErrors, failedIssueError)
	}

	sort.Strings(failedIssueErrors)
	for _, failedIssueError := range failedIssueErrors {
		fmt.Fprintln(opts.IO.ErrOut, failedIssueError)
	}

	if len(failedIssueErrors) > 0 {
		return fmt.Errorf("failed to update %s", text.Pluralize(len(failedIssueErrors), "issue"))
	}

	return nil
}

func applyEditParent(client *api.Client, baseRepo ghrepo.Interface, issue *api.Issue, parentRef string) error {
	hostname := baseRepo.RepoHost()

	if parentRef == "" {
		// Remove parent - use the parent's ID from the fetched issue data
		if issue.Parent == nil {
			return nil // no parent to remove
		}
		return api.RemoveSubIssue(client, hostname, issue.Parent.ID, issue.ID)
	}

	// Set parent with replaceParent=true
	parentID, err := issueShared.ResolveIssueRef(client, baseRepo, parentRef)
	if err != nil {
		return fmt.Errorf("resolving parent: %w", err)
	}
	return api.AddSubIssue(client, hostname, parentID, issue.ID, true)
}

func applyEditSubIssues(client *api.Client, baseRepo ghrepo.Interface, issue *api.Issue, opts *EditOptions) error {
	hostname := baseRepo.RepoHost()

	for _, ref := range opts.AddSubIssues {
		subID, err := issueShared.ResolveIssueRef(client, baseRepo, ref)
		if err != nil {
			return fmt.Errorf("resolving --add-sub-issue reference %q: %w", ref, err)
		}
		if err := api.AddSubIssue(client, hostname, issue.ID, subID, false); err != nil {
			return err
		}
	}

	for _, ref := range opts.RemoveSubIssues {
		subID, err := issueShared.ResolveIssueRef(client, baseRepo, ref)
		if err != nil {
			return fmt.Errorf("resolving --remove-sub-issue reference %q: %w", ref, err)
		}
		if err := api.RemoveSubIssue(client, hostname, issue.ID, subID); err != nil {
			return err
		}
	}

	return nil
}

func applyEditRelationships(client *api.Client, baseRepo ghrepo.Interface, issue *api.Issue, opts *EditOptions, features fd.IssueFeatures) error {
	hasRelationshipFlags := len(opts.AddBlockedBy) > 0 || len(opts.RemoveBlockedBy) > 0 ||
		len(opts.AddBlocking) > 0 || len(opts.RemoveBlocking) > 0
	if !hasRelationshipFlags {
		return nil
	}

	// TODO IssueRelationshipsCleanup
	if !features.IssueRelationshipsSupported {
		return fmt.Errorf("issue relationships are not supported on this GitHub Enterprise Server version")
	}

	hostname := baseRepo.RepoHost()

	for _, ref := range opts.AddBlockedBy {
		blockingID, err := issueShared.ResolveIssueRef(client, baseRepo, ref)
		if err != nil {
			return fmt.Errorf("resolving --add-blocked-by reference %q: %w", ref, err)
		}
		if err := api.AddBlockedBy(client, hostname, issue.ID, blockingID); err != nil {
			return err
		}
	}

	for _, ref := range opts.RemoveBlockedBy {
		blockingID, err := issueShared.ResolveIssueRef(client, baseRepo, ref)
		if err != nil {
			return fmt.Errorf("resolving --remove-blocked-by reference %q: %w", ref, err)
		}
		if err := api.RemoveBlockedBy(client, hostname, issue.ID, blockingID); err != nil {
			return err
		}
	}

	for _, ref := range opts.AddBlocking {
		// --add-blocking swaps args: the OTHER issue is blocked by THIS issue
		blockedID, err := issueShared.ResolveIssueRef(client, baseRepo, ref)
		if err != nil {
			return fmt.Errorf("resolving --add-blocking reference %q: %w", ref, err)
		}
		if err := api.AddBlockedBy(client, hostname, blockedID, issue.ID); err != nil {
			return err
		}
	}

	for _, ref := range opts.RemoveBlocking {
		// --remove-blocking swaps args: the OTHER issue is no longer blocked by THIS issue
		blockedID, err := issueShared.ResolveIssueRef(client, baseRepo, ref)
		if err != nil {
			return fmt.Errorf("resolving --remove-blocking reference %q: %w", ref, err)
		}
		if err := api.RemoveBlockedBy(client, hostname, blockedID, issue.ID); err != nil {
			return err
		}
	}

	return nil
}