import { createHash } from "node:crypto"
import { FastifyInstance } from "fastify"
import { and, asc, desc, eq, gt, inArray, ne, sql } from "drizzle-orm"
import {
    authProfiles,
    authTenantUsers,
    authUsers,
    communicationMessages,
    communicationRoomMembers,
    communicationRoomReads,
    communicationRooms,
    notificationsItems,
    projects,
} from "../../db/schema"
import { NotificationService, UserDirectory } from "../modules/notification.service"

type ChatUser = {
    userId: string
    email?: string | null
    firstName?: string | null
    lastName?: string | null
    fullName?: string | null
}

const getUserDirectory: UserDirectory = async (server, userId) => {
    const [user] = await server.db
        .select({ email: authUsers.email })
        .from(authUsers)
        .where(eq(authUsers.id, userId))
        .limit(1)
    return user || null
}

const displayName = (user: Omit<ChatUser, "userId">) =>
    user.fullName || [user.firstName, user.lastName].filter(Boolean).join(" ") || user.email || "Benutzer"

const directRoomKey = (firstUserId: string, secondUserId: string) => {
    const hash = createHash("sha256")
        .update([firstUserId, secondUserId].sort().join(":"))
        .digest("hex")
        .slice(0, 16)
    return `direct_${hash}`
}

const normalizeRoomKey = (value: string) => value
    .toLowerCase()
    .normalize("NFKD")
    .replace(/[\u0300-\u036f]/g, "")
    .replace(/ß/g, "ss")
    .replace(/[^a-z0-9._=-]+/g, "_")
    .replace(/_+/g, "_")
    .replace(/^[._=-]+|[._=-]+$/g, "")

export default async function communicationRoutes(server: FastifyInstance) {
    const notifications = new NotificationService(server, getUserDirectory)

    const requireTenant = (req: any) => {
        const tenantId = Number(req.user.tenant_id)
        if (!tenantId) throw Object.assign(new Error("Kein aktiver Mandant"), { statusCode: 400 })
        return tenantId
    }

    const tenantUsers = async (tenantId: number): Promise<ChatUser[]> => server.db
        .select({
            userId: authTenantUsers.user_id,
            email: authUsers.email,
            firstName: authProfiles.first_name,
            lastName: authProfiles.last_name,
            fullName: authProfiles.full_name,
        })
        .from(authTenantUsers)
        .innerJoin(authUsers, eq(authUsers.id, authTenantUsers.user_id))
        .leftJoin(authProfiles, and(
            eq(authProfiles.user_id, authTenantUsers.user_id),
            eq(authProfiles.tenant_id, tenantId)
        ))
        .where(eq(authTenantUsers.tenant_id, tenantId))

    const addMembers = async (roomId: string, userIds: string[]) => {
        const uniqueUserIds = Array.from(new Set(userIds.filter(Boolean)))
        if (!uniqueUserIds.length) return
        await server.db.insert(communicationRoomMembers)
            .values(uniqueUserIds.map((userId) => ({ roomId, userId })))
            .onConflictDoNothing()
    }

    const ensureGeneralRoom = async (tenantId: number, creatorId: string) => {
        let [room] = await server.db.select().from(communicationRooms)
            .where(and(eq(communicationRooms.tenantId, tenantId), eq(communicationRooms.key, "allgemein")))
            .limit(1)

        if (!room) {
            const [created] = await server.db.insert(communicationRooms).values({
                tenantId,
                key: "allgemein",
                name: "Allgemeiner Chat",
                topic: "Mandantenweiter Austausch",
                type: "general",
                createdBy: creatorId,
            }).onConflictDoNothing().returning()
            room = created
            if (!room) {
                [room] = await server.db.select().from(communicationRooms)
                    .where(and(eq(communicationRooms.tenantId, tenantId), eq(communicationRooms.key, "allgemein")))
                    .limit(1)
            }
        }

        await addMembers(room.id, (await tenantUsers(tenantId)).map((user) => user.userId))
        return room
    }

    const requireRoom = async (tenantId: number, userId: string, roomKey: string) => {
        const [row] = await server.db.select({ room: communicationRooms }).from(communicationRooms)
            .innerJoin(communicationRoomMembers, eq(communicationRoomMembers.roomId, communicationRooms.id))
            .where(and(
                eq(communicationRooms.tenantId, tenantId),
                eq(communicationRooms.key, roomKey),
                eq(communicationRooms.archived, false),
                eq(communicationRoomMembers.userId, userId)
            ))
            .limit(1)
        if (!row) throw Object.assign(new Error("Chatraum nicht gefunden oder kein Zugriff"), { statusCode: 404 })
        return row.room
    }

    const roomToApi = (room: typeof communicationRooms.$inferSelect) => ({
        id: room.id,
        key: room.key,
        name: room.name,
        topic: room.topic,
        type: room.type,
        entityType: room.entityType,
        entityId: room.entityId,
        entityUuid: room.entityUuid,
        exists: true,
    })

    const messagesForRoom = async (roomId: string, currentUserId: string, tenantId: number, afterId = 0, limit = 50) => {
        const conditions = [eq(communicationMessages.roomId, roomId)]
        if (afterId > 0) conditions.push(gt(communicationMessages.id, afterId))
        const rows = await server.db.select().from(communicationMessages)
            .where(and(...conditions))
            .orderBy(afterId > 0 ? asc(communicationMessages.id) : desc(communicationMessages.id))
            .limit(Math.min(Math.max(limit, 1), 100))
        const orderedRows = afterId > 0 ? rows : rows.reverse()
        const authorIds = Array.from(new Set(orderedRows.map((message) => message.authorUserId)))
        const authors = authorIds.length
            ? await server.db.select({
                userId: authUsers.id,
                email: authUsers.email,
                firstName: authProfiles.first_name,
                lastName: authProfiles.last_name,
                fullName: authProfiles.full_name,
            }).from(authUsers)
                .leftJoin(authProfiles, and(eq(authProfiles.user_id, authUsers.id), eq(authProfiles.tenant_id, tenantId)))
                .where(inArray(authUsers.id, authorIds))
            : []
        const authorById = new Map(authors.map((author) => [author.userId, author]))
        return orderedRows.map((message) => ({
            id: message.id,
            body: message.body,
            sender: message.authorUserId,
            senderDisplayName: displayName(authorById.get(message.authorUserId) || {}),
            timestamp: message.createdAt.getTime(),
            own: message.authorUserId === currentUserId,
        }))
    }

    const notifyMessageRecipients = async (
        tenantId: number,
        room: typeof communicationRooms.$inferSelect,
        senderId: string,
        message: { id: number; body: string }
    ) => {
        try {
            const users = await tenantUsers(tenantId)
            const sender = users.find((user) => user.userId === senderId)
            const memberRows = await server.db.select({ userId: communicationRoomMembers.userId })
                .from(communicationRoomMembers).where(eq(communicationRoomMembers.roomId, room.id))
            const memberIds = new Set(memberRows.map((member) => member.userId))
            const normalizedText = message.body.toLowerCase()
            const recipients = users.filter((user) => {
                if (user.userId === senderId || !memberIds.has(user.userId)) return false
                if (room.type === "direct") return true
                const aliases = [displayName(user), user.fullName, user.firstName, user.email]
                    .filter(Boolean).map((value) => String(value).toLowerCase())
                return aliases.some((alias) => normalizedText.includes(`@${alias}`))
            })
            if (!recipients.length) return
            const senderName = sender ? displayName(sender) : "FEDEO"
            await notifications.trigger({
                tenantId,
                userIds: recipients.map((recipient) => recipient.userId),
                eventType: "communication.message.new",
                title: room.type === "direct" ? `Neue Direktnachricht von ${senderName}` : `${senderName} hat dich erwähnt`,
                message: message.body.length > 160 ? `${message.body.slice(0, 157)}...` : message.body,
                payload: {
                    link: `/communication/chat?room=${encodeURIComponent(room.key)}`,
                    roomKey: room.key,
                    roomName: room.name,
                    roomType: room.type,
                    messageId: message.id,
                    mentioned: room.type !== "direct",
                    direct: room.type === "direct",
                },
                channels: ["inapp", "push"],
            })
        } catch (err) {
            server.log.error({ err }, "Chat-Benachrichtigung konnte nicht ausgelöst werden")
        }
    }

    const unreadNotifications = async (tenantId: number, userId: string) => server.db
        .select({ id: notificationsItems.id, payload: notificationsItems.payload })
        .from(notificationsItems)
        .where(and(
            eq(notificationsItems.tenantId, tenantId),
            eq(notificationsItems.userId, userId),
            eq(notificationsItems.eventType, "communication.message.new"),
            eq(notificationsItems.channel, "inapp"),
            ne(notificationsItems.status, "read")
        ))

    server.get("/communication/chat/status", async () => ({ ready: true, provider: "fedeo" }))

    server.get("/communication/chat/users", async (req: any) => {
        const tenantId = requireTenant(req)
        return { users: (await tenantUsers(tenantId)).map((user) => ({
            userId: user.userId,
            email: user.email,
            displayName: displayName(user),
        })) }
    })

    server.get("/communication/chat/rooms", async (req: any) => {
        const tenantId = requireTenant(req)
        await ensureGeneralRoom(tenantId, req.user.user_id)
        const rows = await server.db.select({ room: communicationRooms }).from(communicationRooms)
            .innerJoin(communicationRoomMembers, eq(communicationRoomMembers.roomId, communicationRooms.id))
            .where(and(
                eq(communicationRooms.tenantId, tenantId),
                eq(communicationRooms.archived, false),
                eq(communicationRoomMembers.userId, req.user.user_id)
            )).orderBy(asc(communicationRooms.name))
        return { rooms: rows.map(({ room }) => roomToApi(room)) }
    })

    server.post("/communication/chat/rooms", async (req: any, reply) => {
        const tenantId = requireTenant(req)
        const body = (req.body || {}) as { key?: string; name?: string; topic?: string }
        const name = body.name?.trim()
        const key = normalizeRoomKey(body.key?.trim() || name || "")
        if (!name || !key) return reply.code(400).send({ error: "Name und gültiger Raumschlüssel sind erforderlich" })
        const [created] = await server.db.insert(communicationRooms).values({
            tenantId, key, name, topic: body.topic?.trim() || null, type: "room", createdBy: req.user.user_id,
        }).onConflictDoNothing().returning()
        const room = created || (await server.db.select().from(communicationRooms)
            .where(and(eq(communicationRooms.tenantId, tenantId), eq(communicationRooms.key, key))).limit(1))[0]
        await addMembers(room.id, (await tenantUsers(tenantId)).map((user) => user.userId))
        return { ...roomToApi(room), alreadyExisted: !created }
    })

    server.get("/communication/chat/project-rooms", async (req: any) => {
        const tenantId = requireTenant(req)
        const [roomRows, projectRows] = await Promise.all([
            server.db.select({ room: communicationRooms }).from(communicationRooms)
                .innerJoin(communicationRoomMembers, eq(communicationRoomMembers.roomId, communicationRooms.id))
                .where(and(eq(communicationRooms.tenantId, tenantId), eq(communicationRooms.type, "project"), eq(communicationRoomMembers.userId, req.user.user_id))),
            server.db.select().from(projects).where(and(eq(projects.tenant, tenantId), eq(projects.archived, false))),
        ])
        const roomsByProject = new Map(roomRows.map(({ room }) => [room.entityId, room]))
        return { rooms: projectRows.map((project) => {
            const room = roomsByProject.get(project.id)
            return room ? { ...roomToApi(room), projectId: project.id, projectNumber: project.projectNumber } : {
                key: `project_${project.id}`,
                name: project.projectNumber ? `${project.projectNumber} · ${project.name}` : project.name,
                topic: `Projektkommunikation zu ${project.name}`,
                type: "project", entityType: "project", entityId: project.id,
                projectId: project.id, projectNumber: project.projectNumber, exists: false,
            }
        }) }
    })

    server.post("/communication/chat/project-rooms/:projectId/provision", async (req: any, reply) => {
        const tenantId = requireTenant(req)
        const projectId = Number(req.params.projectId)
        const [project] = await server.db.select().from(projects)
            .where(and(eq(projects.tenant, tenantId), eq(projects.id, projectId))).limit(1)
        if (!project) return reply.code(404).send({ error: "Projekt nicht gefunden" })
        const key = `project_${project.id}`
        let [room] = await server.db.select().from(communicationRooms)
            .where(and(eq(communicationRooms.tenantId, tenantId), eq(communicationRooms.key, key))).limit(1)
        if (!room) {
            [room] = await server.db.insert(communicationRooms).values({
                tenantId, key,
                name: project.projectNumber ? `${project.projectNumber} · ${project.name}` : project.name,
                topic: `Projektkommunikation zu ${project.name}`,
                type: "project", entityType: "project", entityId: project.id, createdBy: req.user.user_id,
            }).onConflictDoNothing().returning()
            if (!room) {
                [room] = await server.db.select().from(communicationRooms)
                    .where(and(eq(communicationRooms.tenantId, tenantId), eq(communicationRooms.key, key))).limit(1)
            }
        }
        const profileIds = (project.profiles || []) as string[]
        const memberProfiles = profileIds.length
            ? await server.db.select({ userId: authProfiles.user_id }).from(authProfiles)
                .where(and(eq(authProfiles.tenant_id, tenantId), inArray(authProfiles.id, profileIds)))
            : []
        const projectMemberIds = memberProfiles.map((profile) => profile.userId).filter(Boolean) as string[]
        await addMembers(room.id, [req.user.user_id, ...projectMemberIds])
        return roomToApi(room)
    })

    server.get("/communication/chat/direct-rooms", async (req: any) => {
        const tenantId = requireTenant(req)
        const users = (await tenantUsers(tenantId)).filter((user) => user.userId !== req.user.user_id)
        const existingRows = await server.db.select({ room: communicationRooms }).from(communicationRooms)
            .innerJoin(communicationRoomMembers, eq(communicationRoomMembers.roomId, communicationRooms.id))
            .where(and(eq(communicationRooms.tenantId, tenantId), eq(communicationRooms.type, "direct"), eq(communicationRoomMembers.userId, req.user.user_id)))
        const roomsByKey = new Map(existingRows.map(({ room }) => [room.key, room]))
        return { rooms: users.map((user) => {
            const key = directRoomKey(req.user.user_id, user.userId)
            const room = roomsByKey.get(key)
            return room ? {
                ...roomToApi(room),
                name: displayName(user),
                topic: `Direktnachricht mit ${displayName(user)}`,
                entityUuid: user.userId,
                userId: user.userId,
                email: user.email,
            } : {
                key, name: displayName(user), topic: `Direktnachricht mit ${displayName(user)}`,
                type: "direct", entityType: "user", entityUuid: user.userId,
                userId: user.userId, email: user.email, exists: false,
            }
        }) }
    })

    server.post("/communication/chat/direct-rooms/:userId/provision", async (req: any, reply) => {
        const tenantId = requireTenant(req)
        const targetId = String(req.params.userId)
        const target = (await tenantUsers(tenantId)).find((user) => user.userId === targetId)
        if (!target || targetId === req.user.user_id) return reply.code(404).send({ error: "Benutzer nicht gefunden" })
        const key = directRoomKey(req.user.user_id, targetId)
        let [room] = await server.db.select().from(communicationRooms)
            .where(and(eq(communicationRooms.tenantId, tenantId), eq(communicationRooms.key, key))).limit(1)
        if (!room) {
            [room] = await server.db.insert(communicationRooms).values({
                tenantId, key, name: displayName(target), topic: `Direktnachricht mit ${displayName(target)}`,
                type: "direct", entityType: "user", entityUuid: targetId, createdBy: req.user.user_id,
            }).onConflictDoNothing().returning()
            if (!room) {
                [room] = await server.db.select().from(communicationRooms)
                    .where(and(eq(communicationRooms.tenantId, tenantId), eq(communicationRooms.key, key))).limit(1)
            }
        }
        await addMembers(room.id, [req.user.user_id, targetId])
        return {
            ...roomToApi(room),
            name: displayName(target),
            topic: `Direktnachricht mit ${displayName(target)}`,
            entityUuid: targetId,
            userId: targetId,
            email: target.email,
        }
    })

    server.get("/communication/chat/unread", async (req: any) => {
        const tenantId = requireTenant(req)
        const memberships = await server.db.select({
            roomId: communicationRoomMembers.roomId,
            roomKey: communicationRooms.key,
            lastReadMessageId: communicationRoomReads.lastReadMessageId,
        }).from(communicationRoomMembers)
            .innerJoin(communicationRooms, eq(communicationRooms.id, communicationRoomMembers.roomId))
            .leftJoin(communicationRoomReads, and(eq(communicationRoomReads.roomId, communicationRoomMembers.roomId), eq(communicationRoomReads.userId, req.user.user_id)))
            .where(and(eq(communicationRoomMembers.userId, req.user.user_id), eq(communicationRooms.tenantId, tenantId)))
        const rooms: Record<string, { count: number; mentions: number }> = {}
        for (const membership of memberships) {
            const [result] = await server.db.select({ count: sql<number>`count(*)::int` }).from(communicationMessages)
                .where(and(eq(communicationMessages.roomId, membership.roomId), gt(communicationMessages.id, membership.lastReadMessageId || 0), ne(communicationMessages.authorUserId, req.user.user_id)))
            rooms[membership.roomKey] = { count: result?.count || 0, mentions: 0 }
        }
        return { rooms }
    })

    server.get("/communication/chat/rooms/:roomKey/messages", async (req: any) => {
        const tenantId = requireTenant(req)
        const room = await requireRoom(tenantId, req.user.user_id, req.params.roomKey)
        return { ...roomToApi(room), messages: await messagesForRoom(room.id, req.user.user_id, tenantId) }
    })

    server.get("/communication/chat/rooms/:roomKey/sync", async (req: any) => {
        const tenantId = requireTenant(req)
        const room = await requireRoom(tenantId, req.user.user_id, req.params.roomKey)
        const afterId = Math.max(Number(req.query?.afterId || 0), 0)
        const messages = await messagesForRoom(room.id, req.user.user_id, tenantId, afterId, 100)
        return { ...roomToApi(room), messages, nextId: messages[messages.length - 1]?.id || afterId }
    })

    server.post("/communication/chat/rooms/:roomKey/messages", async (req: any, reply) => {
        const tenantId = requireTenant(req)
        const room = await requireRoom(tenantId, req.user.user_id, req.params.roomKey)
        const body = String(req.body?.text || "").trim()
        if (!body) return reply.code(400).send({ error: "Nachricht darf nicht leer sein" })
        if (body.length > 10_000) return reply.code(400).send({ error: "Nachricht ist zu lang" })
        const [created] = await server.db.insert(communicationMessages).values({
            tenantId, roomId: room.id, authorUserId: req.user.user_id, body,
        }).returning()
        await notifyMessageRecipients(tenantId, room, req.user.user_id, { id: created.id, body })
        return { id: created.id, body: created.body, sender: created.authorUserId, senderDisplayName: "Du", timestamp: created.createdAt.getTime(), own: true }
    })

    server.post("/communication/chat/rooms/:roomKey/read", async (req: any) => {
        const tenantId = requireTenant(req)
        const room = await requireRoom(tenantId, req.user.user_id, req.params.roomKey)
        const requestedId = Math.max(Number(req.body?.messageId || 0), 0)
        const [latest] = await server.db.select({ id: communicationMessages.id }).from(communicationMessages)
            .where(eq(communicationMessages.roomId, room.id)).orderBy(desc(communicationMessages.id)).limit(1)
        const latestId = latest?.id || 0
        const messageId = requestedId ? Math.min(requestedId, latestId) : latestId
        await server.db.insert(communicationRoomReads).values({
            roomId: room.id, userId: req.user.user_id, lastReadMessageId: messageId || null, readAt: new Date(),
        }).onConflictDoUpdate({
            target: [communicationRoomReads.roomId, communicationRoomReads.userId],
            set: { lastReadMessageId: messageId || null, readAt: new Date() },
        })
        const notificationRows = await unreadNotifications(tenantId, req.user.user_id)
        const ids = notificationRows.filter((item) => (item.payload as any)?.roomKey === room.key).map((item) => item.id)
        if (ids.length) await server.db.update(notificationsItems).set({ readAt: new Date(), status: "read" }).where(inArray(notificationsItems.id, ids))
        return { read: true, messageId }
    })

    server.get("/communication/chat/rooms/:roomKey/members", async (req: any) => {
        const tenantId = requireTenant(req)
        const room = await requireRoom(tenantId, req.user.user_id, req.params.roomKey)
        const members = await server.db.select({
            userId: authUsers.id, email: authUsers.email,
            firstName: authProfiles.first_name, lastName: authProfiles.last_name, fullName: authProfiles.full_name,
        }).from(communicationRoomMembers)
            .innerJoin(authUsers, eq(authUsers.id, communicationRoomMembers.userId))
            .leftJoin(authProfiles, and(eq(authProfiles.user_id, authUsers.id), eq(authProfiles.tenant_id, tenantId)))
            .where(eq(communicationRoomMembers.roomId, room.id))
        return { members: members.map((member) => ({
            userId: member.userId, displayName: displayName(member), email: member.email, own: member.userId === req.user.user_id,
        })) }
    })
}