import { CHAT_PERMISSIONS, type ChatAttachmentRecord, type ChatMemberChannelRecord, type ChatMessageFeatureRecord } from "@hivegrid/chat";
import { buildChatMessageDeepLink } from "@hivegrid/chat/deep-links";
import type { ChatRealtimeMessage } from "@hivegrid/realtime";
import { getChatThreadDetail, listChatPinnedMessages, sendChatThreadReply, setChatMessagePin, setChatReaction } from "@hivegrid/chat/message-features.server";
import { buildChatPinnedMessagesVM, buildChatThreadVM, type ChatFeatureMessageVM, type ChatPinnedMessagesVM, type ChatThreadVM } from "@hivegrid/view-models";

import type { ChatRouteContext } from "../routes/chatAccess.server";
import { chatChannelPath } from "../routes/chatRoutePaths";
import { toChatAttachmentVM, toChatResolvedMentionVM } from "./chatViewModel.server";

export type ChatMessageFeatureLabels = {
  readonly directMessage: string;
  readonly unnamedGroup: string;
  readonly unnamedProject: string;
  readonly unknownUser: string;
  readonly unknownMention: string;
};

export async function loadChatThreadPage(input: {
  readonly context: ChatRouteContext;
  readonly tenantSlug: string;
  readonly chatId: string;
  readonly threadId: string;
  readonly labels: ChatMessageFeatureLabels;
}): Promise<{ readonly vm: ChatThreadVM; readonly eventCursor: string }> {
  const detail = await getChatThreadDetail({ ...input.context, chatId: input.chatId, threadId: input.threadId });
  const features = new Map(detail.messageFeatures.map((feature) => [feature.messageId, feature]));
  const attachments = groupAttachments(detail.attachments);
  const profiles = new Map(detail.channel.participants.map((profile) => [profile.userId, profile]));
  const canWrite = input.context.permissions.includes(CHAT_PERMISSIONS.write) && detail.channel.member.canWrite && detail.channel.archivedAtIso === null;
  const canAdministerMessages = input.context.permissions.includes(CHAT_PERMISSIONS.admin);
  const canDeleteAsChannelAdmin = detail.channel.member.roleInChat === "admin" || canAdministerMessages;
  const nowIso = new Date().toISOString();

  const vm = buildChatThreadVM({
    chatId: detail.channel.id,
    threadId: detail.parentMessage.id,
    channelTitle: resolveChannelTitle(detail.channel, input.context.userId, input.labels),
    backHref: chatChannelPath(input.tenantSlug, detail.channel.id),
    parent: mapFeatureMessage(
      detail.parentMessage,
      features.get(detail.parentMessage.id) ?? null,
      profiles,
      input.context.userId,
      canWrite,
      detail.channel.kind,
      input.tenantSlug,
      attachments.get(detail.parentMessage.id) ?? [],
      canAdministerMessages,
      canDeleteAsChannelAdmin,
      nowIso,
      input.labels
    ),
    replies: detail.replies.map((message) =>
      mapFeatureMessage(
        message,
        features.get(message.id) ?? null,
        profiles,
        input.context.userId,
        canWrite,
        detail.channel.kind,
        input.tenantSlug,
        attachments.get(message.id) ?? [],
        canAdministerMessages,
        canDeleteAsChannelAdmin,
        nowIso,
        input.labels
      )
    ),
    replyCount: detail.replies.length,
    canReply: canWrite,
  });
  return { vm, eventCursor: detail.channel.eventCursor };
}

export async function loadChatPinnedPage(input: {
  readonly context: ChatRouteContext;
  readonly tenantSlug: string;
  readonly chatId: string;
  readonly labels: ChatMessageFeatureLabels;
}): Promise<{ readonly vm: ChatPinnedMessagesVM; readonly eventCursor: string }> {
  const result = await listChatPinnedMessages({ ...input.context, chatId: input.chatId });
  const profiles = new Map(result.channel.participants.map((profile) => [profile.userId, profile]));
  const canWrite = input.context.permissions.includes(CHAT_PERMISSIONS.write) && result.channel.member.canWrite && result.channel.archivedAtIso === null;
  const vm = buildChatPinnedMessagesVM({
    chatId: result.channel.id,
    channelTitle: resolveChannelTitle(result.channel, input.context.userId, input.labels),
    backHref: chatChannelPath(input.tenantSlug, result.channel.id),
    rows: result.pinnedMessages.map((row) => ({
      message: mapFeatureMessage(
        row.message,
        {
          messageId: row.message.id,
          reactions: [],
          thread: null,
          pin: row.pin,
        },
        profiles,
        input.context.userId,
        false,
        result.channel.kind,
        input.tenantSlug,
        [],
        false,
        false,
        new Date().toISOString(),
        input.labels
      ),
      pinnedAtIso: row.pin.pinnedAtIso,
      pinnedByLabel: row.pinnedBy?.displayName ?? input.labels.unknownUser,
      note: row.pin.note,
      messageHref: buildChatMessageDeepLink({ tenantSlug: input.tenantSlug, chatId: result.channel.id, messageId: row.message.id }),
      canUnpin: canWrite,
    })),
  });
  return { vm, eventCursor: result.channel.eventCursor };
}

export async function createChatThreadReply(input: {
  readonly context: ChatRouteContext;
  readonly chatId: string;
  readonly threadId: string;
  readonly body: string;
  readonly requestId: string;
  readonly clientMessageId: string;
}) {
  return sendChatThreadReply({ ...input.context, ...input });
}

export async function changeChatReaction(input: {
  readonly context: ChatRouteContext;
  readonly chatId: string;
  readonly messageId: string;
  readonly emoji: string;
  readonly active: boolean;
  readonly requestId: string;
}) {
  return setChatReaction({ ...input.context, ...input });
}

export async function changeChatMessagePin(input: {
  readonly context: ChatRouteContext;
  readonly chatId: string;
  readonly messageId: string;
  readonly pinned: boolean;
  readonly requestId: string;
}) {
  return setChatMessagePin({ ...input.context, ...input });
}

function mapFeatureMessage(
  message: ChatRealtimeMessage,
  feature: ChatMessageFeatureRecord | null,
  profiles: ReadonlyMap<string, ChatMemberChannelRecord["participants"][number]>,
  currentUserId: string,
  canWrite: boolean,
  channelKind: ChatMemberChannelRecord["kind"],
  tenantSlug: string,
  attachments: readonly ChatAttachmentRecord[],
  canAdministerMessages: boolean,
  canDeleteAsChannelAdmin: boolean,
  nowIso: string,
  labels: ChatMessageFeatureLabels
): ChatFeatureMessageVM {
  const deleted = message.deletedAt !== null;
  const author = message.authorUserId ? profiles.get(message.authorUserId) : null;
  const ownMessage = message.authorUserId === currentUserId;
  const ageMs = Date.parse(nowIso) - Date.parse(message.createdAt);
  const withinOwnMutationWindow = Number.isFinite(ageMs) && ageMs >= 0 && ageMs <= 24 * 60 * 60 * 1_000;
  const reactionGroups = new Map<string, string[]>();
  for (const reaction of feature?.reactions ?? []) {
    const userIds = reactionGroups.get(reaction.emoji) ?? [];
    userIds.push(reaction.userId);
    reactionGroups.set(reaction.emoji, userIds);
  }
  return {
    id: message.id,
    authorLabel: author?.displayName ?? "?",
    authorAvatarUrl: author?.avatarUrl ?? null,
    bodyMarkdown: deleted ? null : message.body,
    createdAtIso: message.createdAt,
    deleted,
    mentions: deleted
      ? []
      : message.mentions.map((mention) =>
          toChatResolvedMentionVM(mention, profiles, tenantSlug, {
            ...labels,
          })
        ),
    attachments: deleted ? [] : attachments.map((attachment) => toChatAttachmentVM(attachment, tenantSlug)),
    reactions: [...reactionGroups].map(([emoji, userIds]) => ({
      emoji,
      count: userIds.length,
      reactedByViewer: userIds.includes(currentUserId),
    })),
    pinned: feature?.pin !== null && feature?.pin !== undefined,
    canReact: canWrite && !deleted,
    canPin: canWrite && !deleted && channelKind !== "dm",
    canEdit: canWrite && !deleted && (canAdministerMessages || (ownMessage && withinOwnMutationWindow)),
    canDelete: canWrite && !deleted && (canDeleteAsChannelAdmin || (ownMessage && withinOwnMutationWindow)),
  };
}

function groupAttachments(attachments: readonly ChatAttachmentRecord[]): ReadonlyMap<string, readonly ChatAttachmentRecord[]> {
  const grouped = new Map<string, ChatAttachmentRecord[]>();
  for (const attachment of attachments) {
    grouped.set(attachment.messageId, [...(grouped.get(attachment.messageId) ?? []), attachment]);
  }
  return grouped;
}

function resolveChannelTitle(channel: ChatMemberChannelRecord, currentUserId: string, labels: ChatMessageFeatureLabels): string {
  if (channel.kind === "dm") {
    return channel.participants.find((participant) => participant.userId !== currentUserId)?.displayName ?? labels.directMessage;
  }
  return channel.name?.trim() || (channel.kind === "project" ? labels.unnamedProject : labels.unnamedGroup);
}