import { z } from 'zod'
import { TRPCError } from '@trpc/server'
import { router, protectedProcedure, adminProcedure } from '../trpc'
import { logAudit } from '@/server/utils/audit'
import { sendStyledNotificationEmail } from '@/lib/email'

export const messageRouter = router({
  /**
   * Send a message to recipients.
   * Resolves recipient list based on recipientType and delivers via specified channels.
   */
  send: adminProcedure
    .input(
      z.object({
        recipientType: z.enum(['USER', 'ROLE', 'ROUND_JURY', 'PROGRAM_TEAM', 'ALL']),
        recipientFilter: z.any().optional(),
        roundId: z.string().optional(),
        subject: z.string().min(1).max(500),
        body: z.string().min(1),
        deliveryChannels: z.array(z.string()).min(1),
        scheduledAt: z.string().datetime().optional(),
        templateId: z.string().optional(),
      })
    )
    .mutation(async ({ ctx, input }) => {
      // Resolve recipients based on type
      const recipientUserIds = await resolveRecipients(
        ctx.prisma,
        input.recipientType,
        input.recipientFilter,
        input.roundId
      )

      if (recipientUserIds.length === 0) {
        throw new TRPCError({
          code: 'BAD_REQUEST',
          message: 'No recipients found for the given criteria',
        })
      }

      const isScheduled = !!input.scheduledAt
      const now = new Date()

      // Create message
      const message = await ctx.prisma.message.create({
        data: {
          senderId: ctx.user.id,
          recipientType: input.recipientType,
          recipientFilter: input.recipientFilter ?? undefined,
          roundId: input.roundId,
          templateId: input.templateId,
          subject: input.subject,
          body: input.body,
          deliveryChannels: input.deliveryChannels,
          scheduledAt: input.scheduledAt ? new Date(input.scheduledAt) : undefined,
          sentAt: isScheduled ? undefined : now,
          recipients: {
            create: recipientUserIds.flatMap((userId) =>
              input.deliveryChannels.map((channel) => ({
                userId,
                channel,
              }))
            ),
          },
        },
        include: {
          recipients: true,
        },
      })

      // If not scheduled, deliver immediately for EMAIL channel
      if (!isScheduled && input.deliveryChannels.includes('EMAIL')) {
        const users = await ctx.prisma.user.findMany({
          where: { id: { in: recipientUserIds } },
          select: { id: true, name: true, email: true },
        })

        const baseUrl = process.env.NEXTAUTH_URL || 'https://monaco-opc.com'

        for (const user of users) {
          try {
            await sendStyledNotificationEmail(
              user.email,
              user.name || '',
              'MESSAGE',
              {
                name: user.name || undefined,
                title: input.subject,
                message: input.body,
                linkUrl: `${baseUrl}/messages`,
              }
            )
          } catch (error) {
            console.error(`[Message] Failed to send email to ${user.email}:`, error)
          }
        }
      }

      try {
        await logAudit({
          prisma: ctx.prisma,
          userId: ctx.user.id,
          action: 'SEND_MESSAGE',
          entityType: 'Message',
          entityId: message.id,
          detailsJson: {
            recipientType: input.recipientType,
            recipientCount: recipientUserIds.length,
            channels: input.deliveryChannels,
            scheduled: isScheduled,
          },
        })
      } catch {}

      return {
        ...message,
        recipientCount: recipientUserIds.length,
      }
    }),

  /**
   * Get the current user's inbox (messages sent to them).
   */
  inbox: protectedProcedure
    .input(
      z.object({
        page: z.number().int().min(1).default(1),
        pageSize: z.number().int().min(1).max(100).default(20),
      }).optional()
    )
    .query(async ({ ctx, input }) => {
      const page = input?.page ?? 1
      const pageSize = input?.pageSize ?? 20
      const skip = (page - 1) * pageSize

      const [items, total] = await Promise.all([
        ctx.prisma.messageRecipient.findMany({
          where: { userId: ctx.user.id },
          include: {
            message: {
              include: {
                sender: {
                  select: { id: true, name: true, email: true },
                },
              },
            },
          },
          orderBy: { message: { createdAt: 'desc' } },
          skip,
          take: pageSize,
        }),
        ctx.prisma.messageRecipient.count({
          where: { userId: ctx.user.id },
        }),
      ])

      return {
        items,
        total,
        page,
        pageSize,
        totalPages: Math.ceil(total / pageSize),
      }
    }),

  /**
   * Mark a message as read.
   */
  markRead: protectedProcedure
    .input(z.object({ id: z.string() }))
    .mutation(async ({ ctx, input }) => {
      const recipient = await ctx.prisma.messageRecipient.findUnique({
        where: { id: input.id },
      })

      if (!recipient || recipient.userId !== ctx.user.id) {
        throw new TRPCError({
          code: 'NOT_FOUND',
          message: 'Message not found',
        })
      }

      return ctx.prisma.messageRecipient.update({
        where: { id: input.id },
        data: {
          isRead: true,
          readAt: new Date(),
        },
      })
    }),

  /**
   * Get unread message count for the current user.
   */
  getUnreadCount: protectedProcedure.query(async ({ ctx }) => {
    const count = await ctx.prisma.messageRecipient.count({
      where: {
        userId: ctx.user.id,
        isRead: false,
      },
    })
    return { count }
  }),

  // =========================================================================
  // Template procedures
  // =========================================================================

  /**
   * List all message templates.
   */
  listTemplates: adminProcedure
    .input(
      z.object({
        category: z.string().optional(),
        activeOnly: z.boolean().default(true),
      }).optional()
    )
    .query(async ({ ctx, input }) => {
      return ctx.prisma.messageTemplate.findMany({
        where: {
          ...(input?.category ? { category: input.category } : {}),
          ...(input?.activeOnly !== false ? { isActive: true } : {}),
        },
        orderBy: { createdAt: 'desc' },
      })
    }),

  /**
   * Create a message template.
   */
  createTemplate: adminProcedure
    .input(
      z.object({
        name: z.string().min(1).max(200),
        category: z.string().min(1).max(100),
        subject: z.string().min(1).max(500),
        body: z.string().min(1),
        variables: z.any().optional(),
      })
    )
    .mutation(async ({ ctx, input }) => {
      const template = await ctx.prisma.messageTemplate.create({
        data: {
          name: input.name,
          category: input.category,
          subject: input.subject,
          body: input.body,
          variables: input.variables ?? undefined,
          createdBy: ctx.user.id,
        },
      })

      try {
        await logAudit({
          prisma: ctx.prisma,
          userId: ctx.user.id,
          action: 'CREATE_MESSAGE_TEMPLATE',
          entityType: 'MessageTemplate',
          entityId: template.id,
          detailsJson: { name: input.name, category: input.category },
        })
      } catch {}

      return template
    }),

  /**
   * Update a message template.
   */
  updateTemplate: adminProcedure
    .input(
      z.object({
        id: z.string(),
        name: z.string().min(1).max(200).optional(),
        category: z.string().min(1).max(100).optional(),
        subject: z.string().min(1).max(500).optional(),
        body: z.string().min(1).optional(),
        variables: z.any().optional(),
        isActive: z.boolean().optional(),
      })
    )
    .mutation(async ({ ctx, input }) => {
      const { id, ...data } = input

      const template = await ctx.prisma.messageTemplate.update({
        where: { id },
        data: {
          ...(data.name !== undefined ? { name: data.name } : {}),
          ...(data.category !== undefined ? { category: data.category } : {}),
          ...(data.subject !== undefined ? { subject: data.subject } : {}),
          ...(data.body !== undefined ? { body: data.body } : {}),
          ...(data.variables !== undefined ? { variables: data.variables } : {}),
          ...(data.isActive !== undefined ? { isActive: data.isActive } : {}),
        },
      })

      try {
        await logAudit({
          prisma: ctx.prisma,
          userId: ctx.user.id,
          action: 'UPDATE_MESSAGE_TEMPLATE',
          entityType: 'MessageTemplate',
          entityId: id,
          detailsJson: { updatedFields: Object.keys(data) },
        })
      } catch {}

      return template
    }),

  /**
   * Soft-delete a message template (set isActive=false).
   */
  deleteTemplate: adminProcedure
    .input(z.object({ id: z.string() }))
    .mutation(async ({ ctx, input }) => {
      const template = await ctx.prisma.messageTemplate.update({
        where: { id: input.id },
        data: { isActive: false },
      })

      try {
        await logAudit({
          prisma: ctx.prisma,
          userId: ctx.user.id,
          action: 'DELETE_MESSAGE_TEMPLATE',
          entityType: 'MessageTemplate',
          entityId: input.id,
        })
      } catch {}

      return template
    }),
})

// =============================================================================
// Helper: Resolve recipient user IDs based on recipientType
// =============================================================================

type PrismaClient = Parameters<Parameters<typeof adminProcedure.mutation>[0]>[0]['ctx']['prisma']

async function resolveRecipients(
  prisma: PrismaClient,
  recipientType: string,
  recipientFilter: unknown,
  roundId?: string
): Promise<string[]> {
  const filter = recipientFilter as Record<string, unknown> | undefined

  switch (recipientType) {
    case 'USER': {
      const userId = filter?.userId as string
      if (!userId) return []
      const user = await prisma.user.findUnique({
        where: { id: userId },
        select: { id: true },
      })
      return user ? [user.id] : []
    }

    case 'ROLE': {
      const role = filter?.role as string
      if (!role) return []
      const users = await prisma.user.findMany({
        where: { role: role as any, status: 'ACTIVE' },
        select: { id: true },
      })
      return users.map((u) => u.id)
    }

    case 'ROUND_JURY': {
      const targetRoundId = roundId || (filter?.roundId as string)
      if (!targetRoundId) return []
      const assignments = await prisma.assignment.findMany({
        where: { roundId: targetRoundId },
        select: { userId: true },
        distinct: ['userId'],
      })
      return assignments.map((a) => a.userId)
    }

    case 'PROGRAM_TEAM': {
      const programId = filter?.programId as string
      if (!programId) return []
      // Get all applicants with projects in rounds of this program
      const projects = await prisma.project.findMany({
        where: { programId },
        select: { submittedByUserId: true },
      })
      const ids = new Set(projects.map((p) => p.submittedByUserId).filter(Boolean) as string[])
      return [...ids]
    }

    case 'ALL': {
      const users = await prisma.user.findMany({
        where: { status: 'ACTIVE' },
        select: { id: true },
      })
      return users.map((u) => u.id)
    }

    default:
      return []
  }
}