// Copyright 2026 The Gitea Authors. All rights reserved.
// SPDX-License-Identifier: MIT

package app

import (
	"context"
	"errors"
	"fmt"
	"slices"
	"strconv"
	"strings"
	"time"

	"gitea.dev/tea/internal/clierr"
	"gitea.dev/tea/internal/services"
	"gitea.dev/tea/internal/terminal"
	"github.com/spf13/cobra"
)

// notificationScope is the notifications a command acts on: the account's inbox, or one repository's.
type notificationScope struct {
	services.Notifications
	// where names the scope in messages: "in your inbox" or "in alice/project".
	where string
}

func (a *application) notificationCommand() *cobra.Command {
	group := &cobra.Command{Use: "notification", Short: "Read and triage your notifications", Long: `Read and triage the notifications of your account.

Commands act on your whole inbox. -R OWNER/REPO limits them to one repository, and
--this-repo to the repository of the current directory. The IDs that tea notification
list shows identify notification threads; they are not issue numbers.`}
	var mine, thisRepo bool
	group.PersistentFlags().BoolVar(&mine, "mine", false, "Read your whole inbox (the default)")
	_ = group.PersistentFlags().MarkHidden("mine")
	group.PersistentFlags().BoolVar(&thisRepo, "this-repo", false, "Only notifications of the repository in the current directory")
	scope := func(cmd *cobra.Command) (notificationScope, error) {
		t, err := a.resolve(cmd.Context(), thisRepo)
		if err != nil {
			return notificationScope{}, err
		}
		where := "in your inbox"
		if t.Repo != "" {
			where = "in " + t.Repo
		}
		return notificationScope{services.Notifications{Client: t.client, Repository: t.Repo}, where}, nil
	}
	group.AddCommand(a.notificationListCommand(scope), a.notificationWatchCommand(scope), a.notificationViewCommand(scope))
	for _, mark := range []struct {
		verb, status, filter, short, done, example string
	}{
		{"mark-read", "read", "unread", "Mark notifications as read", "Marked %s as read", "$ tea notification mark-read 28\n# Everything in one repository\n$ tea notification mark-read --all -R alice/project"},
		{"mark-unread", "unread", "read", "Mark notifications as unread", "Marked %s as unread", "$ tea notification mark-unread 28 26"},
		{"pin", "pinned", "unread", "Pin notifications", "Pinned %s", "$ tea notification pin 28"},
		{"unpin", "read", "pinned", "Unpin notifications", "Unpinned %s", "$ tea notification unpin 28\n# Unpin everything\n$ tea notification unpin --all"},
	} {
		var all bool
		var filters []string
		var before string
		command := &cobra.Command{
			Use: mark.verb + " [<id>...]", Short: mark.short, Example: mark.example, ValidArgsFunction: a.completeNotifications(),
			Annotations: map[string]string{"tea.confirm": "true"},
			Args: func(_ *cobra.Command, args []string) error {
				if len(args) == 0 && !all {
					return clierr.Wrap(clierr.Usage, errors.New("supply notification IDs or --all"))
				}
				if len(args) > 0 && all {
					return clierr.Wrap(clierr.Usage, errors.New("notification IDs and --all are mutually exclusive"))
				}
				return nil
			},
			RunE: func(cmd *cobra.Command, args []string) error {
				ids, err := resourceNumbers(args)
				if err != nil {
					return err
				}
				if !all && (cmd.Flags().Changed("status") || cmd.Flags().Changed("before")) {
					return clierr.Wrap(clierr.Usage, errors.New("--status and --before require --all"))
				}
				if !cmd.Flags().Changed("status") {
					filters = []string{mark.filter}
				}
				var until time.Time
				if cmd.Flags().Changed("before") {
					parsed, err := parseRunTime(before, a.deps.Now())
					if err != nil {
						return clierr.Wrap(clierr.Usage, fmt.Errorf("invalid --before: %w", err))
					}
					until = *parsed
				}
				s, err := scope(cmd)
				if err != nil {
					return err
				}
				if !all {
					return batchDone(a, cmd, ids, func(id int64) string { return fmt.Sprintf("notification %d", id) }, func(id int64) (services.Notification, error) {
						return s.Mark(cmd.Context(), id, mark.status)
					}, func(item services.Notification) string { return fmt.Sprintf(mark.done, notificationLabel(item)) })
				}
				what := notificationsWith(filters) + " " + s.where
				if settings, err := a.deps.Settings.Load(); err == nil && a.policy(settings).CanPrompt(a.deps.Streams) {
					if err := a.confirmAction(cmd, terminal.Confirmation{Prompt: fmt.Sprintf("%s all %s?", strings.Replace(mark.done, " %s", "", 1), what), DefaultYes: true}); err != nil {
						return err
					}
				}
				results, err := s.MarkAll(cmd.Context(), mark.status, filters, until)
				if err != nil {
					return err
				}
				if a.options.json != "" {
					return a.writeJSON(cmd, results)
				}
				if len(results) == 0 {
					a.warn(cmd, "No %s", what)
					return nil
				}
				a.done(cmd, mark.done, plural(len(results), "notification"))
				return nil
			},
		}
		command.Flags().BoolVar(&all, "all", false, "Apply to every notification that matches --status in the scope")
		command.Flags().StringSliceVar(&filters, "status", nil, "With --all, the statuses to change")
		enumValues(command, "status", "unread", "read", "pinned")
		command.Flags().StringVar(&before, "before", "", "With --all, only notifications updated before a date, timestamp, or duration such as 1h")
		group.AddCommand(command)
	}
	return group
}

// notificationFilters registers the list filters of list and watch.
func notificationFilters(cmd *cobra.Command, opts *services.NotificationOptions, updated *timeRange) {
	pageFlags(cmd, &opts.Limit, &opts.Page)
	cmd.Flags().StringSliceVar(&opts.Statuses, "status", []string{"unread", "pinned"}, "Only notifications with these statuses")
	enumValues(cmd, "status", "unread", "read", "pinned")
	cmd.Flags().StringSliceVar(&opts.Types, "type", nil, "Only notifications about these subjects")
	enumValues(cmd, "type", "issue", "pull", "commit", "repository")
	updated.register(cmd, "since", "Only notifications updated since a date, timestamp, or duration such as 24h", "before", "Only notifications updated before a date, timestamp, or duration such as 1h")
}

// notificationOptions completes the list filters for the API.
func (a *application) notificationOptions(opts services.NotificationOptions, updated timeRange) (services.NotificationOptions, error) {
	types := make([]string, len(opts.Types))
	for i, kind := range opts.Types {
		types[i] = titleCase(kind)
	}
	opts.Types = types
	var err error
	opts.Since, opts.Before, err = updated.parse(a.deps.Now())
	return opts, err
}

func (a *application) notificationListCommand(scope func(*cobra.Command) (notificationScope, error)) *cobra.Command {
	opts := services.NotificationOptions{}
	var updated timeRange
	command := &cobra.Command{
		Use: "list", Short: "List notifications", Args: argsExact(0),
		Example: `$ tea notification list
# Including the ones you read, of one repository
$ tea notification list --status unread,read,pinned -R alice/project
# Pull requests updated today
$ tea notification list --type pull --since 24h`,
		RunE: func(cmd *cobra.Command, _ []string) error {
			listed, err := a.notificationOptions(opts, updated)
			if err != nil {
				return err
			}
			s, err := scope(cmd)
			if err != nil {
				return err
			}
			page, err := s.List(cmd.Context(), listed)
			if err != nil {
				return err
			}
			what := notificationsWith(opts.Statuses) + " " + s.where
			return writeTable(a, cmd, page.Items, listSpec[services.Notification]{
				Columns: notificationColumns, Row: notificationRow, Empty: "no " + what, Context: what,
			}, listPage{Number: opts.Page, More: page.More, Total: page.Total, Counted: page.Counted})
		},
	}
	notificationFilters(command, &opts, &updated)
	return command
}

func (a *application) notificationWatchCommand(scope func(*cobra.Command) (notificationScope, error)) *cobra.Command {
	opts := services.NotificationOptions{}
	var updated timeRange
	var interval, timeout time.Duration
	command := &cobra.Command{
		Use: "watch", Short: "Print notifications as they arrive", Args: argsExact(0),
		Long: `Print notifications as they arrive or change, until Ctrl-C or --timeout. On a terminal
it runs until stopped; otherwise it stops after a minute unless --timeout says otherwise.
With --json it prints one JSON object per line.`,
		Example: "$ tea notification watch\n# Stream new pull request notifications to a script\n$ tea notification watch --type pull --json id,repository,title | ./notify.sh",
		RunE: func(cmd *cobra.Command, _ []string) error {
			listed, err := a.notificationOptions(opts, updated)
			if err != nil {
				return err
			}
			if interval <= 0 || timeout < 0 {
				return clierr.Wrap(clierr.Usage, errors.New("--interval must be positive and --timeout not negative"))
			}
			if !cmd.Flags().Changed("timeout") && !a.deps.Streams.OutTTY {
				timeout = time.Minute
			}
			s, err := scope(cmd)
			if err != nil {
				return err
			}
			ctx := cmd.Context()
			if timeout > 0 {
				var cancel context.CancelFunc
				ctx, cancel = context.WithTimeout(ctx, timeout)
				defer cancel()
			}
			d := a.display()
			if d.TTY && a.options.json == "" {
				fmt.Fprintf(cmd.ErrOrStderr(), "Watching %s %s; press Ctrl-C to stop\n", notificationsWith(opts.Statuses), s.where)
			}
			err = s.Watch(ctx, listed, interval, func(items []services.Notification) error {
				if a.options.json != "" {
					for _, item := range items {
						if err := (terminal.JSONOutput{Fields: a.options.json, Query: a.options.jq}).Write(cmd.OutOrStdout(), item); err != nil {
							return err
						}
					}
					return nil
				}
				if !d.TTY {
					rows := make([][]terminal.Cell, len(items))
					for i, item := range items {
						rows[i] = notificationRow(item)
					}
					_, err := fmt.Fprint(cmd.OutOrStdout(), terminal.Table(notificationColumns, rows, d))
					return err
				}
				for _, item := range items {
					if _, err := fmt.Fprintln(cmd.OutOrStdout(), watchLine(item, d)); err != nil {
						return err
					}
				}
				return nil
			})
			if errors.Is(err, context.DeadlineExceeded) && cmd.Context().Err() == nil {
				return nil
			}
			return err
		},
	}
	notificationFilters(command, &opts, &updated)
	command.Flags().DurationVar(&interval, "interval", 5*time.Second, "Time between checks")
	command.Flags().DurationVar(&timeout, "timeout", 0, "Stop after this long (default: never on a terminal, 1m otherwise)")
	return command
}

func (a *application) notificationViewCommand(scope func(*cobra.Command) (notificationScope, error)) *cobra.Command {
	return &cobra.Command{
		Use: "view <id>", Short: "View a notification and mark it as read", Args: argsExact(1), ValidArgsFunction: a.completeNotifications(),
		Long: `View a notification: its subject, the subject's state and the latest comment. Like
opening it on the web, viewing marks an unread notification as read; pinned ones stay
pinned.`,
		Example: "$ tea notification view 28\n$ tea notification view 28 --json title,url",
		RunE: func(cmd *cobra.Command, args []string) error {
			id, err := number(args[0])
			if err != nil {
				return err
			}
			s, err := scope(cmd)
			if err != nil {
				return err
			}
			item, err := s.View(cmd.Context(), id)
			if err != nil {
				return err
			}
			var comment *services.Comment
			if a.options.json == "" {
				if comment, err = s.LatestComment(cmd.Context(), item); err != nil {
					return err
				}
			}
			if err := writeView(a, cmd, item, func(item services.Notification) terminal.View { return notificationView(item, comment, a.display()) }); err != nil {
				return err
			}
			if item.Unread && !item.Pinned {
				_, err = s.Mark(cmd.Context(), id, "read")
			}
			return err
		},
	}
}

// notificationColumns head notification tables; piped, they add the status and the URL.
var notificationColumns = []terminal.Column{
	{Header: "ID"},
	{Header: "Type"},
	{Header: "Repository"},
	{Header: "Subject", Flex: true},
	{Header: "State"},
	{Header: "Status", PipedOnly: true},
	{Header: "Updated"},
	{Header: "URL", PipedOnly: true},
}

// notificationRow shows a notification under notificationColumns; unread subjects are bold.
func notificationRow(item services.Notification) []terminal.Cell {
	return []terminal.Cell{
		{Text: strconv.FormatInt(item.ID, 10), Link: item.URL},
		{Text: strings.ToLower(item.Type)},
		{Text: item.Repository},
		{Text: notificationSubject(item), Bold: item.Unread, Muted: !item.Unread && !item.Pinned},
		{Text: item.State, Color: stateColors[item.State]},
		{Text: notificationStatus(item)},
		{Time: terminal.ParseTime(item.UpdatedAt)},
		{Text: item.URL},
	}
}

// notificationSubject reads "#17 Improve greeting" for issues and pull requests.
func notificationSubject(item services.Notification) string {
	if item.Number == 0 {
		return item.Title
	}
	return fmt.Sprintf("#%d %s", item.Number, item.Title)
}

// notificationsWith names the notifications with one of statuses: "unread or pinned notifications",
// or "notifications" for every status.
func notificationsWith(statuses []string) string {
	var distinct []string
	for _, status := range statuses {
		if !slices.Contains(distinct, status) {
			distinct = append(distinct, status)
		}
	}
	switch len(distinct) {
	case 0, 3:
		return "notifications"
	case 1:
		return distinct[0] + " notifications"
	}
	return distinct[0] + " or " + distinct[1] + " notifications"
}

// notificationStatus is unread, read or pinned.
func notificationStatus(item services.Notification) string {
	switch {
	case item.Pinned:
		return "pinned"
	case item.Unread:
		return "unread"
	}
	return "read"
}

// notificationLabel names a notification in feedback: "notification 28 (alice/project#17)".
func notificationLabel(item services.Notification) string {
	return fmt.Sprintf("notification %d (%s)", item.ID, subjectRef(item))
}

// subjectRef names the subject of a notification by its repository and number: "alice/project#17".
func subjectRef(item services.Notification) string {
	if item.Number == 0 {
		return item.Repository
	}
	return item.Repository + "#" + strconv.FormatInt(item.Number, 10)
}

// notificationKinds names the subject types in a view footer.
var notificationKinds = map[string]string{"Issue": "issue", "Pull": "pull request", "Commit": "commit", "Repository": "repository"}

// notificationView shows a notification with the latest comment on its subject as the body.
func notificationView(item services.Notification, comment *services.Comment, d terminal.Display) terminal.View {
	meta := item.Repository
	if updated := terminal.ParseTime(item.UpdatedAt); !updated.IsZero() {
		meta += " · updated " + terminal.RelativeTime(d.Now, updated)
	}
	view := terminal.View{
		Title: item.Title, Meta: meta, Kind: notificationKinds[item.Type], URL: item.URL,
		Badges: []terminal.Cell{{Text: titleCase(item.State), Color: stateColors[item.State]}, {Text: notificationStatus(item), Muted: true}},
		Fields: []terminal.Field{{Label: "Notification", Value: strconv.FormatInt(item.ID, 10)}, {Label: "Type", Value: notificationKinds[item.Type]}, {Label: "Repository", Value: item.Repository}},
		Body:   "_No comments yet._",
	}
	if item.Number != 0 {
		view.ID = "#" + strconv.FormatInt(item.Number, 10)
	}
	if comment != nil {
		when := ""
		if created := terminal.ParseTime(comment.CreatedAt); !created.IsZero() {
			when = ", " + terminal.RelativeTime(d.Now, created)
		}
		view.Fields = append(view.Fields, terminal.Field{Label: "Latest comment", Value: comment.Author + when})
		view.Body = comment.Body
	}
	return view
}

// watchLine shows a notification that tea notification watch reports on a terminal:
// "15:04  alice/project#17  Improve greeting  pull · open".
func watchLine(item services.Notification, d terminal.Display) string {
	when := terminal.ParseTime(item.UpdatedAt)
	if when.IsZero() {
		when = d.Now
	}
	subject := subjectRef(item)
	details := strings.ToLower(item.Type)
	if item.State != "" {
		details += " · " + terminal.Colorize(stateColors[item.State], item.State, d.Color)
	}
	return terminal.Colorize("muted", when.Local().Format("15:04"), d.Color) + "  " + terminal.Emphasis(terminal.SafeLine(subject), d.Color) + "  " + terminal.SafeLine(item.Title) + "  " + details
}

// completeNotifications completes the IDs of the notifications in your inbox with their subjects.
func (a *application) completeNotifications() cobra.CompletionFunc {
	return a.apiCompletion(false, func(ctx context.Context, t target, _ string) ([]cobra.Completion, error) {
		page, err := services.Notifications{Client: t.client, Repository: t.Repo}.List(ctx, services.NotificationOptions{Limit: completionLimit, Page: 1, Statuses: []string{"unread", "pinned", "read"}})
		return describe(page.Items, func(item services.Notification) (string, string) {
			return strconv.FormatInt(item.ID, 10), subjectRef(item) + " " + item.Title
		}), err
	})
}