import type { Component } from "svelte";
import type { SvelteHTMLElements } from "svelte/elements";
import AtSign from "$icon/at-sign";
import Ban from "$icon/ban";
import CircleDot from "$icon/circle-dot";
import GitMerge from "$icon/git-merge";
import GitPullRequestClosed from "$icon/git-pull-request-closed";
import GitPullRequestCreate from "$icon/git-pull-request-create";
import MessageSquare from "$icon/message-square";
import Star from "$icon/star";
import UserPlus from "$icon/user-plus";
import UserRoundMinus from "$icon/user-round-minus";
import UserRoundArrowForward from "$lib/components/icons/UserRoundArrowForward.svelte";
import type {
	NotificationCategory,
	NotificationGroups,
	NotificationSummary,
	NotificationType
} from "./types";

type IconComponent = Component<SvelteHTMLElements["svg"]>;

export const SOCIAL_TYPES: NotificationType[] = ["repo_starred", "followed"];

const CATEGORIES: Record<NotificationType, NotificationCategory> = {
	repo_starred: "social",
	followed: "social",
	issue_created: "work",
	issue_commented: "work",
	issue_closed: "work",
	issue_reopen: "work",
	issue_assigned: "work",
	issue_unassigned: "work",
	pull_created: "work",
	pull_commented: "work",
	pull_merged: "work",
	pull_closed: "work",
	pull_reopen: "work",
	pull_assigned: "work",
	pull_unassigned: "work",
	user_mentioned: "work"
};

const ICONS: Record<NotificationType, IconComponent> = {
	repo_starred: Star,
	followed: UserPlus,
	issue_created: CircleDot,
	issue_commented: MessageSquare,
	issue_closed: Ban,
	issue_reopen: CircleDot,
	issue_assigned: UserRoundArrowForward,
	issue_unassigned: UserRoundMinus,
	pull_created: GitPullRequestCreate,
	pull_commented: MessageSquare,
	pull_merged: GitMerge,
	pull_closed: GitPullRequestClosed,
	pull_reopen: GitPullRequestCreate,
	pull_assigned: UserRoundArrowForward,
	pull_unassigned: UserRoundMinus,
	user_mentioned: AtSign
};

// the design system has no purple, and a merged pull already reads as info on
// PullStatePill, so merges land on the same token here.
const TONES: Record<NotificationType, string> = {
	repo_starred: "text-foreground-warning",
	followed: "text-foreground-muted",
	issue_created: "text-foreground-success",
	issue_commented: "text-foreground-muted",
	issue_closed: "text-foreground-muted",
	issue_reopen: "text-foreground-success",
	issue_assigned: "text-foreground-info",
	issue_unassigned: "text-foreground-muted",
	pull_created: "text-foreground-success",
	pull_commented: "text-foreground-muted",
	pull_merged: "text-foreground-info",
	pull_closed: "text-foreground-danger",
	pull_reopen: "text-foreground-success",
	pull_assigned: "text-foreground-info",
	pull_unassigned: "text-foreground-muted",
	user_mentioned: "text-foreground-info"
};

const PHRASES: Record<NotificationType, string> = {
	repo_starred: "starred",
	followed: "followed you",
	issue_created: "opened an issue on",
	issue_commented: "commented on an issue on",
	issue_closed: "closed an issue on",
	issue_reopen: "reopened an issue on",
	issue_assigned: "assigned you to an issue on",
	issue_unassigned: "unassigned you from an issue on",
	pull_created: "created a PR on",
	pull_commented: "commented on a PR on",
	pull_merged: "merged a PR on",
	pull_closed: "closed a PR on",
	pull_reopen: "reopened a PR on",
	pull_assigned: "assigned you to a PR on",
	pull_unassigned: "unassigned you from a PR on",
	user_mentioned: "mentioned you in"
};

export const notificationCategory = (type: NotificationType): NotificationCategory =>
	CATEGORIES[type];

export const notificationIcon = (type: NotificationType): IconComponent => ICONS[type];

export const notificationTone = (type: NotificationType): string => TONES[type];

export const notificationPhrase = (notification: NotificationSummary): string => {
	if (notification.type === "user_mentioned" && notification.subject) {
		return notification.subject.kind === "issue"
			? "mentioned you on an issue in"
			: "mentioned you on a pull request in";
	}
	return PHRASES[notification.type];
};

// the subject of the phrase, which the appview prints as owner/name after it
export const notificationTarget = (notification: NotificationSummary): string =>
	notification.repo ? `${notification.repo.ownerHandle}/${notification.repo.name}` : "";

export const notificationHref = (notification: NotificationSummary): string => {
	if (notification.type === "followed") return `/${notification.actor.handle}`;
	const repo = notification.repo;
	if (!repo) return `/${notification.actor.handle}`;
	const base = `/${repo.ownerHandle}/${repo.name}`;
	const subject = notification.subject;
	if (!subject) return base;
	return `${base}/${subject.kind === "issue" ? "issues" : "pulls"}/${subject.uri}`;
};

// today, the six days before it, then everything older, same buckets the go page
// builds in GroupNotificationsByDate
export const groupNotificationsByDate = (
	notifications: NotificationSummary[],
	now: Date = new Date()
): NotificationGroups => {
	const todayStart = new Date(now.getFullYear(), now.getMonth(), now.getDate()).getTime();
	const weekStart = todayStart - 6 * 24 * 60 * 60 * 1000;

	const groups: NotificationGroups = { today: [], thisWeek: [], older: [] };
	for (const notification of notifications) {
		const created = Date.parse(notification.createdAt);
		if (created >= todayStart) groups.today.push(notification);
		else if (created >= weekStart) groups.thisWeek.push(notification);
		else groups.older.push(notification);
	}
	return groups;
};

export const isEmpty = (groups: NotificationGroups): boolean =>
	groups.today.length === 0 && groups.thisWeek.length === 0 && groups.older.length === 0;