import { NextRequest, NextResponse } from 'next/server'
import prisma from '@/lib/prisma'
import { auth } from '@/auth'
import { z } from 'zod'
import { logActivity } from '@/lib/brainstorm-collab'
import { emitToSession } from '@/lib/socket-emit'

const convertSchema = z.object({
  ideaId: z.string().min(1),
})

export async function POST(
  request: NextRequest,
  { params }: { params: Promise<{ sessionId: string }> }
) {
  const session = await auth()
  if (!session?.user?.id) {
    return NextResponse.json({ error: 'Unauthorized' }, { status: 401 })
  }

  try {
    const { sessionId } = await params
    const body = await request.json()
    const { ideaId } = convertSchema.parse(body)

    const brainstormSession = await prisma.brainstormSession.findFirst({
      where: {
        id: sessionId,
        OR: [
          { userId: session.user.id },
          { participants: { some: { userId: session.user.id } } },
        ],
      },
    })

    if (!brainstormSession) {
      return NextResponse.json({ error: 'Session not found' }, { status: 404 })
    }

    const idea = await prisma.brainstormIdea.findFirst({
      where: { id: ideaId, sessionId },
      include: { noteRefs: { include: { note: true } } },
    })

    if (!idea) {
      return NextResponse.json({ error: 'Idea not found' }, { status: 404 })
    }

    if (idea.status === 'converted') {
      return NextResponse.json({ error: 'Already converted' }, { status: 400 })
    }

    let sourceSection = ''
    let targetNotebookId: string | null = null

    if (brainstormSession.exportedNoteId) {
      const exportedNote = await prisma.note.findUnique({
        where: { id: brainstormSession.exportedNoteId },
        select: { notebookId: true },
      })
      if (exportedNote?.notebookId) {
        targetNotebookId = exportedNote.notebookId
      }
    }

    if (!targetNotebookId && brainstormSession.sourceNoteId) {
      const sourceNote = await prisma.note.findUnique({
        where: { id: brainstormSession.sourceNoteId },
        select: { title: true, id: true, notebookId: true },
      })
      if (sourceNote) {
        sourceSection = `\n\n**Source note**: [${sourceNote.title || 'Untitled'}](note:${sourceNote.id})`
        targetNotebookId = sourceNote.notebookId
      }
    }

    if (!targetNotebookId) {
      const notebookName = brainstormSession.seedIdea.length > 40
        ? brainstormSession.seedIdea.substring(0, 40).trim() + '…'
        : brainstormSession.seedIdea
      let notebook = await prisma.notebook.findFirst({
        where: { userId: session.user.id, name: notebookName, trashedAt: null },
      })
      if (!notebook) {
        const notebookCount = await prisma.notebook.count({ where: { userId: session.user.id, trashedAt: null } })
        notebook = await prisma.notebook.create({
          data: { userId: session.user.id, name: notebookName, order: notebookCount, icon: 'wind' },
        })
      }
      targetNotebookId = notebook.id
    }

    let originSection = ''
    const validRefs = idea.noteRefs.filter(r => r.noteId && r.note)
    if (validRefs.length > 0) {
      originSection = '\n\n## Origin\n'
      for (const ref of validRefs) {
        const relLabel = {
          derived_from: 'Derived from',
          opposes: 'In opposition with',
          extends: 'Extends',
          synthesizes: 'Synthesizes',
          transposes: 'Transposes',
        }[ref.relation] || 'Related to'
        originSection += `- **${relLabel}** [${ref.note?.title || 'Untitled'}](note:${ref.noteId}): ${ref.explanation}\n`
      }
    }

    const noteContent = `# ${idea.title}\n\n${idea.description}\n\n---\n\n**Connection to seed**: ${idea.connectionToSeed || 'N/A'}\n**Novelty score**: ${idea.noveltyScore || 'N/A'}/10\n\n**Source brainstorm**: "${brainstormSession.seedIdea}"${sourceSection}${originSection}`

    const note = await prisma.note.create({
      data: {
        userId: session.user.id,
        title: idea.title,
        content: noteContent,
        type: 'markdown',
        labels: JSON.stringify(['brainstorm', 'idée']),
        notebookId: targetNotebookId,
      },
    })

    const tagPromises: Promise<any>[] = []

    tagPromises.push(
      prisma.brainstormIdea.update({
        where: { id: ideaId },
        data: {
          status: 'converted',
          convertedToNoteId: note.id,
        },
      })
    )

    tagPromises.push(
      prisma.brainstormNoteRef.updateMany({
        where: { ideaId },
        data: { verdict: 'accepted' },
      })
    )

    for (const ref of validRefs) {
      const existingLabels: string[] = (() => {
        try { return JSON.parse((ref.note as any)?.labels || '[]') } catch { return [] }
      })()
      if (!existingLabels.includes('brainstorm-fruitful')) {
        existingLabels.push('brainstorm-fruitful')
        tagPromises.push(
          prisma.note.update({
            where: { id: ref.noteId! },
            data: { labels: JSON.stringify(existingLabels) },
          })
        )
      }
    }

    await prisma.$transaction(tagPromises)

    await logActivity(sessionId, 'idea_converted', session.user.id, { ideaTitle: idea.title, ideaId: idea.id, noteId: note.id })

    await emitToSession(sessionId, 'activity:new', {
      action: 'idea_converted',
      userId: session.user.id,
      userName: session.user.name || 'Guest',
      details: { ideaTitle: idea.title, ideaId: idea.id, noteId: note.id }
    })

    return NextResponse.json({ success: true, data: note }, { status: 201 })
  } catch (error: any) {
    if (error instanceof z.ZodError) {
      return NextResponse.json({ error: error.issues }, { status: 400 })
    }
    console.error('Error converting idea:', error)
    return NextResponse.json(
      { error: error.message || 'Failed to convert idea' },
      { status: 500 }
    )
  }
}